Control of N-Propanol Production in Simulated Liquid State Fermentation of Chinese Baijiu by Response Surface Methodology

Abstract

N-propanol is a vital flavor compound of Chinese baijiu, and the proper n-propanol contents contribute to the rich flavor of Chinese baijiu. However, the excessive content of n-propanol in liquor will reduce the drinking comfort. Based on the Box–Behnken design principle, the response surface test was used to optimize the factors affecting the production of n-propanol in a simulated liquid state fermentation of Chinese baijiu, and the best combination of factors to reduce n-propanol content was determined. Results showed that the content ratio of additional glucose to threonine and temperature had a significant effect on the production of n-propanol (p = 0.0009 < 0.01 and p = 0.0389 < 0.05, respectively). The best combination of fermentation parameters obtained was: the ratio of additional glucose to threonine content was 6:4, the temperature was 32 °C, and the initial pH was 4.40. Under these conditions, the production of n-propanol was 53.84 ± 0.12 mg/L, which was close to the theoretical value. Thus, the fermentation parameter model obtained through response surface optimization is reliable and can provide technical guidance for regulating the production of n-propanol and realizing high-quality baijiu brewing.