Abstract
Beer is a complex mixture - over 400 different compounds have been characterized in beer. Significant health and product quality promoting benefits have been attributed to its bioactive secondary metabolites such as phenolics. Polyphenols and phenolic acids present in beer are natural antioxidants. The aim of the research was to characterize the bioactive compounds in Latvian barley beer, such as phenolic acids and flavanols. In an experiment, different lager-type beers produced in Latvia were analysed. The total phenolic content was determined spectrophotometrically according to the Folin-Ciocalteu colorimetric method and expressed as gallic acid equivalents. Individual phenolic compounds were determined using high performance liquid chromatography (HPLC). The antioxidant potential of beer was analyzed by the 2,2-diphenyl-1-picrylhydraziyl (DPPH) radical assays and expressed as micromoles of Trolox equivalents. The research showed that the total phenolic content of dark beer samples (320.8-863.6 mg GE L-1) was mostly higher than that of the light beers (300.9-475.2 mg GE L-1). In total, eleven phenols were determined in the analysed samples. Also the sum of individual phenolics in dark beer samples was higher than in the light beer brands. All beer samples exhibited a strong DPPH radical scavenging activity: from 441.3 to 1064.2 μmol TE L-1 for the light beer samples, and from 726.2 to 1748.7 μmol TE L-1 for the dark beer. The research suggests that composition of beer phenolic compounds was not dependent on the type of beer - light or dark.