Impact of solid-state fermented Brewer's spent grains incorporation in biscuits on nutritional, physical and sensorial properties
Xianfang Wang, Yujing Xu, Shi Qi Teo, Chin Wee Heng, Delia Pei Shan Lee, Alicia Xinli Gan, Jung Eun Kim
Abstract
Brewer's spent grains (BSG) is the abundant food processing by-product of beer production yet its application in food is limited due to its high susceptibility to microbial putrefaction and undesirable effect on the colour, structure and texture. Solid-state fermentation of BSG with Rhizopus oligosporus (RO) may further improve the nutritional, structural and textural properties of BSG-containing foods thus this study developed fermented BSG-containing biscuits and assessed their nutritional, physical and sensorial properties. Control (no substitution), autoclaved BSG (AB)- and fermented BSG (ROB)-containing biscuits (15/30% wheat flour substitution) were prepared. 30% ROB showed the greatest improvement in nutrient composition and anti-oxidant capacity. In vitro starch digestibility was significantly lowered in 30% ROB than Control, which can be explained by the greatest α-glucosidase inhibition activity of 30% ROB. BSG-containing biscuits were darker, less hard and more fracturable than Control, with no difference between ROB and AB, and gave better Just-about-right score for hardness. However, flavour and overall liking scores were lower in 30% AB and 30% ROB than lower substitution biscuits. Collectively, fermented BSG-substituted biscuits resulted in acceptable flavour and texture, as well as greater improvements in nutrient composition, anti-oxidant capacity, α-glucosidase inhibitory activity and in vitro starch digestibility.