关键词: 牛乳, 气相型电子鼻, 脂肪氧化, 挥发性成分, 贮藏

Abstract: In the process of milk storage, the fat in milk is easy to oxidize and decompose to different degrees with the change of storage conditions, and then change the aroma components of milk. In this study, Gas-Phase Electronic Nose detection and sensory evaluation were used to compare the changes of volatile flavor compounds and sensory properties of pasteurized whole milk, low-fat milk and skim milk at different storage temperature and time. The results showed that the above three kinds of milk products maintained good flavor characteristics under the condition of 4 °C refrigeration. The order of difficulty of fat oxidation was whole milk > low fat milk > skim milk. The flavor substances of whole milk were more complex, a total of 43 volatile compounds were identified, and no obvious rotten flavor was observed during storage. Nonanal, a marker of lipid oxidation, was detected in both skim milk and low-fat milk. Skim milk was more prone to oxidative decomposition of fat, and lipid-oxidized methyl ketones such as 2-butanone, 2-butanedione, 2-hexanone, 2-heptanone and 2-undecanone were detected during storage. The results of artificial sensory evaluation were basically consistent with those of electronic nose, the sweetness and flavor of whole milk were more prominent, the flavor of low-fat milk was the lightest during storage, and skim milk could feel slight bitterness when stored at 25 ℃ for 21 days. This study will provide a scientific basis for monitoring the flavor changes of milk products during storage and improving the quality of milk products.

Key words: milk, Gas-Phase Electronic Nose, fat oxidation, volatile components, storage