Effect of Emulsifiers and Fortification Methods on Light Stability of Vitamin A in Milk

¹ Department of Food Science and Nutrition, Brigham Young University, Provo, UT 84602

Lowfat milk is commercially fortified during processing by adding small quantities of oil containing an emulsifier and vitamin A. Added vitamin A is degraded more rapidly than indigenous vitamin A when milk is exposed to light. The objective of this research was to determine if added vitamin A could be made as stable to light as naturally occurring vitamin A by placing it in the more dilute milk fat environment with naturally occurring emulsifiers.

Using HFLC to quantify retinyl palmitate, the effect of emulsifiers indigenous to milk versus a commercial emulsifier was first investigated. Butter serum, rich in fat globule membrane material, was compared with Durfax 80 in a 1% recombined milk system. No difference was found in vitamin A stability to light due to emulsifier type.

A second experiment on 1% milk compared light stability of vitamin A added in concentrated milk fat emulsion, vitamin A added to all the milk fat, and indigenous vitamin A. Indigenous vitamin A and vitamin A added to all the fat were equally stable and more stable than vitamin A added in a concentrated milk fat emulsion.

Key Words: vitamin A stability • milk • light

Submitted on April 10, 1989
Accepted on January 8, 1990