Isolation and identification of aroma producing strain with esterification capacity from yellow water

Abstract

Kaoliang is a refreshing fragranced type of Chinese spirits with slight apple fragrance that comes from ethyl acetate (EA). Special aromas are produced by esterification microorganisms, which affect the taste and quality of the wine. In this study, new yeast strains were isolated from yellow water, a by-product during fermentation process. Meanwhile, the optimal culture condition was determined for its growth and EA production. Three new strains, Kazachstaniaexigua, Candida humilis and Saccharomyces cerevisiae were identified from yellow water. Among these strains, S. cerevisiae S5 was the new and dominant strain. Results from response surface methodology showed that S. cerevisiae S5 produced 161.88 ppm of EA, in the medium with 4.91% yeast extract, 9.82% peptone, and 20.91% glucose after 96 hours of cultivation at 27.53°C. GC analysis showed that aroma compounds, such as EA, isoamyl acetate and 2-phenylethanol increased from the sample of optimal condition when compared to the one from initial fermentation condition.

Fig 1. The proportion of three yeast strains isolated from yellow water.

Fig 2. The EA concentrations of fermented broths from three yeast strains.

Fig 3

The appearance of S5 (A) and BCRC21447 (B) under microscopy.

Fig 4. Three-dimensional surface and contour plots of three factors on EA production.

The effect of temperature (X₁) and nitrogen sources (X₂) (A), temperature (X₁) and glucose (X₃) (B), and nitrogen sources (X₂) and glucose (X₃) (C) on EA production.