Brewer's spent grain from different types of malt: Evaluation of the antioxidant activity and identification of the major phenolic compounds

Abstract

a b s t r a c t Keywords:Brewer's spent grain Microwave-assisted extraction Polyphenols Antioxidant activity Kilning temperature HPLC-DAD/ESI-MS/MS analysis The antioxidant activity and phenolic composition of brewer's spent grain (BSG) extracts obtained by microwave-assisted extraction from two malt types (light and dark malts) were investigated. The total phenolic content (TPC) and antioxidant activity among the light BSG extracts (pilsen, melano, melano 80 and carared) were significantly different (p b 0.05) compared to dark extracts (chocolate and black types), with the pilsen BSG showing higher TPC (20 ± 1 mg GAE /g dry BSG). In addition, the antioxidant activity assessed by 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and deoxyribose assays decreased as a result of increasing kilning temperatures in the following order: pilsen N melano N melano 80 N carared N chocolate N black. HPLC-DAD/ESI-MS/MS analysis indicated the presence of phenolic acids, such as ferulic, p-coumaric and syringic acids, as well as several isomeric ferulate dehydrodimers and one dehydrotrimer. Chocolate and black extracts, obtained from malts submitted to the highest kilning temperatures, showed the lowest levels of ferulic and p-coumaric acids. These results suggested that BSG extracts from pilsen malt might be used as an inexpensive and good natural source of antioxidants with potential interest for the food, pharmaceutical and/or cosmetic industries after purification.

Brewer’s Spent Grains Protects against Oxidative DNA Damage in Saccharomyces cerevisiae

“…Therefore, the differences observed for pilsen and black BSG extracts can be ascribed to the different composition of the extracts. Ferulic and p-coumaric acids are well known phenolic compounds present in high concentrations in BSG (Moreira et al, 2013). Moreover, previous studies have demonstrated that ferulic acid (FA) protects DNA against oxidative damage caused by H 2 O 2 , as measured by the comet assay (Wang, Sun, Cao, Song, & Tian, 2008).…”

“…BSG samples used in this work were kindly supplied by Unicer -Bebidas de Portugal, S.A. (S. Mamede de Infesta, Portugal) and obtained from barley malt samples supplied by Os Três Cervejeiros, Lda (Porto, Portugal). BSG samples investigated in this work were chosen according to the more pronounced differences in total phenolic content and antioxidant activity, evaluated in a previous work (Moreira et al, 2013), and correspond to BSG samples obtained from pilsen and black malts. Pilsen malt produces very light colored, clean and crisp worts and is used as base malt for all beer styles.…”

“…The BSG samples used for phenolics extraction correspond to the remaining solid fraction obtained following the removal of wort during the pilot scale production of beer in the brewing process. For wort production it was followed the procedure previously described (Moreira et al, 2013), and the obtained solid residue was frozen, lyophilized and then finely ground.…”

“…BSG is a unique source of bioactive ingredients such as hydroxycinnamic acids ferulic and p-coumaric acids (Meneses, Martins, Teixeira, & Mussatto, 2013;Moreira, Morais, Barros, Delerue-Matos, & Guido, 2012;Moreira et al, 2013;Mussatto, Dragone, & Roberto, 2007). Several studies demonstrate that extracts containing hydroxycinnamic acids hold important health benefits, including antioxidant or free radical scavenging (Shahidi & Chandrasekara, 2010), anti-carcinogenic (Gomes et al, 2003), anti-inflammatory (Kim et al, 2012) and antigenotoxic (McCarthy et al, 2012) properties.…”

“…Yeast S. cerevisiae has been chosen has an eukaryotic model to study the cellular response against stress damages due to biochemical and molecular similarities with human cells (Mager & Winderickx, 2005). A recent study by our group on the evaluation of antioxidant activity and identification of the major phenolic compounds of BSG from six malt types (pilsen, melano, melano 80, carared, chocolate and black) has revealed that pilsen BSG exhibits higher total phenolic content and antioxidant activity and black BSG, the lower (Moreira et al, 2013). Therefore, BSG samples used in this study were those whose differences were more pronounced, corresponding to BSG obtained from pilsen and black malts.…”