Mineral bioavailability in three locally consumed pulses processed using popular methods: interpreted using molar ratios with phytic acid

Abstract

Pulses, an essential component of the Sri Lankan diet, have high levels of phytic acid (PA) which chelate essential mineral nutrients limiting their bioavailability. Three locally grown pulses; mung beans, black gram and soya bean were investigated to determine the effects of popular processing methods on their Zn, Fe and Ca bioavailability as affected mainly by phytic acid (PA). Processed mung beans (Vigna radiata var. MI 6) and black gram (Vigna mungo var. MI 1) had very high levels of PA. In mung beans, with increasing germination time, a significant decrease (P=0.05) in PA from 2517 to 1998 mg per 100g (dry weight basis) was observed but PA:Zn molar ratio did not improve. Natural fermentation of black gram, did not affect PA level effectively, but levels decreased when inoculated with a lactic acid bacterium or with Pantoea agglomerans. In soya bean (Glycine max var. Pb), significant (P=0.05) reduction in PA was observed in tempeh (487 mg/100 g dry weight). Overall, in soya products, the Zn bioavailability has increased from low to moderate levels in both tofu and tempeh. The molar ratio of PA:Fe was lower in all soya products. Although, PA:Zn molar ratio has decreased in germinated mung beans, the Ca x PA:Zn ratio exceeded 0.5 indicating that Ca influences Zn bioavailability DOI: http://dx.doi.org/10.4038/cjsbs.v41i1.4534 Ceylon Journal of Science (Bio. Sci.) 41 (1): 19-26, 2012