Fourteenth International Conference on Food Studies

Abstract

Malolactic fermentation (MLF) is carried out by lactic acid bacteria, where L-malic acid must be converted into L-lactic acid. Bacterial population growth in wine is affected by several physical-chemical factors, such as ethanol (Du Plessis et al. 2004). This work assesses the dynamics of malolactic fermentation of a native lactic acid bacterium in a synthetic medium fermented by two different yeasts at three ethanol concentrations. One Chilean native lactic acid bacteria, Levilactobacillus brevis, was used to conduct MLF, and two commercial yeast strains (Saccharomyces cereviceae LAVIN QA23 and LAVIN EC1118) were selected for alcoholic fermentation. First, a synthetic must be designed according to the methodology designed by Costello, Henschke, and Markides (2003). The must was fermented to obtain a synthetic wine and then standardized in three ethanol concentrations: 10%, 11.5%, and 13.5%. The standardized synthetic wine was inoculated with L. brevis to realize the MLF. During MLF, the bacterial count, subtract concentration, and product formation were determined. Growth and kinetics curves were smoothed by a cubic spline function using the R Studio development environment. The smoothed kinetics were then used to calculate the kinetic parameters of the fermentations. Fermentation with two commercial yeast strains did not significantly affect the behavior of the bacteria studied. However, ethanol concentration had an apparent effect. There was a link of proportionality between the specific growth and its metabolism expression. Moreover, citric metabolism was expressed. The results were quantified by a mathematical model comparing the intrinsic metabolism capacity of the strain.