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Efficient pretreatment methods are crucial for the generation of fermentable sugars from the renewable lignocellulose. In this study, γ-valerolactone (GVL), a biomass-derived green solvent, was used to fractionate corn stover (CS). The impact of different additives on the enzymatic hydrolysis and pretreatment of CS within the GVL/water system was carefully investigated. The results demonstrate that the use of H 2 SO 4 -assisted GVL/H 2 O (80:20, w/w) pretreatment at mild conditions successfully facilitates the depolymerization of CS, thereby improving the cellulase accessibility. Furthermore, by increasing the GVL pretreatment temperature to 160 °C with 100 mM H 2 SO 4 addition, the pretreated CS led to nearly 100 % of hydrolysis yield at 2 % (w/v) solid load. Finally, the thermogravimetric analysis (TGA) was performed to evaluate the thermal decomposition characteristics of untreated CS and enzymatic residues based on the H 2 SO 4 -assisted GVL/H 2 O pretreatment. The results indicate that the enzymatic residues had two depolymerization stages from 200 °C to 500 °C with a final residual mass of 22.73 %, which was higher than that of untreated CS (20.56 %). Overall, this study provides an efficient lignocellulose pretreatment for fermentable sugars production and valorization of enzymatic residues. [Display omitted] • Using H 2 SO 4 as γ-valerolactone (GVL) pretreatment additive enhanced xylan removal. • Glucose yield of GVL-pretreated corn stover (CS) was 3–5 folds higher than raw CS. • Sugars production reached 32.4 g/100 g CS by 50 mM H 2 SO 4 -assisted GVL pretreatment. • Enzymatic residues had two decomposition stages in 200–500 °C by thermal analysis. [ABSTRACT FROM AUTHOR]

Recycling of paper sludge waste is crucial for establishing a sustainable green industry. This waste contains valuable sugars that can be converted into important chemicals such as ethanol, poly hydroxybutyrate, and lactic acid. However, the main challenge in obtaining sugars in high yield from paper sludge is the high crystallinity of cellulose, which hinders hydrolysis. To address this, pretreatment using phosphoric acid was optimized using response surface methodology to facilitate cellulose hydrolysis with minimal energy and chemicals. The created prediction model using the response surface method considered factors such as acid concentration (ranging from 60% to 85%), consistency (ranging from 4% to 10%), temperature (ranging from 25°C to 80°C), and time (ranging from 0.5 to 4 h). The results revealed that the model's significant factors affecting the yield were acid concentration, reaction time, temperature, and the product of acid concentration and temperature, while the model's significant factors affecting the crystallinity were the consistency, the temperature, and their product. The results showed that the optimum conditions for pretreatment were using an acid concentration of 64%, temperature of 25°C, consistency of 10%, and time of 30 min. The hydrolysis of the conditionally pretreated paper sludge resulted in a weight loss of 42%, compared to only 18% weight loss in non-pretreated paper sludge. Furthermore, the optimized conditions led to low levels of furfurals and acetic acid, which are undesirable by-products that can interfere with sugar fermentation. The total sugar obtained under the optimized conditions was 0.43 g glucose/g sample (10.46 g/L), while the contents of methyl furfural, furfural, and acetic acid were 21.65, 235.7, and 4.57 mg/L, respectively. This study demonstrates the potential of phosphoric acid for pretreatment and hydrolysis of paper sludge, enabling efficient saccharification and the production of sugars with minimal undesired by-products. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of hydrothermal and alkaline pretreatment methods in enhancing the concentration of fermentable sugars derived from rice husk waste. After the pretreatments, enzymatic hydrolysis and fermentation processes were executed to evaluate the ethanol production from each pretreatment. Rice husk powder measuring ≤250 µm was used. For the alkaline pretreatment, sodium hydroxide (NaOH) was used at concentrations ranging from 0.5, 1 to 1.5% w/v. The efficacy of the hydrothermal pretreatment method was evaluated after 15, 30 and 45 min at 120 °C. The enzymatic hydrolysis process was performed over 144 h at 50 °C, pH 4.8 with an enzyme loading of 30 FPU (filter paper units). Fermentation was carried out at 37 °C using a strain of Saccharomyces cerevisiae Hansen 1883 (NCYC 366). Results indicated that the optimal conditions for alkaline pretreatment were observed at a 1.5% NaOH, while the best hydrothermal procedure was achieved at 120 °C and 45 min. The impact of these pretreatments was assessed based on the efficiency of enzymatic hydrolysis. The alkaline pretreatment resulted in 81.70% conversion of cellulose to glucose and 96.30% conversion of hemicellulose to xylose. In contrast, the hydrothermal pretreatment achieved 93% cellulose-to-glucose conversion and 83.35% hemicellulose-to-xylose conversion. The ethanol production registered ranged from 13 to 13.23 g·L−1, corresponding to a conversion factor of 0.43 for ethanol from fermentable sugars. [ABSTRACT FROM AUTHOR]

Abstract Potato peel waste (PPW) is an underutilized substrate which is produced in huge amounts by food processing industries. Using PPW a feedstock for production of useful compounds can overcome the problem of waste management as well as cost-effective. In present study, potential of PPW was investigated using chemical and thermochemical treatment processes. Three independent variables i.e., PPW concentration, dilute sulphuric acid concentration and liberation time were selected to optimize the production of fermentable sugars (TS and RS) and phenolic compounds (TP). These three process variables were selected in the range of 5–15 g w/v substrate, 0.8–1.2 v/v acid conc. and 4–6 h. Whole treatment process was optimized by using box-behnken design (BBD) of response surface methodology (RSM). Highest yield of total and reducing sugars and total phenolic compounds obtained after chemical treatment was 188.00, 144.42 and 43.68 mg/gds, respectively. The maximum yield of fermentable sugars attained by acid plus steam treatment were 720.00 and 660.62 mg/gds of TS and RS, respectively w.r.t 5% substrate conc. in 0.8% acid with residence time of 6 h. Results recorded that acid assisted autoclaved treatment could be an effective process for PPW deconstruction. Characterization of substrate before and after treatment was checked by SEM and FTIR. Spectras and micrographs confirmed the topographical variations in treated substrate. The present study was aimed to utilize biowaste and to determine cost-effective conditions for degradation of PWW into value added compounds.

Higher cost of production and functioning efficiency are the two most important aspects of cellulolytic enzymes, as they directly affect the bioconversion of cellulosic waste into fermentable sugars. Thus, the current study aims to investigate the production of cellulolytic enzymes from low-cost waste biomass for use in the sustainable hydrolysis of biomass to yield fermentable sugars. Since coconut waste is a major contributor to biodegradable waste, two different parts of coconut, including the hard shell of coconut (CS) and the fibers of the shell (FS), have been used for enzyme production as feedstock. Further, enzyme production has been carried out on co-fermentative and acid-pretreated coconut substrates (CS and FS) at different quantities using mixed bacterial cultures. Following this, a crude enzyme with a maximum 20 U/gds FPA, 62 U/gds BGL, and 167 U/gds EG has been produced by mixed Bacillus cultures under co-fermentation of 0.5 % acid-pretreated CS and FS substrates at a quantity of 5:5 (g:g) at 35 °C and pH 5.0. The crude enzyme showed its thermal stability for 16 h at 50 °C and released ~34 g/L of sugars from the hydrolysis of untreated FS biomass in 24 h. This work may have significant applications in the area of biomass-based biorefining as well as waste management. [ABSTRACT FROM AUTHOR]

Waste generated from Malaysia's paddy milling factories, known as empty and partially filled paddy grain (EPFG), has been improperly managed as it can be further utilized for sustainable resources such as feedstock via biorefinery. However, the critical driver for a biorefinery is whether the proposed design is profitable. In this study, the conversion of EPFG into glucose as an alternative to sustainable management was analysed in terms of their economic performance as feedstock. The process design involved the production of non-concentrated glucose from EPFG using hydrothermal pre-treatment and enzymatic process, which led to the 76% conversion yield. The economic performance for the plant is at 1.04 million USD, 46.9%, and 34.3% for net present value (NPV), return on investment (ROI), and internal rate return (IRR), respectively. The minimum sugar selling price (MSSP), when zero NPV, is at 0.42 $/kg when the co-product revenue is considered. Sensitivity analysis results indicate that the MSSP is highly sensitive to plant size. This economic evaluation serves as an introductory guide to assess the economic performance of paddy milling waste to glucose via enzymatic hydrolysis. The results of the present study could provide insight for the Malaysian paddy industry in managing the EPFG, hence increasing their market potential. [ABSTRACT FROM AUTHOR]

Potato peel waste (PPW) is an underutilized substrate which is produced in huge amounts by food processing industries. Using PPW a feedstock for production of useful compounds can overcome the problem of waste management as well as cost-effective. In present study, potential of PPW was investigated using chemical and thermochemical treatment processes. Three independent variables i.e., PPW concentration, dilute sulphuric acid concentration and liberation time were selected to optimize the production of fermentable sugars (TS and RS) and phenolic compounds (TP). These three process variables were selected in the range of 5–15 g w/v substrate, 0.8–1.2 v/v acid conc. and 4–6 h. Whole treatment process was optimized by using box-behnken design (BBD) of response surface methodology (RSM). Highest yield of total and reducing sugars and total phenolic compounds obtained after chemical treatment was 188.00, 144.42 and 43.68 mg/gds, respectively. The maximum yield of fermentable sugars attained by acid plus steam treatment were 720.00 and 660.62 mg/gds of TS and RS, respectively w.r.t 5% substrate conc. in 0.8% acid with residence time of 6 h. Results recorded that acid assisted autoclaved treatment could be an effective process for PPW deconstruction. Characterization of substrate before and after treatment was checked by SEM and FTIR. Spectras and micrographs confirmed the topographical variations in treated substrate. The present study was aimed to utilize biowaste and to determine cost-effective conditions for degradation of PWW into value added compounds. [ABSTRACT FROM AUTHOR]

Candida boidinii is a methylotrophic yeast with wide geographical distribution. In the present study, the microorganism was isolated from the Bahian semiarid and the enzymatic extract containing β-glucosidase was obtained through submerged fermentation. Response surface methodology was employed to optimize of fermentation medium. The higher production of β-glucosidase was obtained after 71 h of fermentation in an optimized medium composed of 3.35% glucose, 1.78% yeast extract and 1% peptone. The optimum pH and temperature of enzymatic activity were 6.8 (citrate–phosphate buffer) and 71.7 °C, respectively. Salts tested (10 mM) CaCl2, Na2SO4 and ZnSO4 promotes the increase of 91%, 45% and 80% of activity, respectively. The enzyme retained 64% ± 2.3 of its initial activity after 1 h heating at 90 °C. The production of reducing sugars was 95.94% after 24 h of hydrolysis and, with the addition of metal ions, this value increased more than 2 times. Among the supports analyzed for immobilization, chitosan showed higher residual activity during reuse. The immobilized enzyme showed higher activity at 60 °C with pH 6 and preserved almost 100% of the initial activity after 30 min at 70 °C. [ABSTRACT FROM AUTHOR]

To analyze the overall frequency and inter-tooth patterns of caries in three populations from ancient cemeteries located along the western border of the Central Iranian Plateau as a means to explore whether the populations of Iran had greater access to fermentable sugars after the establishment of the great empires. Dental collections from Kafarved-Varzaneh (Early Bronze Age, MNI=66), Estark-Joshaqan (Iron Age, MNI=57), Tappeh Poustchi (Timurid and Safavid Period, MNI=34), together with comparative data from NE Syria. Frequencies of dental caries per tooth categories, location and size of carious lesions are analyzed using Smith's Mean Measure of Divergence, Correspondence Analysis, χ2 and Kruskal-Wallis tests. There are minimal differences in overall frequencies of carious lesions at Iranian sites, regardless of the chronology, but notable differences at Syrian sites. The inter-tooth pattern at the Iron Age cemetery in Estark appears distinctly different than the other Iranian sites and the comparative samples from Syria. Divergent subsistence strategies may be linked with different inter-tooth patterns since people buried at Estark were mobile herders, while the other cemeteries were used by settled farmers. This comprehensive research on dental caries in three chronologically diverse populations in Iran sheds light on the association between dental caries and subsistence strategies, and introduces the Smith's Mean Measure of Divergence to explore inter-tooth carious patterns, which may prove useful to other researchers seeking to understand the relationships between subsistence, diet, and the presence of carious lesions. The studied sample size is relatively small and therefore its temporal/regional distribution produces low-resolution results. More systematic research on the patterns of dental caries is necessary to produce more fine-grained reconstructions of diet and subsistence in Iran and around the globe. [ABSTRACT FROM AUTHOR]

Sweet sorghum was used as a bioenergy crop to improve the enzymatic hydrolysis for releasing fermentable sugars as compared to other crops. Effective pre-treatment with NaOH at 121 °C for up to 50 min was reported in this study before enzymatic hydrolysis. The response surface methodology approach was used to optimize the parameters for alkali pre-treatment. The optimized parameters of pre-treated sweet sorghum residue were 1–3 % NaOH concentration, 0.5–1.5 mm particle size, 10–50 min time studied using box-behnken design. The findings suggest that 2 % NaOH with a 1 mm reduction in particle size in 50 min leads to enzymatic saccharification for fermentable sugars with a maximum loading of 62.7 % of cellulose. Enzymatic hydrolysis was performed with the aid of enzymes cellulase and xylanase. The optimum conditions obtained for fermentable sugars were 50 °C, 72 h of hydrolysis duration with 20 FPU/g substrate of enzyme loading for 20 g/L sorghum residue from one factor at a time approach. Maximum concentration of 78.3 ± 0.23 g/L of glucose, 5.4 ± 0.47 g/L of xylose with 1.53 ± 0.11 g/L of cellobiose was obtained from hydrolysate after 72 h enzymatic treatment. The characterization, before and after pre-treatment were done by FTIR and FESEM shows effective pre-treatment is important for delignification and increase in cellulose digestibility for improving the enzymatic hydrolysis.

The endo-1,4-β-xylanases (EC 3.2.1.8) are the largest group of hydrolytic enzymes that degrade xylan, the major component of hemicelluloses, by catalyzing the hydrolysis of glycosidic bonds β-1,4 in this polymer, releasing xylooligosaccharides of different sizes. Xylanases have considerable potential in producing bread, animal feed, food, beverages, xylitol, and bioethanol. The fungus Aspergillus tamarii Kita produced xylanases in Adams' media supplemented with barley bagasse (brewer's spent grains), a by-product from brewery industries. The culture extract exhibited two xylanase activities in the zymogram, identified by mass spectrometry as glycosyl hydrolase (GH) families 10 and 11 (GH 10 and GH 11). The central composite design (CCD) showed excellent predictive capacity for xylanase production (23.083 U mL−1). Additionally, other enzyme activities took place during the submerged fermentation. Moreover, enzymatic saccharification based on a mixture design (MD) of three different lignocellulosic residues was helpful in the production of fermentable sugars by the A. tamarii Kita crude extract. [ABSTRACT FROM AUTHOR]

Purpose: Globally, the demand for fossil fuels is a major issue that needs attention through replacement using bio resources. This work aims to carry out a comparative study on the production of biofuels from the rinds of Aloe vera and the pods of Delonix regia. Aloe vera rinds have several characteristics, like cellulose, vitamins, enzymes, sugars, lignin, saponins, etc. It was used as the lignocellulosic feedstock for bioethanol production due to the availability of cellulose and hemicellulose content, which can be hydrolyzed into fermentable sugars. Methods: In this research, a physiochemical method employing ionic liquid-assisted nanocatalyst was performed. Pretreatment was carried out along with the application of ultrasound waves to extract the fermentable sugars. The ultrasonication time, concentration of ionic liquid, and nanocatalyst was optimized to extract the maximum amount of fermentable sugars. The ultrasound treatment was found to be efficient for 20 min. Musa acuminata peels was used to synthesize copper oxide nanoparticles (CuO NPs). The size and shape of the CuO NPs was studied by scanning electron microscopy (SEM) analysis. Pretreatment of the Aloe vera rinds and Delonix regia pod was performed using ionic liquid-assisted nanocatalysts separately and in combination with the ionic liquid (triethyl ammonium hydrogen sulfate) and CuO NPs. The combined pretreatment step using the ionic liquid and CuO NPs with ultrasound extraction revealed the highest concentrations of fermentable sugars of 0.3 mg/ml and 0.21 mg/ml for Aloe vera rinds and Delonix regia pods, respectively. High performance liquid chromatography (HPLC) analysis was carried out in the hydrolysates of the feedstock after pretreatment. The cellulose and hemicelluloses content was found to be 0.82% and 0.26% for Aloe vera rinds, 23.65% and 12.67% for Delonix regia pods. Di-nitro salicylic acid assay (DNSA) was performed to estimate the hydrolyzed sugars. Fermentation using Saccharomyces cerevisiae was carried out with the extracted sugars and its growth kinetics were studied. The ethanol produced was 1.01 mg/ml from Aloe vera rinds and 0.81 mg/ml from Delonix regia pods. Conclusion: Thus, the combined pretreatment step increases the efficiency of extraction and the yield of fermentable sugars for bioethanol production. [ABSTRACT FROM AUTHOR]

The nature of a sweet sorghum cultivar influences the recovery of sugars from the bagasse during pretreatment. The sugars recovered are used in applications for conversion to high-value products such as alcohols, organic acids, and other fuels and chemicals. The severity of the pretreatment used plays a crucial role in the yield and quality of the sugars that can be recovered. Therefore, a strategic approach was taken to lower the severity of the pretreatment process to a combined severity factor (CSF) value of 0.48, whilst maintaining a high level of total-sugar recovery (i.e. 68% (w/w) and higher). This was achieved by screening 23 sweet sorghum cultivars for high-performance characteristics at low-severity conditions and optimizing the pretreatment process conditions. The pretreatment conditions included time, temperature, and acid concentration ranges of 5 to 60 min, 150 to 210 oC, and 0.00–0.96% (w/w) H2SO4, respectively. Cultivar AP6 was identified as the best performer, producing the highest total sugar yield of 78.17%. A reduction in total by-product formation from 4.79 to 2.79 g/100 g biomass was also observed. Three preferred cultivars selected for pilot scale pretreatment using steam explosion resulted in maximum total sugar recoveries that exceeded 80% (w/w). Cultivar selection provides an opportunity to utilize sweet sorghum bagasse that will liberate sugars at desired yields while reducing the generation of by-products by implementing low severity pretreatments. [ABSTRACT FROM AUTHOR]

Lignocellulose biomass, as a renewable and biodegradable carbon source, provides a wide range of valuable bioproducts. Their utilization requires an efficient conversion process to break down the complex and variable chemical structure of lignocellulose. In this work, a solid-state fermentation-based pretreatment method for the release of fermentable sugars from corn silage was investigated. The optimal process conditions for water-soluble sugar extraction were initially explored by response surface methodology with the aim to achieve the maximum sugar concentration in the extracts. The optimal extraction conditions were determined: t = 30 min; the liquid-solid ratio L/S = 25 mL g–1; n = 170 rpm; and T = 30 °C. The changes in the content of water-soluble sugars (glucose, fructose, sucrose, maltose, maltotriose) were analyzed during seven days of fungal treatment.

This study investigates the effectiveness of hydrothermal and alkaline pretreatment methods in enhancing the concentration of fermentable sugars derived from rice husk waste. After the pretreatments, enzymatic hydrolysis and fermentation processes were executed to evaluate the ethanol production from each pretreatment. Rice husk powder measuring ≤250 µm was used. For the alkaline pretreatment, sodium hydroxide (NaOH) was used at concentrations ranging from 0.5, 1 to 1.5% w/v. The efficacy of the hydrothermal pretreatment method was evaluated after 15, 30 and 45 min at 120 °C. The enzymatic hydrolysis process was performed over 144 h at 50 °C, pH 4.8 with an enzyme loading of 30 FPU (filter paper units). Fermentation was carried out at 37 °C using a strain of Saccharomyces cerevisiae Hansen 1883 (NCYC 366). Results indicated that the optimal conditions for alkaline pretreatment were observed at a 1.5% NaOH, while the best hydrothermal procedure was achieved at 120 °C and 45 min. The impact of these pretreatments was assessed based on the efficiency of enzymatic hydrolysis. The alkaline pretreatment resulted in 81.70% conversion of cellulose to glucose and 96.30% conversion of hemicellulose to xylose. In contrast, the hydrothermal pretreatment achieved 93% cellulose-to-glucose conversion and 83.35% hemicellulose-to-xylose conversion. The ethanol production registered ranged from 13 to 13.23 g·L−1, corresponding to a conversion factor of 0.43 for ethanol from fermentable sugars.

This study proposes the valorization of sunflower by-product (SbP) using subcritical water treatment. For this purpose, a response surface methodology in a 3 × 3 Box–Behnken design was employed to study the effect of temperature (100–150 °C), extraction time (5–25 min), and solvent-to-feed ratio (10–20 g bidistilled water/g SbP) on the water-soluble compounds. The highest amount of glucose (5.7-mg/g raw material) and xylose (13.5-mg/g raw material) was obtained at 150 °C and solvent-to-feed ratio of 15 after 25 min of extraction. The highest amount of protein (133.5-mg/g raw material) was obtained at 150 °C and solvent-to-feed ratio of 20 after 15 min of extraction. The selected temperature conditions did not promote the formation of final degradation products such as furfural and 5-hydroxymethylfurfural (HMF). The extracts obtained in this study showed simultaneous recovery of free monomeric sugars that could be used for bioenergy or biochemical, proteins that could be used for food and pharmaceutical industries and phenolic compounds that could be used for food and nutraceutical applications. [ABSTRACT FROM AUTHOR]

This study evaluates the microwave pretreatment of sugarcane (Saccharum officinarum) trash and oil palm (Elaeis guineensis Jacq.) empty fruit bunch (OPEFB) to yield-reducing sugars using Al2(SO4)3 as the catalyst and water as the medium. Pretreatment using 1% oxalic acid was also carried out to compare the total reducing sugar yield for both biomasses. The effects of the pretreatment on the changes in functional groups, crystallinity, and surface morphology of the biomass are discussed. Microwave heating of sugarcane trash and OPEFB particles at 180 °C for 5 min with and without the addition of 100 and 200 µmol/g biomass of Al2(SO4)3 catalyst were performed, and the total reducing sugar yield from the pretreatment hydrolysate and the enzymatic hydrolysis was improved, recorded as 0.56 and 0.51 g/g of initial biomass, respectively, representing 88.8 and 81.6% of the theoretical yield. The use of 1% oxalic acid in the pretreatment of sugarcane trash and OPEFB yielded different results of total reducing sugar yield as the two biomasses behaved differently. [ABSTRACT FROM AUTHOR]

The rapid and efficient consumption of carbon and nitrogen sources by brewer's yeast is critical for the fermentation process in the brewing industry. The comparison of the growth characterizations of typical ale and lager yeast, as well as their consumption preference to carbon and nitrogen sources were investigated in this study. Results showed that the ale strain grew faster and had a more extended stationary phase than the lager strain. However, the lager strain was more tolerant to the stressful environment in the later stage of fermentation. Meanwhile, the ale and lager yeast strains possessed varying preferences for metabolizing the specific fermentable sugar or free amino acid involved in the wort medium. The lager strain had a strong capacity to synthesize the extracellular invertase required for hydrolyzing sucrose as well as a strong capability to metabolize glucose and fructose. Furthermore, the lager strain had an advantage in consuming Lys, Arg, Val, and Phe, whereas the ale strain had a higher assimilation rate in consuming Tyr. These findings provide valuable insights into selecting the appropriate brewer's yeast strain based on the wort components for the industrial fermentation process. Key points: • The lager strain is more tolerant to the stressful environment. • The lager strain has the great capability to synthesize the extracellular invertase. • The assimilation efficiency of free amino acid varies between ale and lager. [ABSTRACT FROM AUTHOR]

Studies involving the use of residual biomass from processes have grown substantially. In this context, the efficiency of the production of second-generation ethanol and carboxymethylcellulose from sugarcane bagasse was evaluated in this work. Therefore, sugarcane bagasse was characterized and submitted to pretreatment with different low-cost ionic liquids [sec-butylammonium acetate (IL1); sec-butylammonium lactate (IL2); imidazolium acetate (IL3), and imidazolium lactate (IL4)]. After verifying the greater efficiency of the treatment performed with IL1, a new treatment was carried out with this ionic liquid. The pretreated material was subjected to enzymatic hydrolysis steps, modifying the hydrolysis time and the concentrations of treated sugar cane bagasse (%). The best pretreatment condition (63.8 h, 12.2% of pretreated bagasse, 50 °C, pH 4.8, enzyme concentration of 20 FPU.gram−1 e, 250 rpm) enabled the conversion of pretreated sugarcane bagasse of 54.57 ± 0.28%. The sugarcane bagasse was submitted to the hydrolysis process using this condition, and the hydrolysate was used to the fermentation stage with a yield of 71.77% after 24 h. The residual holocellulose produced after hydrolysis produced a carboxymethylcellulose (CMC), making it possible to obtain it with a degree of substitution equal to 1. [ABSTRACT FROM AUTHOR]

Lignocellulose biomass, as a renewable and biodegradable carbon source, provides a wide range of valuable bioproducts. Their utilization requires an efficient conversion process to break down the complex and variable chemical structure of lignocellulose. In this work, a solid-state fermentation-based pretreatment method for the release of fermentable sugars from corn silage was investigated. The optimal process conditions for water-soluble sugar extraction were initially explored by response surface methodology with the aim to achieve the maximum sugar concentration in the extracts. The optimal extraction conditions were determined: t = 30 min; the liquid-solid ratio L/S = 25 mL g-1; n = 170 rpm; and T = 30 °C. The changes in the content of water-soluble sugars (glucose, fructose, sucrose, maltose, maltotriose) were analyzed during seven days of fungal treatment. [ABSTRACT FROM AUTHOR]

When forests are extensively cleared for infrastructure and agricultural purposes, over half of the wood generated is regarded as waste. To minimize the negative consequences and successfully use renewable energy sources, further applications must be investigated. Biomass has the potential to be converted into biofuels using a process known as hydrothermal liquefaction (HTL). The conversion of wood residue under continuous flow, subcritical HTL, under both untreated and alkaline pretreated conditions was examined in this study. According to the results, pretreatment with 4% NaOH sped up recovery times compared to using raw wood and increased glucose production by 1.8 times (equivalent to 90 g/L) in comparison to using raw wood. Additionally, the fluid's pH was raised from 6.1 to 3.5 due to the alkaline pretreatment, which also switched the hydrolysis of arabinose and cellobiose to rhamnose at 0.2 MPa. The average Net Energy Ratio (NER) for glucose during liquefaction reached values as high as 63%, while the energy output from glucose during the pretreatment reached 246 kJ. The move to green energy transition toward net zero will be aided by these findings, which will usher in new waste conversion techniques to produce sustainable biofuels using continuous flow HTL. [ABSTRACT FROM AUTHOR]

The endo-1,4-β-xylanases (EC 3.2.1.8) are the largest group of hydrolytic enzymes that degrade xylan, the major component of hemicelluloses, by catalyzing the hydrolysis of glycosidic bonds β-1,4 in this polymer, releasing xylooligosaccharides of different sizes. Xylanases have considerable potential in producing bread, animal feed, food, beverages, xylitol, and bioethanol. The fungus Aspergillus tamarii Kita produced xylanases in Adams’ media supplemented with barley bagasse (brewer’s spent grains), a by-product from brewery industries. The culture extract exhibited two xylanase activities in the zymogram, identified by mass spectrometry as glycosyl hydrolase (GH) families 10 and 11 (GH 10 and GH 11). The central composite design (CCD) showed excellent predictive capacity for xylanase production (23.083 U mL−1). Additionally, other enzyme activities took place during the submerged fermentation. Moreover, enzymatic saccharification based on a mixture design (MD) of three different lignocellulosic residues was helpful in the production of fermentable sugars by the A. tamarii Kita crude extract.

Abstract Cold mash is an innovative and promising brewing technique for obtaining free-alcohol and low-alcohol beers, with a sensory profile similar to traditional beers. While traditional mashing is carried out at high temperatures, between 50 and 75 oC, this technique uses low temperatures, around 10 oC, but with a longer time. This allows more intense extraction of flavors and color from the malt while keeping the concentration of fermentable sugars low, as the enzymatic starch hydrolysis does not occur at its maximum efficiency. A study was performed on the mashing stage of the brewing process using the cold mash technique, with subsequent physicochemical characterization, to evaluate possible changes in these parameters. To obtain beer worts with low concentrations of fermentable sugars, modifications were made to mashing temperature and time, and a two-level factorial design was applied to evaluate the influence of these variables, demonstrating that the main factor mashing time was of great importance in the response. The extract content, related to the concentration of carbohydrates, presented results around 6 oBx, while the traditional wort has between 11 and 12 oBx, and the protein content was 0.12 to 0.13%, being below than reported in the literature. For pH, the results were around 6.0, which is above the recommended for brewer's wort, demonstrating that the mashing technique employed promoted changes in this parameter, possibly due to the limited action of the phosphatase enzyme, responsible for lowering the pH through the production of phosphoric acid.

Cellulose and lignin nanoparticles are high‐value‐added products obtained from lignocellulosic biomasses through several steps of cellulose purification and lignin extraction. These steps drastically reduce the potential feedstock revenue when carried out as stand‐alone methodologies. To increase biomass yields, we describe here a strategy to design a biorefinery focused on producing cellulose and lignin nanoparticles as main products, but also aim to recover and benefit from other biomass components using only water‐based processes. Sequential pressurized liquid extractions and diluted acid and alkaline treatments were carried out to fractionate elephant grass biomass, yielding (for every 100 g of biomass): 30 g of cellulose pulp (converted to 9 g of cellulose nanocrystals and 9 g of cellulose nanofibers); 10 g of lignin (used to produce 8.5 g of stable colloidal lignin nanoparticles by probe‐sonication in water); 7.5 g of extractives (e.g. sterols and phenolics) and 23 g of xylose (converted to 4.1 g of furfural). Alternatively, to allow for the flexible use of the cellulose fraction in the proposed biorefinery, 22 g of glucose could be produced by enzymatic hydrolysis. The results demonstrate that water‐based processes are suitable for a holistic use of biomass, providing a comprehensive set of high‐value‐added co‐products that are renewable and cost‐effective chemical, cosmetic, food, polymer and pharmaceutical solutions. [ABSTRACT FROM AUTHOR]

Biohydrogen is a fossil-fuel alternative. Lignocellulosic biomass is a complex part of cellulose-to-simple sugar production. Napier grass, one of the lignocellulosic biomasses, is best for biofuels or biochemicals. The dark fermentation process of Napier grass for biohydrogen proved both cost-effective and environmentally friendly. This grass contains cellulose, hemicellulose and lignin were 35.44 ± 2.01, 20.05 ± 1.55, and 28.473 ± 1.34, respectively. Sodium hydroxide was used in different concentrations to delignify lignocellulose and improve grass glucose recovery. Fermentative hydrogen production from grass biomass processing by microflora was optimized in terms of pH (4.5–7.0) and mesophilic condition (35 ± 2 °C). In this study, mesophilic conditions favored maximum hydrogen production (763.34 ml), indicating that pH 5.5 was suitable for dark-fermentative hydrogen production; study results showed Napier grass could be used successfully for dark fermentation to produce biohydrogen. • Napier grass is used as a sole substrate for biohydrogen production. • Napier grass contains rich cellulose, hemicellulose and lignin compounds. • Napier grass alkaline hydrolysate supplied cellulosic fragment is suitable. • At pH 5.5, Napier grass ferments significant biohydrogen. [ABSTRACT FROM AUTHOR]

Background: The promising use of lignocellulosic materials as a substrate for the synthesis of biochemical and biofuels has long been recognized. The bioconversion of all lignocellulosic sugars into useful products results in high sugar yields, which makes lignocelluloses appealing for use. Pretreatment and hydrolysis of lignocelluloses at high solids loadings are vital throughout industrial processes, making them more cost-effective and ecologically friendly by lowering the need for capital expenditures, energy use, and water use. The high expense of fermentation medium hinders heterotrophic oleaginous microorganisms' ability to metabolically synthesize single-cell oils for biodiesel use. This study's objective was to ascertain whether bagasse hydrolysate could be used as a cost-effective feedstock for oleaginous Rhodococcus opacus to produce microbial lipids. Methods: R. opacus a strain was used in this study. The culture was first of all maintained at soytone nutrient growth medium (i.e. GROTH MEDIUM 56) and subcultured at regular intervals and as well as preserved at 4°C. For the production media, a minimal salt medium is used. Sugarcane bagasse is pretreated by acidic hydrolysis followed by detoxification of hydrolysate and lipid extraction is done by Folch's extraction process. Results: After a brief adaptation/lag phase, the strain showed a viable growth pattern once the nutrients were detoxicated through the removal of inhibitors (e.g. hydroxymethyl-furfural [HMF]). R. opacus was grown via shake flask fermentation in bagasse hydrolysate with different sugar concentrations. When cultivated in S2 experiment, R. opacus obtained over 50% of its dry cell weight as a lipid with a lipid yield of 64.47% and productivity is 0.015 g/L/h. Conclusions: Depending on the available substrates, different microbial oils had different compositions. These findings suggest that lignocellulosic hydrolysate can be utilized as an inexpensive fermentation substrate for the R. opacus to produce microbial lipids. As a result, the range of uses for aqueous liquors produced by lignocellulosic pretreatment has increased, enabling further improvement.

Lignocellulosic biomass and agro-industrial residues are a source of fermentable sugars; however, pretreatments are needed to overcome biomass recalcitrance. This study evaluated the effect of sugarcane bagasse hydrolysis and fermentation in response to dilute acid pretreatment. In natura bagasse, extractive-free bagasse, partially delignified bagasse, and bagasse with added butylated hydroxytoluene antioxidant were pretreated with diluted acid and investigated in semi-simultaneous saccharification and fermentation (S-SSF). The effect of butylated hydroxytoluene (BHT) resulted in lower yields of inhibitors in the liquid fraction of the acid pretreatment (0.01 g L−1 of furfural, 0.01 g L−1 of 5-hydroxymethylfurfural, and 0.68 g L−1 of acetic acid). Partially delignified material and material with BHT resulted in biomass with low hemicellulose and lignin contents, indicating that BHT influenced lignin removal. Extractives removal showed benefits for the acid pretreatment, decreasing the dioxane-soluble material, and a higher yield of glucose and ethanol via S-SSF for the partially delignified material. Enzymatic saccharification of partially delignified material showed 87% of cellulose conversion (24 h with 15 FPU/g), and after 48 h of S-SSF (25 FPU/g), residual 7.06 g L−1 of glucose and production of 15.17 g L−1 of ethanol were observed. The low content of extractives, lignin, and dioxane soluble material resulted in better cellulose accessibility and ethanol yield. Chemical compounds can help remove lignin from biomass favoring ethanol production by S-SSF. [ABSTRACT FROM AUTHOR]

Background: The promising use of lignocellulosic materials as a substrate for the synthesis of biochemical and biofuels has long been recognized. The bioconversion of all lignocellulosic sugars into useful products results in high sugar yields, which makes lignocelluloses appealing for use. Pretreatment and hydrolysis of lignocelluloses at high solids loadings are vital throughout industrial processes, making them more cost-effective and ecologically friendly by lowering the need for capital expenditures, energy use, and water use. The high expense of fermentation medium hinders heterotrophic oleaginous microorganisms' ability to metabolically synthesize single-cell oils for biodiesel use. This study's objective was to ascertain whether bagasse hydrolysate could be used as a cost-effective feedstock for oleaginous Rhodococcus opacus to produce microbial lipids. Methods: R. opacus a strain was used in this study. The culture was first of all maintained at soytone nutrient growth medium (i.e. GROTH MEDIUM 56) and subcultured at regular intervals and as well as preserved at 4°C. For the production media, a minimal salt medium is used. Sugarcane bagasse is pretreated by acidic hydrolysis followed by detoxification of hydrolysate and lipid extraction is done by Folch's extraction process. Results: After a brief adaptation/lag phase, the strain showed a viable growth pattern once the nutrients were detoxicated through the removal of inhibitors (e.g. hydroxymethyl-furfural [HMF]). R. opacus was grown via shake flask fermentation in bagasse hydrolysate with different sugar concentrations. When cultivated in S2 experiment, R. opacus obtained over 50% of its dry cell weight as a lipid with a lipid yield of 64.47% and productivity is 0.015 g/L/h. Conclusions: Depending on the available substrates, different microbial oils had different compositions. These findings suggest that lignocellulosic hydrolysate can be utilized as an inexpensive fermentation substrate for the R. opacus to produce microbial lipids. As a result, the range of uses for aqueous liquors produced by lignocellulosic pretreatment has increased, enabling further improvement. [ABSTRACT FROM AUTHOR]

Cocoa bean shell (CBS), a by-product of the chocolate industry, has been employed as a substrate to obtain poly(3-hydroxybutyrate) (PHB) by fermentation with Bacillus firmus. With this aim, acid-thermal hydrolysis of CBS (20% w/v) was conducted at 135 °C for 10 min so that broths rich in fermentable sugars were obtained. These broths, both non-centrifuged and centrifuged, were employed as fermentation media. Significant polymer production was obtained from the broth with solids (non-centrifuged) with a yield of 107 mg of PHB/g dry matter. These results indicated that the presence of CBS solids played an important role in microorganism metabolism, with them being fundamental to the production of PHB. Experimental data were fitted by a model based on irreversible first-order reactions, and kinetic constants were obtained for solubilisation, hydrolysis, and sugar consumption. Although, several studies on obtaining PHB from other agri-food residues have been published, this is the first work on PHB production from CBS, with the study obtaining promising results with PHB concentrations similar or even higher than the others previously reported. [ABSTRACT FROM AUTHOR]

Malt bagasse is a lignocellulosic byproduct of the brewery industry and is rich in fibers and proteins. It is produced in abundance and can be reused as a substrate to obtain fermentable sugars. However, to obtain an efficient enzymatic saccharification, pretreatments must be used. The objective of this study was to evaluate the combination of ultrasonication in diluted acid medium as a pretreatment of lignocellulosic biomass to obtain fermentable sugars and residual solid fractions with increased susceptibility to enzymatic hydrolysis. The residual solid fractions were characterized according to their composition, morphology, crystallinity, and thermal stability. Malt bagasse was submitted to different pH values (3–5), ultrasonication times (10–60 min), and biomass contents (6–10%, w/v). The effect of the time was the most important variable; more time resulted in higher sugar release and greater changes in the residual solid fraction recovered after pretreatment. In general, the residual solid fractions of pretreated samples demonstrated a higher crystallinity index and thermal stability than raw malt bagasse. The sample processed at pH 5 for 60 min with a biomass concentration of 8% resulted in the highest cellulose content and lowest lignin content. In this study, the use of acid hydrolysis combined with ultrasonication decreased the time required for the maximum hydrolysis efficiency when compared with literature data, and it was which is an interesting result considering an economical point of view; however, future studies should be conducted with the aim of reducing the process times and energy costs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Marine filamentous cyanobacterium Leptolyngbya valderiana was investigated. • Nitrate stress enhanced carbohydrate content by ∼47 % of dry cell weight. • Strategizing two-stage cultivation raised carbohydrate yield by ∼80 %. • The rise in fermentable sugars accumulation resulted ≥80 % higher bioethanol yield. • Standardized physiochemical condition augmented C-phycocyanin production ∼77 %. The investigation aimed to augment carbohydrate accumulation in the marine cyanobacterium Leptolyngbya valderiana BDU 41001 to facilitate bioethanol production. Under the standardised physiochemical condition (SPC), i.e. 90 µmol photon m−2 s−1 light intensity, initial culture pH 8.5, 35 °C temperature and mixing at 150 rpm increased the carbohydrate productivity ∼70 % than the control, while a 47 % rise in content was obtained under the nitrate (N)-starved condition. Therefore, a two-stage cultivation strategy was implemented, combining SPC at the 1st stage and N starvation at the 2nd stage, resulting in 80 % augmentation of carbohydrate yield, which enhanced the bioethanol yield by ∼86 % as compared to the control employing immobilised yeast fermentation. Moreover, biomass utilisation was maximised by extracting C-phycocyanin, where a ∼77 % rise in productivity was recorded under the SPC. This study highlights the potential of L. valderiana for pilot-scale biorefinery applications, advancing the understanding of sustainable biofuel production. [ABSTRACT FROM AUTHOR]

For the techno-commercial success of any lignocellulosic biorefinery, the cost-effective production of fermentable sugars for the manufacturing of bio-based products is indispensable. High-solids enzymatic saccharification (HSES) is a straightforward approach to develop an industrially deployable sugar platform. Economic incentives such as reduced capital and operational expenditure along with environmental benefits in the form of reduced effluent discharge makes this strategy more lucrative for exploitation. However, HSES suffers from the drawback of non-linear and disproportionate sugar yields with increased substrate loadings. To overcome this bottleneck, researchers tend to perform HSES at high enzyme loadings. Nonetheless, the production costs of cellulases are one of the key contributors that impair the entire process economics. This review highlights the relentless efforts made globally to attain a high-titer of sugars and their fermentation products by performing efficient HSES at low cellulase loadings. In this context, technical innovations such as advancements in new pretreatment strategies, next-generation cellulase cocktails, additives, accessory enzymes, novel reactor concepts and enzyme recycling studies are especially showcased. This review further covers new insights, learnings and prospects in the area of lignocellulosic bioprocessing. [ABSTRACT FROM AUTHOR]

Alkaline pretreatment and sequential enzymatic hydrolysis of soybean hull were investigated to obtain fermentable sugars for polyhydroxyalkanoates production along with residual glycerol as low-cost carbon sources. Soybean hull is composed of approximately 32% cellulose, 12% hemicellulose, 6% lignin, and 11% protein. Alkaline pretreatment was carried out with 2% NaOH concentration, 10% (w/v) biomass loading, and 60 min incubation time in an autoclave at 120 °C. The response surface methodology (RSM) based on the central composite design (CCD) tool was employed to optimize the enzymatic hydrolysis process, where the variables of biomass loading, enzymes' concentration, and time were considered. The maximum total reducing sugars concentration obtained was 115.9 g∙L−1 with an enzyme concentration of 11.5 mg protein/g dry substrate for enzyme preparation B1, 2.88 mg protein/g dry substrate for XylA, and 57.6 U/g dry substrate for β-glucosidase, after 42 h at 45 °C, and pH was 4.5. Subsequently, the saccharification step was conducted by increasing the processing scale, using a 1 L tank with stirring with a controlled temperature. Implementing the same enzyme concentrations at pH 4.5, temperature of 45 °C, 260 mL working volume, and incubation time of 42 h, under fed-batch operation with substrate feeding after 14 h and 22 h, a hydrolysate with a concentration of 185.7 g∙L−1 was obtained. Initially, to verify the influence of different carbon sources on Cupriavidus necator DSMz 545 in biomass production, batch fermentations were developed, testing laboratory-grade glucose, soybean hull hydrolysate, and waste glycerol (a by-product of biodiesel processing available in large quantities) as carbon sources in one-factor-at-a-time assays, and the mixture of soybean hull hydrolysate and waste glycerol. Then, the hydrolysate and waste glycerol were consumed by C. necator, producing 12.1 g∙L−1 of biomass and achieving 39% of polyhydroxyalkanoate (PHB) accumulation. To the best of our knowledge, this is the first time that soybean hull hydrolysate has been used as a carbon source to produce polyhydroxyalkanoates, and the results suggest that this agro-industrial by-product is a viable alternative feedstock to produce value-added components. [ABSTRACT FROM AUTHOR]

Acetic acid (HAc) pretreatment has been widely used for the production of xylo-oligosaccharides (XOS), requiring harsh reaction conditions because XOS are intermediates during the xylan degradation process. This complexity makes the pretreatment process difficult to regulate. In this study, a pH-controlled HAc pretreatment using sodium hydroxide (NaOH) was proposed to enhance the yield of XOS and to reduce its degree of polymerization (DP) from corncobs (CC). By employing this method (0.3 M-2.7), 49.7 % of XOS with DP 2-6 was obtained, alongside a notable increase in the fraction of XOS with DP 2-4 (10.1 g/L). This performance significantly surpassed that of the HAc alone (0.3 M). Moreover, the glucose yield from CC via pH-controlled HAc pretreatment was as high as 93.1 % after 72-h enzymatic hydrolysis. These results suggested that the pH-controlled HAc pretreatment could be a promising strategy for the coproduction of low-DP XOS and fermentable sugars., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

[Display omitted] • pH-controlled HAc pretreatment was used for coproduction of low-DP XOS and glucose. • A XOS (DP 2–6) yield of 49.7 % was obtained at 0.3 M HAc at pH 2.7 from CC. • Modulating the pH with NaOH effectively inhibited xylose and furfural generation. • Low DP (2–4) XOS accounted for 68.8 % of the total XOS. • 93.1 % glucose yield was achieved from the CC with pH-controlled HAc pretreatment. Acetic acid (HAc) pretreatment has been widely used for the production of xylo -oligosaccharides (XOS), requiring harsh reaction conditions because XOS are intermediates during the xylan degradation process. This complexity makes the pretreatment process difficult to regulate. In this study, a pH-controlled HAc pretreatment using sodium hydroxide (NaOH) was proposed to enhance the yield of XOS and to reduce its degree of polymerization (DP) from corncobs (CC). By employing this method (0.3 M-2.7), 49.7 % of XOS with DP 2–6 was obtained, alongside a notable increase in the fraction of XOS with DP 2–4 (10.1 g/L). This performance significantly surpassed that of the HAc alone (0.3 M). Moreover, the glucose yield from CC via pH-controlled HAc pretreatment was as high as 93.1 % after 72-h enzymatic hydrolysis. These results suggested that the pH-controlled HAc pretreatment could be a promising strategy for the coproduction of low-DP XOS and fermentable sugars. [ABSTRACT FROM AUTHOR]

Relatively high levels of phytates in buckwheat malt and the low activity of endogenous phytases that limit the effective use of substrates for fermentation and yeast metabolism (starch, proteins, minerals) are an argument for using phytases in beer production technology. Two mash-in programs were applied: (1) the Congress program, typical for basic raw materials, (2) a program with temperature optimized for phytase activity. Commercial preparations of 3-phytase (Finase P) and 6-phytase (Ronozyme) were used in the study. Monitored levels of selected fermentable sugars indicates a statistically significant effect of phytase addition on the glucose content in both mash-in programs used. The SEC-HPLC chromatography allowed to select a key polypeptide with an estimated molecular weight of 40 kDa, whose relative peak area decreases as a result of the applied mash-increase treatment with phosphorolytic enzymes, although this relation was not statistically confirmed in the analysis of free amino acids content. The analyses carried out also indicate that apart from the target molecules, namely phytate and inositol, the use of phytases in the process of buckwheat wort preparation slightly changes the profile of fermentable sugars and causes significant changes in the polypeptide profile of the final mash.

Efficient conversion of sugars into fermentable sugars is a critical challenge in the cost-effective production of lignocellulosic biopolymers and biofuels. This study focuses on various sugar quantification techniques applied to Furcraea Foetida (Mauritius Hemp) samples, utilizing natural deep eutectic solvents (NADES) and deep eutectic solvents (DES) like urea, glycerol, citrates, pyrogallol (PY), and cetyltrimethylammonium bromide (CTAB). Employing a Taguchi-designed experiment, operational conditions were fine-tuned to evaluate the influence of time, concentration, and temperature on each deep eutectic solvent-based process. The emerging green solvent extraction approach demonstrated significant results, achieving notably high sugar yields compared to traditional techniques such as alkali, hot-water, and acid-mediated extraction. At a CTAB:PY molar ratio of 1:3, optimized for 60 min at 50 °C, the highest fermentable sugar (FS) yield of 0.6891 ± 0.0123 g FS/g LCB was attained—2 to 6 times higher than non-optimized values and 0.2 to 0.3 times higher than optimized traditional methods. In light of this, this research study emphasizes the pivotal significance of efficient sugar conversion through optimized deep eutectic solvent-based extraction methods, with a particular focus on Furcraea Foetida fibers, offering promising outcomes for the biofuel and biopolymer production industry. [Display omitted] • The study optimizes fermentable sugars extraction from Furcraea Foetida fibers • Taguchi method is employed to identify the optimal conditions for sugar extraction. • The use of natural deep eutectic solvents is a promising approach for optimizing sugar extraction from lignocellulosic biomass • The highest extraction of fermentable sugars (FS) reached 0.6891 ± 0.0123 g FS/g LCB [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass and agro-industrial residues are a source of fermentable sugars; however, pretreatments are needed to overcome biomass recalcitrance. This study evaluated the effect of sugarcane bagasse hydrolysis and fermentation in response to dilute acid pretreatment. In natura bagasse, extractive-free bagasse, partially delignified bagasse, and bagasse with added butylated hydroxytoluene antioxidant were pretreated with diluted acid and investigated in semi-simultaneous saccharification and fermentation (S-SSF). The effect of butylated hydroxytoluene (BHT) resulted in lower yields of inhibitors in the liquid fraction of the acid pretreatment (0.01 g L−1 of furfural, 0.01 g L−1 of 5-hydroxymethylfurfural, and 0.68 g L−1 of acetic acid). Partially delignified material and material with BHT resulted in biomass with low hemicellulose and lignin contents, indicating that BHT influenced lignin removal. Extractives removal showed benefits for the acid pretreatment, decreasing the dioxane-soluble material, and a higher yield of glucose and ethanol via S-SSF for the partially delignified material. Enzymatic saccharification of partially delignified material showed 87% of cellulose conversion (24 h with 15 FPU/g), and after 48 h of S-SSF (25 FPU/g), residual 7.06 g L−1 of glucose and production of 15.17 g L−1 of ethanol were observed. The low content of extractives, lignin, and dioxane soluble material resulted in better cellulose accessibility and ethanol yield. Chemical compounds can help remove lignin from biomass favoring ethanol production by S-SSF.

The feasibility of bioethanol production from low-grade longan fruit waste material was recently studied as a novel substrate for bioethanol production. First, hydrothermal pretreatment followed by enzymatic hydrolysis converted both the cellulosic and hemicellulosic biomass of the low-grade longan fruit wastes into fermentable sugars, which eventually produced ethanol by yeast fermentation. Therefore, an optimal condition of hydrothermal residence time and pretreatment concentration was determined to obtain the high release of sugars. An experimental design was constructed with the Central Composite Design (CCD) response surface method using factors of the hydrothermal residence time and pretreatment concentration in constant temperature and time. The results revealed optimum reducing sugar yield of 240.396 g/L (R2 = 0.9989), sugar productivity of 240.396 g/L.day (R2 = 0.9763), and sugar yield coefficient of 24.04 g/g (R2 = 0.9989). The highest ethanol yield (16.74 g/L) was achieved at 24 h of fermenting time. These results show that low-grade longan fruit wastes are an excellent feedstock for producing ethanol that could be either used as biofuel or as a beverage. [ABSTRACT FROM AUTHOR]

Fruit production in Thailand has been increasing due to the practical farmers' knowledge of agroecology and sustainable farming. Thailand is one of the productions of the most massive fruit in southeast Asian countries. On the other hand, the status of fruit waste, which becomes stuck previous to landfills, is concerned by researchers over the years. Low-grade and waste longan fruits are also no exceptions that are feedstock material for bioethanol production. Accordingly, this study aims to evaluate bioethanol production from dried low-grade and waste longan fruits by using physical pretreatment (boiling and autoclave) and blue-green algal enzymes for hydrolysis. After pretreatment, total and reducing sugar was 227.63 ± 2.63 g/L and 89.26 ± 1.70 g/L, respectively. Algal enzymes were added at a pH of 7.0 in the hydrolysis process; subsequently, total and reducing sugar were achieved 348.68 ± 3.95 g/L and 183.33 ± 14.70 g/L, respectively. The present study shows that using algal enzymes in the hydrolysis process improves fermentable sugar production and applicable for bioethanol production. [ABSTRACT FROM AUTHOR]

Olive Tree Pruning (OTP) biomass can be considered a suitable source of fermentable sugars for the production of second-generation bioethanol. The present study proposes a remarkable alternative for the valorization of olive tree pruning residues. OTP biomass was processed using a sequential calcium hydroxide pretreatment/enzymatic hydrolysis. A 24–1 half fractional factorial design was adopted for the screening of process variables and a central composite design was used for the optimization stage. Temperature and lime loading resulted statistically significant. The following optimal conditions were obtained: 0.01 g of Ca(OH)2/g of dry material, 20 g of H2O/g of dry material at 160 °C for 2 h. The mathematical model that governs this alkaline pretreatment was obtained with a 76% adjusted determination coefficient, which means that it is a good representation of the process. Under optimal operating conditions, 13% of the cellulose and 88% of the hemicellulose was solubilized. Moreover, the fermentable sugar content increased 1800% compared with the initial conditions, obtaining 240 g of glucose per kg of OTP residue. The fermentable sugars obtained after the calcium hydroxide pretreatment and enzymatic hydrolysis of OTP biomass yielded 2.8 g of ethanol/100 g of raw material. [ABSTRACT FROM AUTHOR]