Optimization of Caproic Acid Production from Clostridium kluyveri H588 and its Application in Chinese Luzhou-flavor Liquor Brewing

摘要

This study focused on the optimization of caproic acid production from Clostridium kluyveri H588 and its application in Luzhou-flavor liquor brewing. The critical variables that affected caproic acid production were identified by Plackette-Burman design (ethanol, sodium acetate, yeast extract and initial pH) and further optimized by using a four factor central composite design of response surface methodology. The results demonstrated that the optimum conditions for caproic acid production were determined to be ethanol concentration of 4.046% (v/v), sodium acetate concentration of 0.982% (w/v), yeast extract concentration of 0.145% (w/v) and initial pH of 6.41. Caproic acid production (214.23 mg/100 mL) in the optimized condition was in good agreement with the value predicted by the model equation (219.11 mg/100 mL), thereby assuring its effectiveness. Furthermore, the optimized condition of the lab-scale bioreactor was scaled-up to 5000 L fermentor and the obtained caproic acid broth was subjected to pit-filling fermentation. The result demonstrated this method of pit-filling fermentation was efficient in improving the quality of Luzhou-flavor liquor.