牛乳中添加不同果汁对明串珠菌发酵产双乙酰的影响

双乙酰是一种对发酵乳口感有较大影响的风味化合物，但目前市售的发酵 乳制品双乙酰含量都比较低．为提高乳制品中双乙酰的含量，改善风味乳制品的 口感和品质，本研究以牛乳为原料，分别加入不同配比的苹果、小西红柿、西瓜 、草莓和菠萝汁，并添加0.2%柠檬酸进行明串珠菌发酵，测定了发酵液中双乙酰 的含量．结果表明，牛乳中加入5种果汁发酵明串珠菌，都能产生双乙酰；产双乙 酰最高的是菠萝汁，可达到20mg/L；其次是草莓汁，达到12.45 mg/L；牛乳-西瓜 汁混合液双乙酰最高可达到4.83 mg/L；牛乳-苹果汁和牛乳-小西红柿汁两种混合 液双乙酰的产量较低．
Diacetyl is one of the popular flavor compounds which are ef fective in the taste of galactozyme. Now, fermentation dairy available in markets contains lower diacetyl. In order to increase the content of diacetyl in dairy products and improve the taste and quality of fla vor galactozyme, five kinds of juices including apples, strawberries, cherry tomatoes, pineapple and watermelon were respectively added in m ilk with different ratios, then added 0.2% citric acid for fermenting using Leuconostoc and assayed the yield of diacetyl. Results indicated that the diacetyl was produced in the above five mixtures. The maximu m yield appeared in prineapple juice and the concentration reached 20 mg/L, and that of strawberry juice reached 12.45 mg/L. The maximum con centration of diacetyl in milk-waterrnelon mixture could reach 4.83 mg /L. The yields of diacetyl were low in both milk-apple and milk-cherry tomatoes mixture.