Optimization of fermentation conditions and effect evaluation of ester production by Saccharomyces cerevisiae in tobacco extract

In order to increase the content of ester compounds in fermented tobacco extract, using tobacco extract as fermentation substrate and Saccharomyces cerevisiae SMR-SC-11 as fermentation strain, the fermentation conditions were optimized by single factor and response surface test with ester contents as evaluation index, and the physicochemical indexes of tobacco extract were analyzed before and after fermentation. The results showed that the optimal fermentation conditions were: fermentation time 111 h, temperature 32 ℃, inoculum 5%, initial pH 6.7. Under the optimized conditions, the ester compounds yield was 2.28 g/L, and the ester compounds contents in tobacco extract after fermentation was increased by 714.28% compared with that before fermentation. The contents of protein, total sugar, reducing sugar and amino acid nitrogen was decreased by 26.7%, 23.6%, 33.0% and 58.3%, respectively, while the contents of Na⁺ and K⁺ had no significant change.