Preparation and Application of an Indigenous Freeze-Dried Oenococcus oeni Ready-To-Use Starter in Winemaking

Malolactic fermentation (MLF) by Oenococcus oeni is an important process for the production of high-quality wine, and the preparation of a high cell viability starter is of great significance to this process. The key way to obtain a high cell viability starter is to select an effective lyoprotectant. In this study, by optimizing the ratio of lyoprotectant and improving its pH, prefreezing temperature, and period of the growth phase, the number of viable bacteria of O. oeni was 1.08 +/- 0.04 X 10(11) CFU/g. MLF experiments on the lab scale and the pilot scale were carried out. Organic acids, fermented aroma volatiles, and sensory scores of samples during MLF were analyzed, and the results showed that there was no significant difference between the lab-scale and pilot-scale MLF. Both O. oeni ES-1 and commercial starters successfully completed MLF, but the aroma volatile type, aroma volatile concentration, and sensory score of O. oeni ES-1 were excellent. In addition, the fermentation capacity of O. oeni ES-1 in the pilot scale was studied first.