Abstract:

Milk samples from dairy cows subjected to duodenal infusion of perilla oil rich in free alpha-linolenic acid were stored in darkness at either 4 or 20 ℃ for different periods of time (0, 72 or 120 h) in order to investigate the effect of storage conditions on the oxidation stability of the milk. It was observed that as the amount of perilla oil infused increased, the oxidation stability of freshly harvested milk samples showed a downward tendency; for milk samples stored for 72 h at 4 ℃, the oxidation stability remarkably decreased; and there was no obvious difference in the oxidation stability of milk samples stored for up to 120 h at the same temperature. Under the storage conditions of 20 ℃ and 72 h, the oxidation stability of milk samples tended to be lower with increasing amount of perilla oil infused. When the length of storage was prolonged up to 120 h at the same temperature, a significant decrease in the oxidation stability of milk samples was observed. Our findings suggested that different amounts of perilla oil infused caused different fatty acid composition in milk, resulting in significant differences in its oxidation stability under the same storage conditions.

Key words: milk, temperature, time, linolenic acid, oxidation stability