2019 Volume 25 Issue 3 Pages 399-404
Preparation of GABA (γ-aminobutyric acid)-rich sourdough using rice bran and raisin was investigated. Preparation of sourdough began with pre-fermented raisin liquid, which is a widely used source of wild yeast and lactic acid bacteria. The number of naturally occurring cells in the liquid was 3.5×107 CFU/mL for yeast cells and 3.4×107 CFU/mL for lactic acid bacteria. The liquid was added to rice bran and then used to make sourdough via a three-stage fermentation process for 42 hours. The numbers of yeast (2.1×108 CFU/g) and lactic acid bacteria (1.3×108 CFU/g) in sourdough increased gradually with repeated fermentation. We also confirmed that the GABA and polyphenol contents of sourdough significantly increased during fermentation. Thus, sourdough enriched with GABA could be rapidly and easily obtained through a three-stage natural fermentation process using rice bran and raisin. These findings also provide useful information for the effective use of milling rice by-products.