Influence of Vitamin A and D Fortification on the Flavor of Instant Nonfat Dry Milk

Abstract

Twenty-one experimental batches of instant nonfat dry milk (NDM) were prepared in cooperation with four commercial manufacturers and three suppliers of vitamins. Vitamins A and D were added to yield levels of 10,000 and 2,000 IU/lb of NDM, respectively, in fortified batches. Flavor evaluations by a trained panel (triangle difference test) were made initially and periodically during storage at 100 and 70F up to 5 and 12 months, respectively.All samples, including nonfortified controls, exhibited significant deterioration in flavor during storage. Staling was evident in one month in samples stored at 100F and in three months in those stored at 70F. Staling was associated with increased protein-reducing substances. In only one sample at one storage period (nine months at 70F) was a hay-like flavor, presumably typical of vitamin A deterioration, evident to a degree sufficient to justify a conclusion that the sample containing vitamin A was different from the nonfortified control. No correlation between vitamin retention and flavor was evident.It is concluded that although a flavor associated with vitamin A deterioration doubtless develops on storage of NDM containing vitamin A of the types and levels added in this study, other changes are of at least equal significance and, in general, overshadow it in importance.