Combinations of spent grains as sources of valuable compounds with highly valuable functional and microbial properties

The potential of spent grains as a source of valuable compounds with various properties has gained attention. They are the by-product of the brewing process, typically resulting from the beer-making process. Five different mixed combinations of spent grains of barley, wheat, rice, maize and finger-millet were formulated and further analyzed and compared. Barley and wheat (BW), barley and rice (BR), barley and maize (BM), and barley and finger-millets (BF) were mixed in a ratio of 1:1 (w/w) and ground into a fine powder to study their techno-functional, phytochemical and in vitro properties. The techno-functional, phytochemical and in vitro properties of barley and maize (BM) were found to be the best choice, making it a promising candidate for applications in value-added products. The WAI (water absorption index) of BM (5.03 g/g) was the highest compared to BB (3.20 g/g), BF (3.56 g/g), BR (4.10 g/g) and BW (4.33 g/g), whereas the WSI (water solubility index) and OAC (oil absorption capacity) of BM (7.06% and 1.90 g/g, respectively) were lower than BW (7.60% and 2.24 g/g, respectively), BR (8.20% and 2.30 g/g, respectively), BF (9.67% and 2.57 g/g, respectively) and BB (10.47% and 2.70 g/g, respectively). A higher percentage of inhibition of DPPH (44.14%) and high phenolic and flavonoid contents (72.39 mg GAE/gm and 66.03 mg QE/gm, respectively) were observed in BM. It also showed higher in vitro properties like amylase and lipase inhibition assay (89.05% and 62.34%, respectively) than the other combinations. The present study provides valuable information about the differences between spent grain varieties and their combinations, with potential applications in various industries.