Kinetics of predominant microorganisms in the multi-microorganism solid-state fermentation of cereal vinegar

Abstract

Multi-microorganism solid-state fermentation (SSF) is a traditional technique to produce fermented foods. However, the fermentation kinetics is difficult to establish due to the irregular and complex growth and metabolism profiles of the microorganisms. In this work, the SSF of vinegar was described and predicted for the first time by using two-stage kinetics. The in situ and in vitro kinetics of cell growth, product formation, and substrate utilization of the predominant microorganisms Acetobacter and Lactobacillus with R2 more than 0.98 were analyzed using Logistic, Luedeking–Piret, and Luedeking–Piret-like modes, respectively. Ethanol, lactic acid, and acetic acid were found to be the main factors responsible for the temporal variation of fermentation profiles. Potential interactions between predominant microorganisms were revealed by in vitro SSF. Acetic acid mainly produced by Acetobacter was proven the main factor for the two-stage profiles, and its modulating role for microbial growth and metabolism was more important than that of lactic acid and ethanol. The thresholds of acetic acid to the negative specific growth rate were 3.05 and 1.68 g/100 g of Cupei for A. pasteurianus and L. helveticus, respectively. These results provide the theoretical modules to understand the SSF of cereal vinegars for further monitoring and modulation.