植物乳杆菌发酵枣汁在冷藏期间的营养品质变化研究

以陕北木枣、新疆和田枣为原料，经植物乳杆菌（Lactobacillus plantarum）发酵制备发酵枣汁，分析两种发酵枣汁在冷藏过程（4 ℃、28 d）中的理化特性、酚类化合物、抗氧化活性以及风味特征变化。结果表明，在冷藏过程中发酵枣汁的活菌数逐渐减少，但28 d后发酵枣汁中活菌数仍高于6.0 lg（CFU/mL）。冷藏过程中发酵枣汁总糖和还原糖含量有所降低，可滴定酸含量有所升高。冷藏28 d后的发酵枣汁总酚含量高于冷藏前的发酵枣汁，冷藏过程较好地保持了发酵枣汁的1,1-二苯基-2-三硝基苯肼（DPPH）自由基清除活性和铁离子还原能力。经过冷藏后的枣汁中风味物质含量相较于冷藏前的发酵枣汁有所降低，但始终高于未发酵枣汁，植物乳杆菌发酵赋予枣汁丰富的花香和果香。

Changes of nutrient quality of jujube juice fermented by Lactobacillus plantarum during refrigerated storage

Using Muzao and Hetian jujube as raw materials, the jujube juice was fermented by Lactobacillus plantarum, and the changes of physicochemical properties, phenolic compounds, antioxidant activity and flavour characteristics of the fermented jujube juice during refrigerated storage (4 ℃, 28 d) were investigated. The results showed that the viable counts in fermented jujube juice gradually decreased during refrigerated storage, but still higher than 6.0 lg CFU/ml after 28 d. The contents of total sugar and reducing sugar in fermented jujube juice were decreased, while the titratable acidity content increased during refrigerated storage. After 28 d of refrigeration, the total phenolic content of fermented jujube juice was higher than that of before refrigeration, and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and ferric ion reducing antioxidant power of fermented jujube juice were maintained during refrigerated storage. In addition, the total content of flavor compounds in fermented jujube juice after refrigeration were lower than that of unrefrigerated jujube juice, but higher than that of unfermented jujube juice. Fermentation by L. plantarum endowed jujube juice flower and fruit odors.