THE TRYPTOPHAN CONTENTS OF WHEAT, MAIZE AND BARLEY GRAINS AS A FUNCTION OF NITROGEN-CONTENT

The tryptophan contents of wheat, maize and barley grains were evaluated for samples originating from commercial and experimental cultivars, using a procedure that allowed the true quantity of this amino acid to be determined. For every cereal, a linear relationship was found between the level of tryptophan and the nitrogen (N) content of the grain. The results showed that previous reports of similar relationships underestimated tryptophan by 10±5%, owing to tryptophan degradation during alkaline hydrolysis prior to analysis. Linear relationships between tryptophan and N have a low predictive value, however, since a high variability was observed in tryptophan content For any given grain nitrogen content. © 1995 Academic Press, Inc.