The nutritive value of amaranth grain (Amaranthus caudatus)

Abstract

The purpose of this investigation was to study the nutritional value of grain amaranth (Amaranthus caudatus) as a supplement to cereals, and to determine the effect of heat on nutritional quality of cereal/amaranth mixtures. Maize, wheat and low-tannin sorghum blends containing 0%, 10%, 25% and 50% of popped amaranth flour were studied in balance experiments with growing rats. The popped amaranth was very high in lysine (5.19 g/16g N), but lysine was still the first limiting amino acid in the blends. However, amino acid scores were raised significantly by amaranth substitution, and the tryptophan deficiency of maize protein was alleviated by addition of amaranth. True protein digestibility was, in general, not affected by amaranth substitution, but the biological value increased considerably with increasing levels of inclusion. Amaranth substitution also resulted in remarkable increases in weight gain of the rats. The energy digestibility of the different blends was quite similar and there was only little variation in the amount of digestible energy of the mixtures.

Cooking produced a very small but significant reduction in protein and energy digestibility. However, the effects of cooking were minor and probably without practical importance. In conclusion, addition of amaranth to cereal flours improved protein quality without affecting energy utilization. Amaranth seems to be an effective source of protein to combine with cereal proteins.