This sthdy investigated the changes in the sensory score, electronic tongue Euclidean distance (ED) and electronic nose odor distance of fresh whole milk during storage at 4, 15, 23 and 30 ℃. Using combination of a zero-order reaction kinetics model and the Arrhenius equation, shelf life prediction models for fresh milk were established based on the thresholds calculated for electronic tongue ED and electronic nose odor distance from the critical point of sensory quality changes, separately. The predicted shelf life using electronic nose and tongue was 16.2 and 15.7 days, respectively, showing 8.0% and 4.7% errors compared with the actual value, respectively. The results showed that electronic nose and electronic tongue technology can effectively monitor the quality changes of milk during accelerated shelf life, which provides a new idea for the determination of milk shelf life.

During storage, milk is prone to different degrees of oxidative degradation of fat with varying storage conditions, which changes the aroma components of milk. In this study, electronic nose based on gas chromatography (GC) and sensory evaluation were used to compare the changes in the composition of volatile flavor compounds and sensory properties of pasteurized whole milk, low-fat milk and skim milk (fat contents of 4, 1.4 and 0 g/100 mL) during storage at different temperatures. The results showed that all three milks maintained good flavor characteristics during storage at 4 ℃. The composition of flavor substances in whole milk was more complex, where 43 volatile compounds were identified, and no obvious stale flavor was perceived. The decreasing order of difficulty of fat oxidation was whole milk > low-fat milk > skim milk. Nonanal, a marker of lipid oxidation, was detected in both skim milk and low-fat milk. Methyl ketones derived from lipid oxidization such as 2-butanone, 2,3-butanedione, 2-hexanone, 2-heptanone and 2-undecanone were detected in skim milk during storage. The results of sensory evaluation were basically consistent with those of electronic nose. The sweetness and milky flavor of whole milk were more prominent, the flavor of low-fat milk was relatively bland, and skim milk tasted slightly bitter after 21 days of storage at 25 ℃. The findings of this study will provide a scientific basis for monitoring the flavor changes of milk products during storage and improving the quality of milk products.