Bioaccessibility of major minerals and trace elements in different varieties of cooked rice, from the Argentina

Abstract

The objective of this work was to evaluate the total and bioaccessible concentration of elemental nutrients in rice varieties, from the provinces of Corrientes and Entre Ríos. The samples of cooked white rice, fine long and fortuna or double carolina varieties, were processed by standardized methods, like moisture, total proteins by Kjeldhal, fiber by a gravimetric-enzymatic method. The macroelements calcium and magnesium were evaluated by complexometry, phosphorus by UV-visible spectrophotometry, and the microelements iron, copper and zinc were performed by atomic absorption spectrophotometry. The bioaccessible fraction was determined by an in vitro dialysis method, using an enzyme complex and successive incubations reproducing the digestion process under physiological conditions. The results of total calcium ranged between 50 mg/100g of the double carolina variety from Corrientes and 87 mg/100g of the fine long from the same province, the dialyzable calcium was between 15 and 16%, the total phosphorus ranged between 39.4 mg/100g in fine long and 56.2 mg/100g in double carolina, both from Entre Ríos, and the dialysable fraction varied between 15 and 20%, the total magnesium content fluctuated between 30.0 mg/100g and 51.0 mg/100g and the dialyzable between 22 and 31%. Regarding iron, it had total concentrations of 6 mg/kg in fine long rice, with 60% of dialyzable fraction and 12 mg/kg in double caroline, but with 35% of dialyzability. Total copper yielded values between 3.45 mg/kg and 5.70 mg/kg with 6 to 30% dialysed fraction. The total zinc content varied between 10.21 mg/kg and 11.48 mg/kg, with a low bioaccessible fraction of 3%. It is concluded that the total and bioaccessible contents of these nutrients is initial information to promove a fortification program in rice, which is the most important crop in the region.