[In vitro analysis of the iron availability in fortified rice]

Cereals are rich in fiber but also in phytate which is considered the principal inhibitor of mineral availability. On this basis, iron availability of fortified rice, and the inhibitory effect of bran phytate was studied in: white rice fortified with electrolytic iron (ABF) from commercial origin; and mixtures of ABF plus 4.76% and 9.09% of rice bran (ABF2 and ABF3 respectively) to simulate brown rice. Samples were analysed before and after phytic acid hydrolysis with phytase: Dietary fiber and phytic acid were assessed according AOAC; iron availability, expressed as dialisable iron by the in vitro method of Kapsokefalou and Miller modified by Valencia et al.; iron content was assessed by AAS. Results showed that added bran depressed iron availability, 9.65%; 4.04% and 1.82% as expected (ABF, ABF2 and ABF3 respectively). After phytic acid hydrolysis iron availability reached 28.20%; 27.95% and 25.30% for the same samples. These values were not different. After phytic acid hydrolysis, fiber content of ABF2 and ABF3 were lower than before. However multiple regression analysis of the data showed that fiber had not influence on iron availability and that phytic acid would be the principal responsible of it. These results indicate that brown rice should have a higher level of iron fortification than in white rice or be combined with other foods that improve iron availability as meats, vegetables or fruits.