| In this paper,the lactic acid bacteria in Hakka rice wine were studied.First,the basic characteristics of lactic acid bacteria were analyzed after the lactic acid bacteria were separated,purified and identified from rice wine according to fermentation conditions.Furthermore,the effects of lactic acid bacteria on the fermentation of rice wine were studied by the dynamic change of the basic indicator of Hakka rice wine.Then,In vitro antioxidant system was selected to explore the antioxidant capacity of lactic acid bacteria.At the same time,the ability of lactic acid bacteria to metabolize ?-aminobutyric acid was also tested.Therefore,research on lactic acid bacteria from Guangdong Hakka rice wine provides a scientific theoretical basis for further study and utilization.The results were as follows:1.Strains A and strains E were obtained by separation and purification of lactic acid bacteria from rice wine yeast and fermented mash.After identified by morphological,biochemical and compared with 16 SrDNA in GenBank,results showed that both strains belonging to Lactobacillus.The results of phylogenetic tree constructed(the affinity of 16 S rDNA sequence up to 99%-100%)by software MEGA 6.0 showed that bacteria A was Lactobacillus plantarum and bacteria E was Lactobacillus pentosus.2.The acid-producing ability of strains was very strong.The growth and breeding of the strain were affected by the increase of salt concentration,bacteria A was more sensitive than bacteria E.When the salt concentration reached 8%,the growth of the strain was greatly inhibited.Both strains could grow in acidic environment,the optimal growth pH of bacteria A and bacteria E were 4-6,which could be inhibited beyond the optimal pH range.The growth of bacteria A and bacteria E would be suppressed with the increase of sugar content,but the strain could grow normally under high sugar content.The strain was strongly inhibited when the ethanol concentration was 6%,but at high ethanol concentration,the strain was still struggling to grow,and the ethanol tolerance of bacteria A was more sensitive than that of bacteria E.3.In order to ensure the total sugar content of the late fermentation,the amount of lactic acid bacteria was controlled in the early stage of fermentation for the main stage of saccharification.Lactic acid was the main metabolite of lactobacillus,which was the main reason for the increase in total acid and also the main contributor to the flavor of rice wine,so increase the content of lactic acid bacteria in the middle of the fermentation,in a certain extent,could increase the aroma of rice wine.Lactic acid bacteria would increase the amino acid nitrogen in the early and middle fermentation,from the technical point of view,increase the amount of lactic acid bacteria in the early stage could increase the amino acid nitrogen content of rice wine.Although lactic acid bacteria could be reduced alcohol content,the effect was weak,so at this time had no need to consider the role of lactic acid bacteria.4.Hakka rice wine as a control,the ability of removal OH? in metabolites of lactic acid bacteria was much higher than Hakka rice wine,and better than mixed lactic acid bacteria.The ability of removal O~2?in bacteria A and mixed bacteria metabolites was very close to Hakka rice wine,but bacteria E was a deviation.The ability of removal DPPH was bacteria A > mixed bacteria > bacteria E> Hakka rice wine.Bacteria A and Hakka rice wine reduction ability was stronger,bacteria E and mixed bacteria reduction ability were weak,in the addition of 0.3 mL/mL no longer increased.The amount of metabolized GABA of lactic acid bacteria was determined after 48 h,result showed that bacteria A was 0.35 g / L,bacteria E was 0.36 g / L,mixed bacteria was 0.37 g / L.Above all this,the function of lactobacillus to Hakka rice wine was demonstrated. |
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