Mutation and selection of Oenococcus oeni for controlling wine malolactic fermentation

Abstract

Malolactic fermentation (MLF), mainly carried out by lactic acid bacterium, is of immense importance in winemaking allowing for improvement of microbiological stability and organoleptic characteristics of wine. However, it is difficult to address the problems of decoloration and loss of taste along with MLF induced by traditional starter culture. To further the aim at realizing a controlled and efficient MLF process, mutant of Oenococcus oeni strains after ultraviolet irradiation was selected to enhance quality of MLF. The treated strains with a lethality rate of 80–90 % were preliminarily screened, and then were secondly screened by evaluating their sensory and fermentation properties, by which O. oeni C10-1 were successfully screened. The malolactic conversion rate of O. oeni C10-1 is up to 38.81 %, which is remarkably increased when compared to original strains. Pivotally, wine fermented by O. oeni C10-1 demonstrated the highest color density of 9.240 and got the score of 5.95 in softness index, suggesting a remission of decoloration phenomenon and improved mouth feeling of wine. In all, these make it highly valuable for industrial application.