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Distribution of free lipids and their fractions in wheat flour milled streams
Abstract
Polar and non-polar lipids both play an important role in determining the quality of wheat flour and its suitability for different bakery products. In order to develop specific flours for different end-uses, polar and non-polar lipid content were determined in streams and both showed wide variation. The total free non-polar lipid (TFNPL) content varied from 0.54 to 1.8% (db) while total free polar lipid (TFPL) content varied from 0.11 to 0.34% (db) in different flour streams indicating the preponderance of TFNPL. Triglycerides were the predominant fraction present in TFNPL while glycolipids predominated in the TFPL fraction. The amounts of these fractions were greater in the IV break stream. In the case of saturated fatty acids, palmitic acid was predominant in TFNPL fractions, whereas, stearic acid was predominant in TFPL. The levels of oleic acid were higher in TFNPL (16.9 to 33.6%). Linoleic acid was the predominant unsaturated fatty acid in both TFNPL and TFPL fractions.
... This milling process produces a large number of flour fractions (or mill streams) which are combined to make flours with different characteristics. For several years, the effect mill streams have on flour properties, such as lipid content (Larsson and Eliasson, 1998;Prabhasankar and Haridas Rao, 1999;Prabhasankar et al., 2000), phenol content Beta et al., 2005), distribution of the total and soluble flour fiber (Ranhotra et al., 1990), distribution of enzymes in the flour (Rani et al., 2001;Every et al., 2006a), and the composition and distribution of pentosan (Delcour et al., 1999;Wang et al., 2006a) have been under study. Rheological characteristics of the flour (Villanueva et al., 2001;Indrani et al., 2003), functionality of the starch (Tang et al., 2005) and color of the flour (Oliver et al., 1993) have also been studied, since the composition of each stream is different due to the irregular distribution of the chemical components in the grain (Glitso and Knudsen, 1999). ...
... This behavior was because, as the milling process progresses, moisture in the flour is lost from evaporation (Gomez et al., 2009). Flour from the last break and reduction streams (B2 and R3) was also observed to have a higher protein and ash content, which coincided with observations indicated by Ranhotra et al. (1990), Prabhasankar et al. (2000) and Wang et al. (2007). This result suggested that the flour from these streams contains more contamination from the outer layers of the grain, specifically, from bran, which contains a higher proportion of proteins (Okrajkova´et al., 2007), fibers (Wang et al., 2006a) and ash (Every et al., 2002;Greffeuille et al., 2005). ...
... The last mill streams (B2 and R3) showed less luminosity (darker color) and higher a* (more reddish) and b* (more yellowish). This result coincided with the results of papers written by Wang and Flores (1999), Prabhasankar et al. (2000), Villanueva et al. (2001) and Sutton and Simmons (2006), for instance, who observed that the flour from the last streams was not as light, since they are somewhat contaminated by fragments of the aleuron layer (Greffeuille et al., 2005). The effects on the color of the crumb, both with and without improver, were the same, since the crumb does not reach 100 C and does not produce Maillard reactions or caramelization, and so its color depends largely on the color of the flour. ...
It is well known that milling influences the characteristics of flour and products made from it. This article analyzed the influence of milling on the quality of low-hydration bread. In general, milling influenced the quality of these products more than the type of wheat selected. Among the various mill streams, the last break and reduction streams produced lower quality bread and must be eliminated in milling. These streams had a higher protein and ash content, showing the presence of components of the outer layers of the grain. The flour was able to absorb more water, but had less extensibility in kneading and the dough generated was weaker due the poorer quality of its proteins and the influence of elements from the outer layers. Thus, bread made from these streams had smaller volume, had a firmer texture and had both darker crumb and crust. These differences, along with the effect of the kind of flour on the flavor and aroma of the bread, made it less acceptable than flour from the rest of the streams studied.
... Since these flours were used in making pasta in this study, the higher levels of these metabolites in the pasta made from 500 m flour could be attributed to the higher fibre contents in the flour. Prabhasankar et al. (2000) for example, showed that palmitic acid (29.3%) was the highest fatty acid in milled wheat. ...
... It gives the best results for many kinds of products, including some yeast breads, quick breads, cakes, cookies, pastries, and noodles [8]. It contains a large amount of starch and other components like proteins, lipids, etc., which affect its properties [9]. ...
The study aimed to optimize the sensory qualities of extruded crunchies using banana flour, cassava starch, and all-purpose flour as the main raw materials. Mixture statistical design was used to determine the optimum formulation of crunchies. Sensory acceptability in terms of color, taste, crunchiness, and general acceptability were evaluated. Results showed that the sensory qualities of crunchies were significantly affected by the level of banana flour, cassava starch, and all-purpose flour. Among the treatments, formulation of crunchies with 100% all-purpose flour, formulation with 50% banana flour & 50% all-purpose flour, and the mixture with 66.67% all-purpose flour, 16.67% banana flour & 16.67% cassava starch were considered as the optimum mixtures. It is recommended to use considerable amount of all-purpose flour with banana flour and cassava starch in the production of extruded crunchies.
... Wheat flour is a key source of baking products. Wheat flour contains a large amount of starch and other components like proteins, lipids, etc., which affect its properties (Prabhasankar et al., 2011). The lipids in wheat flour are only 1%-3% of the total content. ...
The use of enzymes in food processing is an age-old process. With the advancement of R&D and new technologies, several novel enzymes with wide range of applications have been developed. The present article gives an insight into different microbial enzymes which find applications in food processing. Various type of food processing and the use of enzymes in various stages of operation are detailed in the chapter. Enzymes such as amylases, proteases, alpha galactosidase, beta galactosidase, lipase, phospholipase, asparaginase, glutaminase, phytase, naringinase, laccase and invertase have been described in detail with their characteristics pertinent to their use in food processing. Application of these enzymes in food processing and challenges to make these applications economically viable are also discussed.
Keywords: Enzymes; Microbial; Food processing; Fermentation; Applications
... Lipids are quantitatively minor, but significant compounds of wheat, present in the order of 0.9-3.3% in grains. The majority of polar lipids of a wheat grain are present in the starchy endosperm, and the non-polar lipids are predominantly present in the germ and aleurone tissues, and consist of FFA, MAG, DAG and TAG (Prabhasankar et al., 2000). ...
Suitable conditions of temperature and humidity are required to maintain wheat grains quality, but during processing and storage, the grains can be exposed to adverse environmental conditions and presence of infectious fungi. Fusarium graminearum, the main causal agent of Fusarium head blight on wheat, affects crop yields and grain quality by alteration of their biochemical components and mycotoxin contamination, which reduces the possibilities of wheat end use and compromises food safety. Lipid degradation by hydrolytic, oxidative and microbial deterioration is the predominant cause of the loss of sensory acceptability, nutritional value and baking quality. The aim of this research was to determine the influence of adverse environmental conditions –as the increasing moisture– on lipid patterns of whole wheat flours contaminated with F. graminearum in relation to the infection degree. In vitro cultures of F. graminearum were carried out on wheat grains under different degrees of relative humidity (11, 50, 75 and 100%) throughout 45 days of incubation at 28 °C. The fungal biomass measured by q-PCR increased proportionally with the humidity. A decrease in the signals of saturated (palmitic and estearic) and unsaturated (oleic, linoleic and linolenic) fatty acids, analyzed as fatty acid methyl esters (FAMEs) by GC-MS, was observed in relation with the humidity and infection degree. The degradation rate of the lipids was high during the first 15 days of incubation, reaching the fatty acids content, values around 20-40% of those found in the control. From that moment on, the rate of degradation was slower or even null. It was observed that in all treatments, the linolenic acid reached the highest degradation ratio in comparison with the other fatty acids, which may be caused by the action of lipoxygenases. The lipase activity and the content of deoxynivalenol were also determinate on the flours. The lipase activity increased until day 25 of incubation reaching twice the initial value. The deoxynivalenol content also increased along incubation while fatty acids decreased. Our results demonstrated that the magnitude in the signal of fatty acids in whole wheat flours varied in relation to the degree of humidity and fungal infection of the grains from which they were obtained. Otherwise, lipids and their oxidation products are related with the pathogenesis and production of mycotoxins. These observations highlights the importance of an adequate manipulation of wheat grains on the processing chain to prevent quality changes and mycotoxins contamination.
... Flour contains mostly starch (70-75%); however, other components in the flour also clearly affect the properties of the dough. These are proteins (9-14%), lipids (1-3%), non-starch carbohydrates (1-2%), ash (around 0.5%), and moisture (13-14%) (Delcour et al. 2012;Prabhasankar et al. 2000). Over the last decades, several substances (emulsifiers, shortenings, and enzymes) have been used to influence the structural and physicochemical characteristics of the constituents of flour and to optimize the functionality of these constituents. ...
Phospholipids play a central role in all living organisms. Phospholipases, the enzymes aimed at modifying phospholipids, are consequently widespread in nature and play diverse roles, from lipid metabolism and cellular signaling in eukaryotes to virulence and nutrient acquisition in microbes. Phospholipases catalyze the hydrolysis of one or more ester or phosphodiester bonds of glycerophospholipids. The use of phospholipases with industrial purposes has constantly increased over the last 30 years. This demand is rapidly growing given the ongoing improvements in protein engineering and the reduction of enzymes manufacturing costs, making them suitable for industrial use. Here, a general overview of phopholipases A, B, C, and D and their industrial application is presented along with potential new uses for these enzymes. We draw attention to commercial phospholipases used to improve the emulsifying properties of products in the baking, egg, and dairy industries. On the other hand, the improvement of oil degumming by phospholipases is thoroughly analyzed. Moreover, recent developments in enzymatic biodiesel production and the use of phospholipases for the synthesis of phospholipids with pharmaceutical or nutritional value are reviewed.
... konoPka androtkiewicz (2000) demonstrated that native lipids significantly influence the rheological properties of bread, they affect the starch pasting process, mechanical properties of dough and, ultimately, the quality and shelf-life of bread. PraBhasankar and rao (1999) and PraBhasankar et al. (2000) emphasized the role of polar lipids which determine the volume of bread loaf, and of unsaturated fatty acids which improve gluten quality through the oxidation of -SH groups. The above observations were validated by Panazzo et al. (1993) and MaGnus et al. (2000) who suggested that bread loaf volume is determined not only by the content of lipids (free or bound) in flour, but also by lipid type. ...
The aim of the study was to compare the total lipid content, main fatty acids composition and their proportions in dark (high-extracted) flour obtained from the grain of seven spelt wheat (T. spelta) cultivars and one (reference) common wheat cultivar (T. vulgare), grown organically in Poland during two successive years of cultivation. Husked spelt grain cv. Ceralio", Schwabenkorn", Frankenkorn", Holstenkorn", Schwabenspelz", Ostro" and Oberkulmer Rotkorn", and common wheat grain cv. Korweta" were ground in a buhrstone mill on a certified organic farm. The total ash content and the acidity of the produced flour were determined. Total lipid content was evaluated by the Soxhlet method, and fatty acids composition was determined using gas chromatography. The majority of investigated spelt flours characterized by significantly higher total acidity level than the flour from common wheat cv. Korweta". In most studied flours, fat acidity exceeded the allowable standard. The average total lipid content of the tested spelt flours, excluding cv. Ceralio" (from first year of harvest), was significantly higher than in cv. Korweta" wheat flour. The results of the study indicate that linoleic acid was the dominant fatty acid in all flour types, but significantly lower levels of this acid were determined in spelt flour than in the flour obtained from common wheat cv. Korweta". All spelt flours were characterized by significantly higher concentration of oleic acid in comparison with cv. Korweta" wheat flour. The highest total lipid content was reported in cv. Holstenkorn" spelt flour which, in addition to cv. Ceralio" flour, was also marked by the most favorable composition of essential PUFAs. © 2018 University of Warmia and Mazury in Olsztyn. All rights reserved.
... Hence, WGF oil is a good source of PUFAs. The predominant unsaturated fatty acid observed in flour lipids was linoleic acid (C18:2) (Prabhasankar et al., 2000). The main fatty acid composition of the oil extracted from the WGF is shown in (Table 1). ...
We treated whole grain flour (WGF) with ozone gas applied at 5 g/h over intervals of 0, 5, 15, 35, and 45 min. We extracted oil from whole grain flour treated and untreated with ozone gas to investigate how the ozone affected the fatty acid composition. The fatty acid value decreased in the treated flour, whereas the peroxide and p-inisidine values increased with ozone gas treatment. The lipase activity was lower in oil extracted from the flour that had been ozonated for more than 35 min compared to the control sample. We also observed levels of oxidation in the volatile compounds heptanal, hexanal, tetradecane, decanal, 1-hexanol, and nonanal after ozone treatment. The oils extracted from the ozone-treated flour showed higher phenolic content and antioxidant activity.
... Greenblatt et al. (1995) identified galactolipids and phospholipids in greater amounts in soft wheat than in hard wheat (Greenblatt et al. 1995). Polar and nonpolar contents of free lipids or their fatty acid composition in commercially milled flour streams have also been assessed (Prabhasankar et al. 2000). This type of information can be used during the process of blending the streams to produce different traditional products. ...
... (2006) indicated that in the case of fungi from the genus Aspergillus fatty acids are used in the production of aflatoxins, while as early as in 1974Boutigny et al. (2008 reported that the saponified lipid fraction from wheat germ containing a mixture of fatty acids stimulated the production of aflatoxins by Aspergillus flavus. Lipid precursors are stored in cytosolic lipid droplets and are frequently accumulated by Aspergillus spp. as well as saprophytic fungi (Prabhasanar, Vijaya Kumar, Lokesh, & Haridas Rao, 2000). The biosynthesis pathway presented by Ruibal-Mendieta, Delacroix, and Meurens (2002) for long-chain polyunsaturated fatty acids, starting from the 18-carbon chain, in fungal cells takes place up to the saturated stearic acid. ...
Analyses were conducted on 30 winter wheat samples growing under controlled conditions and following inoculation with fungi Fusarium culmorum. In inoculated samples the mean concentration of 30 analysed fatty acids was significantly higher in relation to the control and amounted to 1396 mg/kg vs. 1046 mg/kg in the control kernels. Recorded concentrations for individual cultivars were significantly correlated with the concentration of fungal biomass.
Higher concentration in the control was recorded only for the acid trans C18:2n–6. It was also found that the acid profiles are characteristic of individual cultivars. Statistical analysis showed that trans C18:2n–6, C18:1, C18:3n–3 and C18:3n–6 were the acids with the greatest discriminatory power in distinguishing inoculated samples from the control. Discriminatory analysis separated individual cultivars into quality classes of winter wheat cultivars depending on the presence of a specific fatty acid profile.
... As anticipated, protein content (Lee and Mulvaney, 2003) was the primary factor impacting farinograph quality number (FQN) (r ¼ 0.667, p < 0.05). At the same time, fatty acids, particularly unsaturated fatty acids, could strengthen the gluten by way of oxidation of SH' groups through enzyme-coupled reactions (Addo and Pomeranz, 1992;Prabhasankar et al., 2000). Lipids also have been reported to markedly influence the baking quality of flours and loaf volume of bread (Bekes et al., 1986;McCorrnack et al., 1991). ...
Wheat filter flours are by-products obtained from air-classification of wheat flour. Physicochemical and rheological properties of wheat filter flours were investigated in the present study. Average values of crude protein, gluten, lipid and damaged starch content of filter flours were higher than those of standard flours for the same batch. The positive correlation of particles with size <20 μm and damaged starch was found. Moreover, the filter flours had higher water absorption, stability time except head milling filter flour samples. Short peak time and low peak viscosity were also observed. Different composition of wheat filter flours may be an important factor influencing its properties. This study is very useful for exploring the utilization of wheat filter flours in the food industry.
... Wheat (Triticum aestivum L.) flour contains approximately 2.0e2.5% lipids. The lipid content determined depends not only on the genetic and environmental characteristics but also on the milling and lipid extraction method (Chung et al., 2009; Fisher et al., 1966 Fisher et al., , 1964 Morrison, 1978; Prabhasankar et al., 2000; Prabhasankar and Rao, 1999). Wheat lipids can be divided into polar and non-polar lipids. ...
Lipids exhibit important functional properties in bread making, although they are present in lower levels than starch or protein. They originate from flour, in which they are endogenously present, or from added shortening and/or surfactants. This review discusses lipid sources and their interactions during the entire process of bread making from dough mixing to fermentation, proofing, baking and the stored product. The focus is on lipid interactions with starch and gluten proteins, their role in gas cell stabilisation and their impact on bread loaf volume, crumb structure and crumb firming. Widely accepted views on lipid functionality, although often opposing, are presented and critically discussed.
... This observation agreed with previous reports, in which linoleate, palmitate, and oleate made up approximately 96% of the fatty acid compositions of wheat (Davis et al 1980). Fatty acids, particularly unsaturated fatty acids, are reported to strengthen the gluten by way of oxidation of the sulfhydryl group through enzyme-coupled reactions (Prabhasankar et al 2000). ...
Until now few comparisons of nutritional compounds in premature
green and mature yellow wheat have been reported. In this study, the
contents of amino acids, vitamins, mineral compounds, phytosterols, and
fatty acids as well as the proximate composition of premature green and
mature yellow wheat were investigated. Premature green wheat had lower
protein content (12.0 g/100 g db) and higher dietary fiber content (19.3
g/100 g db) than mature yellow wheat (13.6 and 14.3 g/100 g db for protein
and dietary fiber, respectively). Despite a small difference in total
amino acids, protein in premature wheat had a significantly greater proportion
of essential amino acids: 16.1, 39.9, and 32.7 mg/g of protein formethionine, lysine, and threonine, respectively. Furthermore, the protein
digestibility-corrected amino acid scores of whole grain premature green
and mature yellow wheat were 62.8 and 46.4, respectively, showing significant
difference (P < 0.05). Total fatty acids content was 2.66 g/100 g
db for premature green wheat and 2.21 g/100 g db for mature yellow
wheat. Vitamin C, β-carotene (provitamin A), α- and γ- tocopherol, and
niacin were the major vitamins in premature green wheat, whereas vitamin
C and β-carotene were not detected in mature yellow wheat. The
results obtained indicated that premature green wheat has potential for the
human diet because of its desirable nutritional value.
... The differences between streams obtained during the flour-milling process have been studied for several years. These differences pertain to characteristics such as colour (Oliver et al., 1993), total and soluble fibre distribution (Ranhotra et al., 1990), fat content (Prabhasankar & Haridas Rao, 1999;Prabhasankar et al., 2000a), enzyme distribution (Rani et al., 2001;Every et al., 2006) or rheological properties of dough obtained from such flours (Villanueva et al., 2001;Indrani et al., 2003). Knowledge of these characteristics assists in obtaining flours suitable for different preparation processes. ...
Wheat-milling process generates different flour streams that differ in particle size, composition and functional and cake-making properties. Particle size, composition and pasting properties of flour fractions (two from break and three from reduction system) obtained during milling of three wheats varying in protein content were determined. Shape, textural, colour and sensory analyses were performed on cakes prepared with the different mill streams. The final break and reduction streams had the highest protein and ash contents, pasting temperatures and the lowest starch percentage. Cakes prepared with the last streams showed higher batter density and lower volume. These results could indicate good air incorporation but deficient air distribution. Last streams cakes showed a darker, more reddish and yellowish crumb that was significantly related to flour colour characteristics. Because of these differences, such cakes obtained the lowest sensory scores. In this study, it has been verified that, to adapt flours to cake preparation, the final streams should be eliminated. The particle size of each stream is the most determinant parameter to obtain cakes with better volume and texture, being the flours with small particle size the most adequate.
... 27,28 Linoleic acid C 18 : 2 is the predominant unsaturated fatty acid found in flour lipid. 29 Oxidation of fatty acids may affect its bonding with protein (gluten) and thus affect loaf volume of the bread. Gas chromatography and mass spectrometry of ozone-treated flour (0-40 min) has shown that lipid oxidation results in the production of mainly aldehydes, ketones (2-propanone), alcohols, hydrocarbons and benzene. ...
Ozone gas could be used as a fumigant during grain and flour storage. Experiments were conducted to determine the effects of exposure to ozone and the effects of blending ozone-treated flour with control flour on flour functionality and bread-making quality.
Ozone treatment oxidized lipids, increased brightness and reduced the yellow hue of flour, and increased peak viscosity and setback viscosity of flour. Bread made from flour treated with ozone at 1500 mg kg(-1) for 4.5 min and bread made from flour blended with 100 g kg(-1) ozonated flour had good crust color and a whiter crumb and had more crumb cells, which resulted in a greater specific volume of the bread when compared with control flour. Flour functionality declined as ozone exposure increased beyond 9 min and as the concentration of ozonated flour increased beyond 200 g kg(-1) .
Bread made from flour exposed to ozone for 4.5 min or flour that contained 100 g kg(-1) fully ozonated flour had greater specific loaf volume and whiter crumb compared to bread made with control flour. Exposure of flour to ozone for longer times (9-45 min) and higher blends (200-1000 g kg(-1) ) deteriorated quality of bread.
High-ash flour is made by a regular milling process and its use as a bread ingredient is expected to enable flavor differentiation from conventional breads at a lower cost compared with whole wheat flour made on a dedicated production line. Liquid and gas chromatography/mass spectrometry analysis showed that the taste and volatile components of bread consistently showed different characters when 20 % or more high-ash flour was used. Addition of high-ash flour increased the amount of compounds that were produced during fermentation and the Maillard reaction. On sensory evaluation, “sweetness” and “saltiness” were selected as terms that describe the characteristics of bread made from regular wheat flour, while “smokiness”, “sourness”, and “harshness” were selected as terms that describe the characteristics of 40 % high-ash flour substituted bread. Because the addition of high-ash flour increased fermentation and Maillard reaction products, it was presumed that these compounds affected the sensory evaluation characteristics of bread with high-ash flour. These results indicated that the flavor components of bread changed significantly when the substitution ratio of high-ash flour exceeded 20 %.
During the storage of wheat grains and flours, a natural deterioration occurs due to aging over time, which is accelerated by adverse conditions of temperature and humidity that cause the growth of fungi. The local climates and infrastructure available for storage affect the preservation and duration of the safe storage time. Wheat lipids are a minor component, whose level and composition are decisive in the quality properties of wheat final products. Lipids are easily degraded, which is the main cause of quality loss. The enzymatic degradation of lipids is carried out by the activation of endogenous and/or fungal enzymatic activities, which produces hydrolytic and oxidative rancidity. Fusarium, Aspergillus, Penicillium and Alternaria are the most frequent genera found in infected grains. Wheat infection by Fusarium spp. is associated with considerable economic losses in crops throughout the world. The volatile compounds produced by oxidative rancidity are the main indicators of deterioration. Lipid rancidity must be monitored periodically using a combination of different analytical methods, ranging from traditional to modern alternative techniques of varied scope. Sensitivity to lipid deterioration varies with the wheat cultivar genotype, thus the selection of cultivars with better stability allows to obtain better quality products. In addition, a large proportion of the harvested wheat is usually stored for a long time until use, so achieving suitable environmental conditions and applying control measures prevent quality loss. This review updates the knowledge about wheat lipids, the importance of preserving their integrity during storage, presenting different monitoring alternatives to detect their rancidity, which would allow better decision-making.
Wheat flour is the main ingredient used in the preparation of bread. Factors such as low gluten content and the addition of nontraditional ingredients in baking affect the quality of wheat flour and may limit its use in baking. With the increasing trend of “clean label” products, it may be interesting to develop and use physical processes to improve the quality of wheat flour and avoid the use of chemical additives. High hydrostatic pressure, non-thermal plasma, ultrasound, ozonation, ultraviolet light, and pulsed light treatments are non-thermal emerging technologies (NTETs) that have been studied for this purpose. They were originally developed to inactivate microorganisms and enzymes in foods. Additionally, these technologies can be used at low temperatures to modify the most important component of wheat flour, i.e., gluten and its fractions, which are responsible for the rheological properties of wheat flour dough. Thus, this review focuses on the effects of these NTETs by considering the following factors: (1) the technological properties of gluten, (2) gluten–starch interactions, (3) possible effects of NTETs on minor components of flours, and (4) the quality of wheat flour and the resulting final products.
Les études de sorption d'eau de farines issues de chaque étape de la mouture ont mis en évidence un mécanisme d'hydratation par sites hydrophiles internes aux particules. Pour des aw inférieures à 0,8, l'hydratation est régie par l'amidon, pour des aw supérieures à 0,8 les capacités de sorption de vapeur d'eau dépendent des teneurs en protéines et en pentosanes, mais aussi de la structure de la farine. Les mesures de capacités d'hydratation par immersion confirment cette observation et mettent en évidence l'influence supplémentaire de l'amidon endommagé. L'étude des états physiques de l'eau par RMN et par ATD a confirmé l'affinité de ces composants pour l'eau. Plus la farine est riche en protéines et en amidon endommagé, moins les molécules d'eau sont mobiles. Ces études ont montré que les interactions entre l'eau et la farine évoluent au cours de l'hydratation. Les spectres FTIR ont montrés des modifications structurales des protéines lors de l'hydratation.
Globally wheat is main cereal grain in terms of production, consumptions and trade. Milling is a mechanical gradual reduction process with different sets of break and reduction rolls to ensure maximum removal of bran and germ. Roller mills produce different flours from same grain stock. Chemical constituents are not evenly distributed in wheat kernel resulting variation in chemical composition of flour streams. Protein concentration, composition and fractions vary in distribution both in wheat kernel and flour streams. Salt-soluble proteins are concentrated in sub aleurone cells while endosperm contains mainly salt-insoluble proteins. Stream splitting is useful technique for production of quality flours where desired quality wheat is not available. Mill streams with similar quality and functional properties are blended to produce a variety of flour grades. Blending fulfills economic, qualitative and nutritional constraints and to get standardized flours. Difference in content and chemistry of proteins in different break and reduction flour streams is of immense importance for their characterization and selection for defined end uses. Milled fractions with higher arabinoxylan and protein polymers have a high oxidative potential. Thiol groups and oxidative cross links affect rheological and processing parameters of mill streams. Higher albumins and globulins quantity and lower degree crosslinkings results difference in rheological characters among break and reduction flour. Mill streams vary in dough rheology, baking performance and suitability for baked products. Different flour streams has diverse characteristics making these to suit bread or biscuit process. Selected mill stream blends result in different flour grades and diversified end products.
Lipidomic analyses of milling and pearling fractions from wheat grain were carried out to determine differences in composition which could relate to the spatial distribution of lipids in the grain. Free fatty acids and triacylglycerols were major components in all fractions, but the relative contents of polar lipids varied, particularly lysophosphatidyl choline and digalactosyldiglyceride, which were enriched in flour fractions. By contrast, minor phospholipids were enriched in bran and offal fractions. The most abundant fatty acids in the analysed acyl lipids were 16:0 and 18:2 and their combinations, including 36:4 and 34:2. Phospholipids and galactolipids have been reported to have beneficial properties for bread making, while free fatty acids and triacylglycerols are considered detrimental. The subtle differences in the compositions of fractions determined in the present study could therefore underpin the production of flour fractions with optimised compositions for different end uses.
In the last several decades, food industries have increasingly used lipases as a result of the functional versatility of these enzymes and their potential beneficial effects in terms of processing and product quality. This review article discusses lipases and their functional effects during cereal-based food processing with a focus on the production of bread and cakes. Their dough and batter intermediates, respectively, are essentially semi-solid foams that upon baking are converted into solid cellular sponges. In both cases, the lipid fraction(s) from wheat (in the case of bread and cake), egg and/or bakery fat (in the case of cake) exert major roles in gas incorporation and stabilization in the cited semi-solid foams. An up-to-date overview on the (potential) substrates, the different lipase enzymes, their action mechanism, their functionality, and how they impact bread and cake quality is presented. We also hypothesize on how the observed effects can be interpreted in terms of the altered lipid chemistry.
Lipids are minor components of flours, but are major determinants of baking properties and end-product quality. To the best of our knowledge there is no single solvent system currently known that efficiently extracts all non-starch lipids from all flours without the risk of chemical, mechanical or thermal damage. This paper compares nine ambient solvent systems (monophasic and biphasic) with varying polarities: Bligh and Dyer (BD); modified Bligh and Dyer using HCl (BDHCL); modified Bligh and Dyer using NaCl (BDNaCl); methanol:chloroform:hexane (3:2:1, v/v); Hara and Radin (hexane:isopropanol, 3:2, v/v); water saturated n-butanol; chloroform; methanol and hexane for their ability to extract total non-starch lipids (separated by lipid classes) from wheat flour (Triticum aestivum L.). Seven ambient extraction protocols were further compared for their ability to extract total non-starch lipids from three alternative samples, barley flour (Hordeum vulgare L.), maize starch (Zea mays L.) and tapioca starch (Manihot esculenta Crantz).
For wheat flour the original Bligh and Dyer method and those containing HCl or NaCl tended to extract the maximum lipid and a significant correlation between lipid extraction yield (especially the glycolipids and phospholipids) and the polarity of the solvent was observed. For the wider range of samples BD and BD HCL repeatedly offered the maximum extraction yield and using pooled standardized (by sample) data from all flours total non-starch lipid extraction yield was positively correlated with solvent polarity (r= 0.5682, p<0.05) and water ratio in the solvent mixture (r=0.5299, p<0.05).
In general, Bligh and Dyer based methods showed better extraction yields compared to methods without the addition of water and most interestingly there was much greater method dependence of lipid yields in the starches when compared to the flour samples, which is due to the differences in lipid profiles between the two sample types (flours and starches).
Considering the significant differencies between the chemical composition of the kernel layers, distribution of chemical compounds in intermediate, final and subproducts of the milling process come as a result of the level of dissociation achieved during the milling process. These differences serve as a basis for the mill process control. Ash determination is probably the most widely used tool while even greater differencies exist in cellulose and especialy starch content. In this work efficiency function has been defined and used to evaluate the relative efficiency of the separation of endosperm from the outer pericarp leyers of the kernel. It is based on quantity rates (flour extraction and subproducts yield) and qulitative analyses (starch and cellulose content in the wheat, flour and subproducts).
Wheat whole-meal (WWM) flour is commonly used in Asian breads such as roti and chapati. WWM has higher damaged starch and ash content. Unlike wheat flour, WWM contains the some amount of bran. This is due to during the milling process of WWM; larger bran particles are preferably sifted out, leaving smaller bran particles. Chemical and microstructure changes occurring during processing of wheat into WWM were evaluated by analyzing mill stream (C4, C5 and WWM) samples from a pilot mill. The ash content was 0.43%, 0.90% and 0.75%; while damaged starch content was 8.30%, 10.70% and 10.31% in C4, C5 and WWM streams, respectively. Ash and damaged starch contents were higher in C5 stream as compared to the C4 stream. However, both these parameters were lower in the case of WWM stream, which was a homogenized mixture of C4, and C5 streams. A similar trend was observed for the protein contents of C4, C5 and WWM streams. Scanning electron microscopy (SEM) studies showed A type (lenticular shaped) starch granules without much structural deformation in the C4 stream. On the other hand, deformed A-type and intact B-type (spherical shaped) starch granules were seen in the C5 stream. A WWM stream micrograph revealed a combination of deformed and intact starch granules embedded in the protein matrix. Hence, the present study indicated that there is a relationship between chemical characteristics and microstructure of WWM.
BACKGROUND: Most of rye flour is obtained by a gradual reduction system using roller flour mills, which generate different flour streams. The study of the different flour streams composition is necessary since it determines the flour quality and the flour uses. Four break streams and nine reduction streams were analysed for moisture, ash, starch, protein, damaged starch, falling number, amylose/amylopectin ratio, β‐glucans and colour. Mixing and pasting properties were also determined with a doughLAB and a Rapid Visco Analyser respectively.
RESULTS: As the milling process advanced, moisture and starch content decreased but protein, ash, β‐glucans and damaged starch increased. The differences in composition are probably related to the effect of the roller mills and the increase in the contamination with bran. The absorption, development time, and pasting viscosity increased as the milling proceeded, in detriment of the peak time. The β‐glucan content was positively correlated to absorption, mixing tolerance index and pasting viscosity, and negatively correlated to peak time.
CONCLUSION: Differences in composition, above all, in bran, showed different mixing and pasting properties in rye streams. The most different streams corresponded to the last streams in the break process, in the sizings and in the middlings. Copyright © 2008 Society of Chemical Industry
Fatty acid methyl esters and dimethylacetals suitable for gas chromatographic analysis were prepared by treatment of lipids with boron fluoride–methanol (140 g BF3 per liter of methanol). This reagent is stable and easy to handle. Reaction conditions were investigated for triglycerides, diglycerides, monoglycerides, free fatty acids, sterol esters, phosphatidyl ethanolamines, phosphatidyl serines, phosphatidyl cholines, monophosphoinositides, monogalactosyl glycerides, phosphatidal cholines (choline plasmalogens), digalactosyl glycerides, and sphingomyelins. The methyl esters and dimethylacetals were readily purified by thin-layer chromatography, and yields were quantitative. There were few undesirable side reactions, and they did not affect the validity of the method. The procedure developed is simple, rapid, and generally applicable to lipids.
The effects on test-bake loaf volume of variations in flour lipid content and composition of the order found in the survey (accompanying paper: McCormack et al. Part I. J. Cereal Sci.13 (1991) 255–261) have been directly measured using fractionation and reconstitution methods. Loaf volume decreased linearly for flours from several cultivars when the percentage of lipid that was non-polar was varied from 0 to 100, keeping the total non-starch lipid level constant at its natural value by corresponding adjustment with the polar lipid fraction (i.e. the percentage of polar lipid varied from 100 to 0). This allowed an estimation of the contribution to differences in loaf volume for cultivars having their proportions of non-polar lipid at the low and high ends of the range. This contribution was small relative to differences measured between cultivars of high and low loaf volume potential and this was confirmed by interchange experiments. Differences in the amount of non-starch lipid were also shown to contribute to loaf volume differences but were more important for poorer quality cultivars. A high correlation was found between loaf volumes of defatted and untreated flours from 15 cultivars, again confirming that the lipid contribution to loaf volume, although measureable, was minor compared to that from protein. The magnitude of the lipid contribution to the variation in loaf volume between cultivars, deduced from reconstitution studies, is consistent with that estimated from statistical analysis of the survey data.
Lipids containing 14C-labelled linoleic and linolenic acids were added to flour which was then made into bread doughs with or without 2% enzyme-active soya flour. The 14C-labelled lipids and their oxidation products were analysed as intact lipids or as 14C fatty acid methyl esters by thin-layer chromatography. In the control doughs wheat lipoxygenase oxidised free fatty acids and monoglycerides. In doughs containing soya flour, steryl esters, triglycerides, diglycerides, mono-galactosyl diglycerides, digalactosyl diglycerides and phosphatidyl choline were also oxidised, and the oxidation of these lipids is attributed to soya lipoxygenase.
Kernels from a mixed hard wheat grist were dissected into germ, bran (pericarp, testa and aleurone), and starchy endosperm for direct analysis of tocopherols in lipid extracts by high-performance liquid chromatography. - and β-tocopherols were almost exclusively in the germ, -tocotrienol was mostly in the bran, and β-tocotrienol was equally distributed between the bran and the starchy endosperm. Acyl lipids and tocopherols were quantified in 23 millstreams obtained from this grist. Components related to germ and bran (triglyceride, diacylphospholipids, ã- and β-tocopherols) and testa (flour colour) showed the highest coefficients of variation whereas endosperm components (glycolipids, N-acylphospholipids and β-T-3) showed exceptionally low variation. The quantities of marker tocopherols in the streams were used to calculate the composition of the lipid transferred to the flour from germ and aleurone, and to predict the composition of the basic endosperm, free of aleurone and germ lipids. Low proportions of diacylphospholipids in the lipid transferred to high-grade millstreams indicated the transfer of spherosome lipid. The low-grade streams exhibited high proportions of phospholipids suggesting additional transfer of germ tissue and aleurone tissue containing membrane lipids. Protein and ash contents of the transferred fraction confirmed that a substantial proportion of the transferred lipid was probably accompanied by protein bodies or by tissue fragments. It is estimated that aleurone contributed less than one-quarter of the transferred lipid in any stream. Hexane-extractable free lipids in four representative streams consisted of almost all the non-polar lipids, 40–67% of the glycolipids, 47–54% of the diacylphospholipids and 30–60% of the lysophospholipids.
Lipids play an important role in determining the quality of wheat flour and its suitability for different bakery products. The lipid content and fatty acid composition in various flour streams showed a wide variation. The free lipid content varied from 0·1 to 1·9% (db) and bound lipid content from 0·2 to 2·1% (db) in different flour streams. The amount of bound lipid was more in reduction streams. The palmitic and linoleic acids were the predominant fatty acids present in free and bound lipids. These fatty acids were found to be higher in the «III» «Break coarse», «IV» «Break filter», «III» «Break fine», «1st» and «4th» «middling». The studies showed that the reduction passage flours had more of bound lipids indicating the presence of polar lipids.
Samples of whole and manually degermed Atou wheat were milled on a micro-mill to give straight-run flour, coarse offal, fine offal, finished bran and bran finisher flour. The non-starch lipids in these products were compared with non-starch lipids in the aleurone-free starchy endosperm, and with lipids in the germ and aleurone of the original wheat. About half of the triglyceride in flour was derived from the germ; no glycolipids or phospholipids were derived from germ, and no lipids of any kind were derived from the aleurone. Non-starch lipids in the aleurone-free endosperm of a mixed English soft wheat grist were then compared with the non-starch lipids in 11 flour streams from a commercial mill. All flours had much more triglyceride than the endosperm. In flours from the reduction system there were significant correlations between flour colour grade, sterylester, triglyceride, diglyceride, free fatty acid and diacylphospholipids, but none between ash or protein and colour or any class of lipid. Analysis of the principal components of variation in a simplified matrix describing all 11 flours placed triglyceride, diglyceride, free fatty acid, and diacylphospholipids close together in one group, and all glycolipids and N-acylphospholipids in a separate unrelated group. Sterylester and colour were loosely associated with the first group but could also be regarded as part of a third loose group with ash and protein. The results are interpreted in terms of lipid distribution within the wheat kernel, and their significance in milling and baking practice.
Phospholipids may be measured colorimetrically (as dipalmitoyl lecithin) without conventional acid digestion and color development procedures by forming a complex with ammonium ferrothiocyanate.
Lipids in wheat and their importance in wheat products Recent advances in biotechnology of cereals. Annual of proceeding of Physiochemical Society of Europe
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Relationship between lipid content and composition and loaf volume of twenty-six common spring wheat Relation of polar lipid content to mixing requirement and loaf volume potential of hard red wheat ¯our
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Relationship between lipid content and composition and loaf volume of twenty-six common spring wheat. Cereal Chemistry, 63, 327±331. Chung, O. K., Pomeranz, Y., & Finney, K. F. (1982). Relation of polar lipid content to mixing requirement and loaf volume potential of hard red wheat ¯our. Cereal Chemistry, 59, 14±20.
Eects of lipids and emulsi®ers on alveograph characteristics. Cereal Chemistry, 69, 6±12. AACC (Approved Methods of the MN, USA: American Association of Cereal Che-mists Inc
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Addo, K., & Pomeranz, Y. (1992). Eects of lipids and emulsi®ers on alveograph characteristics. Cereal Chemistry, 69, 6±12. AACC (Approved Methods of the American Association of Cereal Chemists) (1995). MN, USA: American Association of Cereal Che-mists Inc. Bekes, F., Zawistowska, V., Zillman, R. R., & Bushuk, W. (1986).
Carbohy-drate analysis Ð a practical approach
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Morrison, I. M. (1986). In M.F. Chaplin, & J. F. Kennedy, Carbohy-drate analysis Ð a practical approach (pp. 205±221). Washington, USA: IRL Press.
Carbohydrate estimation by phenolsulphuric acid method. Analytical Chemistry, 28, 350. Fig. 5. Percentage of linolenic acid content in TFNPL and TFPL of milled streams
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Dubois, M., Gilles, K. A., Hamilton, J. K., Rebers, P. A., & Smith, F. (1956). Carbohydrate estimation by phenolsulphuric acid method. Analytical Chemistry, 28, 350. Fig. 5. Percentage of linolenic acid content in TFNPL and TFPL of milled streams. P. Prabhasankar et al. / Food Chemistry 71 (2000) 97±103