蓝莓果汁发酵工艺优化及挥发性风味物质分析

为改善蓝莓果汁的风味，采用酿酒酵母（Saccharomyces cerevisiae）和乳酸菌分阶段发酵工艺制备发酵蓝莓果汁。通过单因素试验与正交试验优化发酵蓝莓果汁发酵工艺条件，并利用顶空固相微萃取结合气相色谱-质谱联用（HS-SPME-GC-MS）技术对发酵前后蓝莓果汁挥发性风味物质进行分析。结果表明，最佳发酵条件为酿酒酵母接种量2‰，植物乳杆菌（Lactobacillus plantarum）与干酪乳杆菌（Lactobacillus casei）比例为3∶1，接种量为1.5‰，发酵时间18 h，发酵温度34 ℃。在此优化条件下，发酵蓝莓果汁总酯含量为101.3 mg/L。GC-MS结果表明，发酵后蓝莓果汁共检出19种挥发性香气成分，其中酯类8种，醇类6种、醛类3种，酚类1种及烯烃类1种。与未发酵蓝莓果汁比较，发酵后的蓝莓果汁挥发性风味物质增加10种，其中酯类、醇类物质分别增加7种、3种，含量是未发酵蓝莓果汁的44.6倍、12.8倍。因此，发酵后蓝莓果汁风味物质更加丰富。

Optimization of fermentation process and analysis of volatile flavor compounds of blueberry juice

In order to improve the flavor of blueberry juice, the blueberry juice was prepared by the process of stage fermentation with Saccharomyces cerevisiae and lactic acid bacteria. The fermentation conditions of blueberry juice were optimized by single factor test and orthogonal tests, and the volatile flavor compounds in blueberry juice before and after fermentation were analyzed by headspace solid phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) technology. The results showed that the optimum fermentation conditions were as follows: S. cerevisiae inoculum 2‰, Lactobacillus plantarum and Lactobacillus casei ratio 3∶1 with inoculum 1.5‰, fermentation time 18 h, and temperature 34 ℃. Under these optimized conditions, total ester content of fermented blueberry juice was 101.3 mg/L. The results of GC-MS showed that a total of 19 volatile aroma components were detected, including 8 esters, 6 alcohols, 3 aldehydes, 1 phenols and 1 olefin. Compared with unfermented blueberry juice, there were 10 kinds of volatile flavor compounds increased, among them, the components of esters and alcohols increased by 7 and 3, respectively, and the content was 44.6 and 12.8 times of the unfermented blueberry juice. Therefore, the flavor components of fermented blueberry juice were more abundant.