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Xylose-based oligosaccharides produced from xylan-rich hemicelluloses (xylo-oligomers) are carbohydrates with potential food and pharmaceutical uses. Autohydrolysis of lignocellulosic biomass is an efficient way to produce xylo-oligomers in a reasonable yield and a wide variety of compositions (anhydroarabinose/anhydroxylose and acetyl/anhydroxylos...
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... the end of the desired reaction time, the reactor was extracted from the oil bath and immediately immersed in cold water to quench the reaction. Figure 1 shows the excellent reproducibility of the temperature profiles obtained for a triplicate experiment at 179 °C. The experiments were nonisothermal because of the length of the heating period at the beginning of the reaction (around 8 min), which was as long as the quasi-isothermal period for some of the experiments at the higher temperatures. ...
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Carbohydrate analysis is an important source of the information required for understanding and control of pulp and paper processes. The behavior of cellulose and hemicelluloses in the process, carbohydrate–lignin interactions, and the enzymatic treatment of fibers are examples of situations for which reliable, fast, qualitative, and quantitative me...
The recovery and upgrade of hemicelluloses, a family of heteropolysaccharides in wood, is a key step to making lignocellulosic biomass conversion a cost-effective sustainable process in biorefinery. The comparative selective catalytic C-O bond hydrogenolysis of C5-C6 polyols, sugars, and their mixtures for the production of valuable C6 and C5 deoxy...
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... The portion of lignin in the residues from the 200 and the 220 • C treatments were 31.7 and 39.4 %. Small amounts of cellulose-degraded compounds (up to 3 %) were identified in the liquid resulting from the treatment at 180 • C. HWE of corncob conducted by Nabarlatz et al. and Makishima et al. [133,134] showed that the higher yields of hemicellulose-products in the liquid fraction after the HWE process occurs in the 190-200 • C range of temperatures. The extracts, as in other materials, are constituted mainly by xylan. ...
Thermochemical pretreatments are employed prior to energy, chemicals, and fuels production from biomass. Wet thermochemical processes (WTCP) are treatments used to modify biomass properties in water as the primary solvent, with or without added reactants/catalysts. WTCP includes hot water extraction, steam explosion, hydrothermal liquefaction, hydrothermal carbonization (HTC), and supercritical water gasification. WTCP also includes processes that add chemicals to reduce reaction time and improve efficiency, i.e., organosolv, alkali, and low acid pretreatment. Operational parameters in WTCP are usually selected to optimize the yields of sugars after enzymatic hydrolysis of the resulting solids and biogas from the pretreated solids, or to ensure that hydrochar (e.g., from HTC) performs adequately in environmental applications. However, a key byproduct from WTCPs is an aqueous fraction (rich in nutrients, hemicellulose-derived sugars, and chemicals) often disposed of as waste. The necessity of resource conservation and proper management and the need to make WTCP-based biorefineries economically and environmentally sound require using all the byproducts of biomass processing. Options for downstream conversion of the WTCPs' aqueous byproducts are dispersed in the literature. Thus, this paper aims to put together works that report the parameters of WTCPs that allowed removing hemicellulose-derived fractions and nutrients from biomass (either partially or almost entirely), the yields and properties of this aqueous byproduct, methods of characterization, current and expected uses, and the challenges for scaling up WTCPs and using the aqueous stream. The paper focuses on expected and existing methods that allow the valorization of the aqueous fraction and reduce wastes within a circular bioeconomy framework.
... Hemicellulose also may be responsible for thermal and photochemical discoloration of paper (Lee and Feller 1986). Under more severe conditions of heating, aqueous suspensions of cellulose have been found to decrease in pH, which can be attributed to the same reaction; such acidity contributes to autohydrolysis during certain treatments of biomass for the production of monomeric sugars and various biofuels (Garrote et al. 2001;Nabarlatz et al. 2004;Liu et al. 2015a;Surek and Buyukkileci 2017). ...
For about two millennia, paper has served as a main medium for preservation of people’s ideas, stories, contracts, and art. This article reviews what is known about the various components that make up paper from the perspective of their long-term stability under typical storage conditions. Literature evidence is considered relative to the susceptibility of different paper components to embrittlement, acid hydrolysis, microbiological attack, and discoloration, among others. The cellulose that makes up a majority of most paper items is demonstrably stable enough to persist for many hundreds of years on the shelves of archival collections, though it is susceptible to acid-catalyzed hydrolysis, which can be accelerated by byproducts of decomposition. Though less attention has been paid to the archival performance of various minor components of modern paper products, evidence suggests that at least some of them are subject to likely breakdown, embrittlement, or decay in the course of prolonged storage. Based on these considerations, one can envision different categories of paper that can be expected to meet different levels of storage stability: ancient recipes for handmade papermaking, e.g. washi and hanji, archival-grade paper products, ordinary modern alkaline paper products, and paper manufactured without concerns for its longevity.
... The production of these byproducts, in particular, furfurals and acetic acid, is increased as the extraction process becomes more severe. 38,39 However, it is possible to eventually separate them from the hydrolysate to obtain the hemicelluloses and other components at a considerable purity. 40−42 Other hydrothermal extraction methods include steam explosion and microwave-assisted hydrothermal extraction, each with specific release and degradation kinetics as compared to conventional hydrothermal hydrolysis processes. ...
A holistic utilization of all lignocellulosic wood biomass, instead of the current approach of using only the cellulose fraction, is crucial for the efficient, ecological, and economical use of the forest resources. Use of wood constituents in the food and feed sector is a potential way of promoting the global economy. However, industrially established food products utilizing such components are still scarce, with the exception of cellulose derivatives. Hemicelluloses that include xylans and mannans are major constituents of wood. The wood hemicelluloses are structurally similar to hemicelluloses from crops, which are included in our diet, for example, as a part of dietary fibers. Hence, structurally similar wood hemicelluloses have the potential for similar uses. We review the current status and future potential of wood hemicelluloses as food ingredients. We include an inventory of the extraction routes of wood hemicelluloses, their physicochemical properties, and some of their gastrointestinal characteristics, and we also consider the regulatory route that research findings need to follow to be approved for food solutions, as well as the current status of the wood hemicellulose applications on that route.
... Adding more acids beyond those released naturally from the biomass may enhance Xylan breakdown into XOS. Also, [19] were reported to have produced XOS in good yield by autohydrolysis of corncob biomass at 150°C [15]. Another team of researchers also synthesized XOS via hydrothermal processing of wood chips of Eucalyptus nitens. ...
... This technology is made up of nanofiltration and ultrafiltration. While nanofiltration concentrates XOS by removing low molecular weight substances like phenolic compounds and monosaccharides, ultrafiltration separates XOS from high molecular weight compounds with varying degrees of polymerization (DP) [29,19]. Yuan et al. [30] and Geetha and Gunasekaran, [22] employed nanofiltration and ultrafiltration techniques to recover 44.4% and 74.4% of XOS produced by Bacillus sp., respectively [15]. ...
Xylooligosaccharides derived from Xylan, significant component of hemicellulose in lignocellulosic plant biomass, are essential raw materials used in the food, pharmaceutical and agricultural industries. They find application in these industries due to their unique physicochemical properties such as pH stability, growth regulatory ability, and anti-allergic property. In addition, they have been shown to exhibit promising antimicrobial, anti-cancer, antioxidant and anti-inflammatory activities. Xylooligosaccharides convert waste into valuable foods, pharmaceuticals, and agricultural products, promoting health, the economy, and the environment.
... Alternatively, treatments performed with hot compressed water (autohydrolysis or hydrothermal processing) have been employed to cause the partial hydrolysis of hemicelluloses into both soluble saccharides of lower molecular mass and products derived from them, leaving both cellulose and lignin in the solid phase. Interestingly, the solids from hydrothermal treatments show an increased susceptibility to further processing (for example, delignification or enzymatic hydrolysis) [7,8], enabling an integral benefit of • optimization based on the analysis of time-concentration profiles obtained under isothermal conditions [17,[20][21][22][23]; • data interpretation based on parameters measuring the combined effects of temperature and time, such as the P factor [24] or the severity factor [13,15,16,[25][26][27][28][29]; • empirical modeling based on the Surface Response Methodology or fuzzy neural networks [30][31][32][33][34][35][36][37]; • modeling based on kinetic mechanisms involving multiple reactions (including the breakdown of native polysaccharides into intermediates and the further reactions thereof) [14,15,19,28,[38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55]. ...
... The above studies have been performed for various LCMs, including: (a) woods and woody legumes [16,19,[21][22][23][24]27,[32][33][34]39,42,44,49,50]; (b) seeds, straws, shells, hulls, and various agricultural byproducts or wastes [13,14,21,25,26,28,37,40,41,43,[45][46][47][48][52][53][54][55]; (c) industrial byproducts [30,35,45,51]; (d) herbs and grasses, including dedicated energy crops [15,17,20,21,26,29,36]. ...
... Other studies considered the existence of up to three xylan fractions [53,54] that led to one or more types of oligosaccharides and/or paid attention to the fate of other hemicellulose components, such as arabinan, acetyl groups, and/or uronyl substituents [14,15,51,53,54]. Other studies proposed alternative mechanisms involving the direct formation of xylose from susceptible xylan [50], the production of furfural from arabinose [47], the formation of both furfural and degradation products from xylose [49], the hydrolysis of cellulose into oligosaccharides, and the further reactions of these latter compounds [46,52], as well as the dissolution of solid material [44]. ...
Miscanthus × giganteus samples were characterized for composition and treated with hot compressed water (hydrothermal or autohydrolysis treatments) at temperatures in the range of 190–240 °C. The liquid phases from treatments were analyzed to assess the breakdown of susceptible polysaccharides into a scope of soluble intermediates and reaction products. The experimental concentration profiles determined for the target compounds (monosaccharides, higher saccharides, acetic acid and sugar-decomposition products) were interpreted using a pseudohomogeneous kinetic mechanism involving 27 reactions, which were governed by kinetic coefficients showing an Arrhenius-type temperature dependence. The corresponding activation energies were calculated and compared with data from the literature. The kinetic equations allowed a quantitative assessment of the experimental results, providing key information for process simulation and evaluation.
... A kinetic model integrated the polymeric nature of hemicellulose to explain the polymer decomposition. In 2004, Nabarlatz, Farriol, and Montane developed a kinetic model for the autohydrolysis of xylan, which described the yields of the different reaction products and explained the chemical composition changes of the xylo-oligomers due to reaction temperature and time (Nabarlatz et al., 2004). There were two xylan fractions of three monomers (xylose, arabinose, and acetic acid) with different compositions and reactivity toward hydrolysis. ...
The kinetics studies is of great importance for the understanding of the mechanism of hemicellulose pyrolysis and expanding the applications of hemicellulose. In the past years, rapid progress has been paid on the kinetics studies of hemicellulose hydrolysis. In this article, we first introduced the hydrolysis of hemicelluloses via various strategies such as autohydrolysis, dilute acid hydrolysis, catalytic hydrolysis, and enzymatic hydrolysis. Then, the history of kinetic models during hemicellulose hydrolysis was summarized. Special attention was paid to the oligosaccharides as intermediates or substrates, acid as catalyst, and thermogravimetric as analyzer method during the hemicellulose hydrolysis. Furthermore, the problems and suggestions of kinetic models during hemicellulose hydrolysis was provided. It expected that this article will favor the understanding of the mechanism of hemicellulose pyrolysis.
... As previously indicated [42], the LHW pretreatment method follows a semi-isothermal profile. The temperature profile is divided in three parts: heating phase, pretreatment phase and cooling phase. ...
Liquid hot water pretreatment is considered to be a promising method for increasing biomass digestibility due to the moderate operational conditions without chemical additions. A necessary step towards the scalability of this pretreatment process is performing pilot plant trials. Upscaling was evaluated with a scaling factor of 500, by using 50 mL in the laboratory and 25 L in a pilot plant batch reactor. Pretreatment times were varied from 30 to 240 min, and temperatures used were 180–188 °C, while applying similar heating profiles at both scales. The initial mass fraction of poplar wood chips ranged from 10% to 16%. Liquid hot water pretreatment at laboratory and pilot scale led to analogous results. The acetic acid analysis of the liquid and solid fractions obtained after pretreatment indicated that complete deacetylation of poplar biomass can be achieved.
... After an incubation at 180 • C for 10 min, the XOS-H present in the rice straw liquor mainly contained X 2 at 15.2%, followed by 14.3% X 3 , 11.1% X 4 , 8.8% X 5 , 7.9% arabinose, 6.8% X 6 , 2.1% A 2 XX, 1.4% XA 3 XX and 1.1% A 3 X (Fig. 3B). Nabarlatz, Farriol, and Montane (2004) used autohydrolysis at 150 • C for 50.8 min to treat arabinoxylan from corn cobs, and the largest molar mass of XOS had an average DP of 7. In this study, rice husk and rice straw liquors treated at 170 • C for 10 min released XOS with a DP of 2-6 and some AXOS. Notably, AXOS were inconsistently detected after increasing the treatment time and temperature (Supplementary Tables S1 and S2). ...
In this study, we attempted to maximize arabinoxylan conversion into xylooligosaccharide (XOS) from rice husk and rice straw using two saccharification processes and evaluate the promotion of lactic acid-producing bacterial growth, including an investigation of the role of prebiotics in protecting probiotic bacteria in rice drink products in a high-pressure process (HPP). Hydrothermal treatment followed by enzymatic hydrolysis was designed for XOS recovery from rice husk arabinoxylan (RH-AX) and rice straw arabinoxylan (RS-AX). The hydrothermal treatment performed at 170°C for 20 min and 180°C for 10 min was the optimal condition to produce XOS liquor from rice husk and rice straw, respectively. Pentopan mono BG successfully recovered XOS from rice husk and rice straw residues at 50°C, pH 5.5, an enzyme concentration of 50 U and 100 U/g substrate for 24 h. This design converted 92.17 and 88.34% (w/w) of initial RH-AX and RS-AX into saccharides, which comprised 64.01 and 59.52% of the XOS content, respectively. Rice husk xylooligosaccharide (RH-XOS) and rice straw xylooligosaccharide (RS-XOS) had degrees of polymerization ranging from 2 to 6 with some arabino-xylooligosaccharides. RH-XOS and RS-XOS were used to examine the promotion of the growth of lactic acid-producing bacteria strains in the presence of other prebiotics. RH-XOS and RS-XOS strongly promoted the growth of Lactobacillus sakei and Lactobacillus brevis, while other species showed weak to moderate growth. This study represents the first report of the powerful effect of Lactococcus lactis KA-FF1-4 on altering the utilization of XOS but not xylose. Furthermore, for the first time, we reported the capability of XOS to protect probiotics in rice drinks under high-pressure conditions. RH-XOS and RS-XOS resulted in the highest viability of approximately 11 log cfu/mL and exhibited no significant difference compared with the non-HPP treatment. Hence, rice husk and rice straw can be utilized as alternative prebiotic sources that provide biological activity and food applications in the HPP industry.
... It has biphasic pattern in hydrolytic process comprising fast-rate and slow-rate hydrolysis portions. A comprehensive model of hemicellulose hydrolysis has been proposed on the basis of pseudo-homogeneous assumption following a first-order reaction ( Fig. 4.1) [26][27][28]. The kinetic model can be developed described as Eqs. ...
Liquid hot water (LHW) technology has been thought as a green process which hardly pollutes the environment due to no addition of chemical reagents. It is usually employed as a pretreatment method for producing ethanol, butanol, lactic acid, biogas, and other biochemicals from lignocellulose. It is also used as a technology to directly obtain products from lignocellulose such as xylooligosaccharide, microcrystalline cellulose, hydrochar, and so on. This chapter describes the technological characteristics and development of LHW process, summarizes the way of LHW treatment to influence the physicochemical features of lignocellulose and the biorefinery efficiency, and depicts the application of LHW technology for bioproduct production. It concludes that LHW treatment is a versatile biorefinery technology and outlooks the promising way for the practical application of LHW technology.
... Pubescens was heated to 200 • C in water without addition of catalyst, and more than 95% of hemicellulose could be dissolved (hydrolyzed), while cellulose and lignin structure were hardly destroyed. Nabarlatz et al. built an autocatalytic hydrolysis model for xylan based on the experimental results at 150-190 • C [202]. According to the model, high temperature could promote the conversion of polymers to oligomers. ...
Furan energy platform compounds including furfural and 5-hydroxymethylfurfural (HMF), can be produced by hydrothermal conversion of biomass. After hydrodeoxygenation, these furans can be converted into value-added chemicals and liquid fuels. This will help achieve efficient utilization of biomass and alleviate the environment issues caused by the overuse of fossil fuels. This review introduces the recent progress in the production of furfural and HMF from biomass and its derived sugars in homogeneous catalytic systems. The topics mainly include catalytic mechanisms, catalytic systems, and conversion processes. The synergistical catalytic effect of Lewis acid and Brønsted acid is crucial in furan production. Therefore, the development of metal salts and ionic liquids, which exhibit both kinds of acidity, has been the focus of recent attention. The type and composition of catalyst also play key roles in producing furan products. Thus, the design and improvement of the catalyst based on mechanism research will be helpful to the highly selective hydrothermal conversion of biomass. Reasonable selection of solvent system can improve the conversion efficiency significantly and avoid the occurrence of various side reactions. Especially, the online extraction of the biphasic solvent system can prevent some certain products from being consumed by the secondary reaction. Till now, the lab-scale homogeneous conversion process has been fully developed. Future research will focus on the magnification and commercialization of laboratory process. The key technical problems in the commercialization process is how to increase the recyclability, economy and eco-friendly property of the reaction system under the premise of satisfying product yield.
