Antioxidant effects on retinyl palmitate stability and isomerization in nonfat dry milk during thermally accelerated storage

The effects of antioxidants on vitamin A oxidation and isomerization in nonfat dry milk (NFDM) were evaluated during thermally accelerated storage. High performance liquid chromatography was used to measure all-trans, 13-cis, 9-cis, and 9, 13-di-cis retinol present in two lots of antioxidant-treated, vitamin A and D fortified NFDM samples at zero, one, and two weeks of 50 °C storage. After two weeks, the NFDM sample retaining the most vitamin A was the one treated with butylated hydroxytoluene at 0.29 ppm with 250 ppm ascorbic acid; this treatment retained approximately 76% of its original retinol activity equivalents. The control retained significantly less than this: only 19% of its original vitamin A activity. Butylated hydroxytoluene in combination with ascorbic acid appears to be effective in the preservation of vitamin A in NFDM during heated storage; however, its use in dried beverage mixes is currently prohibited.