The Metabolism of Nitrogen and the Digestibility Coefficient and Biological Value of the Proteins and Net Protein Utilization in Poor Rice Diet Supplemented With Methionine-Fortified Soya Flour or Skim Milk Powder

Abstract

The effect of supplementing a poor rice diet commonly used in India with methionine-fortified soya flour or skim milk powder was studied in seven girls aged 8–9 years, using as criteria: the retention of nitrogen, digestibility coefficient, biological value, and net protein utilization of the proteins. The retention of nitrogen on the rice diet was very low (20.3 mg/kg day). Supplementation of the rice diet with soya flour, methionine-fortified soya flour or skim milk powder, so as to provide about 1 g/kg extra protein, made up the protein deficiency in the rice diet and resulted in a significant increase in nitrogen retention (95.6, 112.1, and 113.6 mg/kg day). The retention of nitrogen on the rice diet supplemented with methionine-fortified soya flour (112.1 mg/kg day) or skim milk powder (113.6 mg/kg day) was nearly the same and significantly higher than that (95.6 mg/kg day) observed with a diet supplemented with soya flour. The biological value and net protein utilization of the mixed proteins of rice – skim milk powder diet and rice–methionine-fortified soya flour diet (62.4 and 62.2 and 53.3 and 54.0 respectively) were nearly the same and significantly higher than those (58.3 and 49.9) of rice – soya flour diet. The results show that methionine-fortified soya flour is almost as good as skim milk powder and significantly superior to soya flour as a protein supplement to rice diet.

Comparative nutritive value, amino acid content, chemical composition, and digestibility in vitro of vegetable- and grain-type soybeans

“…The second limiting amino acids were found to be threonine and valine. This further confirms the findings of earlier workers: Kapoor and Gupta (1975), Coppock (1974( ), Panemangalore et al (1964, and Bookwalter et al (1975). The amino acid composition of soybean varieties reported agrees very closely with that of Singh (1975).…”