关键词: 乳酸菌；酵母抽提物；适应性；生物转化；酵母味

Abstract: A biotransformation system (LSBT) consisting of Lactococcus lactis and Streptococcus lactis was used to eliminate the yeasty odor of eight yeast extracts with different characteristics (FG10, FM88, FM31, KU012, FIG12LS, F58, FIG03 and KA02) with a focus on flavor substances and amino acids. Meanwhile, the applicability and universality of LSBT were evaluated. All yeast extracts had no longer any yeasty flavor after being treated with LSBT, and FG10 and FM88 were provided with a fermented sauce flavor. Producing no indole was found to be one of the key factors for the success of LSBT. At the same time, the lactic acid content of the transformed yeast extract should not be less than 10.00 g/L. The difference of raw materials played an important role in the LSBT. In particular, the deficiency of aspartic acid and excessive accumulation of threonine in raw materials were likely reasons for the unsuccessful conversion of LSBT. Overall, LSBT is applicable to most yeast extracts, but other microbial combination techniques or fermentation conditions need to be explored for specific yeast extracts such as F58, FIG03 and KA02.

Key words: lactic acid bacteria; yeast extract; applicability; biotransformation; yeasty flavor