优良梨汁发酵乳酸菌的筛选与发酵性能分析

Screening and Fermentation Characteristics of Lactic Acid Bacteria for Fermentation of Pear Juice

对10株分离于水果发酵液等不同来源的乳酸菌进行耐受性筛选,得到性能优良的植物乳杆菌ZG2和干酪乳杆菌GG8作为梨汁发酵菌株,并通过测定发酵过程中梨汁的活菌数、pH值、有机酸与挥发性成分对2株乳酸菌的发酵性能进行比较。结果表明:ZG2发酵前期活菌数下降迅速,发酵持续时间较短;GG8发酵结束后pH值低于ZG2;2种发酵液中有机酸种类相似,ZG2产乳酸能力较强,GG8发酵产柠檬酸和总酸含量明显多于ZG2;发酵前后构成梨汁主体风味的物质相似,分别为2-甲氧基-3-甲基吡嗪、芳樟醇和松油醇,2株菌均在发酵中期产生的挥发性成分最丰富,发酵后期GG8产挥发性风味物质较丰富。相较植物乳杆菌ZG2,干酪乳杆菌GG8具有更大发酵潜力和研究价值。

Ten strains of lactic acid bacteria from different sources including fermented fruit were screened for tolerance to stress conditions. Lactobacillus plantarum ZG2 and Lactobacillus casei GG8 were selected as the best for the fermentation of pear juice. We compared the fermentation performance of the two strains by measuring the viable count, pH value, organic acids and volatile components of pear juice during the fermentation process. The results showed that the viable count of ZG2 decreased rapidly during the early part of the fermentation process, lasting for a short time of period. The pH value at the end of fermentation for GG8 was lower than that for ZG2. The organic acid compositions of the two fermented juices were similar although ZG2 exerted stronger lactic acid-producing ability while GG8 produced larger amounts of citric acid and total acids. The primary flavor compounds of pear juice changed little before and after fermentation, 2-methoxy-3-methylpyrazine, linalool and terpineol. Both strains produced the most abundant volatile compounds during the middle stage of fermentation, and GG8 also produced abundant volatile compounds during the late stage. Compared with L. plantarum ZG2, L. casei GG8 has greater potential for research and application.