Chemical compositions, antioxidant activities and techno-functionality of spent grain treated by autoclave treatment: evaluation of water and temperature levels

Abstract

Autoclave heating (AH) has been applied to modify the dietary fibre composition of dried brewers' spent grain (BSG) flour, which required multiple drying processes. The current study aimed to investigate the influence of the thermal levels and water ratio on AH, as an alternative, in altering the chemical compositions, antioxidant properties, and functionality of undried fresh BSG. The results showed that AH converted the saturated fatty acids into polyunsaturated fatty acids. AH reduced ketones and furans regardless of the water ratio while the amounts of aldehydes, alcohols, alkenes, and fatty acids depended on the water ratio. The elimination and formation of several volatile compounds were identified due to the AH depending on the water ratio. The total flavan-3-ols, antioxidant activities, and water-holding capacity of BSG were improved as an impact of thermal elevation and regardless of the water ratio. In conclusion, AH treatment on fresh, undried BSG showed a beneficial performance in improving the quality of BSG for further valorisation as a value-added by-product.