Phenolic Acids, Antioxidant Capacity, and Estimated Glycemic Index of Cookies Added with Brewer's Spent Grain.

Brewers' spent grain (BSG) is the major by-product of the brewing industry, with great potential as a functional ingredient due to its bioactive compounds. Thus, BSG could be suitable for improving the low nutritional quality of wheat-based snacks highly consumed by young people. The objective of this study was to substitute wheat flour with BSG (0, 10, 20, and 30%) for cookies elaboration, and evaluate the dough rheology, phenolic acids, antioxidant capacity, arabinoxylans content and proximate composition of the cookies Protein content and bioactive compounds (ferulic and p-coumaric acids, water unextractable arabinoxylans) of cookies significantly (p < 0.05) increased with the substitution level. In comparison to the wheat-alone cookies, the 20% BSG-containing cookies showed a lower hydrolysis and glycemic index (GI), and less total starch. The low cost, protein-rich BSG with antioxidant capacity improves the nutritional quality of cookies and may confer health benefits beyond basic nutrition.