The Research Of Wine By Mix Malolactic Fermentation

During malolactic fermentation,Lactic acid bacteria convert sharp-sour tasted L-malic acid into round-saturated L-lactic acid,which not only reduces the acidity of the wine,increases the stability of the microorganisms,but also improves the aroma and taste of the wine..Oenococcus oeni is a good strain that initiates malolactic fermentation,Lactobacillus plantarum also has high ?-glucosidase activity,can use aroma precursors to generate various aroma components.Therefore,the potential of mixed bacteria for malolactic fermentation was measured.At the same time,the optimal combination of Lactobacillus plantarum and Oenococcus oeni inoculation ratios,inoculation intervals,and inoculum amounts was selected to improve the quality of the wine.The main findings are as follows:(1)In the simulated wine environment,the bacterial density of Oenococcus oeni can be kept stable,while the number of Lactobacillus plantarum continues to decline.In the process of winemaking,the rate of alcohol fermentation was not affected by lactic acid bacteria after inoculation of lactic acid bacteria in the early and middle stages of alcohol fermentation.The qPCR(real-time quantitative PCR)experiment had good accuracy and could rapidly count and analyze lactic acid bacteria in wine.(2)Mixed-culture of Oenococcus oeni and Lactobacillus plantarum and Lactobacillus plantaruminoculated in the early stage of alcohol fermentation almost completed the malolactic fermentation at the same time.The metabolic rate of malic acid exceeded 95%,and there was no significant difference in total acid content and volatile acid production.There was no significant difference in the alcoholicity of wines in the mid-alcohol fermentation of mixed fermentation and the fermentation of Oenococcus oeni.The total acid content of the mixed bacteria fermentation and the volatile acid content produced were lower than those of the single strain of wine.The time cost of inoculation after alcohol fermentation with Oenococcus oeni was less than that with mixed bacteria fermentation.The inoculation of lactic acid bacteria in the early and middle stages of alcoholic fermentation can more efficiently complete the malolactic fermentation and reduced the fermentation time.(3)After malolactic fermentation,the order of primary and secondary effects on wine sensory scores was: inoculation volume> inoculation interval> inoculation ratio.The optimal combination for orthogonal experiment was the ratio of Lactobacillus plantarum to Oenococcus oeni inoculation was 8:1,the interval time was 4 days,and the total inoculation volume was 10%.(4)For the orthogonal mixing of different inoculation intervals,inoculation ratio and inoculum size,the volatile aroma components were determined by solid-phase microextraction(SPME)and analyzed quantitatively.A total of 78 aroma components were measured,compared with the control group,60 kinds of aroma components were measured.In the nine groups of orthogonal tests,considering aroma substances,aroma values,total acid reduction,fermentation time,volatile acid production,and sensory evaluations were used to screen out treatments that performed well in all aspects(The ratio of Lactobacillus plantarum and Oenococcus oeni inoculum was 4:1,the inoculation interval was 4 days,and the inoculation volume was 10%)compared with the control group.There was no significant difference in the volatile aroma components from the mixed bacteria fermentation and the total content of components produced by Lactobacillus plantarum.The results showed that mixed fermentation can increase the type and content of volatile aroma components of wine.(5)From the fermentation time,volatile acid production and acid reduction,the mixed bacteria fermentation was between the inoculation of Oenococcus oeni and Lactobacillus plantarum.From the aroma evaluation point of view,the difference between single and mixed-culture of Lactobacillus plantarum is small,but the acidity of wineproducing by Lactobacillus plantarum is sharper,and the acidity of the mixed bacteria fermentation is softer and more refreshing.Therefore,sensory evaluation of mixed bacteria fermentation was considered superior to other control groups.From the sensory evaluation,there was a rich aroma of Lactobacillus plantarum,and a soft lactic acid producing by Oenococcus oeni.It showed that the mixed bacteria fermentation has a certain commercial potential.