The influence of milling on the nutritive value of flour from cereal grains. 7. Vitamins and tryptophan

Rye, wheat, barley, rice, maize and sorghum were milled into more or less refined fractions, and the content of thiamin, riboflavin, vitamin B₆, folate, biotin, niacin and tryptophan were determined. Differences in vitamin content between the different cereal grains were rather small. Refining resulted in marked losses of all vitamins studied. On average, 70%–80% of the vitamins were lost during the milling process. The lowest vitamin content was found in highly refined rice, containing only about 5% of the folate and 10% of the niacin present in brown rice. Maize had a low content of tryptophan, and the concentration was greatly reduced by degerming. For the other cereal grains, milling had only a slight effect on tryptophan concentrations.