Lupinwhey as a Perspective Substrate for Bioethanol Production

Abstract

Abstract The study deals with the investigation of processing parameters of acidic water extraction of protein-free compounds from lupin flour in presence of hydrolytic enzymes with different substrate specificity. An important objective of the study was to analyze content of the liquid extract (lupin whey) and its perspectives for biofuel production. Commercial cytolytic enzyme systems (Cellulase-100, Cellolux-A, -F) were used in the extraction process. Multienzyme complex complied of individual enzymes such as cellulase, xylanase and α-amylase was used as an alternative. The optimized multienzyme complex was composed from 1.1 ± 0.2 units g -1 of cellulase, 5.2 ± 0.4 units g -1 of xylanase and 2.5 ± 0.2 units g -1 of α-amylase. The enzymatic treatment resulted in 19% increase of the total sugar content of lupin whey versus to the control whey obtained without enzyme addition. The lupin whey was condensed by evaporation to 48−50% dry matter content. Condensed whey was used as nutrient medium for cultivation of yeasts Saccharomyces cerevisiae. After fermentation the yield of bioethanol reached 1.6 g/l. The proposed technology of complex processing of vegetable raw materials allows to obtain lupin protein concentrates with a crude protein content up to 63.2 ± 1.3% on dry matter basis and lupin whey with a total sugar content of up to 29% on dry matter basis. The lupin whey could be used as an organic substrate for biofuel production.