Malt and beer-related by-products as potential antioxidant skin-lightening agents for cosmetics

Abstract

Malt and beer-related by-products, namely caramalt, aromatic malt, roasted malt, malt sprouts, dark beer spent grains, and wheat beer spent grains were extracted with water under moderate conditions to exploit the potential as sources of bioactive compounds. After characterizing the extracts in terms of carbohydrate, amino acid, and phenolic contents and composition, their antioxidant potential was assessed in vitro using keratinocyte cell cultures. Malt sprouts provided highest yields of glucose (50.1 mg g-1) and fructose (38.4 mg g-1), while the other materials gave up to 13.5 mg g-1. Furthermore, malt sprouts gave a total amino acid content of 57.6 mg g-1. Extracts of darker malts such as caramalt and roasted malt exhibited the highest yields of phenolic compounds of about 12.9 mg gallic acid equivalents (GAE) g-1 and extracts from spent grains had the lowest total yield with 5.1 and 1.8 mg GAE g-1 (dark beer and wheat beer spent grains), respectively. Phenolic compounds in caramalt extract inhibited the tyrosinase activity by 78% and 87%, when applying extract concentrations of 0.5% and 1%, respectively. Dark malt, roasted malt as well as the malt sprouts extracts achieved similar effects of 86% and 80% inhibition, when using a 1% extract. In contrast, extracts of spent grains showed low inhibitory effects. This study indicates the potential of malt and beer-related by-products as biological sources of ingredients for cosmeceutical products, for instance, in skin whitening.