Vitamin A Stability in Ultra-High Temperature Processed Milk

Stability of vitamin A in partly skimmed (2% fat) fortified and unfortified ultra-high temperature processed milk was examined over 15 wk.Milk samples (stored at 23 +-2°C) were analyzed weekly for retinyl palmitate and dissolved oxygen.Significant losses of 71 and 73% were observed in replicate samples of fortified milk containing initial vitamin A of 119 and 91 /ag retinyl palmitate/100 ml, respectively.An unfortified milk sample with initial vitamin A of 86 /~g retinyl palmitate/100 mI showed a loss of 62% whereas the replicate sample with initial vitamin A of 28 /ag retinyl palmitate/100 ml remained unchanged during storage.Dissolved oxygen in all four milk samples underwent significant changes.During the first 7 wk, oxygen declined or remained constant.After 7 wk, oxygen in all samples steadily increased.