Impact Of Heat Processing On The Bioavailability Of Zinc And Iron From Cereals And Pulses

Influence of heat processing on the bioavailability of zinc and iron from food grains consumed in China was evaluated. Cereals-rice, barley, buckwheat, wheat, and oat, and pulses-chickpea -whole and decorticated, green gram-whole and decorticated, decorticated black gram, decorticated red gram, cowpea, and faba bean were examined for zinc and iron bioavailability by employing an in vitro dialysability procedure. Both pressure-cooking and microwave heating were tested for their influence on mineral bioavailability. Zinc bioavailability from food grains was considerably reduced upon pressure-cooking, especially in pulses. Among cereals, pressure-cooking decreased zinc bioavailability by 50.5% and 58.4% in barley and rice, respectively. All the pressure-cooked cereals showed similar percent zinc bioavailability with the exception of barley. Bioavailability of zinc from pulses was generally lower as a result of pressure-cooking or microwave heating. The decrease in bioavailability of zinc caused by microwave heating ranged from 14.3% in chickpea (whole) to 65.8% in cowpea. Decrease in zinc bioavailability was 40.0% in pressure-cooked whole chickpea, 51% and 57% in pressure-cooked or microwave-heated whole green gram, 20.6% and 24.9% in pressure cooked or microwave-heated decorticated green gram, and 46.5% in microwave-heated black gram. Iron bioavailability, on the other hand, was significantly enhanced generally from all the food grains studied upon heat treatment. Thus, heat treatment of grains produced contrasting effect on zinc and iron bioavailability. (c) All Rights Reserved