Abstract: In order to increase the yield of ethyl butyrate and ethyl hexanoate in the fermentation process of Luzhou-flavor Baijiu, solid-state fermentation conditions for mixed culture fermentation of Saccharomyces cerevisiae and three strains of esterifying bacteria from Baijiu cellar pit mud were optimized using one-factor-at-a-time method and Box-Behnken design response surface methodology. The results showed that the water content and acidity of sorghum-based medium and inoculum quantity had significant effects on the production of ethyl hexanoate and ethyl butyrate (P < 0.01), while fermentation temperature had no significant effect (P > 0.05). The optimum fermentation conditions were as follows: temperature 32 ℃, water content 78.00%, acidity 2.60 mmol/100 g, and inoculum quantity 4.60%. Experiments carried out under these conditions led to yields of 9.55 mg/100 g and 1.87 mg/100 g for ethyl hexanoate and ethyl butyrate, respectively, which were 99.07% and 100% as compared to the predicted values, respectively. The optimal process was validated to be reasonable and feasible, which provides a theoretical basis for further improving the quality of Luzhou-flavor Baijiu and the application of functional microorganisms from Baijiu cellar pit mud in actual production.

Key words: response surface methodology; Box-Behnken design; co-fermentation; Saccharomyces cerevisiae; esterifying bacteria in Baijiu cellar pit mud; ethyl hexanoate; ethyl butyrate