Direct determination of amino acids in brewery worts produced by different processes by capillary zone electrophoresis

Abstract

The direct and simultaneous determination of cysteine, histidine, phenylalanine, lysine, tryptophan and arginine in brewery worts by capillary zone electrophoresis (CZE) was applied to evaluate the effects of temperature control and protease supplementation during mashing on the changes of these amino acids (AAs) wort composition. A cation exchange resin was used for AAs extraction from wort samples prior to CZE determination. The separation was achieved using a 50 mmol/L phosphate buffer at pH 12.5, containing 0.4 mmol/L cetyltrimethylammonium bromide (CTAB), as background electrolyte (BGE) solution; -20 kV; 20°C and hydrodynamic injection time of 15 s, at 50 mbar. Recovery evaluation using worts led to values between 83.1 and 96.2%, demonstrating the method feasibility, which was successfully applied in the quantification of AAs in wort samples. This study showed that temperature control and addition of exogenous proteases in the mashing may increase the AAs concentration in wort, improving the final product quality (beer). The present method is a good alternative for monitoring specific AAs in worts and their determination can allow the brewing process optimization.

Keywords: Amino acids; Capillary zone electrophoresis; Direct determination; Mashing processes; Wort composition.