Factors affecting levels of ferulic acid, ethyl ferulate and taste-active pyroglutamyl peptides in sake

Publication date: Available online 28 October 2019Source: Journal of Bioscience and BioengineeringAuthor(s): Katsumi Hashizume, Toshihiko Ito, Karin Shirato, Naomi Amano, Tetsuo Tokiwano, Tsuyoshi Ohno, Sho Shindo, Seiei Watanabe, Masaki OkudaFactors affecting ferulic acid, ethyl ferulate and taste-active pyroglutamyl (pGlu) peptides levels in sake were analyzed using small-scale sake brewing tests on eighteen rice samples with differing cultivar variety, cropped year and area, and polishing rate. Ferulic acid concentration in sake was highly positively correlated with its content in rice (r = 0.782**) (double asterisk indicates 1% significance level), feruloylesterase (FE) activity (r = 0.804**) and feruloylated saccharide forming activity (FSFA) (r = 0.619**) in the rice koji. The results suggested that ferulic acid in rice induced FE activity and FSFA, and these two enzymes accelerated the formation of ferulic acid in sake mash. The concentration of bitter-tasting peptides in sake was highly positively correlated with crude protein content in rice (r = 0.786**), and negatively correlated with acid carboxypeptidase (ACP) activity to (pGlu)LFGPNVNPWH (r = −0.612**), fermentation length (r = −0.820**), and pyroglutamyl leucine ((pGlu)L) concentration in sake (r = −0.502*; 5% significance level). The observation suggested that bitter-tasting peptides are initially formed in sake mash in accordance with protein content in rice, and are then hydrolyzed to sma...
Source: Journal of Bioscience and Bioengineering - Category: Biomedical Science Source Type: research