益生菌发酵苹果汁工艺优化及有机酸的变化

Optimization of Fermentation of Apple Juice by Probiotics and Organic Acids Evolution during Fermentation

以红富士苹果为原料,进行乳酸菌发酵苹果汁工艺条件优化并分析发酵期间苹果汁有机酸的变化。选择Lactobacillus paracasei 20241、Bifidobacterium animalis 6165、Streptococcus thermophilus 6063和Lactobacillus acidophilus 6005混合发酵苹果汁,以活菌数和感官评分为主要指标,在单因素试验基础上进行响应面优化试验,研究不同的菌种比例、接种量、发酵时间等对苹果汁活菌数和感官评分的影响。结果表明,乳酸菌发酵苹果汁的优化工艺条件为菌种比例1∶1∶1∶1、接种量2%、发酵时间24 h、发酵温度37℃,在此条件下得到的活菌数为1.985×108 CFU/mL,感官评分为80.23分。采用最佳工艺条件发酵苹果汁,利用高效液相色谱法对发酵过程中苹果汁有机酸的变化情况进行分析,结果表明:经过发酵后,苹果酸和琥珀酸含量下降明显(P<0.05),而乳酸、奎宁酸、柠檬酸、酒石酸、丙酮酸和莽草酸含量均显著提高(P<0.05)。

The fermentation of Fuji apple juice by lactic acid bacteria was optimized and changes in organic acids during fermentation were analyzed. Lactobacillus paracasei 20241, Bifidobacterium animalis 6165, Streptococcus thermophilus 6063 and Lactobacillus acidophilus 6005 were used as mixed cultures in the fermentation of apple juice. The optimization of culture composition, inoculum size and fermentation time was performed using one-factor-at-a-time method and response surface methodology. Viable cell count and sensory score were used as response variables. The results showed that the optimal fermentation conditions were as follows： ratio of four probiotic strains, 1：1：1：1; inoculum size, 2%; fermentation time, 24 h; and temperature, 37 ℃. Under these conditions, viable cell count was 1.985 × 108 CFU/mL and sensory score was 80.23 points. Malic acid and succinic acid contents decreased significantly after fermentation（P 0.05）, while lactic acid, quinic acid, citric acid, tartaric acid, pyruvic acid and shikimic acid contents significantly increased（P 0.05） as demonstrated by HPLC analysis.