Fractionation of Brewer’s Spent Grain Using a Cascade Process for Carbohydrate Release and the Simultaneous Production of Protein and Fiber Fractions Targeting the Food Industry

Abstract

Brewer’s spent grain (BSG) contains a large fraction of proteins, lignin, and carbohydrates. However, its heterogeneous composition limits its use in the food industry. The current work evaluated a cascade process for fractionation of these compounds. Two different thermally diluted acid pretreatments prior to enzymatic hydrolysis steps were evaluated. Condition 1 (C1) corresponded to 0.49% (v/v) HCl at 87.7 °C for 92.7 min, and C2 used 0.80% HCl at 121.0 °C for 142 min. Three different solid fractions were obtained for each condition, a fine solid (FS) (particle size <25μm), a coarse solid (CS) rich in protein and fiber, and an alkaline solid (AS) rich in fiber. The fractions had water retention capacities between 4.0 and 8.8 g_H2O/g_TS. The highest protein content was obtained for C1-FS (31.5% w/w), and the highest total fiber content for C2-AS (>80%). Some of those fractions have characteristics similar to those of current market ingredients used in the food industry.