Study On Direct Inoculation Of Oenococcus Oeni SD-2A Active Dry Powder To Conduct Wine Malolactic Fermentation

In order to study the fermentation properties of active dry powder of Oenococcus oeni SD-2a, different scales of inoculum were directly inoculated into Cabernet Sauvignon dry red wine with different pH, ethanol. Commercial freeze-drying starter(Viniflora® Oenos)was used as control. The results were showed as follows:1. Active dry powder of Oenococcus oeni SD-2a met requirements as expected. The number of active cells was about 8×1011cfu/g, and the moisture content was less than 5%. Sensory evaluation and technical indicators analysis showed that the powder completely met the expected requirements of the products.2. The rates of MLFs conducted by active dry powder of Oenococcus oeni SD-2a in wine and two model wines were quite different. The MLF rates in model wines were slower than in wines. So in this study, wine was chosen for further studyas it can not be replaced by model wines.3. Paper chromatography was used to monitor the MLF in wines. The results showed that, in some conditions, SD-2a active dry powder can successfully finish MLF after inoculated. Among the 27 experiment groups, there were 11 groups that completed MLF after inoculated. Considering the cost, we chose No.1(pH 3.2, 1# wine, inoculum dose 10mg/L), No.2(pH 3.4, 2# wine, inoculum dose 10mg/L) and No.3(pH 3.4, 3# wine, inoculum dose 50mg/L) to conduct the further experiment comparing to commercial powder.4. In the conditions of the selected wines, both of SD-2a group and control group were able to finish MLF. After MLF, it was found that the content of malic acid decreased by 2.3~2.5g and the degradation ration of malic acid was 62.5~68.24%. In 1# wine of pH=3.2, under the inoculum dose of 10 mg/L, Oenococcus oeni SD-2a active dry powder finished MLF in 20 days, 4 days later than control. In 2# wine of pH=3.4, under the direct inoculum dose of 10 mg/L, Oenococcus oeni SD-2a active dry powder can finish MLF in 24 days, 4 days later than control. In the 3# wine of pH=3.4, under the direct inoculum dose of 50mg/L, Oenococcus oeni SD-2a active dry powder and CK finished MLF in 28 days. By sensory evaluation, MLF improved the overall quality of the both wines of Oenococcus oeni SD-2a active dry powder and commercial control.