Subsequent Enzymatic Hydrolysis Research Articles

Ultrasound-Assisted Alkaline Pretreatment of Biomass to Enhance the Extraction Yield of Valuable Chemicals

As a renewable and sustainable resource, lignocellulosic biomass serves as a crucial raw material for the production of biofuels, biochemicals, and various value-added products. This paper aims to develop and optimize a mild alkaline treatment of sawdust assisted by ultrasound, along with enzymatic hydrolysis of the pretreated material. The alkaline sonochemical pretreatment emerged as the optimal approach to enhance the susceptibility of cellulose to subsequent enzymatic hydrolysis to improve the yield of reducing sugars. A comparative study was performed using various ultrasonic applicators (horn and bath) and conventional assisted alkaline pretreatment. The ultrasonic-assisted pretreatment revealed a higher delignification of 68% (horn) and 57% (bath) compared with conventional pretreatment. Processes were optimized using a statistical analysis based on a 23 factorial design. The ratios between sawdust and alkaline solution (RSL = 0.5–1.5 g/100 mL), US amplitude (A = 20–60%), and working temperature (t = 30–50 °C) were selected as process factors. The optimal operating conditions to maximize the reducing sugar yield (138.15 mg GE/gsubstrate) were found as follows: a solid/liquid ratio of RSL,opt = 1.25 g/100 mL, US amplitude of Aopt = 60%, and pretreatment temperature of topt = 50 °C. The overall outcomes clearly confirmed the intensification of delignification by ultrasound-assisted alkaline pretreatment.

A reaction–diffusion coupled kinetic model for hydrothermal acid pretreatment of wheat straw

Hydrothermal acid pretreatment is a promising method to overcome the recalcitrance of lignocellulosic biomass for subsequent efficient enzymatic hydrolysis and biofuel production. However, little is known about heterogeneous catalysis reactions involving the proton diffusion in the pore of lignocellulosic biomass coupled with the hydrolysis of hemicellulose and cellulose catalyzed by proton. In this study, a reaction–diffusion coupled kinetic model for hydrothermal acid pretreatment of wheat straw was developed based on the visualization of particle geometry and pore features. The increase rate of average proton concentration in the pores is higher at a higher temperature or a smaller particle size. A mathematical model was successfully developed to describe the time courses of average proton concentration dictated by initial acid concentration and an unsteady diffusion fitting parameter. The kinetic parameters of each reaction step for hydrothermal acid pretreatment of wheat straw were obtained by fitting experimental data. The activation energies for the hydrolysis of slow-hydrolyzing cellulose, fast-hydrolyzing cellulose, and hemicellulose were determined of 937.8 kJ·mol−1, 90.7 kJ·mol−1, and 39.8 kJ·mol−1, respectively, indicating the temperature dependence of slow-hydrolyzing cellulose with a high crystalline index is strongest. The prediction accuracy of this model can be further improved at higher stirring speeds and initial acid concentrations. Additionally, the model demonstrates high prediction accuracy across three different particle sizes. Generally, this model can gratifyingly correlate data of formation and degradation of monosaccharides and furfural in the hydrothermal acid pretreatment of wheat straw with fair accuracy.

An integrated pretreatment strategy for enhancing enzymatic hydrolysis efficiency of poplar: Hydrothermal treatment followed by a twin-screw extrusion

To reduce the dependence on chemical inputs during biomass pretreatment, an integrated process on the basis of hydrothermal pretreatment followed by twin-screw extrusion for poplar was proposed. A comparative study was conducted on the pore structure, crystallinity, relative surface lignin concentration, cellulose accessibility, and enzymatic hydrolysis efficiency of the pretreated materials. Results suggested that the relative surface lignin concentration of fibers pretreated by hydrothermal treatment (conducted at 170 ℃ for 90 min) coupled with extrusion (HE) treatment was decreased compared to the sole hydrothermal (H) process, which had a positive impact on the subsequent enzymatic hydrolysis. Additionally, the HE process resulted in an increase in pore size by 34.4%, pore volume by 447.5%, and specific surface area by 93.5%, which enhanced the penetration and interaction of water into the fibers and thus increased cellulose accessibility by 143.2%. SEM and TEM observations revealed that fibers were separated and finely fibrillated, large amounts of fragmentary structure and cracks appeared on the fiber. In addition, the cell wall structure was deformed and damaged, when pretreated by HE process. Overall, this work showed that hydrothermal treatment followed by twin-screw extrusion was an achievable strategy for high fermentable sugar production of hardwood.

Ultrasonication and enzymatic treatment of apple and orange bagasses: Molecular characterization of released oligosaccharides and modification of techno-functional and health-related properties

Apple and orange bagasse were subjected to ultrasonication (US) and subsequent enzymatic hydrolysis (EH) with a cellulase-pectinase mixture. US did not affect oligosaccharide profile and water and oil holding capacities (WHC/OHC) in both substrates but enhanced bile acid adsorption capacity (BAC) and total phenolic content (TPC) in orange bagasse. EH increased glucose/xylose and xylobiose (XOS-2) contents and caused the release of cellobiose (COS-2) and pectin derived oligosaccharides (POS), mainly methylated oligogalacturonides with degree of polymerization (DP) 3–4. Hydrolyzed orange bagasse exhibited higher total POS content (31.56 g/100 g bagasse) than apple bagasse (21.13 g/100 g bagasse), but apple bagasse showed higher diversity in methylated and acetylated POS. After combined treatment, POS quantities in apple bagasse were enhanced whereas in orange bagasse COS-2 and POS-2 formation significantly increased, making physical opening before enzymatic degradation an effective strategy for maximizing oligosaccharide concentrations. EH decreased techno-functional properties and TPC but led to a 24.9 % increase of BAC in apple bagasse and a 7.8 % increase in orange bagasse, highlighting that the efficacy of US and EH depends on the applied DF substrate. This study offers guidance for selecting modification technologies for fruit by-products to obtain ingredients with elevated oligosaccharide content, improved techno-functional and health-related properties.

Pretreatment and enzymatic hydrolysis optimization of lignocellulosic biomass for ethanol, xylitol, and phenylacetylcarbinol co-production using Candida magnoliae.

Cellulosic bioethanol production generally has a higher operating cost due to relatively expensive pretreatment strategies and low efficiency of enzymatic hydrolysis. The production of other high-value chemicals such as xylitol and phenylacetylcarbinol (PAC) is, thus, necessary to offset the cost and promote economic viability. The optimal conditions of diluted sulfuric acid pretreatment under boiling water at 95°C and subsequent enzymatic hydrolysis steps for sugarcane bagasse (SCB), rice straw (RS), and corn cob (CC) were optimized using the response surface methodology via a central composite design to simplify the process on the large-scale production. The optimal pretreatment conditions (diluted sulfuric acid concentration (% w/v), treatment time (min)) for SCB (3.36, 113), RS (3.77, 109), and CC (3.89, 112) and the optimal enzymatic hydrolysis conditions (pretreated solid concentration (% w/v), hydrolysis time (h)) for SCB (12.1, 93), RS (10.9, 61), and CC (12.0, 90) were achieved. CC xylose-rich and CC glucose-rich hydrolysates obtained from the respective optimal condition of pretreatment and enzymatic hydrolysis steps were used for xylitol and ethanol production. The statistically significant highest (p ≤ 0.05) xylitol and ethanol yields were 65% ± 1% and 86% ± 2% using Candida magnoliae TISTR 5664. C. magnoliae could statistically significantly degrade (p ≤ 0.05) the inhibitors previously formed during the pretreatment step, including up to 97% w/w hydroxymethylfurfural, 76% w/w furfural, and completely degraded acetic acid during the xylitol production. This study was the first report using the mixed whole cells harvested from xylitol and ethanol production as a biocatalyst in PAC biotransformation under a two-phase emulsion system (vegetable oil/1M phosphate (Pi) buffer). PAC concentration could be improved by 2-fold compared to a single-phase emulsion system using only 1M Pi buffer.

Double in-situ lignin modification in surfactant-assisted glycerol organosolv pretreatment of sugarcane bagasse towards efficient enzymatic hydrolysis

Organosolv pretreatment effectively fractionates lignocellulosic biomass for efficient enzymatic hydrolysis, yielding fermentable sugars. However, substantial lignin redeposition on the substrate surface and residual lignin content exacerbate lignin’s inhibitory effects on subsequent enzymatic hydrolysis. An in-situ lignin modification is proposed to address this challenge by incorporating polyethylene glycol (PEG) series into glycerol organosolv (GO) pretreatment. According to the results obtained, PEG-assisted GO pretreated substrate exhibited significantly increased sugar yield during enzymatic hydrolysis, particularly with PEG 4000, showing 35.4% higher glucose yield over 72 h. The improved glucose yield with PEG could be attributed to changes in the physicochemical structure and properties of residual lignin, mitigating its non-productive interaction with cellulase enzymes. PEG's presence in GO pretreatment also increased β-O-4 linkages preservation by 55% and reduced phenolic hydroxyl groups by 28% in lignin fragments versus no surfactants. This outcome resulted from introducing glycerol and PEG hydroxyl tails into the lignin structure, forming α-etherified lignin and rendering it more hydrophilic. Simulations confirmed strong Van Der Waals and hydrogen bonding interactions between lignin units and PEG, hindering lignin fragments repolymerization. Incorporating PEG in the organosolv pretreatment proves highly beneficial for cellulase-mediated lignocellulosic biorefinery, resembling a lignin-first strategy. The optimized process enables efficient biomass utilization for sustainable fuels and chemicals production.

Hydrodynamic cavitation-assisted acid pretreatment and fed-batch simultaneous saccharification and co-fermentation for ethanol production from sugarcane bagasse using immobilized cells of Scheffersomyces parashehatae

A new alternative for hydrodynamic cavitation-assisted pretreatment of sugarcane bagasse was proposed, along with a simultaneous saccharification and co-fermentation (SSCF) process performed in interconnected columns. Influential variables in the pretreatment were evaluated using a statistical design, indicating that an ozone flow rate of 10 mg min−1 and a pH of 5.10 resulted in 86 % and 72 % glucan and xylan hydrolysis yields, respectively, in the subsequent enzymatic hydrolysis process. Under these optimized conditions, iron sulfate (15 mg L−1) was added to assess Fenton pretreatment, resulting in glucan and xylan hydrolysis yields of 92 % and 71 %, respectively, in a material pretreated for 10 min. In SSCF, ethanol volumetric productivities of 0.33 g L−1 h−1 and of 0.54 g L−1 h−1 were obtained in batch and fed-batch operation modes, achieving 26 g L−1 of ethanol in 48 h in the latter mode.

Effects of soybean endogenous enzyme hydrolysis on the quality of soymilk after blanching

This study examined the relationship between the endogenous enzymatic hydrolysis conditions and the quality and flavor of soymilk derived from blanched soybeans. Results represented that following blanching, the lipoxygenase activity of soybeans decreased by 88.50% and the endogenous protease activity greatly improved compared to unblanched. During the subsequent endogenous enzymatic hydrolysis, the stability factor and sensory score dropped as the amount of okara rose, although the content of peptides and amino acids nitrogen increased. At an enzymolysis temperature of 50 °C, the soymilk had the highest sensory score. After 60 min of enzymolysis, the beany odor was weakened maximumly; the levels of polypeptide and amino acid nitrogen increased by 45.00% and 43.33%, respectively. Enzymatic hydrolysis at 50 °C for 60 min without okara generated the finest soymilk. Blanching diminished the primary components of the beany odor of raw soymilk. Enzymolysis of blanched pretreatment soymilk further dropped the content of beany odor components and exhibited a richer variety and concentration of volatile components. Following the hydrolysis of endogenous enzymes generated after blanching, the overall quality of soymilk was enhanced.

Proximate and compositional assessment of pretreatment methods on selected lignocellulose biomass for biogas production


 The efficient conversion of lignocellulosic biomass into biogas is a critical avenue in sustainable bioenergy production. Pretreatment enhances the accessibility of lignocellulose components for subsequent enzymatic hydrolysis and biogas production. This study evaluated the proximate and compositional changes induced by various pretreatment techniques on lemon grass and fluted pumpkin stalk, with a focus on optimizing biogas yield. Alkaline, hydrothermal, and combined hydrothermal pretreatment processes were applied on the feedstocks. The biomass surface characteristics were determined through proximate and compositional analysis.The characterization of the untreated biomass showed that lemon grass and fluted pumpkin stalk recorded; dry matter, moisture content, fixed carbon, total kjeldahl nitrogen and ash content in the ranges of 94.49%-94.56%, 5.44%-5.51%, 26.35%-28.95%, 1.33%-1.932% and 6.00%-12.00% respectively. The cellulose values of the untreated biomass ranged from 34.04% for fluted pumpkin stalk to 38.66% for lemon grass. However, the content of the cellulose increased with pretreatment to values ranging from 44.20% to 51.06%. The results of this analysis showed that the selected lignocellulose biomass has properties that are consistent with past literature stating them as suitable substrates for biogas production. Nonetheless, the potential for increased biogas yield from anaerobic digestion is greater when combined hydrothermal and alkaline pretreatment is used.

Comprehensive insights into hydrothermal pretreatment of rice straw from physicochemical structure, organic matter transformation and hydrolysate reuse

Anaerobic digestion is an effective means of biomass utilization from solid waste, but the complex structure and low biodegradability of lignocellulose severely limit the anaerobic degradation conversion efficiency. In this study, hydrothermal pretreatment combined with chemicals was conducted to investigate physicochemical structure, chemical composition and changes, and enzymatic hydrolysis performance of rice straw under various combination hydrothermal pretreatment. The transformation mechanism of main components during alkaline-thermal pretreatment and the potential reuse of hydrolysate were further explored. Results showed that the total sugar concentration after hydrothermal pretreatment was 1.49 times higher than that after dissolution pretreatment. Hydrothermal-KOH pretreatment could destroy the waxy and siliceous layer on the straw surface. The roughness increased from 0.525 to 1.170 nm, and the average pore size 6.20 to 8.99 nm. Alkaline-thermal pretreatment could facilitate lignin dissolution and retained more cellulose and hemicellulose in the solid phase, and sugar concentration after pretreatment could reach 40.82 g/L. Porosity was affected by the dissolution of chemicals, and the pore structure also affected subsequent enzymatic hydrolysis. Dissolution of cellulose and hemicellulose resulted in a reduction in particle size and the formation of micropores, while re-aggregation and precipitation of lignin after dissolution led to the pore collapse and an increase in pore size. Furthermore, the hydrolysates contained nutrients, humic acids, plant hormones, and micronutrients, which had the potential to be developed into foliar fertilizers and reused. The results of this study will provide new insights and technical support for high-value utilization of straw.

Long term study of cell wall saccharification and high added value phenolic acids production from Phalaris aquatica L. energy crop

Phalaris aquatica L. is a cool-season perennial grass of the Mediterranean that has been used for forage production, while recently was identified as a novel candidate for sustainable second-generation bioethanol production. This study provides for the first time evidence about this energy crop long-term performance (five years of growth), the cell wall saccharification efficiency and the production of high added value compounds during this period. High biomass production was recorded constantly after the first year of plant growth, with a maximum of 22.4 ± 0.5 t of dry mass (DM) per ha and stable structural polysaccharides concentration 68.8% ± 0.8 w/w DM from the third year on. Independently from crop age, dilute acid pretreatment (120 °C, 1.5% H2SO4, 45 min) promoted the subsequent enzymatic hydrolysis of P. aquatica L. biomass. The dilute acid pre-treatment positive effect is attributed both to the hemicellulose solubilization and the breakage of intermolecular bonds between polysaccharides and phenolic acids, as supported by the present study results These combined acid/enzymatic hydrolysis processes were able to convert more than 80% of cell wall polysaccharides into fermentable sugars, releasing simultaneously a substantial amount of phenolic acids of 2.16% ± 0.48 w/w DM. The ratio of ferulic to p-coumaric acid in the acid hydrolysate can be used for the prediction of the subsequent cellulose enzymatic saccharification efficiency, by the model described here. The protocatechuic acid, which can find many technological applications, was the main bioactive polyphenol in the final hydrolysate with concentration ∼1% w/w DM. These results are supportive of Phalaris aquatica L. suitability as a sustainable biorefinery crop, under the semi-arid Mediterranean climatic conditions contributing to this region biodiversity and prosperity.

Evaluating the In Vitro and In Vivo Prebiotic Effects of Different Xylo-Oligosaccharides Obtained from Bamboo Shoots by Hydrothermal Pretreatment Combined with Endo-Xylanase Hydrolysis.

Xylo-oligosaccharides (XOS) enriched with high fractions of X2-X3 are regarded as an effective prebiotic for regulating the intestinal microflora. In this study, the original XOS solution was obtained from bamboo shoots through hydrothermal pretreatment under optimized conditions. Subsequently, enzymatic hydrolysis with endo-xylanase was performed on the original XOS solution to enhance the abundance of the X2-X3 fractions. The results demonstrated that hydrothermal pretreatment yielded 21.24% of XOS in the hydrolysate solution, and subsequent enzymatic hydrolysis significantly increased the proportion of the X2-X3 fractions from 38.87% to 68.21%. Moreover, the XOS solutions with higher amounts of X2-X3 fractions exhibited superior performance in promoting the growth of probiotics such as Bifidobacterium adolescentis and Lactobacillus acidophilus in vitro, leading to increased production of short-chain fatty acids. In the in vivo colitis mouse model, XOS solutions with higher contents of X2-X3 fractions demonstrated enhanced efficacy against intestinal inflammation. Compared with the colitis mice (model group), the XOS solution with higher X2-X3 fractions (S1 group) could significantly increase the number of Streptomyces in the intestinal microflora, while the original XOS solution (S2 group) could significantly increase the number of Bacteroides in the intestinal microflora of colitis mice. In addition, the abundances of Alcaligenes and Pasteurella in the intestinal microflora of the S1 and S2 groups were much lower than in the model group. This effect was attributed to the ability of these XOS solutions to enhance species diversity, reversing the imbalance and disorder within the intestinal microflora. Overall, this work highlights the outstanding potential of XOS enriched with high contents of X2-X3 fractions as a regulator of the intestinal microbiota and as an anti-colitis agent.

The green novel approach in hydrolysis of pistachio shell into xylose by microwave-assisted high-pressure CO2 /H2 O.

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 /H2 O hydrolysis (MW-HPCO2 ) comprising a combination never previously used was performed to produce xylose from pistachio shell. Response surface methodology with a Box-Behnken design was implemented to optimize microwave-assisted high-pressure CO2 /H2 O 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 . 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.

Combined sulfuric acid and choline chloride/glycerol pretreatment for efficiently enhancing enzymatic saccharification of reed stalk

In this study, an efficient combination of pretreatment solvents involving Choline chloride/Glycerol (ChCl/Gly) and H2SO4 was firstly developed to assess the pretreatment performance and determine optimal pretreatment conditions. The results illustrated that the H2SO4-[ChCl/Gly] combination efficiently removed lignin (52.6%) and xylan (80.5%) from the pretreated reed stalk, and subsequent enzymatic hydrolysis yielded 91.1% of glucose. Furthermore, several characterizations were conducted to examine the structural and morphological changes of the reed stalk, revealing apparently enhanced accessibility (128.4 to 522.6 mg/g), reduced lignin surface area (357.9 to 229.5 m2/g), and substantial changes on biomass surface. Based on the aforementioned study, possible mechanisms for the H2SO4-[ChCl/Gly] pretreatment of reed stalks were proposed. The comprehensive understanding of combined H2SO4-[ChCl/Gly] pretreatment system for enhancing the saccharification of the reed stalk was interpreted in this work. Overall, this novel approach could be efficiently applied to pretreat and saccharify reed stalks, empowering the biomass refining industry.

Hydrodynamic cavitation as a promising pretreatment technology to enhance the efficiency of cellulose nanocrystal production via enzymatic hydrolysis

Enzymatic hydrolysis to produce cellulose nanocrystals (CNCs) offers economical and sustainability advantages. However, since this is still an emerging technology, further improvements are needed to make the process feasible for scale-up. In our study, we propose a novel approach using hydrodynamic cavitation (HC) as a pretreatment technology to enhance the efficiency and yield of CNC production. HC treatments conducted under various scenarios induced structural modifications of the cellulose fibers that facilitated their defibrillation and subsequent enzymatic hydrolysis. Isolation through hydrolysis involved the synergistic action of specific enzymes, including xylanase and endoglucanase. Xylanase acted on the hemicellulosic fraction, breaking down the xylan structure and exposing the cellulose fibers. Subsequently, endoglucanase targeted the amorphous regions of cellulose, releasing CNCs. By integrating the HC pretreatment with enzymatic hydrolysis, we achieved remarkable results. High-yield CNCs, reaching approximately 60%, were obtained with a crystallinity index ranging from 81% to 85%. Moreover, this process demonstrated a significant reduction in total energy consumption of approximately 56%, contributing to its economic viability. Furthermore, CNCs with diverse morphologies, aspect ratios, and viscosity profiles were produced, enabling the tailoring of their properties for specific and new applications.

Bioprocess development for the production of xylooligosaccharide prebiotics from agro-industrial lignocellulosic waste

The development of sustainable biorefineries and bioeconomy has been the mandate of most of the governments with major focus on restricting the climate change concerns and finding new strategies to maintain the global food supply chain. Xylooligosaccharides (XOS) are short-chain oligomers which due to their excellent prebiotic potential in the nutraceutical sector has attracted intense research focus in the recent years. The agro-industrial crop and food waste can be utilized for the production of XOS which are derived from hemicellulose fraction (xylan) of the lignocellulosic materials. The extraction of xylan, is traditionally achieved by acidic and alkaline pretreatments which, however, have limited industrial applications. The inclusion of cutting-edge and environmentally beneficial pretreatment methods and technologies such as deep eutectic solvents and green catalysts are preferred. Moreover, the extraction of xylans from biomass using combinatorial pretreatment approaches may help in economizing the whole bioprocess. The current review outlines the factors involved in the xylan extraction and depolymerization processes from different lignocellulosic biomass and the subsequent enzymatic hydrolysis for XOS production. The different types of oligosaccharides and their prebiotic potential for the growth of healthy gut bacteria have also been explained. The introduction of modern molecular technologies has also made it possible to identify enzymes and microorganisms with the desired characteristics for usage in XOS industrial production processes.

Cane Pretreatment by Deep Eutectic Solvents to Increase its Reactivity During Enzymatic Hydrolysis with Cellulases

Cane was pretreated with a number of deep eutectic solvents (DESs) based on choline chloride (ChCl) as a hydrogen bond acceptor. Among hydrogen bond donors, lactic (LA) and oxalic (OA) acids were the most effective. Substrate pretreatment conditions (ratio of DES-components, temperature and exposure time) were optimized, which resulted in the highest yield of reducing sugars (RS) and glucose during subsequent enzymatic hydrolysis with cellulase preparation based on Penicillium verruculosum. It was established that in the case of a mixture of ChCl with LA (the molar ratio of components was 1 : 5) pretreatment should be carried out at 80°C for 24 hours, and in the case of a mixture of ChCl with OA (1 : 1), optimal conditions were 80°C and 6 hours. The degree of conversion of the pretreated substrate after 48 hours of hydrolysis in the presence of the enzyme preparation (EP) B537 was 80 and 86% by absolutely dry substances for selected mixtures of ChCl/LA and ChCl/OA, respectively.

Elucidating the nonproductive adsorption mechanism of cellulase with lignin fractions from hydrothermally pretreated poplar using multi-dimensional spectroscopic technologies

A multi-dimensional nondestructive spectroscopic technique is proposed to analyze the influence of pretreatment lignin distribution on subsequent enzymatic hydrolysis and build a “lignin structure-cellulase interaction” relationship.

Non‐thermal plasma as an efficient pretreatment to lignocellulosic raw materials

AbstractNon‐thermal plasma is an ecologically correct technique that is increasingly being explored. In this work, plasma was applied as a delignification technique for different lignocellulosic residues (brewery, banana peel, and mango seed peel). The influence of non‐thermal plasma on the physical and chemical characteristics of the residues was also explored by the techniques scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), x‐ray diffraction (XRD), and RAMAN spectroscopy. Delignification of approximately 48% was observed in 5 min of the process for the brewery by‐product, 35% the mango seed shell, and 24% the banana peel. Small changes in morphology (SEM), degradation temperature (DSC), compositional analysis (FTIR, XRD, and RAMAN) after pretreatment with non‐thermal plasma were observed. Thus, we bring unprecedented results using non‐thermal plasma as an alternative pretreatment for different lignocellulosic residues, indicating an attractive technique for subsequent enzymatic hydrolysis and thus obtaining added‐value products, such as bioethanol and xylooligosaccharides.

Instant catapult steam explosion: An efficient preprocessing step for the robust and cost-effective chemical pretreatment of lignocellulosic biomass

The biorefinery based on lignocellulosic biomass requires an efficient preprocessing step to address problems regarding with the high cost of biomass transportation and the low cost-effectiveness of subsequent chemical pretreatment . In this study, the instant catapult steam explosion (ICSE) was investigated as an alternative preprocessing method to treat corn stalk feedstocks , and compared with conventional milling preprocessing. Besides reducing the particle size, ICSE can modify the microstructure and improve enzymatic degradability of the corn stalks as well. These preprocessed feedstocks were further pretreated by moderate chemical pretreatment methods, including dilute acid, dilute alkali, acid and alkali, organosolv, and ionic liquid. The ICSE-treated feedstocks showed 3-fold to 7-fold increase in enzymatic saccharification when compared with milled and untreated feedstocks. Meanwhile, its energy consumption only accounted for 5%–20% of the milling process, thereby resulting in an 80%–85% of energy savings. Therefore, the ICSE-based preprocessing can potentially be integrated with the supply chain of lignocellulosic biomass and enhance the economic efficiency of biorefinery. • Instant catapult steam explosion (ICSE) as a preprocess is superior to milling for the downward chemical pretreatment. • ICSE, modifying lignocellulose's structure and composition, prompts the chemical pretreatment and subsequent enzymatic hydrolysis. • The energy consumption of ICSE is significantly lower than the traditional milling process. • ICSE facility can be adopted by the regional biomass preprocessing center to improve the cost-effectiveness of biorefinery.