Influence of milk fat, milk solids, and light intensity on the light stability of vitamin A and riboflavin in lowfat milk.

Retinyl palmitate and riboflavin were quantified in milk samples exposed to fluorescent light. Effects of compositional factors were determined by comparing rates of loss of riboflavin and vitamin A in milks with different amounts of milk fat and milk solids. Upon exposure to fluorescent light, rates of vitamin A and riboflavin loss were lower in whole milk than in skim milk. Riboflavin degraded more slowly in skim milk with 1% added nonfat dry milk than in skim milk with no added solids. No additional protective effect for riboflavin was found when added solids were increased from 1 to 3%. Compared with milk with no added solids, 1% added nonfat dry milk did not increased protection for vitamin A, but a protective effect was noted when the skim milk was fortified with 3% nonfat dry milk. Increasing light intensity increased the rates of loss of both vitamins, and riboflavin was lost at a greater rate.