Phenolic profile and antioxidant properties of a crude extract obtained from a brewery waste stream

The main aims of this study were to determine the phenolic profile of a crude extract obtained (at pilot scale) from a brewery waste stream and to evaluate the antioxidant activity of the extract. The total phenolic content was determined by the Folin-Ciocalteu assay, which revealed that 50% of the extract comprised phenolic compounds. The polyphenols, identified and quantified by RP-HPLC-DAD and HPLC-ESI-TOF-MS, were mainly flavonoids (catechin, epicatechin, gallocatechin, epigallocatechin, quercetin) and phenolic acids (ferulic acid, p-coumaric acid, caffeic acid, protocatechuic acid). The crude extract displayed a high DPPH radical scavenging activity (0.18 g/L), similar to that of BHA (0.248 g/L) and higher than that of BHT (2.54 g/L). All three tested products displayed a similar ability to decrease oxidative bleaching of beta-carotene (antioxidant activity coefficient of 623.8 for the crude extract, 653.3 for BHA, 559.6 for BHT). This type of brewery waste stream may be a promising source of natural antioxidants to replace the synthetic antioxidants currently used in the food industry. (C) 2013 Elsevier Ltd. All rights reserved.