Characterization of γ-aminobutyric acid (GABA)-producing Saccharomyces cerevisiae and coculture with Lactobacillus plantarum for mulberry beverage brewing.

One elite γ-aminobutyric acid (GABA) producing strain of Saccharomyces cerevisiae SC125 was isolated and identified from Chinese traditional paocai. S. cerevisiae SC125 and Lactobacillus plantarum BC114 were used as cooperative species to ferment mulberry (Morus alba L.) and produce a novel beverage enriched with GABA. The GABA, organic acids and volatile compounds in different fermentation stages were determined by high-performance liquid chromatography (HPLC) and headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS). It was noted that coculture changed the profiles of flavor compounds in mulberry beverage. The tartaric and succinic acid contents increased to 1.34 g/L and 0.39 g/L, respectively. Lactic, malic, citric, and oxalic acid levels ranged between 0.92 and 2.56 g/L, and ethanol and glycerol were produced at 2.66 g/L and 1.81 g/L, respectively. More volatile compounds were detected in the coculture with significantly enhanced concentrations of fruity esters including ethyl caproate, ethyl propionate, butyl acetate, ethyl butyrate, ethyl caprylate and ethyl caprate, and alcohols of phenylethyl alcohol, 1-pentanol and 2-amino-1,3-propanediol. Also, a yield of 2.42 g/L GABA was achieved in the coculture. In conclusion, S. cerevisiae SC125 and L. plantarum BC114 coculture promotes the production of flavor compounds and GABA in mulberry beverage brewing.