Studies On The Malolactic Fermentation Of Lactobacillus Plantarum R23 In Loquat Wine

Malolactic fermentation is one process which carried out the conversion of malic acid to lactic acid and released CO2 using lactic acid bacteria for bio-deacidification. Malolactic fermentation is a indispensable secondary fermentation in loquat wine which can effectively reduce the acerbity and roughness of the fruit wine to improve the flavor;it also can enhance the organoleptic charactcteristic and increase the microbiological stability of loquat wine.In this research, according to discussing on the nutritional requirement and growth characteristics of Lactobacillus plantarum R23, the most suitable medium was screened out; Using "jiefangzhong" loquat wine as base liquor,the malolactic fermentation kinetics of Lactobacillus plantarum R23 in loquat wine was researched; To provide theoretical basis and technical support for brewing high-quality loquat wine,the changes of flavor compounds in loquat wine after malolactic fermentation were compared and analyzed and producing approaches of flavor compounds in loquat wine were studied. The results showde that:(1) Studied on growth characteristics and optimization of medium of Lactobacillus plantarum R23Lactobacillus plantarum R23 is gram-positive bacteria, facultative anaerobic, the most suitable growth temperature is 30℃and the most suitable growth pH value is 6.0. By this research the obtained recipe of LH16 medium (non-Mn2+) which was suitable for growth of Lactobacillus plantarum R23 was that tomato juice 100mL, yeast extract 7.4g, beef extract 10g, glucose 30g, magnesium sulfate 0.36g, sodium malate 20g, tween 80 1g, tryptone 15g, ammonium citrate 2g, the volume was up to 11 by watering, pH value adjusted to 6.0±0.2. By culturing in the this medium at 25℃for 24h, the cell densities of Lactobacillus plantarum R23 were 3.40×109 cfu per mL, twice than the MRS medium (non-Mn2+)(2) Effects of the growth and MLF of Lactobacillus plantarum R23 on environmental factors of loquat wineThe cell densities of Lactobacillus plantarum R23 were downtrend generally,its survival rate and malolactic fermentation were improved in the loquat wine with the suitable fermentation temperature,pH value and anaerobic condition;they were inhibited with alcohol and sulfur dioxide. When the inoculation amount was 108cfu/mL,the maloalctic fermentation was completed while the total sulfur dioxide concentration less than 70mg/L and the alcohol degree less than 12.7%,and it isn't completed while the pH value less than 3.3.(3) Studies on the kinetics of the malolactic fermentation in loquat wineBased on four factors quadratic orthogonal design, to determine the accomplish ratio of MLF(Y1) and the augmenter of the volatile acid (Y2),Four factors including the inoculation amount of the Lactobacillus plantarum R23 (X1), the alcohol degree in loquat wine(X2), the total sulfur dioxide concentration in loquat wine(X3) and the fermental temperature(X4) were chosen to study their effect on the malolactic fermentation in loquat wine.The result showed that the factors was arranged from max to min according to its effect on MLF of the Lactobacillus plantarum R23 in loquat wine:the inoculation amount of the Lactobacillus plantarum R23> the total sulfur dioxide concentration in loquat wine>the fermental temperature> the alcohol degree in loquat wine. The kinetics model of the malolactic fermentation in loquat wine was established: Y1=83.5167+9.4208X1-1.8708X2-2.4875X3+1.9458X4, Y2=0.05917+0.02112X1+0.01129X4+0.00694X1X2There was goodness of fit for the two above regression equations (P< 0.01). The above regression equations could be applied to monitor the malolactic fermentation in real production of the loquat wine. Moreover, the above regression equations could not only provide a preference for how to choose the suitable inoculation amount and the fermental temperature of the loquat wine in defferent environment,but also a the oretical basis on the industrialization of the perfect loquat wine on a large scale.(4) Effects of the quality of loquat wine on malolactic fermentationMalolactic fermentation in loquat wine could reduce the total acid,increase the content of volatile ester, obtain a more soft and coordinate taste and a heavier flavour;Both sensory evaluation and flavor balance index were better in loquat wine after MLF; the content of diacetyl could not significantly change after MLF.