The nutritive value of amaranth grain (Amaranthus caudatus). 3. Energy and fibre of raw and processed grain.

Digestibility of dietary fibre (DF) and energy of three pale-seeded and one dark-seeded variety of Amaranthus caudatus were studied in balance experiments with growing rats. Effects of processing: popping, toasting and flaking were also examined. The pale seeds contained about 8% of DF and the black seeds about twice as much. The soluble DF fraction made up 33-44% of the total DF (TDF) fraction in the pale-seeded varieties, but only 18% in the black seeds. The monomer sugar composition of the DF was very similar in all products. However, the black seeds were very high in lignin, and DF of the black-seeded products were more resistant to digestion than that of the pale-coloured products. In the pale amaranth products digestible energy (DE) varied between 86 and 91%. In the dark-seeded products DE was lower, and there was a significant negative correlation (r = -0.92) between DE and TDF. Processing of pale seeds had only minor effects on TDF and DE, but increased the proportion of soluble DF and the digestibility of DF in one variety. The food intake tended to be lower in rats fed raw pale seeds compared with those consuming processed products, indicating the presence of heat-labile factors reducing palatability. In conclusion, the pale seeds had a lower content of DF than most cereal grains and the DF was more easily digested. As a source of energy, amaranth grains seem to be comparable to other cereals.