Antioxidant profile at the different stages of craft beers production: the role of phenolic compounds

Abstract

The antioxidant composition from four samples, brewer’s spent grain (BSG), brewer’s spent yeast (BRY), a part of the process (POP—after hop addition), and craft beer (CRB) from five popular craft beers were evaluated. The total phenolics, flavonoids, tannins, and ascorbic acid, as well as the antioxidant capacity, were determined. Furthermore, phenolics content was determined by LC–MS/MS technique. The cytotoxicity of BRY on fibroblasts cells and the anti-tumor effect of craft beers on colon adenocarcinoma cells were determined by cell viability and membrane integrity assays. The darker samples presented the highest total phenolics and antioxidant capacities. Phenolics, tannins, and ascorbic acid showed a strong correlation with antioxidant activity. Moreover, among nine phenolics characterized, catechin, and ferulic and p-coumaric acids were the majority compounds. Besides, no cytotoxicity was detected by BRY samples, and the darker craft beers, American Ipa and Imperial Stout demonstrated antiproliferative activity in the tumor cell line. Therefore, the comprehensive vision of the antioxidants into the entire brewing process is useful to optimize and valorize the end product and residues. This study also enlightened the potential benefits to human health, pointing new approaches to increase the interest in craft beer and its bioproducts avoiding the high costs of discard and possible negative impacts on the environment.