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Herein, an efficient biphasic pretreatment process was developed to improve the production of furfural (FF) and glucose from Eucalyptus. The influence of formic acid and NaCl on FF production from xylose in water and various biphasic systems was investigated. Results showed that the addition of formic acid and NaCl significantly promoted the FF yield, and the biphasic system of MIBK (methyl isobutyl ketone)/water exhibited the best performance for FF production. Then the Eucalyptus was pretreated in the MIBK/water system, and a maximum FF yield of 82.0% was achieved at 180°C for 60min. Surface of the pretreated Eucalyptus became relatively rough and loose, and its crystallinity index increased obviously due to the removal of hemicelluloses and lignin. The pretreated Eucalyptus samples showed much higher enzymatic hydrolysis rates (26.2-70.7%) than the raw Eucalyptus (14.5%)., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

BACKGROUND: Pistachio shell is a valuable lignocellulosic biomass because almost 90% of its hemicellulose fraction is xylan, which can be converted into high value‐added compounds such as xylooligosaccarides, xylose, xylitol and furfural. The present study represents a green and novel approach to produce xylose from lignocellulosic biomass. Microwave‐assisted high‐pressure CO2/H2O hydrolysis (MW‐HPCO2) comprising a combination never previously used was performed to produce xylose from pistachio shell. RESULTS: Response surface methodology with a Box–Behnken design was implemented to optimize microwave‐assisted high‐pressure CO2/H2O hydrolysis (MW‐HPCO2). The effect of temperature, time and liquid‐to‐solid ratio was studied in the ranges of 180–210 °C, 10–30 min and 5–30 mL g−1, respectively. A maximum xylose yield of 61.39% and minimum degradation compounds (5‐hydroxymethyl furfural and furfural) of 11.07% were attained under reaction conditions of 190 °C, 30 min and 18 mL g−1. CONCLUSION: The results showed that hydrolysis temperature, time and liquid‐to‐solid ratio had a strong influence on the xylose yield, as well as on the formation of degradation compounds. MW‐HPCO2 significantly increased accessibility to cellulose‐derived products in the subsequent enzymatic hydrolysis. The results of the present study reveal that MW‐HPCO2 can be a promising green technique for the hydrolysis of lignocellulosic biomass. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Areca nut husk is the most promising alternative source of low-cost raw materials because it contains a considerable amount of five-carbon monosaccharide sugar in the form of xylose. This polymeric sugar can be isolated and transformed into a value-added chemical using fermentation. To extract sugars from areca nut husk fibers, preliminary pretreatment, such as dilute acid hydrolysis (H2SO4), was performed. The hemicellulosic hydrolysate of areca nut husk can produce xylitol through fermentation, but toxic components inhibit the growth of microorganisms. To overcome this, a series of detoxification treatments, including pH adjustment, activated charcoal, and ion exchange resin, were carried out to reduce the concentration of inhibitors in the hydrolysate. This study reports a remarkable 99% removal of inhibitors in the hemicellulosic hydrolysate. Subsequently, a fermentation process using Candida tropicalis (MTCC6192) was executed with the detoxified hemicellulosic hydrolysate of areca nut husk, yielding an optimum xylitol yield of 0.66 g/g. This study concludes that detoxification techniques like pH adjustment, activated charcoal, and ion exchange resins are the most economical and effective methods for eliminating toxic compounds in hemicellulosic hydrolysates. Therefore, the medium derived after detoxification from areca nut hydrolysate may be considered to have significant potential for xylitol production. [ABSTRACT FROM AUTHOR]

Waste disposal issue is among of highly concerned issue all over the world. In Malaysia, this waste usually ends up being in landfills. This is not any exception especially in agriculture and manufacturing industry whose has to deal with many-by-products after a production. Thus, in this study focuses on by-product from canning and beverage industry which is pineapple peel for its xylose recovery. The aim of this recovery is to provide cost effective means of producing high-end product such xylitol. In this study, crucial parameter of mild hydrolysis was optimized by using One-Factor at Time (OFAT) method. Batch hydrolysis was carried out with the following parameters: acid concentration (0.5-7%), residence time (5-50 min), and temperature (80-130 °C). As a result, the highest xylose concentration obtains around 20 g/L under the condition of 5 % nitric acid concentration, 105°C for 20 min residence time. The result showed this method can yield up to 85 % of actual xylose concentration from the hemicellulose degradation. Altogether, the finding of this study is beneficial to the pineapple industry, especially in light of recent discussion in terms of waste disposal issue and its impact on greenhouse gas emission. [ABSTRACT FROM AUTHOR]

Sustainable and renewable sources of liquid and solid fuels are essential to prevent fossil fuel use from damaging the environment. Secondary agricultural residues, which are already transported to food processing centers, have great potential to be converted into biofuels. The wastes from coffee roasting, sugar production, and rice milling have been investigated using hydrothermal carbonization (HTC) to produce aqueous products containing monosaccharides alongside solid biofuels. These sugar-laden liquid products were characterized after pretreating coffee silverskins, sugarcane bagasse, and rice husks with HTC. They were then concentrated using direct contact membrane distillation (DCMD), a low-energy process that can use waste heat from other biorefinery processes. The higher heating value of the solid products was also characterized by bomb calorimetry. The liquid products from HTC of these wastes from food production were found to contain varying concentrations of glucose, xylose, galactose, and arabinose. DCMD was capable of concentrating the liquid products up to three times their original concentrations. Little difference was found among the higher heating values of the solid products after 180 °C HTC pretreatment compared to 200 °C pretreatment. HTC of waste from food processing can provide solid biofuels and liquid products containing sugars that can be concentrated using DCMD. [ABSTRACT FROM AUTHOR]

Xylanolytic enzymes, with both endo‐xylanase and arabinoxylan arabinofuranohydrolase (AXH) activities, are attractive for the economically feasible conversion of recalcitrant arabinoxylan. However, their characterization and utilization of these enzymes in biotechnological applications have been limited. Here, we characterize a novel bifunctional enzyme, rAbf43A, cloned from a bacterial consortium that exhibits AXH and endo‐xylanase activities. Hydrolytic pattern analyses revealed that the AXH activity belongs to AXHd3 because it attacked only the C(O)‐3‐linked arabinofuranosyl residues of double‐substituted xylopyranosyl units of arabinoxylan and arabinoxylan‐derived oligosaccharides, which are usually resistant to hydrolysis. The enzyme rAbf43A also liberated a series of xylo‐oligosaccharides (XOSs) from beechwood xylan, xylohexaose and xylopentaose, indicating that rAbf43A exhibited endo‐xylanase activity. Homology modelling based on AlphaFold2 and site‐directed mutagenesis identified three non‐catalytic residues (H161, A270 and L505) located in the substrate‐binding pocket essential for its dual‐functionality, while the mutation of A117 located in the −1 subsite to the proline residue only affected its endo‐xylanase activity. Additionally, rAbf43A showed significant synergistic action with the bifunctional xylanase/feruloyl esterase rXyn10A/Fae1A from the same bacterial consortium on insoluble wheat arabinoxylan and de‐starched wheat bran degradation. When rXyn10A/Fae1A was added to the rAbf43A pre‐hydrolyzed reactions, the amount of released reducing sugars, xylose and ferulic acid increased by 9.43% and 25.16%, 189.37% and 93.54%, 31.39% and 32.30%, respectively, in comparison with the sum of hydrolysis products released by each enzyme alone. The unique characteristics of rAbf43A position it as a promising candidate not only for designing high‐performance enzyme cocktails but also for investigating the structure–function relationship of GH43 multifunctional enzymes. [ABSTRACT FROM AUTHOR]

This work presents the study of heterogeneous catalysis of sugarcane bagasse hydrothermal treatment spent liquors using a sulfonated resin. Besides, results were compared with those obtained by a conventional route using sulfuric acid as a homogeneous catalyst. Heterogeneous catalysis is suitable for the hydrolysis of sugarcane bagasse hydrothermal liquors under mild conditions (100°C and 6 h). The obtained maximum xylose yield was 82% due to furfural formation, which causes a xylose selectivity drop. The hydrogenation of this xylose-rich liquor at 100 °C and 3 MPa of hydrogen pressure employing a supported Ni/γ-Al2O3 produced the total conversion of xylose with a selectivity towards xylitol of 100% by using a catalyst to xylose mass ratio of 0.5. Heterogeneous catalysis in a two-step route (hydrolysis and hydrogenation) constitutes an outstanding alternative to producing xylitol from sugarcane bagasse hydrothermal spent liquors since materials can be easily separated and reused in several reaction cycles.

A dilute acid hydrolysis of rice husk (RH), wheat straw (WS), and their extractive-free residues was investigated with the objective of recovering the highest yield of xylose while keeping at minimum its conversion into furfural. The hydrolysis conditions were determined for different concentrations of sulfuric acid and different reaction times at 121 °C. The pre-extraction with ethanol-water (1:1, v/v) was also examined as a parameter. Using response surface methodology, the optimum conditions for xylose production were identified as 1.8% of acid and 41.4 min of hydrolysis time for RH, while those for its counterpart EF-RH (extractives-free rice husks) were 1.0% acid concentration, for 60 min. The same conditions were also predicted for WS and its EF-WS. Under these conditions, the xylose yield was 79.6%, 82.8%, 94.3%, and 88.6% for RH, EF-RH, WS, and EF-RW, respectively. Under these conditions the minimal furfural yields obtained were 1.2% and 1.3% for RH and EF-RH, and 0.8% and 1.5%, for WS and EF-WS, respectively. These results suggested that the pre-extraction step before the acid hydrolysis affected, at least in part, the xylose recovery from RH, but it was not necessary for a better xylose yield of WS for its bioconversion into valuable bioproducts like xylitol.

In the context of a biorefinery, lignocellulosic materials represent an important source of raw material for the bioconversion of cellulose, hemicellulose, and lignin into value-added products, such as xylose for fermentation, oligosaccharides, and bioplastics for packaging. Among the most abundant lignocellulosic materials in Brazil, sugarcane bagasse biomass stands out, as it is rich in cellulose and hemicellulose. In this context, through an experimental design, this study developed a robust enzyme cocktail containing xylanases and accessory enzymes to complete the hydrolysis of xylan from sugarcane bagasse, obtaining a low xylose yield and concentration (9% and 1.8 g/L, respectively, observed in experiment number 16 from the complete hydrolysis of a xylan assay), a fermentable sugar that is important in the production of second-generation ethanol, and a high xylooligosaccharides (XOS) yield and concentration (93.1% and 19.6 g/L, respectively, obtained from a xylooligosaccharides production assay); in general, xylan has prebiotic activities that favor an improvement in intestinal functions, with immunological and antimicrobial actions and other benefits to human health. In addition to completely hydrolyzing the sugarcane bagasse xylan, this enzymatic cocktail has great potential to be applied in other sources of lignocellulosic biomass for the conversion of xylan into xylose and XOS due to its enzymes content, involving both main chain and pendant groups hydrolysis of hemicelluloses. [ABSTRACT FROM AUTHOR]

The main components of the birch wood were fractionated into a microcrystalline cellulose, xylose and enterosorbents by an integration of heterogeneous catalytic processes of an acidic hydrolysis and a peroxide delignification of the wood biomass for the first time. The wood hemicelluloses were hydrolyzed to xylose at a temperature of 150°C in the presence of the Amberlyst® 15 solid acidic catalyst. Then, the lignocellulosic product of the wood hydrolysis was subjected to the peroxide delignification in the formic acid–water medium in the presence of the solid TiO2 catalyst with a formation of the microcrystalline cellulose (MCC) and the organic-soluble lignin. Yields of MCC and the organic-soluble lignin proved to be 64.5 and 11.5 wt % of a mass of the prehydrolyzed wood, respectively, under the determined optimal conditions (100°C, 7.2 wt % of Н2О2, 37.8 wt % of НСООН, LWR 15, and a duration of 4 h). The enterosorbents were prepared by a treatment of the organic-soluble lignin with 0.4% NaHCO3 or hot water. The sorption capacity of these enterosorbents was 97.7 and 236.7 mg/g according to methylene blue and gelatin, respectively. These values were significantly higher than those of the Polifepan commercial enterosorbent (44 and 115 mg/g, respectively). The products of the catalytic fractionation of the birch wood were characterized by physicochemical (FTIR, XRD, SEM, and GC) and chemical methods. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effect of extrusion at high solid loading on corn stover (CS) properties and its enzymatic hydrolysis. This biomass was extruded under different screw speeds and different solid loadings and the impact of these parameters on the physicochemical properties was evaluated. It was found that lignocellulosic components were not significantly affected by the pretreatment, while the surface area increased with solid loading and rotation speed. Different enzyme cocktails were used for the enzymatic hydrolysis of extruded and untreated CS. Overall, mild twin‐extrusion enhanced the enzymatic hydrolysis of CS through an increase in glucose and xylose yields by 134–212% and 214–294%, respectively, when using Trichoderma longibrachiatum cellulase. The highest sugar content was obtained from CS extruded under 400 g total solids per liter and 200 rpm. The energy efficiency of the pretreatment was also assessed and was found to be maximal at 400 g total solids per liter and 200 rpm. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Xylose is an abundant bioresource for obtaining diverse chemicals and added-value products. The production of xylose from green alternatives like enzymatic hydrolysis is an important step in a biorefinery context. This research evaluated the synergism among four classes of hydrolytic purified enzymes—endo-1,4-β-xylanase, α-l-arabinofuranosidase, β-xylosidase, and α-d-glucuronidase—over hydrolysis of glucuronoarabinoxylan (GAX) obtained from brewers' spent grain (BSG) after alkaline extraction and ethanol precipitation. First, monosaccharides, uronic acids and glycosidic-linkages of alkaline extracted GAX fraction from BSG were characterized, after that different strategies based on the addition of one or two families of enzymes—endo-1,4-β-xylanase (GH10 and GH11) and α-l-arabinofuranosidase (GH43 and GH51)—cooperating with one β-xylosidase (GH43) and one α-d-glucuronidase (GH67) into enzymatic hydrolysis were assessed to obtain the best yield of xylose. The xylose release was monitored over time in the first 90 min and after a prolonged reaction up to 48 h of reaction. The highest yield of xylose was 63.6% (48 h, 40 ℃, pH 5.5), using a mixture of all enzymes devoid of α-l-arabinofuranosidase (GH43) family. These results highlight the importance of GH51 arabinofuranosidase debranching enzyme to allow a higher cleavage of the xylan backbone of GAX from BSG and their synergy with 2 endo-1,4-β-xylanase (GH10 and GH11), one β-xylosidase (GH43) and the inclusion of one α-d-glucuronidase (GH67) in the reaction system. Therefore, this study provides an environmentally friendly process to produce xylose from BSG through utilization of enzymes as catalysts. [ABSTRACT FROM AUTHOR]

A dilute acid hydrolysis of rice husk (RH), wheat straw (WS), and their extractive-free residues was investigated with the objective of recovering the highest yield of xylose while keeping at minimum its conversion into furfural. The hydrolysis conditions were determined for different concentrations of sulfuric acid and different reaction times at 121 °C. The pre-extraction with ethanol-water (1:1, v/v) was also examined as a parameter. Using response surface methodology, the optimum conditions for xylose production were identified as 1.8% of acid and 41.4 min of hydrolysis time for RH, while those for its counterpart EF-RH (extractivesfree rice husks) were 1.0% acid concentration, for 60 min. The same conditions were also predicted for WS and its EF-WS. Under these conditions, the xylose yield was 79.6%, 82.8%, 94.3%, and 88.6% for RH, EF-RH, WS, and EF-RW, respectively. Under these conditions the minimal furfural yields obtained were 1.2% and 1.3% for RH and EF-RH, and 0.8% and 1.5%, for WS and EF-WS, respectively. These results suggested that the pre-extraction step before the acid hydrolysis affected, at least in part, the xylose recovery from RH, but it was not necessary for a better xylose yield of WS for its bioconversion into valuable bioproducts like xylitol. [ABSTRACT FROM AUTHOR]

BACKGROUND: Bulgur bran (BB) is a potential source for the production of value‐added products such as fermentable sugars and xylooligosaccharides (XOs). In this study, alkali combined twin‐screw extrusion pretreatment was performed and statistically optimized to enhance fractionation and enzymatic hydrolysis of BB. The pretreatment conditions (barrel temperature, screw speed and alkali impregnation) were optimized by Box–Behnken design (BBD) to obtain the highest hemicellulose separation from BB. The obtained fractions were analyzed for the production of fermentable sugars and XOs. RESULTS: The results revealed that twin‐screw extrusion of BB performed at 67 °C barrel temperature and 250 rpm screw speed after alkali impregnation at 0.02 g alkali g−1 biomass concentration provided 40.4% higher hemicellulose separation yield compared to the untreated BB. Alkali combined twin‐screw extrusion pretreatment increased the enzymatic hydrolysis yield of BB fourfold, whereas a 13‐fold increase was achieved after the separation of hemicellulose from pretreated BB. Xylose (X1)‐free xylobiose (X2) was the main product after xylanase hydrolysis of hemicellulose fraction. SEM images confirmed the morphological modifications in BB, which were in agreement with the enhanced fractionation performance and the higher enzymatic hydrolysis yield. CONCLUSION: The results of this study suggested that pretreatment by alkali combined twin‐screw extrusion followed by alkali extraction could be a reliable and effective process for fractionation of BB and production of fermentable sugars and XOs. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Glycoside hydrolases (GHs) are enzymes that hydrolyze glycosidic bonds, but some of them can also catalyze the synthesis of glycosides by transglycosylation. However, the yields of this reaction are generally low since the glycosides formed end up being hydrolyzed by these same enzymes. For this reason, mutagenic variants with null or drastically reduced hydrolytic activity have been developed, thus enhancing their synthetic ability. Two mutagenic variants, a glycosynthase engineered from a β-glucosidase (BGL-1-E521G) and a thioglycoligase from a β-xylosidase (BxTW1-E495A), both from the ascomycete Talaromyces amestolkiae, were used to synthesize three novel epigallocatechin gallate (EGCG) glycosides. EGCG is a phenolic compound from green tea known for its antioxidant effects and therapeutic benefits, whose glycosylation could increase its bioavailability and improve its bioactive properties. The glycosynthase BGL-1-E521G produced a β-glucoside and a β-sophoroside of EGCG, while the thioglycoligase BxTW1-E495A formed the β-xyloside of EGCG. Glycosylation occurred in the 5″ and 4″ positions of EGCG, respectively. In this work, the reaction conditions for glycosides' production were optimized, achieving around 90% conversion of EGCG with BGL-1-E521G and 60% with BxTW1-E495A. The glycosylation of EGCG caused a slight loss of its antioxidant capacity but notably increased its solubility (between 23 and 44 times) and, in the case of glucoside, also improved its thermal stability. All three glycosides showed better antiproliferative properties on breast adenocarcinoma cell line MDA-MB-231 than EGCG, and the glucosylated and sophorylated derivatives induced higher neuroprotection, increasing the viability of SH-S5Y5 neurons exposed to okadaic acid. [ABSTRACT FROM AUTHOR]

Commercially available cellulase cocktails frequently demonstrate high efficiency in hydrolyzing easily digestible pretreated biomass, which often lacks hemicellulose and/or lignin fractions. However, the challenge arises with enzymatic hydrolysis of mildly pretreated lignocellulosic biomasses, which contain cellulose, hemicellulose and lignin in high proportions. This study aimed to address this question by evaluating the supplementation of a commercial cellulolytic cocktail with accessory hemicellulases and two additives (H 2 O 2 and Tween® 80). Statistical optimization methods were employed to enhance the release of glucose and xylose from mildly pretreated sugarcane bagasse. The optimized supplement composition resulted in the production of 304 and 124 mg g−1 DM of glucose and xylose, respectively, significantly increasing glucose release by 84% and xylose release by 94% compared to using only the cellulolytic cocktail. This enhancement might be attributed to a coordinated hemicellulases action degrading hemicellulose, creating more space for cellulase activity, potentially boosted by the presence of H 2 O 2 and Tween® 80. However, the addition of different concentrations of H 2 O 2 in combination with hemicellulase and Tween® 80 did not result a significant difference on sugar release, which could be attributed to the limited range of concentrations studied (5 to 65 µM). The results obtained in this study using the mix of three supplements were also compared to the addition of only hemicellulase and only Tween® 80 to the cellulolytic cocktail. A significant increase in glucose release of 39% and 41%, respectively, was observed when using the optimized combination. For xylose, the increase was 38% and 41%, respectively. This study underscores the substantial potential in optimizing enzyme cocktails for the hydrolysis of mildly pretreated lignocellulosic biomass by using enzymes and additive combinations tailored to the specific biomass composition. [Display omitted] • Enzyme cocktail composition was optimized using a Box-Benhken design. • Addition of hemicellulase and Tween® 80 led to higher glucose and xylose production. • Addition of H2O2 (5-65 μM) did not result a significant difference on sugar release. • Optimum condition increased glucose and xylose production in 84% and 94% respectively. [ABSTRACT FROM AUTHOR]

Hydrolysis of sugarcane bagasse to xylose using a dilute sulfuric acid catalyst was investigated. An optimum xylose yield of roughly 0.18 g/g of dry bagasse was obtained in 32 min with 0.77% sulfuric acid at 143 °C. Model-Based Calibration Toolbox in MATLAB software was used for the design of experiments, statistical modeling, and optimization. The mathematical model for the hydrolysis of sugarcane bagasse to xylose was developed using experimental data obtained based on the Central composite design. Although the combined effect of temperature, acid concentration, and time was positive towards the formation of glucose and furfural, harsher treatment conditions have negative effects on the yield of xylose. With a maximum yield of 54.09%, the teff straw-based solid acid catalyst (TSSC) was stable and successful in converting the sugarcane bagasse hydrolysate into furfural. [ABSTRACT FROM AUTHOR]

The effectiveness of chemical steeping was examined as a novel pretreatment prior to hydrolysis to influence the extractable yield of glucose and xylose from oil palm trunk (OPT). The chemical steeping parameters were 0.2% sodium metabisulphite (w/v), 0.5% lactic acid (v/v), 26 ± 2 °C, and 1 h, followed by dilute acid hydrolysis (2%, 4%, and 6% of sulphuric acid (v/v); 115 °C, 120 °C, and 130 °C; 15 min, 30 min, and 60 min). For comparison, the glucose and xylose yield extracted from untreated OPT was also examined. Thermal analysis showed that the lactic acid and sodium metabisulphite successfully degraded the lignocellulose of OPT. The total extracted glucose and xylose yield was improved, and was approximately 2.5% to 28.8% higher than the yield extracted from non-pretreated OPT fines. RSM analysis showed that the 130 °C x 50 min x 2% was predicted as the optimum parameters for the extraction of glucose and xylose through chemically treated OPT, and followed the dilute acid hydrolysis process. Analysis of variance showed that the hydrolysis parameters were significant model terms for the glucose and xylose yield. In conclusion, chemical steeping was successful as a pretreatment to increase the extractable glucose and xylose yield from OPT. [ABSTRACT FROM AUTHOR]

This study aimed to determine an appropriate unstructured kinetic model describing the growth of Debaryomyces hansenii with the hydrolysis of oil palm empty bunches as the substrate sources. We tested the well-known cell growth kinetic models for approximating the xylitol fermentation data. We modeled the extracellular process by considering the biomass as a variable, xylose as the substrate and xylitol as the product. The appropriate kinetic model was determined by fitting the models to the experimental data. The fitting process involved an optimization procedure that minimizes a least-squared error between the model solution and the experimental data using a gradient-based method. We found that the unstructured model with Monod specific kinetic growth model had the best approximating ability to describe the dynamics of the batch xylitol fermentation data. Some factors were highlighted as the key factors that influence the growth of yeast cells. One of them is the maximum growth rate of the yeast cell which had a high sensitivity to the maximum production of new cells and xylitol as the main product. As Monod was the best-approximated model, it implies that inhibitory effects by substrate and product played an important role in controlling the growth of yeast cells. There was a certain maximum growth rate for the yeast cell that generates maximum production of new cells and xylitol within a relatively short fermentation time. This result indicates that the growth rate parameter played an important role in adjusting the fermentation process for optimality purposes. [ABSTRACT FROM AUTHOR]

The hemicellulose content present in corn cobs can help in producing a high amount of xylooligosaccharides (XOS) in an eco-friendly manner. In this work, the XOS was produced from alkali pre-treated corn-cobs having a true yield of 38 ± 1.4% via enzymatic hydrolysis with the help of xylanase from T. lanuginosus VAPS-24. The production process was optimized to achieve a high concentration of XOS using innovative multi-objective optimization through machine learning modeling and finding out the most suitable parameters where xylobiose production is higher than xylose. The Multi-objective connected neural networks (MOCNN) model with tangent sigmoid activation function yielded a correlation coefficient of 96.51%; there were six optimal sets where xylobiose concentration was higher than xylose. The best-optimized conditions yielded 3.03 mg/ml of xylobiose and 1.31 mg/ml of xylose. Therefore, this novel approach of machine learning can target the increasing demand for xylooligosaccharides in the growing industrial market of prebiotics. [ABSTRACT FROM AUTHOR]

Summary: Considering its worldwide abundance, cellulose can be a suitable candidate to replace the fossil oil‐based materials, even if its potential is still untapped, due to some scientific and technical gaps. This work offers new possibilities demonstrating for the first time the ability of a cerato‐platanin, a small fungal protein, to valorize lignocellulosic Agri‐food Wastes. Indeed, cerato‐platanins can loosen cellulose rendering it more accessible to hydrolytic attack. The cerato‐platanin ThCP from a marine strain of Trichoderma harzianum, characterized as an efficient biosurfactant protein, has proven able to efficiently pre‐treat apple pomace, obtaining a sugar conversion yield of 65%. Moreover, when used in combination with a laccase enzyme, a notable increase in the sugar conversion yield was measured. Similar results were also obtained when other wastes, coffee silverskin and potato peel, were pre‐treated. With respect to the widespread laccase pre‐treatments, this new pre‐treatment approach minimizes process time, increasing energy efficiency. [ABSTRACT FROM AUTHOR]

Enzymatic hydrolysis is an essential step in the lignocellulosic biomass treatment for the conversion of cellulose and hemicellulose into fermentable sugars. In the present study, a physical steam explosion (200°C) and chemical alkaline pre-hydrolysis (10% v/v) were applied to hemp (Cannabis sativa L.) biomass, to verify the effectiveness of different pretreatment processes, in order to increase enzymatic hydrolysis and the final sugar yield. The enzymatic degradations were carried out also utilizing extremophilic microorganisms, exploited as a source of (hemi)cellulases to be used as components of the enzymatic cocktail applied in the bioconversion into fermentable sugars for production of second generation ethanol and high value products. Alkaline pretreatment showed to be superior over the physical method with respect to the rate of enzymatic hydrolysis, with the obtainment of an hydrolysis yields of 90% xylose and 40% glucose, respectively. [ABSTRACT FROM AUTHOR]

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• Semi-continuous subcritical hydrolysis of orange wastes to obtaining fermentable sugars. • Yields for platform chemicals (organic acids, furfural, and HMF) are also addressed. • Effects of biomass pretreatment (extraction by soxhlet e supercritical CO 2) were discussed. • 5.3 g/100 g orange peel of hydrolyzed solution was obtained at 180 °C and 15 MPa. • Also, 4.3 g/100 g orange bagasse of hydrolyzed solution was obtained at 200 °C and 20 MPa. Results for the obtaining of fermentable sugars (FSs) and platform chemicals (PCs) from the subcritical hydrolysis of orange wastes (peel and bagasse) are presented. Unlike what is typically reported in similar studies involving lignocellulosic biomasses, the hydrolysis process was performed in a semi-continuous configuration, which allowed the examination of how temperature (180 to 220 °C) and pressure (15 to 25 MPa) influenced the compounds' kinetic profile. Furthermore, studies have been found that evaluated these points for such biomasses. The best yields of hydrolyzed solution were obtained for biomasses pretreated by soxhlet with hydrolysis conducted at 180 °C and 15 MPa (orange peel, OP) and 200 °C and 20 MPa (orange bagasse, OB), yielding 5.31 and 4.26 g (100 g biomass)−1, respectively. Among the FSs, xylose was the monosaccharide predominantly obtained for both biomasses: 21.12 g L −1 for OP pretreated with SCO 2 (hydrolysis at 180 °C and 15 MPa); and 24.45 g L −1 for untreated OB (hydrolysis at 220 °C and 25 MPa). Regarding the PCs, furfural was the main compound obtained for both biomasses: 10.86 g L −1 for untreated OP and 7.33 g L −1 for OB pretreated with SCO 2 , with both hydrolysis conducted at 220 °C and 25 MPa. [Display omitted] [ABSTRACT FROM AUTHOR]

This study aims to examine the potential of Babool wood (Acacia nilotica) as an alternative and sustainable resource to produce value added chemicals and/or useful intermediates like sugars. The performance of Babool wood digestability and hydrolysis to sugars was compared using three acids: H 2 SO 4 /H 3 PO 4 /HCl and ionic liquid [Bmim] Cl catalyzed by modified activated carbon. Hydrolysis using sulphuric acid treated Babool wood leads to the formation of total reducing sugar (TRS) ranging from 53.34% to 83.67% yield under different conditions. Babool wood treated with acid was characterized using Fourier Transformation Infrared Spectroscopy, X- Ray Diffraction and Lignocellulosic compositional analysis. Further, the effect of process variables such as acid strength, acid concentration, acid to Babool wood ratio, Babool wood particle size, hydrolysis time, and temperature on the TRS yield was explored. Maximum TRS yield was observed to be 83.67% in a reaction time of 60 min using −80 + 100 mesh of Babool wood at 393 K. Kinetic results were successfully simulated with literature model (R2 > 0.9) for rate of formation of sugar. This study provides a single step approach for Babool wood hydrolysis to sugars. • Alternative and sustainable forestry biomass to produce value added products. • Acid/IL combination catalyzed by solid acid catalyst without delignification step. • Acid strength and concentration, particle size and reaction time influence TRS yield. • Simulation of Kinetic results with literature model (R2 > 0.9). [ABSTRACT FROM AUTHOR]

Dilute sulfuric acid hydrolysis of Pennisetum (sp.) hemicellulose was investigated in this work. The hemicellulose was obtained by ethanol precipitation of hydrolysate produced via the microwave-assisted H2O2-NaOH extraction from the Pennisetum (sp.). Acid hydrolysis was performed by varying the process parameters, including the sulfuric acid concentration, hydrolysis temperature, solid to liquor ratio, and the reaction time. The xylose yield was selected as the target of process optimization and the orthogonal experiment of L9 (34) was designed to optimize the process conditions. The highest xylose yield of 86.5% could be obtained under the conditions of an acid concentration of 1%, the hydrolysis temperature of 105 °C, a solid to liquor ratio of 1:15, and a reaction time of 4 h. Fourier transform infrared spectroscopy (FTIR) analysis confirmed that most of the hemicellulose had been depolymerized into xylose.

Graphical abstract Highlights • Hydrothermal fractionation of brewer´s spent grains in a semi-continuous reactor. • Temperature influenced production of compounds solubilized in subcritical water. • The flow rate of 20 mL/min with an S/F: 64, maximize production of sugars. • The maximum RS yield was 5.89% and the maximum TRS yield was 35.11%. • Maximum yield of C5 was approximately 3.35%. Abstract The objective of this work was to produce C-5 sugars from the hydrolysis of the spent grains of the brewery. The total sugar recovery and formation of by-products were evaluated as a function of the reaction temperature (140, 160, 180 and 210 °C), flow rate (10 and 20 mL min–1) and the solvent/feed ratio (S/F: 64, 80 and 112). The total carbohydrate yields were dependent on the hydrolysis temperature. Arabinose was the main product, followed by xylose and the arabinose yield increased with increasing the S/F ratio and the flow rate. Yields of furfural were sensitive to flow rate. The hemicellulose content of the residual solids was reduced by approximately 90% after hydrolysis, with the parallel formation of carbonyl and carbonized species. The effects of flow rate on the efficiency of converting hemicellulose into simple sugars were complex, suggesting roles for the formation of autocatalytic acids. [ABSTRACT FROM AUTHOR]

Hemicellulose in the complex structure of lignocellulosic substances is mainly composed of xylan which is a polymer based on monosaccharide xylose. Using acidic or enzymatic hydrolysis, hemicellulose can be depolymerized into its constituent monomer. The kinetics of hemicellulose depolymerization and decomposition in oat hull was investigated under moderate pressures with catalyst (H2SO4) concentration up to 0.55 N and temperatures of up to 130 °C for a total residence time of 150 min. Different trends of recovery or generation and kinetic mechanisms obtained for the components in the hydrolysate which could be described by different kinetic models, that is, a single-phase kinetic mechanism with product decomposition (two-step sequential reaction) could describe xylose generation. However, generation of arabinose, furfural, and acetic acid followed a single-phase mechanism with no decomposition (one-step reaction). Generation of glucose in the hydrolysate followed a biphasic mechanism due to the fast- and slow-releasing fractions into the liquid phase which was apparently with no decomposition. A pentose recovery of almost 80% was achieved under optimal conditions. Parameters of xylitol bioproduction indicated that a xylitol/xylose conversion yield of 0.80 g/g is achievable from the concentrated hydrolysate with no complementary treatment proving its low toxicity compared to other hemicellulose resources. [ABSTRACT FROM AUTHOR]

Abstract Rice straw is an agricultural residue rich in cellulose and hemicelluloses. Therefore, the objective of this study was to obtain fermentable sugars and bioproducts from this biomass by subcritical water hydrolysis (SWH) in a scaleable semi-continuous mode. Temperatures of 180 °C, 220 °C and 260 °C, and liquid/solid mass ratios of 7.5 g water/g straw and 15 g water/g straw were evaluated on the reducing sugar yield (Y RS), efficiency of conversion (E), kinetic profiles, composition of inhibitors and bioproducts, and physicochemical characteristics of remaining solid material. The pressure was set at 25 MPa and the reaction time was evaluated up to 15 min. The thermogravimetric analysis and Fourier Transform Infrared Spectroscopy provided additional information on the bulk and surface modification of the residual biomass. The highest Y RS (33.4 ± 4.3 g/100 g dry straw) and E (72.1 ± 4.6 g sugar equivalents in glucose per 100 g of carbohydrates) were obtained at 220 °C and liquid/solid mass ratio of 7.5 g water/g straw. The analysis of the hydrolyzed solution indicated xylose (0.29–7.81 wt.%), arabinose (0.35–4.85 wt.%), cellobiose (0.04–3.41 wt.%), glucose (0.05–1.54 wt.%), and levulinic acid (0.04–0.77 wt.%). The fermentable sugars and bioproducts can be applied in several industrial fields, especially for the production of bioethanol and other higher value-added chemical compounds. Furthermore, SWH performed in semi-continuous mode is a green technology within the biorefinery concept that can be operated at industrial scale for processing lignocellulosic biomass. Graphical abstract Image 1 Highlights • Subcritical water hydrolysis was applied to obtain fermentable sugars and bioproducts. • Temperature (180 °C, 220 °C, 260 °C) and water to solid mass ratio were evaluated. • 33.4 wt.% reducing sugars and 0.77 wt.% levulinic acid were obtained at 220 °C. • Conversions of cellulose and hemicelluloses into reducing sugars were up to 70 wt.%. • Dissociation of the lignocellulosic structure was evaluated by thermogravimetry. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Weak acid solid catalyst prepared by pyrolysis of lignin and KOH from black liquor. • Mechanochemical pretreatment of catalyst and substrate gave high hydrolysis yields. • 76.3% glucose yield was achieved from cellulose in 0.015 wt% HCl aqueous solution. • The catalyst showed good stability and recyclability in the aqueous reaction system. • A promising process for the comprehensive utilization of lignocellulosic biomass. Abstract In this work, carbonaceous materials bearing only weakly acidic COOH and phenolic OH groups were directly prepared by the pyrolysis of lignin and KOH in black liquor generating from rice straw that was pretreated with KOH aqueous solution. The synthesized carbon materials were used for the hydrolysis of cellulose or the alkali pretreated rice straw in water, after mixed ball-milling pretreatment, and provided a high glucose yield of 76.3% for cellulose, high yields of 52.1% glucose and 66.5% xylose for alkali pretreated rice straw, respectively, in 0.015 wt% HCl aqueous solution at 200 °C for 60 min. The weakly acidic catalyst showed good stability and recyclability in the aqueous reaction system. This work provides an efficient process for the hydrolysis of lignocellulose by biomass-derived weakly acidic catalysts in water and should have wide applications in biomass utilization. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hydrothermal acid hydrolysis was applied to treat the pre-hydrolysis liquor. • A maximum lignin removal rate of 57.1% was achieved by hydrothermal acid hydrolysis. • Most hemicelluloses were converted into xylose after hydrothermal acid hydrolysis. • The obtained lignin showed high surface hydrophilicity and thermal stability. Abstract In this study, the effect of traditional acidification and hydrothermal acid hydrolysis on the separation of lignin and xylose from the pre-hydrolysis liquor (PHL) of kraft pulping process was comparatively evaluated. The PHL was acidified at room temperature or hydrothermally treated under acidic conditions to isolate lignin and xylose. As compared with the lignin removal rate of 26.8–32.7% by traditional acidification method, a much higher lignin removal rate of 57.1% was achieved by hydrothermal acid hydrolysis. Meanwhile, the content of xylose in the PHL increased dramatically from 7.91 to 13.91–34.82 g/L after the hydrothermal acid hydrolysis. The hydrophilicity of the obtained lignin gradually increased as evidenced by the decrease of the corresponding water contact angel. Additionally, the thermal stability of the lignin sample increased steadily with the increment of acid dosage. The hydrothermal acid hydrolysis provides an effective approach to fractionate lignin and xylose from PHL. [ABSTRACT FROM AUTHOR]

Highlights • Extrusion process imparted physical and structural changes to the wood particles. • Specific mechanical energy had a strong positive correction with sugar yield. • The lowest moisture content and temperature led to the highest sugar yield. • Recrystallization and agglomeration occurred after the extrusion process. Abstract The impact of independent variables of extrusion on dependent variables of pre-milled Douglas-fir forest residuals was studied to enhance the enzymatic hydrolysis for production of fermentable sugar without catalysts. Co-rotating twin screw extruder was operated with three different feedstock moisture contents (30, 40, and 50%) at four different barrel temperatures (25, 50, 100, and 150 °C) as a pretreatment. The specific mechanical energy input ranged from 0.07 and 0.30 kWh/kg and had a very strong positive correlation with torque (r = 0.96, p < 0.01), glucose (r = 0.92, p < 0.01) and xylose/mannose yields with (r = 0.84, p < 0.01). Douglas-fir residuals extruded at lowest moisture content (30%) and temperature (25 °C) had the highest sugar yield, requiring the highest SME. Higher barrel temperature increased the median particle size and had lower glucose and xylose/mannose yields. Recrystallization and agglomeration were observed under higher temperature conditions. [ABSTRACT FROM AUTHOR]

Abstract: The preparation of an ionic liquid (pyridinium propyl sulfobetaine; PPS)-heteropolyacid (tungstophosphoric acid; H3PW12O40; TPA) composite catalyst and its performance during hydrolysis of waste wood powder are reported. The acidic strengths of various aqueous PPS-TPA and sulfuric acid (H2SO4) solutions were assessed by 31P nuclear magnetic resonance (NMR) spectroscopy using the dissolved trimethylphosphine oxide (TMPO) as the probe molecule. Accordingly, an aqueous PPS-TPA catalyst with acidic strength resembling that of a conventional industrial liquid acid, namely 2 wt% aqueous H2SO4 solution, was selected for further studies. The aqueous PPS-TPA catalysts, which exhibited unique physicochemical properties and self-separation characteristics, were found to exhibit superior catalytic performances for hydrolysis of wood powder compared to that of aqueous H2SO4 solutions. In addition, the organic-inorganic PPS-TPA composite catalysts tend to inhibit the formation of inhibitors such as 5-hydroxymethylfurfural (HMF) and furfural during hydrolysis of lignocellulosic biomass, hence, well-suited for the productions of glucose and xylose.Graphical Abstract: [ABSTRACT FROM AUTHOR]

An efficient pretreatment with various concentrations of FeCl 3 (0.005–0.2 mol/L) was developed to extract hemicellulose in sugarcane bagasse and enhance the enzymatic hydrolysis of cellulose in pretreated solids. It was found that 0.025 mol/L FeCl 3 pretreated substrate yielded a high glucose yield of 80.1% during enzymatic hydrolysis. Then the characterization of raw material and pretreated solids was carried out to better understand how hemicellulose removal affected subsequent enzymatic hydrolysis. In addition, Tween 80 and Bovine Serum Albumin (BSA) were added to promote enzymatic hydrolysis of pretreated substrate. Together with that obtained from pretreatment, the highest glucose yield reached 97.7% with addition of Tween 80, meanwhile, a reduction of 50% loading of enzyme yielded the same level of glucose. However, the increased yields with additives decreased gradually as the hydrolysis time was extended. Furthermore, the enhancement mechanisms of Tween 80 and BSA were determined. [ABSTRACT FROM AUTHOR]

In this study, a novel biomass pretreatment process using three kinds of deep eutectic solvents (DESs) was developed to improve saccharification efficiency and lignin valorization. The major components of xylose residue including cellulose and lignin fractions were released, recovered and utilized. Pretreatment with betaine/lactic acid system at 120 °C for 2 h was found to be the optimal conditions with prominently increased enzymatic digestibility (from 55.3% to 96.8%). The efficient conversion was mainly ascribed to the significant delignification efficiency of 81.6% after betaine/lactic acid pretreatment, which caused incompact structure and corrosive surface of treated xylose residue. The recoverable lignin had high purity, low molecular weight (630–2040 g/mol) and polydispersity (1.07–1.76). Based on the comprehensive analysis, the one-pot DESs system provides us a facile and effective approach for whole components valorization of lignocellulosic materials. [ABSTRACT FROM AUTHOR]

Abstract Due to the commitments for environment preservation, there has been a growing interest in the use of alternative energy sources for the production of bioproducts of added value. In this context, sisal has been considered a promising alternative to meet the global demand in a more sustainable way. Thus, the aim of this study was to optimize the acid hydrolysis of sisal bagasse to obtain hydrolyzed liquor rich in xylose and arabinose for a future development process in a biorefining context. Thermal analysis was held for bagasse characterization, and sugars and fermentation inhibitors (acetic acid, furfural and hydroxymethylfurfural) in the prehydrolyzed liquor. The 23 + 3 factorial experimental design was applied with a total of 11 experiments to investigate the influence of variables temperature, bagasse/acid diluted and acid concentration to evaluate the release of pentoses (xylose and arabinose) and hexose (glucose) in the prehydrolyzed liquor, fixing the reaction time in 1 h. The liquor from the acid hydrolysis should operate under conditions at levels −1 (110 ºC, 1,5% and 1:12), obtaining pentose yields (xylose and arabinose), which are the best conditions indicated in planning with 34.39% conversion. It was observed that acid treatment liquor is very effective in providing high-susceptibility substrates for arabitol and xylitol production. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomasses have a very important role as a raw material to produce biofuels and biochemicals. However, a sustainable, efficient, and economically competitive process for the release of sugars from such materials has still not been achieved. In this work, the optimization of the enzymatic hydrolysis cocktail was evaluated as an approach to maximize sugar extraction from mildly pretreated sugarcane bagasse. Different additives and enzymes, including hydrogen peroxide (H 2 O 2), laccase, hemicellulase and the surfactants Tween 80 and PEG4000 were added to a cellulolytic cocktail with the aim of improving biomass hydrolysis. An increase of 39 % and 46 % of glucose and xylose concentrations, respectively, compared to the control (when only the cellulolytic cocktail (20 or 35 FPU g−1 dry mass), was obtained when H 2 O 2 (0.24 mM) was added at the beginning of the hydrolysis. On the other hand, the addition of hemicellulase (81–162 μL g−1 DM) increased the production of glucose up to 38 % and xylose up to 50 %. The findings of this study reveal that it is possible to increase the extraction of sugars from mildly pretreated lignocellulosic biomass by using an appropriate enzymatic cocktail supplemented with additives. This opens up new opportunities for the development of a more sustainable, efficient, and economically competitive process for biomass fractionation. [Display omitted] • Supplementation of additives to the cellulolytic cocktail improves the hydrolysis of biomass. • Knowing the biomass composition is crucial to define the cocktail to be used in hydrolysis. • An optimized enzymatic cocktail can be used on biomass subjected to mild pretreatment. • Lytic Polysaccharide Monooxygenases action can be boosted using hydrogen peroxide. • Addition of surfactants improves the production of sugars during enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]