Defatted rice bran pretreated with deep eutectic solvents and sequential use as feedstock for subcritical water hydrolysis

Harnessing deep eutectic solvent for enhanced inulinase production from agricultural via submerged fermentation with Aspergillus niger

This study aimed to enhance inulinase production from agricultural biomass pretreated with deep eutectic solvents (DES) using Aspergillus niger A42 (ATCC 204447). Barley husk (BH), wheat bran (WB), and oat husk (OH) were selected as substrates and were pretreated using different molar ratios of choline chloride: glycerol (ChCl: Gly) and choline chloride: acetic acid (ChCl: AA). DES pretreatment was followed by dilute sulfuric acid hydrolysis. The fermentable sugar content (FSC), sugar profiles, and inhibitory components in the hydrolysates were analyzed. DES pretreatment improved the FSC in all substrates, with wheat bran showing the highest FSC of 72.54 g/mL. Considering the fermentable sugar contents, ChCl: Gly (1:2) was selected as the most suitable DES. The analysis of biomass composition after pretreatment indicated a reduction in extractives and lignin, along with an increase in cellulose content. Subsequently, inulinase fermentation using Aspergillus niger A42 has demonstrated that DES-pretreated wheat bran was the most effective substrate, yielding 416.05 U/mL inulinase activity (Iase) and 486.22 U/mL invertase-type (Sase) activity. The enzyme solution was partially purified via Spin-X UF membranes (50 kDa cut-off), resulting in Iase activity of 769.93 U/mL and Sase activity of 566.69 U/mL. The purification coefficients were 1.88 and 0.92 for inulinase and invertase-type activity, respectively. In conclusion, DES pretreatment was successfully applied to produce inulinase enzyme from BH, WB, and OH. Among the materials studied, WB emerged as the most suitable biomass for producing inulinase from Aspergillus niger A42.

Valorization of corn stover in a single experimental unit: The synergistic effects of steam explosion and semi-continuous subcritical water processing

Lignocellulosic waste, like corn stover (CS), is widely produced and serves as a key feedstock for biofuels and biochemicals. Semi-continuous subcritical water hydrolysis (SWH) is an eco-friendly method that breaks down cellulose and hemicellulose bonds. To boost fermentable sugar (FS) yields, steam explosion (SE) pretreatment was tested on CS, achieving a cellulose content of 74.06 % at 200 °C for 10 min. Hydrolysis of untreated (UCS) and pretreated (PCS) CS was conducted at temperatures of 230 °C and 260 °C, with solvent/biomass ratios (R-20, R-40). Maximum FS yields were 11.67 g/100 g for UCS and 19.28 g/100 g for PCS. Although SE increased FS yields, it also led to more inhibitors due to the higher sugar production. Overall, integrating SE with SWH improved FS yields.

Protein and Polysaccharide Recovery from Shrimp Wastes by Natural Deep Eutectic Solvent Mediated Subcritical Water Hydrolysis for Biodegradable Film

Environmental pollution is a significant problem due to the improper disposal of plastics and shrimp shells outdoors. Therefore, the synthesis of biodegradable film from waste materials is highly important. The novelty of this research lies in the extraction of protein hydrolysates and chitosan from shrimp shells, as well as the fabrication of biodegradable film from these materials. In this study, the composite films were produced using the solution casting method. Moreover, the combined effect of ultrasound pretreatments (UPT) and natural deep eutectic solvents (NADES) was investigated as extraction media, to determine their potential impact on shrimp waste subcritical water hydrolysis (SWH). Shrimp shells were submitted to UPT in NADES solution, followed by SWH at different temperatures ranging from 150 to 230 °C under 3 MPa for 20 min. Then, the physiochemical properties and bioactivities of the hydrolysates were assessed to determine their suitability for use in biodegradable packaging films. Additionally, the physiochemical properties and bioactivities of the resulting hydrolysates were also analyzed. The highest amount of protein (391.96 ± 0.48 mg BSA/g) was obtained at 190 °C/UPT/NADES, and the average molecular size of the protein molecules was less than 1000 Da with different kinds of peptide. Overall, combined UPT and SWH treatments yielded higher antioxidant activity levels than individual treatments. Finally, the application of composite films was evaluated by wrapping fish samples and assessing their lipid oxidation. The use of higher concentrations of protein hydrolysates significantly delayed changes in the samples, thereby demonstrating the film's applicability.

Sequential Process of Subcritical Water Hydrolysis and Hydrothermal Liquefaction of Butia Capitata Endocarp to Obtain Fermentable Sugars, Platform Chemicals, Bio-oil, and Biochar

Butia capitata endocarp (BCE) is a biomass residue with the potential to produce a wide variety of bio-products. The processing of BCE in a sequential process of subcritical water hydrolysis (SWH) and hydrothermal liquefaction (HTL) was investigated to obtain fermentable sugars, platform chemicals, bio-oil, and biochar. The SWH was evaluated at 230 and 260 °C and solvent: feed mass ratios (R) of 10 and 20 for the production of fermentable sugars and platform chemicals. The solid residue from SWH was sequentially submitted to the HTL at 330 and 360 °C for bio-oil and biochar production. The results were analyzed by comparing the sequential (SWH/HTL) and individual (HTL only) processes. The highest yields of fermentable sugars (5.26 g/ 100 g BCE) were obtained for SWH at 260 °C and R-20 with higher contents of xylose (2.64 g/100 g BCE) and cellobiose (1.75 g/100 g BCE). The highest yields of platform chemicals (2.44 g/100 g BCE) were obtained for SWH at 260 °C and R-10 with higher contents of acetic acid (1.78 g/100 g BCE) and furfural (0.54 g/100 g BCE). The highest yield of bio-oil (25.30 g/100 g BCE) occurred in HTL individual process at 360 °C and R-20. Sequential process SWH/HTL showed a decrease in bio-oil yield but maintained a similar biochar yield compared to HTL, in addition to the production of fermentable sugars and platform chemicals.

Low temperature desolventization: effect on physico-chemical, functional and structural properties of rice bran protein

De-oiled rice bran is a good source of high-quality protein; however, the current practice of desolventization at high temperature (110-120 °C) denatures the protein, making its extraction difficult and uneconomical. The present study aims to investigate the effect of low temperature desolventization of de-oiled rice bran (LTDRB) on extraction, yield, and purity of protein and its comparison with protein obtained from high temperature desolventized de-oiled rice bran (HTDRB). The optimal conditions for preparation of protein from LTDRB were: extraction pH 11.00, extraction duration 52 min, and extraction temperature 58 °C resulting in an extraction efficiency, yield, and purity of 54.0, 7.23, and 78.70%, respectively. The LTDRB showed a positive impact on the color, solubility, foaming capacity and stability of protein whereas the absorption and emulsification properties were better for HTDRB protein. Significant decrease in enthalpy (ΔH) for denaturation was observed for LTDRB protein as compared to HTDRB protein. Scanning electron microscopy analysis revealed that HTDRB protein was more compact than LTDRB protein. LTDRB protein had smaller particle size distribution than HTDRB. Study suggested that low temperature desolventization can result in higher protein extraction with better physico-chemical, structural, and functional properties of protein obtained from DRB.

Semi-continuous hydrothermal processing of pine sawdust for integrated production of fuels precursors and platform chemicals

This research reports data for the integrated obtaining of fermentable sugars (FSs), bio-oil (BO), and hydro-char (HC) - all fuel precursors - as well as platform chemicals (PCs - acetic, formic, and levulinic acid, besides furfural, and hydroxymethylfurfural) through semi-continuous hydrothermal processing of sawdust from pine wood. The influence of temperature (260, 300, and 340 °C) and the water-to-biomass ratio (25 and 50 g H2O (g biomass)-1) were the parameters considered to evaluate the mass yields, kinetic profiles, and BO properties. For FSs (and PCs), a detailed analysis considering the kinetic profiles of obtaining cellobiose, glucose, xylose, and arabinose is presented. For the conditions evaluated, a distinct behavior concerning the process parameters was observed, where 7.11 and 9.28 g (100 g biomass)-1 of FSs and PCs were synergistically obtained, respectively, after 30 min, 20 MPa, 260 °C, and 50 g H2O (g biomass)-1. Contextually, 17.59 g (100 g biomass)-1 of BO was obtained at 340 °C and the same water/biomass ratio. FTIR analysis of the BO samples suggested the presence of aldehydes, carboxylic acids, ketones, hydrocarbons, ethers as well as aromatic, alcohols, and nitrogenous compounds. Similar HC yields were achieved among the conditions analyzed, where 24.68 g (100 g biomass)-1 were obtained at 340 °C and 50 g H2O (g biomass)-1 for a higher heating value of 29.14 MJ kg-1 (1.5 times higher than the in natura biomass).