Transformation of residual starch from brewer’s spent grain into fermentable sugars using supercritical technology

Optimization of the Multienzyme-Assisted Extraction Procedure of Bioactive Compounds Extracts from Common Buckwheat (Fagopyrum esculentum M.) and Evaluation of Obtained Extracts

Optimization of the extraction procedure using a multienzymes cocktail for common buckwheat (Fagopyrum esculentum M.) is important due to the yield, fermentable sugars, oligosaccharides and bioactive compounds for creating higher added value products. This study was undertaken to find out the optimum multienzymes-water extraction on yield and total phenolic compounds for common Buckwheat using response surface methodology (RSM). Three independent variables, time (2, 13, and 24 h), temperature (60 °C, 70 °C, 80 °C), and non-starch polysaccharide (NSP) enzymes mixture (0.10, 0.55, and 1.00 mL), were analyzed to optimize the response variables. NSP hydrolyzing enzymes, cellulase, xylanase, and β-glucanase, were produced by Trichoderma reesei. Estimated optimum conditions for F. esculentum were found: time-2 h, temperature-65 °C, and cellulase activity-8.6 CellG5 Units/mL. Different optimization run samples were collected and lyophilized for further analysis until the hydrophilic property using the water contact angle methodology and rutin content using HPLC was determined. Results indicated NSP enzymes activity did not differ between water contact angles after 13 h of enzymatic water extraction. However, longer fermentation time (24 h) decreased static water contact angle by approximately 3-7° for lyophilized water extract and 2-7° for solid fraction after fermentation. It implies enzymatic hydrolysis during water extraction increased hydrophilic properties in solid fraction and decreased hydrophilicity in water fraction due to the enzymes cleaved glycosidic bonds releasing water-soluble compounds.

Starch and protein recovery from brewer's spent grain using hydrothermal pretreatment and their conversion to edible filamentous fungi - A brewery biorefinery concept

This study aimed at recovering a highly concentrated starch and protein stream from the brewer's spent grain (BSG). The effect of pretreatment temperature and retention time on the solubilization of starch and protein; and the generation of fermentation inhibitors were studied. Then, the application of recovered streams for fungal cultivation was evaluated using different edible fungi Aspergillus oryzae, Neurospora intermedia, and Rhizopus delemar. The hydrothermal pretreatment resulted in the highest solubilized starch concentration, 43 g/L, corresponding to 83% solubilization of initial BSG starch content. The highest protein concentration was 27 g/L (48% solubilization of initial BSG protein content). Cultivation with Neurospora intermedia on the recovered streams from the two best pretreatment conditions, 140 ℃ for 4 h and 180 ℃ for 30 min, resulted in pure fungal biomass with the highest protein content 59.62% and 50.42% w/w, respectively. Finally, a brewery biorefinery was proposed for the valorization of BSG.

Intensification of Xylo-oligosaccharides Production by Hydrothermal Treatment of Brewer's Spent Grains: The Use of Extremely Low Acid Catalyst for Reduction of Degradation Products Associated with High Solid Loading

Brewers' spent grains (BSG) make up to 85% of a brewery's solid waste, and is either sent to landfill or sold as cheap animal feed supplement. Xylo-oligosaccharides (XOS) obtained from BSG are antioxidants and prebiotics that can be used in food formulations as low-calorie sweeteners and texturisers. The effect of extremely low acid (ELA) catalysis in liquid hot water (LHW) hydrothermal treatment (HTT) was assessed using BSG with dry matter contents of 15% and 25%, achieved by dewatering using a screw press. Batch experiments at low acid loadings of 5, 12.5 and 20 mg/g dry mass and temperatures of 120, 150 and 170 °C significantly affected XOS yield at both levels of dry mass considered. Maximum XOS yields of 76.4% (16.6 g/l) and 65.5% (31.7 g/l) were achieved from raw BSG and screw pressed BSG respectively, both at 170 °C and using 5 mg acid/g dry mass, after 15 min and 5 min, respectively. These XOS yields were obtained with BSG containing up to 63% less water and temperatures more than 20 °C lower than that reported previously. The finding confirms that ELA dosing in LHW HTT allows lowering of the required temperature that can result in a reduction of degradation products, which is especially relevant under high solid conditions. This substantial XOS production intensification through higher solid loadings in HTT not only achieved high product yield, but also provided benefits such as increased product concentrations and decreased process heat requirements.

Modified Supercritical Carbon Dioxide Extraction of Biologically Active Compounds from Feijoa Sellowiana Leaves

For the first time, the modified supercritical carbon dioxide extraction (MSCE) of biologically active compounds from Feijoa sellowiana leaves was investigated. Total yield (TY) and bioactivity of biocompounds in terms of DPPH• (%DPPHsc) and HO• (%HOsc) radicals scavenging were maximized via multivariate optimization. The optimized conditions were the pressure of 272.34 bar, supercritical carbon dioxide flow rate of 1.58 mL min−1, temperature of 52.48 °C, and dynamic extraction time of 110.62 min. The predicted values of the TY, %DPPHsc, and %HOsc were 81.12 mg g−1, 85.16 %, and 75.66 %, respectively. The chromatographic analysis demonstrated gallic acid as the main biophenolic (136.20 ± 0.16 mg g−1). The scanning electron microscopy images showed dramatic disruption of cells treated with MSCE. A comprehensive comparison was made between current findings and other techniques (conventional and ultrasonic waves assisted extraction). More TY was achieved using conventional method but the bioactivity of MSCE products was considerably better.