Steam Pretreatment Research Articles

Steam pretreatment of lignocellulosic material for enhanced enzymatic hydrolysis - Lab scale studies and pilot scale application

Steam pretreatment of lignocellulosic material for enhanced enzymatic hydrolysis - Lab scale studies and pilot scale application

Comparison between high-pressure steam and vinegar stir-frying on grinding characteristics and nutrient components of turtle shells: Difference between carapace and plastron

The nutritional differences between the carapace and plastron of turtle shells, and their grinding challenges, are not well understood. This study aimed to evaluate the nutritional differences between a turtle shell’s carapace and plastron, and the effects of high-pressure steam (HP) and vinegar stir-frying (VS) pretreatments. The carapace showed higher crude protein and fat but lower ash than the plastron. Both pretreatments reduced grinding energy and increased ash content while decreasing protein and amino acids levels. HP resulted in more water-soluble extract (15.13 %), protein (17.26 %), and peptide (20.77 %), whereas total free amino acids (FAAs: 545.62 mg/100 g) were increased by VS. Nutritional value was comparable between carapace and plastron. Additionally, in contrast to the conventional VS pretreatment approach, the HP method not only enhances the grinding process of turtle shells but also promotes the release of their water-soluble constituents. This advancement sets a solid foundation for future comprehensive studies aimed at exploring the nutritional potential of turtle shells.

Analytical Pyrolysis of Soluble Bio-Tar from Steam Pretreatment of Bamboo by Using TG-FTIR and Py-GC/MS.

Steam pretreatment at high temperatures enables fresh bamboo to possess antifungal and antiseptic properties. The process produces a large amount of wastewater that urgently needs to be recycled. Soluble bio-tars derived from wastewater under low-temperature (LTS-tar) and high-temperature (HTS-tar) steam pretreatments of moso bamboo were studied with a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis-gas-chromatography/mass spectrometry (Py-GC/MS). Thermogravimetric analysis showed that in the three stages of the thermal decomposition process, the final residue of the bamboo and HTS-tar had two main peaks of 0.88 wt% and 6.85 wt%. The LTS-tar had much more complicated thermal decomposition behavior, with six steps and a high residue yield of 23.86 wt%. A large quantity of CH4 was observed at the maximum mass loss rates of the bamboo and bio-tars. Acids, aldehydes, ketones, esters, and phenolic compounds were found in the pyrolysis products of the bamboo and soluble bio-tars. Both bio-tars contained carbohydrates and lignin fragments, but the LTS-tar under mild steam conditions had more saccharides and was much more sensitive to temperature. The lignin in the bamboo degraded under harsh steam conditions, resulting in high aromatic and polymeric features for the HTS-tar. The significant differences between LTS-tar and HTS-tar require different techniques to achieve the resource utilization of wastewater in the bamboo industry.

Influence of feedstock selection on cellulosic ethanol production based on densified biomass with calcium hydroxide and regular steam pretreatment

Feedstock selection is a key factor affecting the process of cellulosic ethanol production. Densifying lignocellulosic biomass with chemicals (calcium hydroxide) followed by regular steam autoclave (DLCA(ch)) is an emerging and efficient pretreatment technology. In this study, different crop straws were selected as feedstock in a DLCA(ch) based process for cellulosic ethanol production, and their experimental and economic performances were evaluated. Both single crop straws and mixed crop straws were used and compared as feedstock for DLCA(ch) based biorefinery. Among single crop straws of corn stover, rice straw and wheat straw, wheat straw had the highest ethanol yield and the lowest feedstock cost, with a minimum ethanol selling price of 2.03 $/gal ethanol considering a 10 % internal rate of return and a 2000 tons crop straw per day biorefinery scale. When mixed crop straws were used as the feedstock, both feedstock cost and ethanol production cost were further reduced, and the minimum ethanol selling price was reduced to 2.02 $/gal ethanol. In addition, the use of mixed crop straws has great potential for large scale DLCA(ch) based process for cellulosic ethanol production.

Feedstock/pretreatment screening for bioconversion of sugar and lignin streams via deacetylated disc-refining

Recent publications have shown the benefits of deacetylation disc-refining (DDR) as a pretreatment process to deconstruct biomass into sugars and lignin residues. Major advantages of DDR pretreatment over steam and dilute acid pretreatment are the removal of acetyl and lignin during deacetylation. DDR does not generate hydroxymethylfurfural (HMF) and furfural which are commonly produced from steam and dilute acid pretreatments. Acetate, lignin, HMF, and furfural are known inhibitors during enzymatic hydrolysis and fermentation. Another advantage of deacetylation is the production of lignin-rich black liquor, which can be upgraded to other bioproducts. Furthermore, due to the lack of sugar degradation during deacetylation, DDR has significantly less sugar loss than other pretreatment methods. Previous studies for DDR have primarily focused on corn stover, but lacked the investigative studies of other feedstocks. This study was designed to screen various DDR process conditions at pilot scale using three different feedstocks, including corn stover, poplar, and switchgrass. The impact of the pretreatment conditions was evaluated by testing hydrolysates for bioconversion to 2,3-butanediol. Pretreatment of biomass by DDR showed high-conversion-yields and 2,3-BDO fermentation production yields. Techno-economic analysis (TEA) of the pretreatment for biomass to sugar was also developed based on NREL’s Aspen Model. This study shows that the cellulose and hemicellulose in poplar was more recalcitrant than herbaceous feedstocks which ultimately drove up the sugar cost. Switchgrass was also more recalcitrant than corn stover but less than poplar.

The impact of thermal pretreatment on phytochemical profiles and bioactivity of freeze-dried lily bulbs (Lilium lancifolium)

Lily bulbs are susceptible to deterioration during storage if improperly handled. To resolve this problem, it is necessary to investigate suitable processing techniques. The aim of this study is to evaluate the effects of steaming, blanching and microwave pretreatment on freeze-dried lily bulbs in terms of color, phenolic content and bioactivity. Results showed that appropriate steaming and blanching pretreatment could contribute to product characteristics similar to those of freeze-dried lily bulbs, with the maximum L* value reduced by only 7.57% and 0.55% respectively. Thermal pretreatment affected the retention, degradation and transformation of polyphenol, especially for regalosides. The polyphenol was closely associated with the browning of lily bulbs. Thermal processing caused the decline of regaloside A and the increase of regaloside B, which were the major phenolic monomers that can effectively inhibit the browning of lily bulbs. The antioxidant activity of freeze-dried lily pretreated with blanching for 6 min was the highest (4.39 ± 0.32 μmol TE/g DW), with an improvement of nearly 25.39% compared to that of untreated freeze-dried lily. Thus, the combination of freeze-dried with steaming or blanching pretreatment could be proposed as a sustainable strategy to improve the quality of lily bulbs for industrial application.

Chemical-free saturated steam pretreatment of oil palm empty fruit bunch for improved enzymatic saccharification

Oil palm empty fruit bunch (EFB) as the main lignocellulosic residue from the oil palm industry serves as suitable feedstock for enzymatic saccharification, yielding fermentable sugars. Due to complex inter-association between hemicellulose, cellulose and lignin within EFB lignocellulosic matrix, different saturated steam conditions at 140-230 °C, 0.3-2.3 MPa was chosen as a pretreatment strategy, targeted to hydrolyze hemicellulose and reduce crystallinity of cellulose to enhance enzymatic saccharification which need no chemical requirement and potential for energy recovery. As a result, SEM analysis of EFB morphology indicated that the enhanced silica body removal from 190-230 °C of saturated steam pretreatment correspondingly led to substantial 82% removal of hemicellulose. Consequently, enzymatic saccharification yielded between 0.621-0.637 g glucose per g EFB, equivalent to 93-95% of cellulose saccharification by Acremonium cellulase on EFB treated with saturated steam at 210-230 °C. Notably, a short duration pretreatment of EFB at 210 °C for 2 min was proved sufficient for high fermentable sugar production. The potential energy estimated for employing saturated steam pretreatment of EFB in a palm oil mill was sufficient by 2.2 x 1012 kJ/year.

A Comparative Study on the Effects of Chemical and Hydrothermal Pretreatment Methods on the Valorization of Lignocellulose Agricultural Waste (Sugarcane Bagasse)

To effectively valorize agricultural waste (sugarcane bagasse) through biorefinery process, pretreatment which can be carried out in several ways is inevitable. This study explored the effects of chemical (acid and alkaline) and hydrothermal (steaming and autoclave) pretreatment methods on reducible sugar and ethanol yield from sugarcane bagasse. Acid pretreatment chemicals which include hydrogen peroxide and acetic acid were mixed together with sugarcane residue and heated at 85 oC for one hour. In alkaline pretreatment sodium hydroxide was mixed with the sugarcane waste and allow to incubate at 50 oC for one hour. The steaming approach involved using a steam distillation equipment. The sugarcane bagasse was first placed in a steam bag and then into a steam distillation unit which was steamed over a heating mantle for an hour. Autoclave pretreatment method used a stove type autoclave to disintegrate the processed sugarcane residue at 121oC. Each of these pretreated samples underwent independent hydrolysis and simultaneous saccharification and fermentation operations. Sugar yield was determined by the 3,5-dinitrosalicylic acid method, whereas the bioethanol yield was determined from refractometer readings. Sugarcane bagasse pretreated with acids gave a sugar yield of 995.567 mg/l and ethanol concentrations of 1.7303% in both enzymatic and acid hydrolysis, and 2.0758% ethanol concentration in simultaneous saccharification and fermentation process. Alkaline-pretreated sample gave a fermentable sugar yield of 441.2591 mg/l with 0.8655%, 0.6938%, and 1.73033% ethanol concentrations from enzymatic hydrolysis, acid hydrolysis and simultaneous saccharification and fermentation processes respectively. Steaming yielded 913.4849 mg/l of fermentable sugar, whereas the ethanol concentrations in the enzymatic hydrolysis, acid hydrolysis and simultaneous saccharification and fermentation methods were 1.2121%, 0.6938%, and 0.8666% respectively. Autoclave pretreatment resulted in a fermentable sugar yield of 800.9 mg/l with ethanol concentration of 1.3848% in both the enzymatic and acid hydrolysis, while that of simultaneous saccharification and fermentation was 1.0393%.

Silencing ScGUX2 reduces xylan glucuronidation and improves biomass saccharification in sugarcane.

There is an increasing need for renewable energy sources to replace part of our fossil fuel-based economy and reduce greenhouse gas emission. Sugarcane bagasse is a prominent feedstock to produce cellulosic bioethanol, but strategies are still needed to improve the cost-effective exploitation of this potential energy source. In model plants, it has been shown that GUX genes are involved in cell wall hemicellulose decoration, adding glucuronic acid substitutions on the xylan backbone. Mutation of GUX genes increases enzyme access to cell wall polysaccharides, reducing biomass recalcitrance in Arabidopsis thaliana. Here, we characterized the sugarcane GUX genes and silenced GUX2 in commercial hybrid sugarcane. The transgenic lines had no penalty in development under greenhouse conditions. The sugarcane GUX1 and GUX2 enzymes generated different patterns of xylan glucuronidation, suggesting they may differently influence the molecular interaction of xylan with cellulose and lignin. Studies using biomass without chemical or steam pretreatment showed that the cell wall polysaccharides, particularly xylan, were less recalcitrant in sugarcane with GUX2 silenced than in WT plants. Our findings suggest that manipulation of GUX in sugarcane can reduce the costs of second-generation ethanol production and enhance the contribution of biofuels to lowering the emission of greenhouse gases.

Effects of Superheated Steam Pretreatment on Muscle Release and Meat Quality of Shucked Tropical Oyster (Crassostrea iredalei)

Effects of Superheated Steam Pretreatment on Muscle Release and Meat Quality of Shucked Tropical Oyster (Crassostrea iredalei)

Diluted Sulphuric Acid Hydrolysis of Destarched Sago Fibre assisted with Selected Pre-treatments for Glucose and Xylose Production

In Sarawak, Malaysia, approximately 7 t of sago fibre waste is produced daily from a single sago starch processing mill and it is currently disposed of either directly into a river nearby or in open spaces. On a dry basis, sago fibre contains 58% starch, 23% cellulose, 9.2% hemicellulose and 4% lignin. Our previous study used the trapped starch of sago fibre as a substrate for producing glucose through an enzymatic hydrolysis process in which the destarched fibre (DSF) remained unused. This study represents an attempt to utilise destarched sago fibre (DSF) as a raw material for glucose and xylose production. The DSF initially underwent a pre-treatment process via dilute sulphuric acid hydrolysis to liberate xylose for which four parameters were studied: the solid-to-liquid ratio (5:100-40:100), the dilute sulphuric acid concentration (0% (v/v) - 9% (v/v)), reaction time (30, 60 and 90 minutes) and the effects of steaming and microwave pre-treatment. Steaming pre-treatment led to the highest xylose (28.19 ± 0.78 g/L) and glucose (78.63 g/L ± 0.22 g/L) production, for which the dilute sulphuric acid concentration was set at 2% (v/v), reaction time was set at 60 minutes. The solid-to-liquid ratio was 30:100. Overall, this work indicates that the optimal pre-treatment of DSF can yield glucose and xylose which can be used to produce bioethanol and xylitol. The study also suggests that DSF can be an alternative raw material for xylitol production.

스팀 및 동결 전처리가 건조 감잎 열수추출물의 이화학적 특성에 미치는 영향

This study was conducted to develop a preservation technology that can induce changes in physicochemical properties to effectively utilize of persimmon leaves. The application effects of steaming or freezing technique were investigated. Astringent persimmon leaves were steam-blanched (100°C, 30 sec) or frozen (−20°C, 15 d), followed by hot-air drying (50°C). The physicochemical properties of the extract obtained by hot-water leaching from the dried leaves were compared. The extract of leaves dried without pretreatment was used as a control. L* value was higher in steamed than in control and frozen. a* value was highest in the control. The browning index was higher in the frozen and lower in the steamed than in the control. Soluble solids were the highest in the steamed and the lowest in the frozen. Sucrose content was relatively high in the steamed, and the glucose and fructose contents were relatively high in the frozen. Total polyphenol content and DPPH radical scavenging activity were higher in steamed and lower in frozen than in control. Thus, it was confirmed that steam or freeze pretreatment after harvesting persimmon leaves affects the extraction yield, color, antioxidant capacity and component changes of dried persimmon leaves. Unlike steaming, freezing pretreatment showed the effect of promoting decomposition and browning reactions, and it is considered useful when such an effect is needed.

Energy performance of compressed biomethane gas production from co-digestion of Salix and dairy manure: factoring differences between Salix varieties

Biogas from anaerobic digestion is a versatile energy carrier that can be upgraded to compressed biomethane gas (CBG) as a renewable and sustainable alternative to natural gas. Organic residues and energy crops are predicted to be major sources of bioenergy production in the future. Pre-treatment can reduce the recalcitrance of lignocellulosic energy crops such as Salix to anaerobic digestion, making it a potential biogas feedstock. This lignocellulosic material can be co-digested with animal manure, which has the complementary effect of increasing volumetric biogas yield. Salix varieties exhibit variations in yield, composition and biomethane potential values, which can have a significant effect on the overall biogas production system. This study assessed the impact of Salix varietal differences on the overall mass and energy balance of a co-digestion system using steam pre-treated Salix biomass and dairy manure (DaM) to produce CBG as the final product. Six commercial Salix varieties cultivated under unfertilised and fertilised conditions were compared. Energy and mass flows along this total process chain, comprising Salix cultivation, steam pre-treatment, biogas production and biogas upgrading to CBG, were evaluated. Two scenarios were considered: a base scenario without heat recovery and a scenario with heat recovery. The results showed that Salix variety had a significant effect on energy output–input ratio (R), with R values in the base scenario of 1.57–1.88 and in the heat recovery scenario of 2.36–2.94. In both scenarios, unfertilised var. Tordis was the best energy performer, while the fertilised var. Jorr was the worst. Based on this energy performance, Salix could be a feasible feedstock for co-digestion with DaM, although its R value was at the lower end of the range reported previously for energy crops.

Effect of alkaline and steam pre-treatment on saccharification of corn cob and production of cellullase from fungal consortium

Lignocellulosic biomass as fossil fuel alternative comes with its challenges such as its inherent stability and recalcitrance. The use of commercial cellulase in the removal of lignin comes with high cost. This research seeks to answer questions on how alkaline and steam pre-treatment improve cellulose/glucose liberation from lignocellulosic biomass (corn cobs) using a consortium of <i>pichia kudriavzevii</i> and <i>cyberlindnera fabianii.</i><br /> In the current study, the effectiveness of steam and sodium hydroxide (NaOH) pre-treatment for reducing corn cob structure was examined, and the pre-treated biomass afterwards was exposed to the hydrolyzing activity of a consortium enzyme cocktail that was custom-formulated. The results of an analysis of composition showed that while alkaline pre-treated corn cob (APC) had 1.2% lignin, 75.8% cellulose, and 10.9% hemicellulose, steam pre-treated corn cob (SPC) had 2.5% lignin, 67.2% cellulose, and 25% hemicellulose. Lignin was eliminated from the biomass of corn cobs using both steam and NaOH pre-treatment. The hydrolyzing effect of the holocellulolytic enzyme cocktail, prepared with two multifunctional enzymes, was applied to the alkaline and steam pre-treated samples. This hydrolyzed SPCs more effectively than APC feedstocks, revealing that steam was a more effective pre-treatment attaining a remarkable 8.33 U/mg endoglucanase, 5.56 U/mg exoglycanase and 8.97U/mg beta-glucosidase levels (event 1) and glucose peak concentration of 0.433 mol/mL at 48 hours (event 2); according to a thorough examination of cellulase capacity and glucose levels.<br /> Overall, the consortium enzyme cocktail effectively hydrolyzed agricultural feedstocks that had undergone alkaline pre-treatment, making it a desirable option for usage in the bioconversion procedure in the biorefinery sector. This study demonstrates an effective technique for turning agricultural waste (corn cob) into high-value products through effective and practical chemical pre-processing.

Steam pre-treatment of sugarcane bagasse and wheat straw as a cleaner feedstock for black soldier fly larvae rearing

Abstract With the pressing need for alternative waste management strategies that are friendly to the environment, black soldier fly larvae (BSFL) are being cultivated as exceptional insects for the bioconversion of organic waste into larval biomass rich in protein and fat content. Agricultural residues, such as wheat straw and sugarcane bagasse are recognised as important renewable biomass sources, with potential to replace insufficient amount of suitable organic wastes available for BSFL feeding. This study evaluated the steam pre-treatment from 140 to 215 °C and enzymatic hydrolysis of lignocelluloses as BSFL feed supplement prior to blending in an equal ratio (50:50) with the standard feed for BSFL rearing. Key findings illustrated that steam pre-treatment and enzymatic hydrolysis are vital in liberating the sugar monomers of the lignocellulose biomass for BSFL utilisation, with an optimum steam pre-treatment temperature of 185 °C. With a lignocellulosic feed prepared at this temperature plus supplemented standard feed, a BSFL dry-weight bioconversion of 16% was achieved in 8 to 11 days of rearing. The inhibitory by-products formed by degradation of lignocelluloses during pre-treatment had a significantly negative effect on the rearing of the BSFL, particularly a furan concentration of 0.2 g/L, which should be investigated for efficient BSFL rearing. Finally, the crude protein content in the BSFL reared on the standard feed was higher than the feed substrate supplemented with lignocellulose. This study demonstrated the need for process optimisation and component supplements in the BSFL feed substrates that contain lignocellulosic feedstocks.

Comparison of milling methods on the properties of common buckwheat flour and the quality of wantuan, a traditional Chinese buckwheat food.

The microstructural and techno-functional properties of buckwheat flour and its processability for making wantuan, as affected by different milling methods, were investigated. Results showed that the particle sizes (d(0.5)) of the flours made by stone-milling (SM), hammer-milling (HM), laboratory grinding with steaming pretreatment for 5min (LG-5) and 10min (LG-10) were 95.5, 111.5, 35.4 and 41.1μm, respectively. Moreover, SM and HM flours had less liberated starch granules and 20.84%-24.32% higher relative crystallinity than LG-10 flour. Slurries of laboratory-grinded flours showed excellent suspension stability. LG-10 flour had lowest pasting viscosities but greatest storage modulus and loss modulus. Color differences among the wantuan made from different flours were not visibly perceived (ΔE<5). Wantuan made from LG-5 flour exhibited highest textual quality due to its greatest resilience (0.376), good springiness (0.933) and accepted chewiness (1093.31). Concluding, steaming prior to grinding could improve the qualities of buckwheat flour for wantuan making.

Effects of superheated steam pretreatment on phenolics and its antioxidant activity in camellia oleifera oil

Camellia oleifera oil (COO) is a high-quality woody edible oil, and the oilseed pretreatment is an important part of the oil processing in the edible oil production. This study investigated the effect of superheated steam (SHS) pretreatment on the phenolics and the corresponding antioxidant properties of COO. Results showed that SHS pretreatment time and temperature had significant impact on oil yield and the phenolic content of different forms of camellia seeds (P＜0.05). SHS pretreatment at 150 °C and 180 °C increased the free phenolics (FP) content, and the antioxidant properties of FP and conjugated phenolics (CP) in COO after SHS pretreatment under optimal condition. Then, the effect of SHS on two phenolic substances with high contents of COO, di-O-methylquercetin and 4-chloro-2-hydroxybenzoic acid was studied. SHS pretreatment had a positive effect on COO, and it may increase its biological activity and reduce its irritation. In addition, four phenolics that were significantly associated with the antioxidant properties of camellia phenolics were found. This study can provide new ideas and directions for oilseed pretreatment.

Two-stage sulfite steam pre-treatment achieves extraordinary bioethanol titer from simultaneously saccharification and fermentation of softwood whole slurries

Softwood biomass, which contains rich portion of readily fermentable sugars, is a type of abundant biomass in Canada and Nordic countries. However, its recalcitrant structure has severely limited its utilization in bioconversion. Sulfite treatment during steam pre-treatment to simultaneously enhance ease of hydrolysis and fermentation of softwood biomass has turned to be an attractive strategy to unlock the possibility of converting softwood to bioethanol. Our previous work showed applying one-stage sulfite treatment during the steam pre-treatment under neutral/alkaline conditions could maximize the sulfonation/delignification and hemicellulose sugar retention, while the use of acidic conditions could enhance the homogenous substrates size reduction. To take the advantages of both the neutral/alkaline and acidic conditions, we developed two-stage sulfite steam pre-treatment to maximize the sugar and ethanol production by utilizing Na2SO3 in the first alkaline steam pre-treatment stage and SO2 in a second acidic steam pre-treatment stage. The resulting substrates showed high sulfonation/delignification extent, nearly 100 % sugar recovery, homogeneous substrates size reduction and sufficient detoxification. Without extra hydrolysate detoxification and concentration, 160 g/L fermentable sugars were obtained from the hydrolysis of two-stage sulfite steam pretreated softwood whole slurry at 25% solid loading. And 80 g/L ethanol was generated by directly fermenting these sugars in the whole slurry hydrolysate without additional detoxification or concentration processes. This work significantly contributed to the development of the industrial relevant bioethanol production from softwood biomass.

Effects of Steam Pretreated Rice Biomass Condensate Containing Soluble Solid Inhibitors on Disruption of Pomacea Canaliculata Egg

Pomacea canaliculata is an invasive freshwater snail species that has become a serious pest of rice in irrigation and paddy fields and is popularly known as the golden apple snail. They are species that are capable of surviving and spreading rapidly, causing significant changes in the ecosystem. The application of natural by-products of a physicochemical method of biomass steam pre-treated condensate is one option for disrupting Pomacea Canaliculata egg. This experiment was conducted to investigate the feasibility of steam pre-treated rice biomass condensate which contained soluble solid inhibitors as a biopesticide to eradicate Pomacea canaliculata. Rice straw, rice husk, and a combination of rice straw and rice husk (1:1) were pre-treated by the saturated steam pre-treatment in a batch reactor at high temperatures (190°C and 210°C) for 10 min. The steam condensate produced from this system was analysed for major degraded products or inhibitors such as furfural, hydroxymethylfurfural (HMF), and phenol. The steam condensate which contained soluble solid inhibitors was then analysed for solubility test on P. canaliculata eggs. The effect of soluble solid inhibitors on the eggs was structurally examined by using a scanning electron microscope (SEM). The results revealed that rice husk which was pre-treated at 210°C reflected the highest contents of furfural (0.300 g/L), HMF (1.670 g/L), and phenol (0.087 g/L). However, the combination of rice biomass sample (1:1) condensate at 210°C demonstrated the greatest solubility percentage (11.51%) when treated to the eggs P. canaliculata eggs. The image of the egg structure examined by SEM clearly displayed the fractures forming on the cuticle layer of the eggs. SEM results demonstrated that the condensate from saturated steam pre-treated rice biomass has the possibility to be used as a biopesticide to disrupt the eggs and eventually could prevent the snails’ invasion. &#x0D;

Hydrolysate production from sugarcane bagasse using steam explosion and sequential steam explosion-dilute acid pretreatment for polyhydroxyalkanoate fermentation

Polyhydroxyalkanoates (PHAs) are potential alternatives to conventional petroleum-based plastics. One of the barriers to the commercialization of PHAs is its high production cost, which is primarily due to substrate. Agricultural lignocellulosic residues, such as sugarcane bagasse, can be used as substrates to lower production costs. In order to effectively convert the substrate to PHA, sugarcane bagasse must be pretreated. In this study, steam explosion and sequential steam explosion–dilute H2SO4 pretreatment of sugarcane bagasse were optimized to effectively release reducing sugars through enzymatic hydrolysis. Experiments using response surface methodology (RSM) revealed that steam temperature had the greatest influence on lowering sugar content for both sequential and steam explosion pretreatments. The optimum steam explosion conditions were 230 °C steam temperature and 701 s holding time. The concentration of reducing sugars in the enzymatic hydrolysate produced by the hydrolysis of steam-exploded sugarcane bagasse was 6.91 g/L (46.07% yield). On the other hand, the optimum conditions for sequential pretreatment were 230 °C steam explosion temperature, 137 °C dilute acid temperature, 42 min of dilute acid reaction time, and 4.75% w/v H2SO4 concentration, resulting in a hydrolysate with a reducing sugar content of 12.89 g/L (85.93% yield). When steam explosion and diluted H2SO4 pretreatment were combined, a yield increase of reducing sugar of 87% was observed. PHA in the form of polyhydroxybutyrate (PHB) was successfully synthesized using the hydrolysate through bacterial fermentation, with a concentration of 1.99 g/L (16.79% yield) after 24 h. As a result, sequential pretreatment was effective in producing enzymatic hydrolysates from sugarcane bagasse that could be utilized to produce PHA.