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 91µg retinyl palmitate/100ml, respectively. An unfortified milk sample with initial vitamin A of 86µg retinyl palmitate/100ml showed a loss of 62% whereas the replicate sample with initial vitamin A of 28µg retinyl palmitate/100ml 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.