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Extraction and characterization of polysaccharides from green roasted Coffea arabica beans
Abstract
Polysaccharides were sequentially extracted from green and roasted Coffea arabica beans with water (90 °C), EDTA, 0.05, 1, and 4 M NaOH and characterized chemically. Additionally, the beans were subjected to a single extraction with water at 170 °C. Green arabica coffee beans contained large proportions of 1→4-linked mannans, of which on average 1 in every 23 mannopyranose residues was branched with single unit galactose side-chains at O-6. A part of these galactomannans could be extracted relatively easy with water and EDTA. These galactomannans were found to have a relatively high degree of branching (gal:man∼1:8) and a relatively low molecular weight in comparison to the remaining galactomannans (gal:man∼1:15–24). Additionally, 1→3-linked galactans, heavily branched at O-6 with side-chains containing arabinose and galactose residues, were present in the green coffee beans, as well as smaller amounts of pectins, cellulose, and xyloglucans.Roasting resulted in a loss of 8% of the dry weight. This could be partly explained by the relatively high percentage of sugars which was lost during the roasting process, most probably as a result of conversion into, e.g. Maillard and pyrolysis products. After roasting the extractability of polysaccharides was increased significantly. A decrease in the degree of branching as well as a decrease in molecular weight of arabinogalactans, galactomannans, and xyloglucans was observed after roasting.
... Due to the effects on the organoleptic properties of coffee beverages, cell wall polysaccharides from coffee beans have been investigated (Fischer, Reimann, Trovato, & Redgwell, 2001;Oosterveld, Harmsen, Voragen, & Schols, 2003). Type II arabinogalactans (AG II) and (galacto) mannans are the main polysaccharides found in coffee beans and beverages. ...
... Sequential extractions were performed according to Oosterveld et al. (2003) with modifications ( Fig. 1). Successive extractions (solid:liquid ratio of 1:15) were performed in a mechanical stirrer and centrifugation was used to separate the extracts from the solid material. ...
... The total yield (polysaccharide fractions + final residue) was low (~ 42 %), suggesting possible losses of lower molar mass polysaccharides that were not precipitated. Similar results were found for the sequential extraction of green coffee beans (total yield of 56 %) (Oosterveld et al., 2003). In our study, the lower value may be due to: the higher number of extractions, as they were carried out exhaustively, increasing the number of steps and losses; water from washings between extractions was discarded and could contain polysaccharides; ripe coffee pulp has high amount of low molar sugars and phenolics that may not have been totally removed by the initial treatment with 80 % ethanol. ...
... The molecular structure of coffee's AGs was first proposed by Wolfram & Patin in 1965 47 and consists of a backbone composed by a D-galactose monomers chain covalently linked through β(1→3) bonds with lateral branches in the sixth position linked through β(1→6) bonds ( Figure 5) 4,11,16,39,48 . It is in the lateral branches where the monomers of D-galactose or L-arabinose are located 16,39,48,49 . ...
... Ostilio R. Portillo and Ana C. Arévalo Volume 7 / Issue 3 / 11 • http://www.revistabionatura.com to extraction to recover the coffee beans' polysaccharide fraction. Extraction with hot water, ethylenediaminetetraacetic acid (EDTA), EDTA/NaOH, and NaOH at concentrations of 0.05, 1 and 4 M, among others, have been reported 35,39,49 . c. ...
... The hydrolysis of neutral sugars is carried out with H 2 SO 4 or trifluoroacetic acid (TFA), using specific times and temperatures according to the analysis protocols. Hydrolysis allows the monomers to be released and subsequently transformed into their corresponding alditol acetate derivatives 41,49,50,53,54 . ...
Only two species have gained economic importance in coffee production: Coffea arabica L. (Arabica coffee) & Coffea canephora Pierre ex A. Froehner var. Robusta, with 65 and 35% of world production attributed to C. arabica http://wsx5customurl.comL. & C. canephora P. respectively. In general, it is estimated that 6 mt of fresh and ripe fruits produce approximately 1 mt of raw and dry grains. The grain endosperm is mainly composed of cellulose, hemicelluloses, proteins, minerals and lipids, but starch and tannins are absent. However, the seed's chemical composition of C. arabica and C. canephora, before roasting, differs concerning their primary and secondary metabolites content, which serve as precursors for the synthesis of volatile compounds during the roasting process. For this reason, there are marked organoleptic differences between both species' roasted and ground grain. However, the evidence suggests that such differences can also be attributed to other factors since coffees grown in cool, highland areas generally have better sensory attributes than their counterparts grown in hot, lowland areas. It has been speculated that environmental conditions in cool, highland areas induce the slow accumulation of primary and secondary metabolites during the endosperm development resulting in sensorial differences after roasting. This essay focuses on the study of coffee beans' carbohydrates (primary metabolites) before and after roasting, their influence on cup quality, biosynthesis and differences linked to the involved species, their metabolism, solubility and extraction, as well as a discussion on the analytical techniques used for its determination. Keywords: sucrose synthase, sucrose phosphate phosphatase, sucrose phosphate synthase, aploplasm, cytoplasm, Manan synthase, Galactosyl transferase.
... Moreover, coffee quality relies mainly on the soluble sugar concentration in its grains, such as sucrose, glucose, and fructose. These components indicate the physiological maturity of plants, and therefore, the most appropriate harvesting time [10][11][12][13][14][15]. ...
... Due to appropriate combinations of the stationary phase and the detection system, it allows fast separation of mixture components with high resolution. Thus, it is commonly applied in the separation of coffee constituents such as the following: chlorogenic acid, trigonelline, caffeine, sugars, and amino acids [10,[21][22][23][24]. ...
... In the study of Passos & Coimbra (2013), extraction using a microwave resulted in lower yields of carbohydrates compared to the present study, ranging from 0.34 to 0.96 g/L [40]. Oosterveld, Harmsen, Voragen, & Schols (2003) extracted sugars from green coffee with hot water at 170°C, which increased yields of galactomannans and galactans [10], unlike the present study that tested a maximum temperature of 60°C. The higher extraction temperature contributes to the solubilization of structural carbohydrates. ...
An optimal condition for extraction of soluble sugars from green coffee using water and a validated chromatographic method for its separation and quantification were proposed in this research. An orbital incubator shaker (OIS) and microwave-assisted extraction (MAE) were the 2 techniques used to extract soluble sugars. In such experiments, the variables: sample amount (300, 400, and 500 mg), time (30, 60, and 90 min), and temperature (30, 45, and 60 °C) were tested. The separation of sugars was performed in a chromatographic system (high-performance liquid chromatography refractive index detector [HPLC-RID]), which presented the selectivity for the analytes, a limit of detection of 0.020 g/L, a limit of quantification of 0.0625 g/L, and recovery rates greater than 95%. The repeatability and inter-day precision had low dispersion, RSD < 2.0% and < 3.0%, respectively. Sucrose content ranged from 0.65 to 2.39 g/L using an OIS and from 1.19 to 2.72 g/L by MAE, while glucose and fructose concentration varied from 0.08 to 0.12 g/L using both methods. The OIS technique is preferably indicated for extraction of soluble sugars at the following conditions: 500 mg of grounded green coffee, 90 min, and 60 °C. The proposed method for soluble sugar extraction and quantification may be applied in research laboratories and food industries since it is a low-cost and environment-friendly technique.
... content, assuming a degree of substitution of 1:20, meaning a substitution with single residues of galactose for every 20 residues of mannose in the main chain, i.e., a 5% degree of branching. This is in accordance with the degree of branching of GM (3-6%) obtained from roasted coffee infusions prepared with different roasting degrees from distinct coffee species and also GM extracted from spent coffee grounds [21][22][23][24]. For the estimation of the content of arabinogalactans (AG), it was accounted the amount of galactose from which the galactose content was subtracted that is part of GM structure and the content of arabinose was added. ...
... After removing the non-significant terms (p > 0.05), the full quadratic model (R 2 = 0.82, p < 0.0001) for the carbohydrate data fits a second-order polynomial equation, with non-significant lack-of-fit (Table 2). Moreover, the analysis of the initial extract shows that the roasted coffee has 48.8 ± 3.7%w/w of sugars in its composition, in accordance with literature [21,26]. Considering the overall yield and sugars extraction, it was observed that 6.2-18.2% of coffee carbohydrates ends up in the extract, with a clear distinction in lower (20 °C, 6.2-10.4%w/w) ...
... The results obtained show that the extraction of coffee powder at high temperatures (in conventional systems, not comparable to industrial extraction performed at extreme temperatures way over 100 °C) may produce a coffee extract with low amount of GM. According to literature, high temperatures originates extracts and brews with GM as the main polymer present [5,21]. However, this occurs only for short periods of time and low mass-volume ratios, as used to prepare home coffee brews. ...
Coffee infusion experiments were conducted to infer how operational variables (time, temperature, mass to volume ratio, and grinding) might affect the efficiency and/or selectivity of compounds extraction. Although the different variables have extensively been reported independently, to the best of our knowledge, no experimental design was yet delineated to study the simultaneous effect of variables in coffee composition. This study fulfills this gap by constructing surface models that reflect the responses in a wide-ranging design space. The freeze-dried extracts were compared regarding the overall yield of extraction, carbohydrate content and composition, caffeine, chlorogenic acid (5-CQA) content, color, and viscosity. Temperature was the major factor for coffee extracts differentiation, regarding both overall and carbohydrates yield and composition. The extraction process efficiency is more related to galactomannans extraction than arabinogalactans. Varying operational conditions, coffee extracts with distinct chemical properties are obtained from the same roasted coffee, broadening their applications in food formulations.
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... CWP were further analyzed in coffee beans processed by the three distinct processes and were found to be in the descending order of wet > semi-dry > dry process. Arabinose, mannose, and galactose are the main monosaccharides, and galactomannans and arabinogalactans the predominant polysaccharides (Fischer, Reimann, Trovato, & Redgwell, 2001;Oosterveld, Harmsen, Voragen, & Schols, 2003a). Arabinose is found in greater amounts in processed beans, whereas galactose and mannose contents decrease in processed beans. ...
... Among carbohydrates, 2 kinds of polysaccharide predominate, that is, type II arabinogalactans and galactomannans (Fischer et al., 2001). Roasting lessens the degree of branching in complex insoluble polysaccharides and converts the insoluble form of polysaccharides to soluble forms and other products, that is, monomers and furfural-like compounds, which also react with Maillard reaction products (produced from proteins, amino acids, amines, peptides and organic acids) to generate featured aroma and flavor compounds (Figure 2) (Oosterveld et al., 2003a(Oosterveld et al., , 2003bRedgwell et al., 2002). In this whole process, variations in roasting conditions definitely influence the extent of debranching, degradation and solubility of polysaccharides, followed by oligomer and monomer reactions with Maillard reaction products and, consequently, variations in the aroma and flavor of coffee (Redgwell , 2002). ...
... Extractable polysaccharides are mainly composed of soluble arabinogalactans of which the major part is converted into sugar degradation products. There are a further 2 classes of extractable polysaccharide, that is, high-molecular-weight arabinogalactans with a low degree of arabinosylation, and lower-molecular-weight arabinogalactans with a high degree of arabinosylation (Oosterveld et al., 2003a(Oosterveld et al., , 2003bRedgwell et al., 2002). Recovery studies from brews have revealed that unextractable polysaccharides are chiefly composed of insoluble galactomannans, and (light) roasting conditions increase the solubility of galactomannans by debranching and converting (almost 12%) them into extractable polysaccharides, oligosaccharides, monosaccharides, and degradation products ( Figure 2) (Oosterveld et al., 2003a(Oosterveld et al., , 2003bRedgwell et al., 2002). ...
... CWP were further analyzed in coffee beans processed by the three distinct processes and were found to be in the descending order of wet > semi-dry > dry process. Arabinose, mannose, and galactose are the main monosaccharides, and galactomannans and arabinogalactans the predominant polysaccharides (Fischer, Reimann, Trovato, & Redgwell, 2001;Oosterveld, Harmsen, Voragen, & Schols, 2003a). Arabinose is found in greater amounts in processed beans, whereas galactose and mannose contents decrease in processed beans. ...
... Among carbohydrates, 2 kinds of polysaccharide predominate, that is, type II arabinogalactans and galactomannans (Fischer et al., 2001). Roasting lessens the degree of branching in complex insoluble polysaccharides and converts the insoluble form of polysaccharides to soluble forms and other products, that is, monomers and furfural-like compounds, which also react with Maillard reaction products (produced from proteins, amino acids, amines, peptides and organic acids) to generate featured aroma and flavor compounds (Figure 2) (Oosterveld et al., 2003a(Oosterveld et al., , 2003bRedgwell et al., 2002). In this whole process, variations in roasting conditions definitely influence the extent of debranching, degradation and solubility of polysaccharides, followed by oligomer and monomer reactions with Maillard reaction products and, consequently, variations in the aroma and flavor of coffee (Redgwell , 2002). ...
... Extractable polysaccharides are mainly composed of soluble arabinogalactans of which the major part is converted into sugar degradation products. There are a further 2 classes of extractable polysaccharide, that is, high-molecular-weight arabinogalactans with a low degree of arabinosylation, and lower-molecular-weight arabinogalactans with a high degree of arabinosylation (Oosterveld et al., 2003a(Oosterveld et al., , 2003bRedgwell et al., 2002). Recovery studies from brews have revealed that unextractable polysaccharides are chiefly composed of insoluble galactomannans, and (light) roasting conditions increase the solubility of galactomannans by debranching and converting (almost 12%) them into extractable polysaccharides, oligosaccharides, monosaccharides, and degradation products ( Figure 2) (Oosterveld et al., 2003a(Oosterveld et al., , 2003bRedgwell et al., 2002). ...
... CWP were further analyzed in coffee beans processed by the three distinct processes and were found to be in the descending order of wet > semi-dry > dry process. Arabinose, mannose, and galactose are the main monosaccharides, and galactomannans and arabinogalactans the predominant polysaccharides (Fischer, Reimann, Trovato, & Redgwell, 2001;Oosterveld, Harmsen, Voragen, & Schols, 2003a). Arabinose is found in greater amounts in processed beans, whereas galactose and mannose contents decrease in processed beans. ...
... Among carbohydrates, 2 kinds of polysaccharide predominate, that is, type II arabinogalactans and galactomannans (Fischer et al., 2001). Roasting lessens the degree of branching in complex insoluble polysaccharides and converts the insoluble form of polysaccharides to soluble forms and other products, that is, monomers and furfural-like compounds, which also react with Maillard reaction products (produced from proteins, amino acids, amines, peptides and organic acids) to generate featured aroma and flavor compounds (Figure 2) (Oosterveld et al., 2003a(Oosterveld et al., , 2003bRedgwell et al., 2002). In this whole process, variations in roasting conditions definitely influence the extent of debranching, degradation and solubility of polysaccharides, followed by oligomer and monomer reactions with Maillard reaction products and, consequently, variations in the aroma and flavor of coffee (Redgwell , 2002). ...
... Extractable polysaccharides are mainly composed of soluble arabinogalactans of which the major part is converted into sugar degradation products. There are a further 2 classes of extractable polysaccharide, that is, high-molecular-weight arabinogalactans with a low degree of arabinosylation, and lower-molecular-weight arabinogalactans with a high degree of arabinosylation (Oosterveld et al., 2003a(Oosterveld et al., , 2003bRedgwell et al., 2002). Recovery studies from brews have revealed that unextractable polysaccharides are chiefly composed of insoluble galactomannans, and (light) roasting conditions increase the solubility of galactomannans by debranching and converting (almost 12%) them into extractable polysaccharides, oligosaccharides, monosaccharides, and degradation products ( Figure 2) (Oosterveld et al., 2003a(Oosterveld et al., , 2003bRedgwell et al., 2002). ...
The production and consumption of coffee are increasing despite the roadblocks to its agriculture and global trade. The unique, refreshing, and stimulating final cupping quality of coffee is the only reason for this rising production and consumption. Coffee quality is a multifaceted trait and is inevitably influenced by the way it is successively processed after harvesting. Reportedly, 60% of the quality attributes of coffee are governed by postharvest processing. The current review elaborates and establishes for the first time the relationship between different methods of postharvest processing of coffee and its varying organoleptic and sensory quality attributes. In view of the proven significance of each processing step, this review has been subdivided into three sections, secondary processing, primary processing, and postprocessing variables. Secondary processing addresses the immediate processing steps on the farm after harvest and storage before roasting. The primary processing section adheres specifically to roasting, grinding and brewing/extraction, topics which have been technically addressed more than any others in the literature and by industry. The postprocessing attribute section deals generally with interaction of the consumer with products of different visual appearance. Finally, there are still some bottlenecks which need to be addressed, not only to completely understand the relationship of varying postharvest processing methods with varying in‐cup quality attributes, but also to devise the next generation of coffee processing technologies.
... Roasting increases arabinogalactan and galactomannan solubility by loosening the cell-wall structure as the beans swell and by polysaccharide depolymerization, and yet only a small amount (~30%) is extracted during beverage preparation (Oosterveld et al., 2003), and most of the polysaccharides remain bound to the SCG matrix (Mussatto et al., 2011a;. Hence, SCG contain high amounts of monosaccharides polymerized into cellulose and hemicellulose structures. ...
... Based on these sugars, the SCG material has a diverse composition of hemicelluloses, with mannans (galactomannan and arabinogalactan) as the main type, proposed to be presented in a cellulose-mannan complex (Brabury, 2006). Minor components xylan (xyloglucan and arabinoxylan) can be present (Oosterveld et al., 2003). Moreover, according to the industrial instant coffee production, the hemicelluloses composition of SCG residue can vary. ...
... The arabinogalactan is more easily degraded during coffee roasting, facilitating its solubilization into the coffee brew. In fact, roasting facilitates the extraction of this polysaccharide with sodium hydroxide solution (Oosterveld et al., 2003). Arabinogalactan is more reactive than galactomannan, which agrees with the lower amount of this polysaccharide found in SCG. ...
Coffee is one of the most popular beverages (almost 9 million tons of coffee was consumed in 2014) and the second largest commodity traded worldwide. Coffee beans have long been used for human consumption, in the last centuries, producing coffee brews and instant coffee. About 50% of the coffee produced is directed for the production of soluble coffee generating spent coffee grounds (SCG) as a byproduct that is rich in carbohydrates, protein, lipids and bioactive molecules. SCG has found application as compost (soil conditioner), animal feed (poultry and ruminants), mushroom production, a substrate for fermentation (enzymes) and energy (biogas, liquid biofuel and bioelectricity). SCG composition and structure depends on the coffee beans used in the coffee production, as well as the industrial extraction process. The instant coffee manufacturing uses several hot water extraction steps with different temperature and its severity influences in the soluble solids extraction from the roasted beans and the characteristics of the generated SCG. The industrial process impacts on the amount of SCG generated and soluble compounds extraction, in average 4 kg of wet SCG per kilogram of instant coffee produced. Moreover, the structure of the remained polysaccharides in SCG, cellulose, galactomannan and arabinogalactan, can be more recalcitrant to further use. The SCG still contain extractable compounds (flavor and oil) in a lignocellulosic matrix formed by cellulose, hemicelluloses and lignin. These structural compounds are organized in the cell wall as a recalcitrant structure to the biological conversion process. Moreover, SCG is resistant to degradation and may need a pretreatment to make the material suitable for biotechnological conversion. The pretreatment disrupts the cellulose-hemicellulose-lignin structure, changing its properties and allowing a complex of cellulolytic and hemicellulolytic enzymes breaking down polysaccharides into fermentable sugars. The factors responsible for SCG recalcitrance is related to its chemical composition, structural and physicochemical properties that influence the pretreatment response end requires a complex pool of enzymes to its hydrolysis. This review will focus on discuss the recalcitrance properties of the SCG, based on its composition and structural organization, and the complex enzyme necessary for its conversion, highlighting its impact on biotechnology and bioenergy process.
... Roasting increases arabinogalactan and galactomannan solubility by loosening the cell-wall structure as the beans swell and by polysaccharide depolymerization, and yet only a small amount (~30%) is extracted during beverage preparation (Oosterveld et al., 2003), and most of the polysaccharides remain bound to the SCG matrix (Mussatto et al., 2011a;. Hence, SCG contain high amounts of monosaccharides polymerized into cellulose and hemicellulose structures. ...
... Based on these sugars, the SCG material has a diverse composition of hemicelluloses, with mannans (galactomannan and arabinogalactan) as the main type, proposed to be presented in a cellulose-mannan complex (Brabury, 2006). Minor components xylan (xyloglucan and arabinoxylan) can be present (Oosterveld et al., 2003). Moreover, according to the industrial instant coffee production, the hemicelluloses composition of SCG residue can vary. ...
... The arabinogalactan is more easily degraded during coffee roasting, facilitating its solubilization into the coffee brew. In fact, roasting facilitates the extraction of this polysaccharide with sodium hydroxide solution (Oosterveld et al., 2003). Arabinogalactan is more reactive than galactomannan, which agrees with the lower amount of this polysaccharide found in SCG. ...
There is growing interest in the presence of OTA in coffee since it was detected in green coffee beans, roasted and infusions. Numerous studies show that the roasting process influences the destruction of OTA, although the results are quite contradictory, as some authors believe that no significant differences were detected below 12% in relation to OTA reduction roasting operation, while others have argued that OTA production around 80%, or even higher values is reduced. Species Allium cepa is an efficient test organism to study the genotoxic effects induced by mycotoxins such as OTA. A. cepa were studied for genotoxic properties of roasted coffee beans and artificially contaminated with OTA. Genotoxicity tests in meristem cells indicated that the roasting process was not efficient enough for the degradation of OTA as the mutagenic and clastogenic effects were not reduced. This demonstrates that the compounds of OTA degraded possibly combined with compounds of Coffee arabica form toxic compounds for plant cells.
... Roasting increases arabinogalactan and galactomannan solubility by loosening the cell-wall structure as the beans swell and by polysaccharide depolymerization, and yet only a small amount (~30%) is extracted during beverage preparation (Oosterveld et al., 2003), and most of the polysaccharides remain bound to the SCG matrix (Mussatto et al., 2011a;. Hence, SCG contain high amounts of monosaccharides polymerized into cellulose and hemicellulose structures. ...
... Based on these sugars, the SCG material has a diverse composition of hemicelluloses, with mannans (galactomannan and arabinogalactan) as the main type, proposed to be presented in a cellulose-mannan complex (Brabury, 2006). Minor components xylan (xyloglucan and arabinoxylan) can be present (Oosterveld et al., 2003). Moreover, according to the industrial instant coffee production, the hemicelluloses composition of SCG residue can vary. ...
... The arabinogalactan is more easily degraded during coffee roasting, facilitating its solubilization into the coffee brew. In fact, roasting facilitates the extraction of this polysaccharide with sodium hydroxide solution (Oosterveld et al., 2003). Arabinogalactan is more reactive than galactomannan, which agrees with the lower amount of this polysaccharide found in SCG. ...
The quality control of coffee and related products needs to consider several factors that are known to play important roles in the final organoleptic characteristics perceived by the consumers. The aroma exhibited by a coffee is determined by variables such as climate, soil, coffee species/variety, post-havest processing and the quality of the beans, as well as by the storage and roasting conditions. For instance, different degrees of roasting give rise to drinks with varying aromatic profiles, ranging from coffees with aromas rich in volatile acids and furans (responsible for fresh and floral notes), to coffees with aromas rich in compounds like pyrazines and pyridine (responsible for characteristic roasted and earthy notes). The geographic provenance of the coffee is also associated with characteristic compositional compounds, which can be used as markers to confirm or disclose the origin of a given sample.
This chapter focuses on two of these factors, namely the geographic origin (associated with climate and soil) and the roasting procedure, and aims at providing a systematic assessment of the chemical compounds that are mainly responsible for the quality of coffee samples. In this respect, multivariate statistical analysis can be employed with advantage to build discriminant models able to differentiate coffee samples, as well asto identify the key chemical compounds suitable for such differentiation. Although more than 800 compounds have already been identified in coffee samples, the discriminant models can rely on only a few markers such as aldehydes, pyrazines, pyrroles, and furans. An evaluation is also made of the link between key compounds and the organoleptic characteristics perceived by the consumer. This approach provides reliable means of complementing typical quality control procedures that rely on sensorial evaluation (cup tests), because not all the odorant compounds present are useful for differentiating geographical origins and degrees of roasting, while some non-organoleptically active molecules are statistically decisive for an enhanced discrimination.
... In most of the cases, the presence of isobaric/isomeric compounds was confirmed by ESI-MS n , n = 3−4. As an example, it is shown the tandem MS-based strategy to discriminate between the pairs Hex 3 /(Pent 3 Hex − 4H 2 O) (m/z 527) and Pent 3 /(Hex 3 − 5H 2 O) (m/z 437). ...
... In the MS analysis of carbohydrate-rich samples, the ion (or product ion) at m/z 527 is usually indicative of Hex 3 . The ESI-MS 2 spectrum acquired from the A50M50 mixture submitted to the T1 treatment ( Figure 1B) is similar to that acquired from the untreated mixture ( Figure 1A), suggesting the exclusive presence of the precursor ion [Hex 3 + Na] + , as corroborated by Figure 2 show the ESI-MS 2 spectra of the ion at m/z 437 acquired from the A75M25, A50M50, and A25M75 mixtures, respectively, subjected to the T2 treatment. ...
... However, new product ions, absent in the ESI-MS 2 spectrum acquired after T1 (Figure 1B), namely, the product ions at m/z 401 (−126 Da) and 395 (−132 Da), identified as resulting from the loss of (Hex − 3H 2 O) and Pent res , and the product ions at m/z 287 and 263, attributed to [PentPent res + Na] + and [HexPent − 4H 2 O + Na] + , respectively, were observed in the ESI-MS 2 spectra acquired after the longer treatments, T2 (C) and T3 (D). These new ions suggest the presence of the precursor ion [Pent3 Hex − 4H 2 O + Na] + beyond [Hex 3 + Na] + , as corroborated by high-resolution and high mass accuracy MS data. The relative abundance of the new product ions at m/z 401 and 395 increases with increasing treatment time, whereas that at m/z 365 (−162 Da, −Hex res ) decreases. ...
Three mixtures containing different molar proportions of (β1→4)-D-mannotriose and (α1→5)-L-arabinotriose, oligosaccharides structurally related to coffee polysaccharides (galactomannans and arabinogalactans), were roasted at 200 °C for different periods. Electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MSn) analyses of labeled (18O) and unlabeled samples allowed identification of non-hybrid oligosaccharides, but also hybrid oligosaccharides composed by both hexose and pentose units. The identification of hybrid oligosaccharides allowed us to infer the occurrence of non-enzymatic transglycosylation reactions involving both oligosaccharides in the starting mixtures. Also, it was observed that using different proportion of the oligosaccharides in the starting mixtures and extent of the thermal treatment lead to a variation in the composition of the compounds formed. These results have led to the conclusion that, depending on the distribution of the polysaccharides in the bean cell walls and the roasting conditions, different non-hybrid and hybrid structures can be formed during coffee roasting.
... In C. arabica, the seed of red fruits (stage 7) is mainly composed of three types of polysaccharides, i.e., galactomannans, arabinogalactans and b-1,4 glucan. Galactomannans, the most abundant polysaccharide, represents at least 25 % of its mass and 50 % of all polysaccharides (Fischer et al. 2001;Oosterveld et al. 2003;Redgwell and Fisher 2006). Galactomannans consist of a linear backbone with galactose side chains at various intervals along the mannan backbone. ...
... They are responsible for secondary cell wall thickening in endosperm cells (Fischer et al. 2001;Pettolino et al. 2001;Sutherland et al. 2004;Somerville et al. 2004). Arabinogalactans represent the next most abundant group of polysaccharides, comprising up to 35 % of green seed polysaccharides (Fischer et al. 2001;Oosterveld et al. 2003). Their structure consists of a main backbone of b-1,3 galactose with side chains of b-1,6 galactose oligosaccharides. ...
... The b-1,6 side chains are substituted by arabinose mono-and oligosaccharides, and also contain terminal rhamnose (Nunes et al. 2008). Finally, 20 % of the green seed consists of b-1,4 glucan (Fischer et al. 2001;Oosterveld et al. 2003). Arabinogalactans and cellulose predominate in the early stage of bean development (Fischer et al. 2001). ...
Key message
Cell wall polysaccharide composition changed over seed development. Differences between B and BP only concerned the fruit growth period.
Abstract
Coffea arabica var. Laurina, also known as ‘Bourbon Pointu’ (BP), is a natural mutant of Coffea arabica var. Bourbon (B). BP is known for its high organoleptic quality, which is today compared with the well-known ‘Blue Mountain’. Cell wall composition of seeds could explain the better cup quality of BP. To test this hypothesis, we investigated possible impacts of the laurina mutation on the cell wall composition of
seeds over a time course, and more precisely on polysaccharides. The identification of cell wall polysaccharides (CWP) was deduced from permethylation analysis, whereas cell wall monosaccharide (CWM) composition was estimated using trifluoroacetic acid (TFA) and H2SO4. The observation of CWM over time allowed defining three phases. The φ 1 phase, from the 8th to 14th week after flowering (WAF), was characterized by the predominance of arabinogalactans, arabinoxylans and arabinans. The φ 2 phase, from the 14th to 20th WAF, was mainly characterized by the increased importance of highly branched galactomannans at the expense of arabinoxylans. Lastly, galactomannans constituted the main CWP present in the third phase (from the 20th to the 32nd WAF), associated with arabinogalactans and arabinans. Variations in CWP composition were connected to fruit and seed development. The end of the φ 1 phase coincides with the end of the fruit growth, i.e., with the end of the endosperm development. During the φ 2 phase, endosperm becomes milky and then hard due to the galactomannan deposition. Moreover, the φ 3 phase corresponded to the fruit maturation stage in which CWM composition did not change over time. Galactomannans were less substituted and constitute the main seed CWP. Lastly, the evidence of laurina mutation impact on cell wall polysaccharides of seeds was only observed during the fruit growth period. Consequently, the difference of cup quality between B and BP would not be due to CWP composition at the end of the φ 3 phase, i.e., when coffee beans are harvested.
... Les xyloglucanes sont présents dans les graines de café et les feuilles (Cecy & Correa, 1984;Kacurakova et al., 2000 ;Oosterveld et al., 2003 ;Lima et al., 2013). ...
... The galactomannans, the most abundant polysaccharide and represent at least 25% of its mass and 50% of the whole polysaccharides (Fischer et al., 2000;Oosterveld et al., 2003;Redgwell & Fisher, 2006). Galactomannans consists of a linear backbone with galactose side chains at various intervals along the mannan backbone. ...
... Galactomannans are deposited during the stage 5 in a relative short period (Redgwell et al. 2003;Joët et al. 2009) and are responsible of the secondary cell wall thickening of the endosperm cells (Fischer et al., 2000;Pettolino et al., 2001;Sutherland et al., 2004;Somerville et al., 2004). The next most abundant group of polysaccharides is the arabinogalactans which comprise up to 35% of the green seed polysaccharides (Fischer et al., 2000;Oosterveld et al., 2003). Their structure consists in a main backbone of β-1,3 galactose with side chains of β-1,6 galactose oligosaccharides. ...
Coffea arabica var Laurina (Bourbon pointu, BP), is a natural mutant of C. arabica ‘Bourbon’ (B). The laurina mutation is recessive, monolocus and Mendelian, with pleiotropic effects. This work highlighted new effects of this mutation, with histological, morphological and biochemical approaches on seeds development and on seedlings. Simultaneous fitting of growth curves of B and BP and their standardization allow comparisons of these varieties and fine study of polysaccharide cell wall (PCW) composition over time. Thus, anatomic specificities, development stages (st) and fruit age were linked (growth: st 1-2 to 4; maturation: st 5 to 7). When taking in account the CWP evolution in time-course, three phases occurred: φ 1 (st 1-2, 3), φ 2 (st 3, 4 and the beginning of 5), and φ 3 (the end of 5, st 6, 7). The two first were affected by the mutation probably through maternal effect (perisperm). In seedlings, the hypocotyls semi-dwarfism in light growth condition is an effect of the mutation and was due to a lower cell number than in B. The phytohormones content was also affected (ABA, auxine, cytokinins). But, neither CWP composition nor chlorogenics acids (CQA) content were affected by the mutation, or growth condition (expected for CQA content in roots). The composition in CWP and CQA was different depending on organs. Finally, caffeine (CAF) content was affected by the mutation in light or darkness conditions. These results represent an important step in 1/ the characterization of the pleiotropic effects of the laurina mutation, 2/ the understanding of the CWP evolution in seed time course, and 3/ new knowledge on seedlings (hormone, CAF, CQA and CWP composition).
... Unlike commercially available galactomannans such as guar and locust bean gum, which, respectively, present a mannose/galactose molar ratio of 1.6-1.8 and 3.9-4.0, galactomannans from green coffee have a degree of branching averaging one galactose in the side chain to 23 mannose units in the main chain (M/G = 23) (Oosterveld, Harmsen, Voragen & Schols, 2003). Thus, coffee galactomannan molecules present highly unsubstituted crystalline regions, making it difficult to dissolve them in common solvents, the same as cellulose . ...
... The main differences were the shift of the peak at 1008 cm − 1 to 1012 cm − 1 from DULT-53 to IMRPr or its disappearance (DUHT-67) (Fig. 4b), which are respectively associated with stretching of C-O and C-C stretching of mannans (Liu, Renard, Bureau & Le Bourvellec, 2021). In other words, this treatment has duly acted on the highly unsubstituted portion of the galactomannan molecules (with a mannose: galactose ratio up to 30:1) with a high degree of polymerisation, thus allowing for their dissolution (Fischer, Reimann, Trovato & Redgwell, 2001;Oosterveld et al., 2003). ...
Spent coffee grounds (SCG) are rich in polysaccharides, which can be recovered and used for various applications. However, the polysaccharides in SCG are not soluble in water, and an alternative non-toxic solvent is required to dissolve the polysaccharides. Zinc chloride aqueous solution is suitable for such a task because it is non-toxic, non-volatile, and can be easily recovered, thus being an environmentally friendly solvent. To evaluate its effects on polysaccharides, the treatment was performed with alkaline hydrogen peroxide to remove condensed phenolics from SCG. Then, the material was dissolved in 53, 60, and 67% ZnCl2 solutions, assisted by ultrasound. Thermal analysis results indicated that ZnCl2 decreased the thermal stability of the samples. However, the sample dissolved in 53% ZnCl2 assisted by ultrasound showed the highest thermal stability amongst the other samples. FT-IR spectra suggested that the zinc chloride solution had reduced the crystallinity of the material, as indicated by XRD data. However, it was not observed that the appearance of peaks indicated changes in the structure of the polysaccharide molecules. The study demonstrated the relevance of understanding the effects of ZnCl2 solution concentration on the dissolution of polysaccharides, which are essential for lignocellulosic materials applications.
... During the coffee production processes, the CWSPs undergo some structural changes through various stages. After roasting, 20-40 per cent of CWSPs are degraded, with galactose and mannose being the two most heat-sensitive sugar components Oosterveld et al., 2003). For galactomannan, arabinoses, acetyl groups, and glucoses all show different levels of degradation in the infusion of roast coffee compared to green coffee beans (Nunes et al., 2005). ...
... Additionally, the content of arabinogalactans is reduced compared to early stages and represents around 34 per cent of the total polysaccharides in the mature bean, with the galactose/arabinose ratio increasing to 2.6:1. Finally, pectic polysaccharides, which accounted for up to 16 per cent of the young fruit weight, dramatically drop to 4 per cent in the mature bean, and arabinoxylans are merely residuals (Oosterveld et al., 2003;Redgwell and Fischer, 2006;Adler et al., 2015). ...
The coffee beverage is the second most consumed drink worldwide after water. In coffee beans, cell wall storage polysaccharides (CWSPs) represent around 50 per cent of the seed dry mass, mainly consisting of galactomannans and arabinogalactans. These highly abundant structural components largely influence the organoleptic properties of the coffee beverage, mainly due to the complex changes they undergo during the roasting process. From a nutritional point of view, coffee CWSPs are soluble dietary fibers shown to provide numerous health benefits in reducing the risk of human diseases. Due to their influence on coffee quality and their health-promoting benefits, CWSPs have been attracting significant research attention. The importance of cell walls to the coffee industry is not restricted to beans used for beverage production, as several coffee by-products also present high concentrations of cell wall components. These by-products include cherry husks, cherry pulps, parchment skin, silver skin, and spent coffee grounds, which are currently used or have the potential to be utilized either as food ingredients or additives, or for the generation of downstream products such as enzymes, pharmaceuticals, and bioethanol. In addition to their functions during plant development, cell walls also play a role in the plant's resistance to stresses. Here, we review several aspects of coffee cell walls, including chemical composition, biosynthesis, their function in coffee's responses to stresses, and their influence on coffee quality. We also propose some potential cell wall-related biotechnological strategies envisaged for coffee improvements.
... During the coffee production processes, the CWSPs undergo some structural changes through various stages. After roasting, 20-40 per cent of CWSPs are degraded, with galactose and mannose being the two most heat-sensitive sugar components Oosterveld et al., 2003). For galactomannan, arabinoses, acetyl groups, and glucoses all show different levels of degradation in the infusion of roast coffee compared to green coffee beans (Nunes et al., 2005). ...
... Additionally, the content of arabinogalactans is reduced compared to early stages and represents around 34 per cent of the total polysaccharides in the mature bean, with the galactose/arabinose ratio increasing to 2.6:1. Finally, pectic polysaccharides, which accounted for up to 16 per cent of the young fruit weight, dramatically drop to 4 per cent in the mature bean, and arabinoxylans are merely residuals (Oosterveld et al., 2003;Redgwell and Fischer, 2006;Adler et al., 2015). ...
The coffee beverage is the second most consumed drink worldwide after water. In coffee beans, cell wall storage polysaccharides (CWSPs) represent around 50 per cent of the seed dry mass, mainly consisting of galactomannans and arabinogalactans. These highly abundant structural components largely influence the organoleptic properties of the coffee beverage, mainly due to the complex changes they undergo during the roasting process. From a nutritional point of view, coffee CWSPs are soluble dietary fibers shown to provide numerous health benefits in reducing the risk of human diseases. Due to their influence on coffee quality and their health-promoting benefits, CWSPs have been attracting significant research attention. The importance of cell walls to the coffee industry is not restricted to beans used for beverage production, as several coffee by-products also present high concentrations of cell wall components. These by-products include cherry husks, cherry pulps, parchment skin, silver skin, and spent coffee grounds, which are currently used or have the potential to be utilized either as food ingredients or additives, or for the generation of downstream products such as enzymes, pharmaceuticals, and bioethanol. In addition to their functions during plant development, cell walls also play a role in the plant’s resistance to stresses. Here, we review several aspects of coffee cell walls, including chemical composition, biosynthesis, their function in coffee’s responses to stresses, and their influence on coffee quality. We also propose some potential cell wall–related biotechnological strategies envisaged for coffee improvements.
... Pada penelitian ini kandungan karbohidratnya berkisar antara 58,00-66,10%. Penelitian yang dilakukan oleh Oosterveld et al. (2003) menyebutkan bahwa pada kopi arabika terdapat 55% karbohidrat. Karbohidrat berperan dalam memberikan efek warna, busa yang terbentuk, dan aroma karena merupakan prekursor reaksi Maillard (Farah, 2012;Oosterveld et al., 2003). ...
... Penelitian yang dilakukan oleh Oosterveld et al. (2003) menyebutkan bahwa pada kopi arabika terdapat 55% karbohidrat. Karbohidrat berperan dalam memberikan efek warna, busa yang terbentuk, dan aroma karena merupakan prekursor reaksi Maillard (Farah, 2012;Oosterveld et al., 2003). Komposisi proksimat kopi arabika yang dianalisis statistik menunjukkan bahwa kopi-kopi yang telah disangrai tersebut memiliki kandungan kimia yang berbeda nyata satu sama lain (p<0,05), kecuali parameter lemak yang tidak berbeda nyata (p>0,05). ...
... 2−5 Additionally, previous research has indicated that the roasting process opens the cell wall matrix, enables the hydrolysis reactions of polysaccharides, and promotes the formation and release of oligosaccharides (OS). 6 OS are carbohydrates generally consisting of 2−20 monomers linked by a variety of O-glycosidic bonds. 7 Other than sucrose, a tiny amount of raffinose (0.77%), and stachyose (0.51%), there is no evidence for the presence of naturally occurring OS in green coffee beans. ...
... This result can be partially due to the effect of roasting on opening the cell wall structures and facilitating the release of polysaccharides and OS. 6 Effects of Roasting on the Formation and Abundance of OS. The diversity in OS structures, including monosaccharide compositions, linkages, and isomers and the range of sizes provides the basis for a selective support of probiotic growth. ...
... Similarly, several studies found that roasting causes on average weight loss a 16% (Hicks, 2002) and 14% (Scholz et al., 2013) when coffee beans roasted to dark brown color. According to Oosterveld et al. (2003), the weight loss of 15% was recorded for selective harvested and medium roasted coffee beans. During roasting, the physical and chemical changes in coffee beans cause roast weight losses (Schenker et al., 2002; Oosterveld et al., 2003) Processing methods also highly significantly affected roast bean weight loss. ...
... According to Oosterveld et al. (2003), the weight loss of 15% was recorded for selective harvested and medium roasted coffee beans. During roasting, the physical and chemical changes in coffee beans cause roast weight losses (Schenker et al., 2002; Oosterveld et al., 2003) Processing methods also highly significantly affected roast bean weight loss. The maximum roast weight loss (15.52%) was recorded for coffee processed under semi washed followed by wet processed coffee (14.55%). ...
Physical Quality Analysis of Roasted Arabica Coffee Beans Subjected to Different Harvesting and Postharvest Processing Methods in Eastern Ethiopia
Mohammedsani Amin Ameyu
Oromia Agricultural Research Institute, Mechara Research Center, Coffee Research Case Team; P.O.Box: 19,
Mechara, Ethiopia
Abstract
Improper pre and postharvest processing practices are among the factors that has been directly or indirectly affecting the physical quality of green and roasted coffee beans. Thus, comprehensive information on the effect of harvesting and postharvest processing methods and their interaction on physical roast coffee bean quality are very crucial. From this point of view, this study was conducted to evaluate the effect of harvesting and postharvest processing methods on the physical quality characteristics of roasted coffee beans. The coffee samples were prepared from one Hararghe coffee genotype (H-622/98) at Mechara Agricultural Research Center. The experiment was designed as a factorial combination of two harvesting (selective and strip harvesting) and six postharvest processing methods (dry processed dried on bare, cemented and plastic sheet ground floor, and dry, wet and semi-washed processed dried on raised mesh wire) in CRD with three replications. The results indicated that the main of effect of harvesting and postharvest processing methods was highly significantly influenced all physical roast quality attributes whereas their combined effects was highly significantly affected roast volume change and bulk density of roasted bean. Selective harvesting was better than strip harvesting in producing low roast weight loss and volume change. Selective harvesting coupled with dry processing and drying on raised mesh wire was best in producing roast coffee beans with lowest (55%) roast volume change and highest (0.41 g/ml) bulk density of roasted bean. Variation on roast physical properties of Arabica coffee due to different harvesting and postharvest processing methods was profound for coffee quality. The result can be used to improve cup quality of Arabica coffee directing at different harvesting and postharvest processing methods.
Keywords: roast coffee beans; physical quality; weight loss; volume change; bulk density
... En la fabricación del café soluble las moléculas de arabinogalactano permanecen disueltas pero algunas de las más lineales moléculas de galactomananos son menos solubles y precipitan, formando sedimentos que están compuestos principalmente por estos (alrededor de 60%), (7). El porcentaje de sedimentos insolubles varía con el grado de tostación del café pero representa un 40% para un grado de tostación ligero, el 36% para un grado medio y el 33% para un grado oscuro (8). Los extractos de café son procesados en cafés solubles o concentrados para exportación. ...
... Los galactomananos liberados con las condiciones de extracción suave (agua a 170ºC) presentaron un alto grado de ramificación (gal:man~1:8) y un bajo peso molecular, en comparación con los galactomananos obtenidos con el medio de extracción fuerte (agua, EDTA y NaOH) y con los que permanecieron en el residuo (gal:man~1:15-24). Los autores concluyen que en la pared celular del grano de café verde, existe una diversidad de galactomananos, los cuales varían en su grado de ramificación y posiblemente en su peso molecular, especulando que el grado de ramificación de estos galactomananos muy posiblemente afecta las propiedades físico-químicas de la matriz de la pared celular, (8). ...
... Regarding hemicellulose, the main difference between SCG and CS is represented by the presence of xylose, that is the main sugar in CS hemicellulose, but it is not present in the SCG(Ballesteros et al., 2014). The high glucose content is given by the cell wall polysaccharide cellulose and the xylose is related to the dicotyledonous type of coffee plants(Hall et al., 2022;Oosterveld et al., 2003). Moreover,Borrelli et al. (2002) studied CS from several Italian coffee plants and underlined the high amount of soluble dietary fiber (about 14% of the total fiber) and the very high antioxidant activity. ...
In a world where a greener approach is increasingly necessary, it is mandatory to reduce waste production and reuse residues from the company's supply chain. Spent Coffee grounds (SCG) and Coffee Silverskin (CS) are two important by-products of coffee production, being sources of important dietary fibers and bioactive compounds, which is why some authors have proposed their reuse in the nutraceutical, food and cosmetic industries. However, their nutrients chemical content has been insufficiently studied. Therefore, the aim of the present review was to investigate the main components, such as carbohydrates, dietary fibers, lipids, and bioactive compounds of SCG and CS. In addition, the most common extraction methods to obtain these aforementioned nutrients were evaluated.
... There has been a great effort to extract polysaccharides presented in coffee and SCG was done with various extraction techniques. Oosterveld et al. [15] extracted sugars from green coffee with hot water at 170 °C providing higher yields of galactomannans and galactans. Later, Mussatto et al. [5] reported that the optimal extraction was achieved using dilute acid hydrolysis (100 mg H2SO4/g dry SCG matter) and 10 g/g liquid-to-solid ratio at 163 °C for 45 min with hydrolysis efficiency levels of 100%, 77.4%, 89.5% and 87.4% for galactan, mannan, arabinan and hemicellulose, respectively. ...
Large amounts of solid wastes such as spent coffee grounds (SCGs) from brewing provide a valuable sugar source to investigate. The effects on the sugar properties of extraction factors were studied. Different solvent extractions using an autoclave showed distinguishable sugar contents and properties. Water extracted the highest total sugar content while alkali extracted the highest total phenolic content (TPC). The ultrasonic-water-bath-assisted extraction with water did not produce any significant content or TPC. Finally, the combination of ultrasonic-autoclave-assisted extraction with water at 40% amplitude for 10 min produced the highest total sugar content and TPC, similar to that found in samples from the autoclave extraction with water. The FT-IR spectra of SCGs sugar revealed both amorphous and crystalline structures. All sugar extracts from SCGs contained phosphorus, potassium and calcium as the main mineral elements. Thus, sugar extracts from SCGs can be considered as an alternative additive with a good TPC for food products.
... Spent coffee grounds contain large amounts of organic compounds (proteins, phenolics, cellulose, lipids, lignin, hemicellulose and other polysaccharides), which showcases its value as a by-product [193]. Polysaccharides fraction covers about 50% the total mass of spent coffee grounds, of which about 50% are galactomannans, 25% arabinogalactans and 25% cellulose [194]. Presence of mannose, galactose, glucose and arabinose, polymerized into hemicellulose and cellulose (Ballesteros et al., 2014) [195] and high content of galactomannans are highlighted in spent coffee grounds, lignin being also present in a significant amount [196]. ...
Agricultural production, agro-industrial food processing, distribution and consumption generate high Amounts of varied food by-products and waste which place a heavy burden on the environment and cause losses to the food industry. The most common disposal methods of food wastes are the use of landfills and incineration, which lead to several environmental, social, and economic issues. However, many of these by-products and wastes have been reported to be Review Article Ngwasiri et al.; AJB2T, 8(3): 32-61, 2022; Article no.AJB2T.87188 33 higher than the final product in terms of nutritional or functional properties, making them potential raw materials for application in the agro-food industry. Together with the recent sustainable development goals of food security, environmental protection, and energy efficiency, these are the key reasons why food waste valorization is necessary. Valorization of food waste within the bio-economy approach offers an economical and environmental opportunity that can serve as a solution to the issues faced with the conventional disposal methods. Traditionally, in Africa, especially in Cameroon, food by-products and waste have been valorized into a range of products for application in food and food preparation, including food additives and spices, food emulsifiers and stabilizers, food salts and nutraceuticals. Traditional Waste valorization methods could achieve sustainable development in technologically underdeveloped countries by going beyond improving agro-food waste management to the production of useful biochemicals, food ingredients and food products, which can be referred to as value added products from waste. In addition, the processing and conversion of these agro-food by-products and waste generated in the poor regions of the world for the production and formulation of novel foods and biochemicals will directly benefit the local communities by reducing environmental pollution and increasing income in the food industry. This review aims at providing insight into current trends in food waste valorization using traditional methods in an African country such as Cameroon. This paper presents the variety and type of food waste within the food chain that can be valorized into various products using traditional methods. Furthermore, a series of examples of key food waste valorization schemes and value added products as case studies to demonstrate the advancement in traditional bioconversions are described, bringing out the opportunities and challenges for the Cameroon bioeconomy.
... The flow of free sugar during the time of boiling may be the cause of the reduction of total carbohydrates from the raw samples during the processing (Guoado et al. 2011). Roasting also resulting in the degradation of carbohydrates depending on the degree of roasting temperature (Oosterveld et al. 2003). Starch content did not vary much while three genotypes were subjected under different treatments and NSP-2 contained the maximum amount of starch content (from raw to roasting 5.87% reduction) and at par with raw NSP-6 while the least amount of starch content had been found in NSP-12 (57.70%) under roasted condition (Table 1). ...
Three sweet potato genotypes NSP-2, NSP-6 (white flesh) and NSP-12 (orange flesh), were subjected under different processing techniques (boiling, steaming, and roasting) to check the nutritional status. Sugars like glucose, fructose, sucrose, and maltose was increased under roasting treatment for all of the genotypes. Crude fiber, cellulose, hemicellulose and ash content were significantly deferred within different genotypes but different treatments remained at par with various processing techniques. Steaming was proved to be the best treatment to decrease loss of vitamin C and phenol content where as roasting was the best performing treatmant to decrease the antinutrients like phytic acid and trypsin inhibitor activity. Comparatively, higher antioxidant activity was observed in steaming treatmet. NSP-12 revealed comparatively lower Glycemic index (GI) indicating high amylase: amylopectin ratio may become a good source of good carbohydrate for diabetic friendly food for near future.
... Concerning the group of structural carbohydrates, galactomannans and mannans, arabinogalactans, hemicellulose and cellulose are the major components. Pectic polysaccharides and xyloglucans are usually only found in trace amounts (Oosterveld, Harmsen, Voragen, & Schols, 2003;Redgwell, Curti, Fischer, Nicolas, & Fay, 2002). Here we shall refer to arabinogalactans as arabinogalactan-proteins (AGPs), as the vast majority of these polysaccharides in coffee is present in complexes with proteins (Redgwell et al., 2002). ...
Coffee cup quality is primarily determined by the type and variety of green beans chosen and the roasting regime used. Furthermore, green coffee beans are not only the starting point for the production of all coffee beverages
but also are a major source of revenue for many sub-tropical countries. Green bean quality is directly related to its biochemical composition which is influenced by genetic and environmental factors. Post-harvest, on-farm
processing methods are now particularly recognised as being influential to bean chemistry and final cup quality.
However, research on green coffee has been limited and results are fragmented. Despite this, there are already indications that multiple factors play a role in determining green coffee chemistry – including plant cultivation/fruit ripening issues and ending with farmer practices and post-harvest storage conditions. Here, we provide the first overview of the knowledge determined so far specifically for pre-factory, green coffee composition. In addition, the potential of coffee waste biomass in a biobased economy context for the delivery of useful bioactives is described as this is becoming a topic of growing relevance within the coffee industry. We draw
attention to a general lack of consistency in experimentation and reporting and call for a more intensive and united effort to build up our knowledge both of green bean composition and also how perturbations in genetic
and environmental factors impact bean chemistry, crop sustainability and ultimately, cup quality.
... This is mainly because of the loss in sugars taking place in the Millard reaction, pyrolysis, and acrylamide formation [37]. Vargas-Elias et al. [38] found a strong positive correlation (r 2 = 0.98) between the mass loss and the roasting index when the mass loss of coffee beans was above 0.8%. ...
Attempts being made to increase the awareness for addressing the acrylamide issues among barley breeders and food technologists. Selection from existing hulled barley varieties and genotypes for low free asparagine accumulation and specifying the optimal roasting conditions in coffee-substitutes based on roasted barley offer suitable mitigation interventions and strategies at the agronomic and the industrial scales to avoid excessive acrylamide formation and to generate safe barley products for dietary use. To these interventions, this study aims to compare the acrylamide forming potential of three hulled barley varieties with different genotypic origins grown under normal agronomic conditions during two growing seasons of 2018/2019 and 2019/2020, then used for roasted coffee-substitutes manufacture, and correlate this to different roasting temperatures and acrylamide concentrations. Mean squares of genotypes were highly significant (P ≤ 0.05) for all agronomic characteristics and free asparagine accumulation (12.96**, 12.65**) in both seasons. Acrylamide concentrations in coffee substitutes showed strong negative or weak correlations with glucose, sucrose, fructose, and maltose and strong positive correlations (r =0.8029& 0.8025) with free asparagine contents (318.2-682.3& 322.3-681.5 mg Kg-1) in the grains in both seasons. Indicating free asparagine is the main determinant of acrylamide-forming potential in different barley genotypes. The acrylamide concentrations in the ground (<10-242.8 µg kg-1) and brewed (0.26-1.70 µg 70 mL-1) coffee substitutes significantly (P ≤ 0.05) increased as roasting temperatures increased at 180, 200 & 220C, except for variety Giza133 decreased shortly at 220C. These levels did not exceed the recommended limit (500 µg kg-1) by the European Commission; however, overconsumption should be of concern. Roasting temperatures significantly (P ≤ 0.05) influenced the physical properties of the roasted barley grains and the physicochemical properties of coffee substitutes with strong correlations with acrylamide concentrations. This study exhibits an indicator to help risk managers and decision-makers to set priorities for further action for addressing the acrylamide problem.
... The high glucose content is mainly due to the cell wall polysaccharide cellulose (see below). Being a dicotyledonous plant, coffee cell walls also contain xyloglucans as demonstrated by Oosterveld et al. [46] potentially contributing to both glucose and xylose contents measured here. Uronic acids were detected at levels of 9.8 ± 0.3 g/100 g (arabica CS), 10.1 ± 0.2 g/100 g (canephora CS), and 8.6 ± 0.3 g/100 g (CS pellets). ...
Coffee silver skin is produced in large amounts as a by-product during the coffee roasting process. In this study, coffee silver skin of the species Coffea arabica L. and Coffea canephora Pierre ex A. Froehner as well as silver skin pellets produced in the coffee industry were characterized with respect to both nutritional value and potential heat-induced contaminants. Enzymatic-gravimetric/chromatographic determination of the dietary fiber content showed values ranging from 59 to 67 g/100 g with a comparably high portion of soluble fiber, whereas low molecular weight soluble fiber was not detected. Compositional and methylation analysis indicated the presence of cellulose and xylans in the insoluble dietary fiber fraction, whereas pectic polysaccharides dominate the soluble dietary fiber fraction. The protein content as determined by the Kjeldahl method was in the range of 18 to 22 g/100 g, and all essential amino acids were present in coffee silver skin; whereas fat contents were low, high ash contents were determined. Elemental analysis by inductively coupled plasma mass spectrometry (ICP-MS) showed the presence of macroelements in large amounts, whereas toxic mineral elements were only detected in trace amounts or being absent. Acrylamide was quantified with levels of 24–161 µg/kg. Although 5-hydroxymethylfurfural was detected, its concentration was below the limit of determination. Furfuryl alcohol was not detected.
... High PAH concentrations have been reported in charcoal grilled/barbecued meat grilled under prolonged and severe conditions. Several PAHs such as benzo(a)pyrene are carcinogenic and mutagenic as well [5]. It can be concluded that PAHs have mutagenic or carcinogenic potential and they are widely believed to make a substantial contribution to the overall burden of cancer in humans [6][7][8][9]. ...
The present study was conducted to assess the carcinogenic and non-carcinogenic health risks of PAHs contamination in roasted plantain collected from three different locations within Osogbo metropolis, Nigeria. The PAHs were extracted using Soxhlet extraction technique with n-hexane and dichloromethane (3:1) as the extracting solvent. A column, packed with silica gel, was used for clean-up process and the levels of the targeted PAHs were determined by a gas chromatograph–flame ionization detector (GC-FID). The result revealed that the concentrations of total PAHs detected in the roasted samples at location A, B, C were 3.958 μg/kg, 3.654 μg/kg and 3.217 μg/kg. The HMW carcinogenic PAHs constitute about 32% of the total PAHs in the roasted plantain samples where benzo(a)pyrene, which is a marker for carcinogenicity, was found to be 9%. Comparing these results with the regulatory limits, all the analyzed roasted plantain samples were found below the maximum residual limit (MRL) of 5 μg/kg, but the calculated carcinogenic risk (CR) presented value greater than 1×10-4, signifying health risk associated with the consumption of the roasted plantain. The major source of the PAHs using diagnostic ratios (Fla/Pyr and Ph/Ant) showed that the charcoal used in roasting is a major contributing factor to the high levels of PAHs detected in the roasted plantain samples.
... Based on coffee polysaccharides structural features, it may be estimated the content of GM and AG Passos et al., 2019) in the MAE extracts, the commercial I.C. sample, and in the experiments made at 80°C through MAE and infusion method (Fig. 4). The I.C. sample showed a predominance of AG over GM, while the extractions at 80°C showed GM as the main polysaccharide present (53-58%), in accordance with previous analyses of roasted coffee infusions Nunes & Coimbra, 2001;Oosterveld, Harmsen, Voragen, & Schols, 2003). Indeed, in hot roasted coffee brews, from infusion to espresso coffee, the GM are the predominant carbohydrate structures, while AG are present as major polysaccharides in cold coffee brews, once such structures are easily extracted and GM are more dependent on extraction conditions (Lopes et al., 2016Nunes & Coimbra, 2001;Shin, 2017). ...
Microwave-assisted extraction (MAE) allows to quickly achieve soluble compounds from solid matrices due to the promotion of temperatures higher than the solvent (atmospheric) boiling point, once a closed-vessel system is used for operating at high pressure. In this study, the feasibility of MAE for producing high yield coffee extracts with properties that allow their commercial application was tested through a quality by design approach. It was studied the influence of time of extraction (1, 5.5, 10 min), temperature (120, 150, 180 °C) and the mass-to-volume (m/V) ratio (2, 4, 6 g/60 mL) in the overall extraction yield (24-47%, w/w), carbohydrates content (18-43%, w/w), sugars composition, caffeine (4-7%, w/w), 5-caffeoylquinic acid (1-2%, w/w), colour and antioxidant activity of the extracts. FTIR analysis was used to study the resemblance of coffee extracts and commercial instant coffee. MAE allowed overall extraction yields considerably higher than the home brewing methods, mainly when performed at 180 °C, with a substantial increase in arabinogalactans (AG) extraction associated to higher temperatures. Temperature exerted a crucial role in coffee extracts differentiation, although time and m/V ratio also lead to different values in the responses. Under a circular economy concept, MAE was able to produce extracts that can be used as defined food/brew ingredients and provides a galactomannan and cellulose rich residue that can also be valued as a source of dietary fibre.
... Arabinogalactans have a -1, 3 linked galactose backbone with side chains of galactose and arabinose residues. The higher degree of branching in arabinogalactans is thought to contribute to a lower thermal stability than galactomannans during roasting, leading to lower recoveries of the corresponding monomers upon acid hydrolysis of SCG (Ballesteros et al., 2017b;Farah, 2012;Oosterveld et al., 2003;Simões et al., 2014). Utilisation of the SCG polysaccharide fraction as antixodiant dietary fibre and a prebiotic is further discussed in Section 5.1. ...
The valorisation of food waste is an increasingly practical and sustainable solution to the problem of a growing demand for chemicals, fuels and materials and the rising tonnage of municipal waste sent to landfill. Spent coffee grounds (SCG) are the end product of the coffee processing industry, generated after beverage preparation, and have been exploited as a valuable source of polysaccharides, lipids, protein, minerals and bioactive secondary metabolites including diterpenes, sterols, chlorogenic acids, flavonoids and caffeine. Within the biorefinery paradigm, where renewable resources are converted into a range of high, medium and low value products, in an analogous manner to fossil fuels in a petrochemical refinery, SCG have been established as an amenable lignocellulosic feedstock through numerous research efforts. In this critical review, we give an extensive overview for the first time of the primary and secondary product suites that can be generated from SCG, along with their potential applications. The handful of preliminary technoeconomic and lifecycle assessment of using SCG for bioenergy is discussed, highlighting the economic limitations of a single capability, phase one biorefinery operating under the current scale and logistics of SCG collection. A concluding perspective towards future SCG-based biorefineries is presented, where isolation and production of higher value bioactive products is expected to be integral to the economic feasibility of the process.
... Application of Tukey´s test demonstrated that the compositions of AE and THE differed in terms of free sugars, total sugars, and non-free sugars. For all the samples evaluated, galactose, mannose, arabinose, and glucose were the main sugars present, reflecting the constitutions of the three polysaccharides present in the structure of coffee (Oosterveld et al., 2003). However, the composition was also directly influenced by the extraction/hydrolysis conditions. ...
Conventional production of instant coffee is based on solubilisation of polysaccharides present in roasted coffee. Higher process temperatures increase the solubilisation yield, but also lead to carbohydrate degradation and formation of undesirable volatile compounds. Enzymatic hydrolysis of roasted coffee is an alternative to minimize carbohydrate degradation. In this work, products obtained from thermal and enzymatic processes were compared in terms of carbohydrates and volatiles composition. Roasted coffee was extracted with water at 125 °C, and spent coffee was processed by thermal (180 °C) or enzymatic hydrolysis. Enzymatic hydrolysis experiments were carried out at 50 °C using the commercial enzyme preparations Powercell (Prozyn), Galactomannanase (HBI-Enzymes), and Ultraflo XL (Novozymes). These formulations were previously selected from eleven different commercial enzyme preparations, and their main enzymatic activities included cellulase, galactomannanase, galactanase, and β-glucanase. Enzymatic hydrolysis yield was 18% (dry basis), similar to the extraction yield at 125 °C (20%), but lower than the thermal hydrolysis yield at 180 °C (28%). Instant coffee produced by enzymatic hydrolysis had a low content of undesirable volatile compounds and 21% (w/w) of total carbohydrates. These results point to the enzymatic process as a feasible alternative for instant coffee production, with benefits including improved quality as well as reduced energy consumption.
... During the roasting of coffee beans, a decrease in the degree of branching of polysaccharides as well as a decrease in their molecular weight has been reported. 14,15) For sesame seeds, the degradation of cell wall polysaccharides could possibly occur during roasting and so change the fracture properties. The moisture content of roasted sesame seeds depends on the roasting conditions. ...
We investigated the effects of soaking, residence time before roasting and roasting conditions on the fracture properties and structure of the cross-section of sesame seeds. Soaking time affected only the size of the side voids of the seed cross-section. The fracture force and strain of the roasted seeds decreased as residence time increased. The center void of the roasted seeds, important for seed crispness increased as residence time increased. In contrast, the side void of the roasted seeds only increased with residence time during the first 10 min. Seeds roasted at higher temperatures had smaller fracture forces and larger central voids than those roasted at lower temperatures. During roasting at 300 °C, the fracture force and strain decreased as the center void ratio increased. Overall, both a sufficient time for moisture diffusion in the seeds and a high roasting temperature were necessary to produce crisp roasted seeds.
... Nowadays, lots of techniques such as hot-water method [6], acid-alkali method [7], enzyme-assisted extraction method [8] and solvent extraction method [9] can be used for the extraction of polysaccharide. The hot-water technology is the main conventional method for the extraction of a All values are expressed on a grams per 100 g of defatted peanut cake, and data are reported as mean˘standard deviation of mean (n = 3). ...
The hot-water extraction, purification and characterization of polysaccharides from defatted peanut cake (PPC) were investigated in this study. A Box-Behnken factorial design (BBD) was used to investigate the effects of three independent variables, namely extraction temperature (X₁), extraction time (X₂) and ratio of water to raw material (X₃). The optimum conditions were 85 °C, 3 h and 20:1 (mL/g) respectively. Regression analysis was done to reveal the experimental results which include 34.97% extraction rate while the value verified under these conditions was 34.49%. The crude PPC was sequentially further purified by Sephadex G-100 chromatography, and one purified fraction was obtained. The PPC purified fraction was characterized by FT-IR, HPAEC; SEC-MALLS. The average molecular weight of the PPC purified fraction was 2.383 × 10⁵ Da. The polysaccharide was mainly composed of glucose, galactose, arabinose and xylose. The PPC have the typical absorption of polysaccharide.
... Besides carbohydrates the green Arabica beans contained 11.3% w/w fat and 6% w/w protein. These results are in agreement with the results of this study in Yemeni Green Coffee and the values found in the literature for green Arabica beans, (Oosterveld et al., 2003). On the other hand the lipids found in green coffee include: linoleic acid, palmitic acid, oleic acid, stearic acid, arachidic acid, diterpenes, triglycerides, unsaturated long-chain fatty acids, esters and amides. ...
The present study aims to determine the proximate chemical composition of Yemeni green coffee (Coffea arabica L.), by analyzing 70 samples which were collected between 2010 and 2011. The moisture content, crude proteins, total lipids, carbohydrates and ash % averages were 6.99 ± 0.48, 10.95 ± 0.44, 6.13 ± 0.36, 22.12 ± 1.77 and 4.16 ± 0.52 %, respectively. Other chemical constituents such as dextrins, chlorogenic acid, and caffeine % averages were 35.89 ± 2.59, 7.19 ± 0.4 and 1.49 ± 0.29 %, respectively. Finally organic and metallic pigments were not found in any of Yemeni neutral green coffee samples.
... Questo è probabilmente dovuto a degradazione termica delle catene polisaccaridiche, che rilasciano monosaccaridi che a loro volta vengono coinvolti in reazioni di Maillard. La rottura delle catene polisaccaridiche spiegherebbe anche l'aumento di solubilità, parametro estremamente importante nella produzione del caffè solubile (Redgwell et al 2002b;Oosterveld et al 2003). ...
This research aimed to compare the in vitro digestibility and fermentability of melanoidins extracted from cocoa nibs fast-roasted with a fluidized bed roaster (FR-melanoidins), melanoidins from cocoa nibs slow-roasted in a convective oven (SR-melanoidins), and native high molecular weight compounds extracted from unroasted cocoa nibs (UR-HMWC). Data showed that both types of melanoidin extracts, especially FR-melanoidins, better release polyphenols during digestion and earlier produce short-chain fatty acids during in vitro fermentation than UR-HMWC. The delayed catabolism of UR-HMWC resembled that of dense fibers, while FR- and SR-melanoidins resembled oligosaccharides. The production of SCFA was positively correlated with the increase in Bacteroides sp. The profile of the genera identified in the proximal colon showed the differences in fermentability between FR- and SR-melanoidins, with FR-melanoidins having the higher relative growth of nonpathogenic bacteria. This study demonstrated the in vitro digestibility of bound phenolic compounds and the potential prebiotic activity of cocoa melanoidins.
Most polymeric materials are synthetic and derived from petroleum, hence they accumulate in landfills or the ocean, and recent studies have focused on alternatives to replace them with biodegradable materials from renewable sources. Biodegradable wastes from food and agroindus-try, such as spent coffee grounds (SCGs), are annually discarded on a large scale and are rich in organic compounds, such as polysaccharides, that could be used as precursors to produce films. Around 6.5 million tons of SCGs are discarded every year, generating an environmental problem around the world. Therefore, it was the aim of this work to develop films from the SCGs polysac-charide fraction, which is comprised of cellulose, galactomannans and arabinogalactans. Two types of crosslinking were performed: the first forming coordination bonds of calcium ions with polysac-charides; and the second through covalent bonds with 1,4-phenylenediboronic acid (PDBA). The films with Ca 2+ ions exhibited a greater barrier to water vapor with a reduction of 44% of water permeability vapor and 26% greater tensile strength than the control film (without crosslinkers). Films crosslinked with PDBA presented 55-81% higher moisture contents, 85-125% greater perme-ability to water vapor and 67-150% larger elongations at break than the films with Ca 2+ ions. Film biodegradability was demonstrated to be affected by the crosslinking density, with the higher the crosslinking density, the longer the time for the film to fully biodegrade. The results are promising and suggest that future research should focus on enhancing the properties of these films to expand the range of possible applications.
Emulsions fortified with polyunsaturated fatty acids are highly relevant from a nutritional perspective; however, such products are prone to lipid oxidation. In the current work, this is mitigated by the use of natural antioxidants occurring in coffee. Coffee fractions with different molecular weights were extracted from roasted coffee beans. These components were positioned either at the interface or in the continuous phase of emulsions where they contributed to emulsion stability via different pathways. Coffee brew as a whole, and its high-molecular-weight fraction (HMWF), was able to form emulsions with good physical stability and excellent oxidative stability. When added post-homogenization to the continuous phase of dairy protein-stabilized emulsions, all coffee fractions were able to slow down lipid oxidation considerably without altering the physical stability of emulsions, though HMWF was more effective in retarding lipid oxidation than whole coffee brew or low-molecular-weight fraction. This is caused by various effects, such as the antioxidant properties of coffee extracts, the partitioning of components in the emulsions, and the nature of the phenolic compounds. Our research shows that coffee extracts can be used effectively as multifunctional stabilizers in dispersed systems leading to emulsion products with high chemical and physical stability.
The processing of green coffee for the extraction of polyphenols resulted in green coffee spent (GCS) accounting 90% dietary polysaccharides. The GCS rich in Non-digestible carbohydrates (oligosaccharides) represent promising prebiotic nutrients. These Non-digestible oligosaccharides were extracted and characterized for valorization of the GCS. The enzymatic (Viscozyme), thermal (roasting) and aqueous (hot water infusion) extraction yielded 19.92 ± 2.1% of Mono-oligosaccharides with mannose (6.90 ± 0.9 μg/Mg) and galactose (8.35 ± 1.0 μg/Mg) as major components. Further, the GCS oligosaccharides were evaluated for prebiotic efficiency using Lactobacillus species (L. plantarum, L. casei and L. fermentum). The GCS oligosaccharides also stimulated the growth of Lactobacillus casei (MTCC 1423) and Lactobacillus fermentum (MTCC 903) by increasing their number from 8.96 Log CFU/ml to 9.82 Log CFU/ml and from 8.97 Log CFU/ml to 9.66 Log CFU/ml respectively. The maximum utilisation of Mannose (70%) and galactose (66%) was observed in L. plantarum. Additionally GCS oligosaccharides tested for acid resistance and found resistant towards artificial human gastric juice. The non-digestibility of GCS oligosaccharides noted 90% at pH 1. This study provides insights about bio-sustainable approach of use of GCS in designing synbiotic functional food.
The fermentation of green coffee beans by Yarrowia lipolytica led to significant changes in the volatile and non-volatile profiles of green coffees (Part I). Therefore, the objective of this continuation study was to evaluate the effects of fermentation after roasting by characterizing the volatile profiles of coffees at three different roast levels and non-volatile profiles of coffee where the effects of fermentation on volatiles were most prominent (light roast). Y. lipolytica fermentation led to significant changes in the volatile profiles of roasted coffees which arose from both the modification of aroma precursors and the retention of volatile profile changes observed in green fermented coffees. The levels of 4-vinylguaiacol and 4-vinylphenol were 1.2-fold and 1.6-fold higher in light roasted fermented coffees respectively and could be explained by the higher levels detected in green fermented coffees before roasting. The levels of γ-butyrolactone were 5 times higher in light roasted fermented coffees than unfermented coffees. The increase in sulfur compounds levels and decrease in ketones levels were attributed to changes in the concentrations of aroma precursors like sugars and amino acids. Thus, this study highlighted the potential of utilizing yeast fermentation of green coffee beans for coffee aroma modulation.
The origin and the formation pathways of the buttery smelling α-diketones 2,3-butanedione and 2,3-pentanedione upon coffee roasting were studied by means of biomimetic in-bean experiments combined with labeling experiments. For this purpose natural sucrose in the coffee bean was replaced by fully or partially 13C labeled sucrose or by a mixture of unlabeled and fully 13C labeled sucrose (CAMOLA approach). The obtained data point out that sucrose contributes to both α-diketones, however its importance and reaction pathways clearly differ. Whereas the major part of 2,3-pentanedione originates from sucrose (about 76%), its contribution to 2,3-butanedione is much lower (about 35%). Formation from intact sugar skeleton is the major pathway generating 2,3-pentanedione from sucrose, while 2,3-butanedione is mainly generated by recombination of sucrose fragments. The contribution of glucose and fructose moieties of sucrose to both α-diketones is comparable. Finally, kinetic experiments with fully labeled sucrose showed that contribution of sucrose changes during roasting.
The extraction of polysaccharides by autohydrolysis of spent coffee grounds (SCG) was studied. Experimental assays were performed using different temperatures (160 to 200 °C), liquid/solid ratios (5 to 15 ml water/g SCG) and extraction times (10 to 50 min) in order to determine the conditions that maximize the extraction of polysaccharides with high antioxidant activity. Autohydrolysis was demonstrated to be an efficient technique to recover antioxidant polysaccharides from SCG. The best process conditions consisted in using 15 ml water/g SCG, during 10 min at 160 °C. The polysaccharides obtained under these conditions were mainly in the form of galactomannans and arabinogalactans. They presented high antioxidant activity (assessed by four different methods), were thermostable in a large range of temperature, and had a typical carbohydrate pattern, being of interest for industrial applications, mainly in the food area.
Effects of roasting on physical (weight, volume, density and color) and chemical properties (total phenol, caffeine, chlorogenic acid and antioxidant properties) of three Arabica coffee beans (Brazil Bourbon, Indonesia Mandheling and Kenya Tatu) were investigated. A steady weight loss, volume increase, and bean density decrease were observed during the roasting process. The L*, a*, and b* values tended to decrease as the roasting temperature and time increased. Caffeine level was approximately 0.73% in green beans, and increased to 40-67% for darker roasts. Green beans contained the highest chlorogenic acid content, which decreased as the roasting temperature and time increased. The light- and medium-roasted coffee showed the highest total phenolol contents. The antioxidant activities were measured using DPPH and ABTS. The light-roasted coffee beans showed the highest antioxidant activities, and an approximately 36-51% loss in antioxidant activity was observed after further roasting. The flavor patterns of roasted coffee beans were analyzed using an electronic nose system based on gas chromatography. This analysis demonstrated that an electronic nose system can be applied to identify the green bean variety and the degree of roasting.
Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic compounds included in priority pollutant lists because of their mutagenic and carcinogenic properties. Several studies have shown that exposure to benzo[a]pyrene (BaP), amember of the PAHs increases the risk of cancer. This study investigated the effects of firewood smoking and oil frying onthe BaP levels in Nile perch (Lates niloticus) sold in Western Kenya. The methodology involved BaP extraction with cyclohexane and dimethylformamide-water, clean up on silica gel column and determination by high performance liquid chromatography (HPLC) using fluorescence detection. Variable levels of BaP were detected ranging from 7.46 to 18.79 μg/kg in smoked fish and 4.17 to 11.26 μg/kg in oil fried fish. These levels were further compared with the regulatory limits. All smoked fish samples were found to exceed the acceptable Maximum residual limit (MRL) of 5 μg/kg while 20% of the oil fried samples were within theacceptable limit. BaP was not detected in raw fish samples analysed. It was concluded that firewood smokingas practiced in the study areas resulted in higher levels of BaP contamination compared to oil frying.
Pomelo peel was used to prepare polysaccharide by hot water extraction and organic solvent precipitation combined with low temperature. Differences of the physical structure and chemical composition of six tobacco carriers were determined by scanning electron microscopy (SEM) and chemical analysis. The moisturizing dynamics of polysaccharides from pomelo peel on the carriers were also studied. The results showed that the different carriers had different smoothness and stomata. The distribution of stomata on upper leaves B3F was higher than that in the middle leaves C2F. The lowest distribution was found in leaves B1F. The chemical composition showed that organic acid content DY2 was the highest of 28.1%, and DY3 was the lowest of 16.2%. The polyphenol content increased from 2.2 mg/kg to 5.58 mg/kg, and there was significant difference among varieties. Total sugar content exhibited the highest in C2F of 26.37%, and was significantly higher than that of other parts. The nicotine content was the minimum in DY1 for 2.82%, while the maximum value was found in B3F for 5.12%. The moisturizing properties showed the moisturizing dynamics of polysaccharides from pomelo peel on the six carriers had different trends. The moisturizing effect on B3F was the best, and relatively poor in B1F.
Fast pyrolysis of spent coffee waste, a major non-cellulosic material, and oak wood chips, a cellulosic material, was carried out in a micro tubular reactor over a temperature range of 550 to 750°C with sweep gas flow rates of 20 and 500 mL/min. When the temperature was raised from 550 to 750°C, the gas yields were significantly enhanced, but the liquid yields were reduced. The highest liquid yield, 63.4 wt%, was obtained after pyrolysis of spent coffee waste at 550°C at a sweep gas rate of 500 mL/min. The highest gas yield, 65.74 wt%, was obtained after pyrolysis of the oak wood chips at 750°C at a sweep gas flow rate of 20 mL/min. The gas products primarily included considerable amounts of CO, CO2, and hydrocarbon-rich gases but no hydrogen. Furthermore, regardless of the biomass source, the hydrocarbon-rich gases were qualitatively similar and largely consisted of methane, ethane, ethylene, propane, and propylene. The gas chromatography-mass spectrometry analysis of the pyrolyzed bio-oils demonstrated that the major compounds were phenol derivatives, aldehydes, ketones, acids, and alcohols.
• Galactomannans are the most abundant polysaccharides of green coffee beans.
• The majority of green coffee galactomannans are insoluble in water.
• The roasting process improves the extractability of coffee galactomannans but also induces several structural modifications on their structures.
• Coffee galactomannans are involved in several reactions during the roasting process such as depolymerization, debranching, caramelization, isomerization, oxidation, decarboxylation, Maillard reaction, and also possibly polymerization/transglycosylation.
• Coffee galactomannans have been associated to beneficial health effects.
• As the most abundant polysaccharides of coffee beverages, galactomannans have an important role in the foam stability of espresso coffee and are responsible for the viscosity coffee extracts.
Plant polysaccharides associated with cellulose in the cell wall are commonly isolated using selective extraction procedures. The terms pectic substances, denoting those materials extracted with water alone or with hot aqueous solutions of chelating agents for calcium, such as disodium ethylenedinitrilotetraacetate or sodium hexametaphosphate, and hemicelluloses, denoting polysaccharides extracted with dilute alkali alone or with added borate, are useful in describing broad groups of polysaccharides. However, a more complete and precise classification based on structure is necessary to avoid the difficulties which arise when obviously related polysaccharides, differing in some small and apparently trivial feature such as extent of branching or degree of esterification, show marked differences in physical properties such as solubility.
During roast coffee extraction the yield of acids is proportional to the extraction degree. Thereby, the contents of formic acid, chinic acid and acetic acid are more increasing than that of citric and malic acid. This is the reason for a qualitative and quantitative change of acidic taste in the course of extraction... Opposite to roast- and ground coffees, the investigated coffee extracts contained free carbohydrates in low concentrations. In the beginning of extraction above all arabinose is released. In the second phase of extraction, mannose and galactose are dissolved by hydrolytic cleavage of mannanes and galactanes. These hydrolyses are of special importance for the content of dry matter during Instant Coffee production. 5-Hydroxymethyl-2-furfural and 2-furfural are formed from carbohydrates during the extractin process. The total liquid coffee extract investigated in this paper contained the 3,5-fold amount of these furaldehydes than the ground coffee which was used for its production.
This chapter summarises the vast literature on the composition* of green coffee beans paying particular attention to those components which are peculiar to coffee. The corresponding data are given for roasted beans and where possible for soluble powders. Attention is focused on compositional factors that might be determinants of acceptability, and situations where the data are incomplete or contradictory with the intention of provoking thought, comment and further investigation.
The carbohydrates of green and roasted Santos coffee were identified and measured. The soluble sugars of green coffee were sucrose, 6 to 7%, and a trace of glucose; those of roasted coffeee were sucrose, glucose, and fructose. The holocellulose fractions of green and roasted coffee were isolated. The 10% potassium hydroxide-insoluble holocellulose of green coffee was hydrolyzed by a new method employing anhydrous sulfuric acid. It contained the following ratio of sugars: L-arabinose, 1; D-galactose, 2; D-glucose, 2; D-mannose, 6. Little, if any, lignin, cellulose, or pectin was found. The holocellulose was partially solubilized on roasting. The arabinose was easily acid-hydrolyzable. Other coffee constituents identified and estimated were caffeine, trigonelline, caffeic acid, chlorogenic acid, "isochlorogenic" acid, and 10 amino acids. The free amino acids disappeared on roasting. A method was developed for locating caffeine on chromatograms.
The chemical structures of green coffee bean polysaccharides have been determined by methylation analysis of whole beans and of extracted polymer-rich fractions. Ground beans were completely solubilized in 4-methylmorpholine N-oxide, and the Hakomori methylation procedure was applied directly. The polysaccharide fraction in Robusta beans constitutes 48% of the dry weight and is principally composed of three polymers: arabinogalactan, mannan, cellulose. The arabinogalactan has a β1→3-linked galactan main chain with frequent arabinose and galactose residue containing side chains, whereas the mannan resembles cellulose in that it has a linear β1→-4-linked structure. Only occasional single-residue galactose side chains are present in the mannan fraction. Polysaccharide compositions of Robusta and Arabica beans are similar; the only significant difference is the higher content (approximately 3%) of arabinogalactan in the former type.
Technically produced extracts from roasted Arabica and Robusta coffees contain, just like the infusions prepared in the home, 20–36% carbohydrates, depending on the degree of extraction. They are composed predominantly of mannan and galactan in about the same proportions, the share of glucan and araban making up only 1–3% of the extracts. With dialysis a group of polysaccharides with a molecular weight of more than 10 000 can be separated. They make up about half of the carbohydrates of the extracts. Their composition corresponds to that of the latter. Finally, one can obtain yet another group of almost intact high polymeric carbohydrates as copper complexes. However, they consist only of mannan and galactan, mannan predominating significantly. Arabica and Robusta coffees showed differences in this respect. Whereas Arabica coffee was able to release only a certain amount of these very high-polymeric carbohydrates, Robusta coffee delivered ever greater amounts of these polysaccharides with increasing extract yields.
A method for the simultaneous quantitative analysis of methoxyl and acetate groups in pectin has been developed, using h.p.l.c. on a cation exchange resin in the protonated form and refractive index detection. Saponification conditions for release of methoxyl and acetate from pectins for direct injection on the column are described. With this h.p.l.c. method results were obtained which were in reasonable agreement with conventional methods. © 2009, Elsevier Ltd. All rights reserved. All rights reserved.
Essentially all of the L-arabinose and D-galactose present in the green coffee bean (Coffea arabica) are shown to occur as a water-soluble arabinogalactan (2:5). The L-arabinose can be removed from this polysaccharide by dilute acid leaving a galactan. Methylation analysis of the arabinogalactan and of its component galactan can be interpreted tentatively as indicating I which has a backbone chain of β-D-(1→3)-linked galactopyranose units to some of which are attached at the C-6 position terminal L-arabinofuranose side chains containing an occasionally interposed (1→3)-linked D-galactopyranose entity.
Quantification of chlorogenic acid content in large populations of green coffee beans needs an accurate, fast, and unbiased purification method. Five different procedures of purification were compared. The first consisted of a successive use of different organic solvents, the second was based on a filtration through a C18 cartridge, the third used two combined reagents, and the remaining two methods (4 and 5) were a simplification of the third. One of the two simplest methods of purification (method 4) was also the fastest, the most accurate, and the least biased. Consequently, this method could be used routinely to quantify chlorogenic acids in green coffee beans. Keywords: Chlorogenic acids; Coffea sp.; purification procedures; HPLC
In expresso coffee (EC) brew, persistent foam is of great importance as it is responsible for the visual acceptability of the drink and for trapping the volatilized aromas. The foam stability of EC is related to the amount and type of polysaccharides extracted from the roasted ground coffee, where they behave as viscosity improvers. This work relates the changes of the molecular weight of the polysaccharides present in the infusion caused by the roast that the coffees were submitted to and the foam stability of the resulting EC. The polymeric carbohydrates of each EC were precipitated with 55 and 75% ethanol solutions (Et55 and Et75, respectively). Fraction Et55, composed mainly of galactomannans, was fractionated by size-exclusion chromatography and two type of polymers were separated. The polymers that eluted with the void volume (2000 kDa) were inferred to be composed of polysaccharide and protein, possibly products of Maillard reactions caused by the roasting process. The molecular weight of the major fraction was estimated to average 70 kDa. The amount of material recovered with higher molecular weight gave a high correlation with the foam stability of EC. The results show that the amount of material of high molecular weight, in addition to the viscosity of the continuous phase, can also be responsible for the stabilization of the EC foam.
Advances in determination of polymer structure and in preservation of structure for electron microscopy provide the best view to date of how polysaccharides and structural proteins are organized into plant cell walls. The walls that form and partition dividing cells are modified chemically and structurally from the walls expanding to provide a cell with its functional form. In grasses, the chemical structure of the wall differs from that of all other flowering plant species that have been examined. Nevertheless, both types of wall must conform to the same physical laws. Cell expansion occurs via strictly regulated reorientation of each of the wall's components that first permits the wall to stretch in specific directions and then lock into final shape. This review integrates information on the chemical structure of individual polymers with data obtained from new techniques used to probe the arrangement of the polymers within the walls of individual cells. We provide structural models of two distinct types of walls in flowering plants consistent with the physical properties of the wall and its components.
Es wurden die Polysaccharide von vier Proben von rohem Arabica-Kaffee verschiedener Herkunft, nmlich je ein Columbia-, Haiti-, Santos- und Kenya-Kaffee, untersuchr. Dabei ergab sich, da Rohkaffee stets vier Anteile oder Komplexe hochpolymerer Kohlenhydrate enthlt, die sich in ihrer Lslichkeit und in ihrer Zusammensetzung sehr bezeichnend unterscheiden. Der eine davon ist in kaltem Wasser lslich, ein zweiter dagegen nur in heiem Wasser. Beide stellen Mannoarabinogalaktane dar, in denen das Galaktan den Hauptbestandteil bildet. Diese wasserlslichen Komplexe machen jedoch nur etwa 3,4 % der Trockenmasse des Rohkaffees aus. Beim Aufschlu des mit kaltem und heiem Wasser erschpfend extrahierten Untersuchungsmaterials mit Chlordioxid erhlt man eine sog. Holocellulose, die auer Cellulose nur Galaktan und Mannan enthlt, wobei letzteres mehr als die Hlfte dieser Fraktion ausmacht. Beim Aufschlu geht ein vierter Komplex, der als Aufschlu-Polysaccharid bezeichnet wird, in Lsung. Er besteht aus Galaktan, Araban und Mannan. Galaktan ist zu rund 70 % darin enthalten, whrend von Mannan nur wenige Prozent bis herunter zu nicht mehr bestimmbaren Mengen vorhanden sind. Es drfte sich um das von WOLFROM u. Mitarb. isolierte Arabinogalaktan handeln.
A polysaccharide fraction was obtained from the hot water extract of defatted ground dark roasted coffee (pure Coffea arabica blend for espresso brewing technique) by means of classical precipitation methods. This high molecular weight (〈Mw〉=10 900 Da) product was shown to be composed of mannose, galactose, arabinose and traces of proteinaceous material. Further fractionation yielded two different carbohydrate polymers, which were structurally characterized. One polysaccharide was identified as a β-d-(1-4) mannan containing small amounts of galactose and arabinose. The second polysaccharide, obtained in low yield after removal of the mannose-containing polymeric material, was identified as an arabinogalactan. The starting fraction was found to be composed of about 80% (mol basis) of mannan and of about 20% of arabinogalactan. 13C-NMR spectra revealed that the arabinogalactan has a backbone chain of β-(1-3)-d-galactopyranose units. Some of these units were substituted with either terminal β-d-galactose or terminal α-l-arabinofuranose side chains mainly in C-6 position. Both the mannan and the arabinogalactan isolated are structurally related to the polysaccharides originally present in the green coffee beans.
A sequential fractionation method to isolate water-soluble fractions of green Arabica coffee is described. Low- and high-molecular-weight fractions were obtained by treating the dried water extract with aqueous ethanol (80%, v/v). High-performance gel filtration chromatography was used to show some differences in molecular weight distribution between fractions. Flavour precursors were detected in both fractions. Arabinogalactan was the main polysaccharide found in the water-soluble high-molecular-weight fraction, together with large amounts of protein. Important flavour precursors such as sucrose, trigonelline and chlorogenic acid were detected in the low-molecular-weight fraction. A simple and rapid headspace method was developed to obtain the volatile profiles produced by the roasted fractions. Volatiles were immediately collected after roasting in a sealed tube and submitted to gas chromatography. The chromatographic profiles obtained showed considerable differences between fractions and revealed an important contribution to aroma formation.
Arabinose and ferulic acid rich polysaccharides were extracted from sugar beet pulp using two extraction methods: a sequential extraction with H2O (2 times), NaOH/EDTA (2 times), and 4 M NaOH (2 times; method A) and a sequential extraction in which the NaOH/EDTA extraction was replaced by an autoclave extraction (2 times; method B). Both extraction method A and B yielded approximately 45% of the sugar beet pulp polysaccharides. For both method A and B, three extracts with increasing neutral sugar content were obtained: two NaOH/EDTA extracts and a 4 M NaOH extract for method A next to two autoclave extracts and a 4 M NaOH extract for method B. The sugar linkage composition indicated the presence of arabinose rich rhamnogalacturonan ('hairy regions') and homogalacturonan ('smooth regions') in all extracts. The sugar compositions of the NaOH/EDTA extracts were very similar to the autoclave extracts. A remarkable difference was the higher amount of ester groups in the autoclave extracts: next to methyl esters and acetyl groups, they also contained relatively high amounts of feruloyl groups. Size-exclusion chromatography using RI- and UV-detection showed that all extracts were heterogeneous with respect to molecular weight distribution. Ferulic acid was particularly located in the high molecular weight populations of the autoclave extracts.
Advances in determination of polymer structure and in preservation of structure for electron microscopy provide the best view to date of how polysaccharides and structural proteins are organized into plant cell walls. The walls that form and partition dividing cells are modified chemically and structurally from the walls expanding to provide a cell with its functional form. In grasses, the chemical structure of the wall differs from that of all other flowering plant species that have been examined. Nevertheless, both types of wall must conform to the same physical laws. Cell expansion occurs via strictly regulated reorientation of each of the wall's components that first permits the wall to stretch in specific directions and then lock into final shape. This review integrates information on the chemical structure of individual polymers with data obtained from new techniques used to probe the arrangement of the polymers within the walls of individual cells. We provide structural models of two distinct types of walls in flowering plants consistent with the physical properties of the wall and its components.
Pectic polysaccharides were extracted from sugar beet pulp to yield fractions representing homogalacturonans, rhamnogalacturonans, arabinans and relatively small amounts of glucomannans and xyloglucans. The homogalacturonans had an apparent molecular weight of 21 kDa and contained relatively high amounts of methyl esters and relatively low amounts of acetyl groups as compared with the ramified 'hairy' regions. Three populations which originated from the ramified 'hairy' regions of pectin were distinguished. Two of these were rhamnogalacturonans with high apparent molecular weights of 1300 and 120 kDa, respectively. These populations had a high Ara and ferulic acid content. Despite the high neutral sugar content, these rhamnogalacturonans strongly bound to a DEAE column. The third population which originated from the ramified 'hairy' regions was a neutral population, which did not interact with the DEAE column and had a low apparent molecular weight and a high Ara and ferulic acid content. The arabinan side-chains of the rhamnogalacturonans were heavily branched in all populations. Enzymatic degradation of the xyloglucans showed similarities with apple xyloglucans with respect to the substitution with Fuc and Gal.
Two independent procedures for the quantitative determination of the polysaccharide content of Arabica Caturra (Coffea arabica var. Caturra) and Robusta ROM (Coffea canephora var. ROM) green coffee beans showed that they both contained identical amounts of polysaccharide. Cell wall material (CWM) was prepared from the beans and partial solubilisation of component polysaccharides was effected by sequential extraction with water, 1 M KOH, 0.3% NaClO2, 4 M KOH and 8 M KOH. The monosaccharide compositions of the CWMs were similar, although Arabica beans contained slightly more mannose than Robusta. In the latter, more arabinogalactan was solubilised during preparation of the CWM and the water-soluble fraction of the CWM contained higher amounts of galactomannan than in Arabica. Linkage analysis indicated that the galactomannans possessed unbranched to branched mannose ratios between 14:1 and 30:1 which is higher than previously reported. No major difference in the structural features of the galactomannans between species was found. The arabinogalactans were heterogeneous both with regard to the degree of branching and the degree of polymerisation of their arabinan side-chains. Compared to Arabica, Robusta appeared to contain greater amounts of arabinogalactans with longer side chains. It is concluded that there was no detectable difference between the Arabica and Robusta varieties of this study in their absolute polysaccharide content or in the gross structural features of their galactomannans. Differences were apparent both in the structural features and ease of solubility of the arabinogalactans but a more detailed study of several varieties of Arabica and Robusta will be required to determine whether these differences occur consistently between species.
The polysaccharides present in coffee infusions are known to contribute to the organoleptic characteristics of the drink, such as the creamy sensation perceived in the mouth known as "body", the release of aroma substances, and the stability of espresso coffee foam. To increase the knowledge about the origin, composition, and structure of the polysaccharide fraction, the high molecular weight material (HMWM) was extracted with hot water from two green and roasted ground arabica coffees: Costa Rica (wet processed) and Brazil (dry processed). The polysaccharides present in the green coffees HMWM were arabinogalactans (62%), galactomannans (24%), and glucans, and those found in roasted coffees were galactomannans (69%) and arabinogalactans (28%). The polysaccharides of the HMWM of the roasted coffees were less branched than those of the green coffees. The major green coffee proteins had molecular weights of 58 and 38 kDa, and the 58 kDa protein had two subunits, of 38 and 20 kDa, possibly linked by disulfide bonds. The protein fraction obtained from roasted coffees had only a defined band with < or =14 kDa and a diffuse band with >200 kDa. The majority of the galactomannans were precipitated with solutions of 50% ethanol, and the size-exclusion chromatography of the roasted fractions showed coelution of polysaccharides, proteins, phenolics, and brown compounds. The use of strong hydrogen and hydrophobic dissociation conditions allowed us to conclude that the phenolics and brown compounds were linked by covalent bonds to the polymeric material.
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