Evaluation of in vitro bioaccessibility of Cr, Ni and Pb in rice varieties. Effect of cooking, dietary components and risk assessment

Abstract

Cr, Ni and Pb content and bioaccessibility of six rice varieties (Oryza sativa L.) were studied. Raw rice samples showed values ranged between 0.079 - 0.138 μg/g; 0.063–0.405 μg/g; 0.094–0.223 μg/g for Cr, Ni and Pb respectively. Cr and Ni contents in rice cooked in glass cookware did not vary significantly from that initially present in the raw samples. Conversely, cooking rice in stainless steel containers implied an increase in Cr and Ni concentration about 1.5–3 fold with respect to the raw samples. Nevertheless, Cr and Ni bioaccessible concentrations in the later were very similar to those found for the same rice varieties cooked in glass containers. Pb content in cooked rice showed a high bioaccessibility. A negative correlation was observed between dietary fibre content and bioaccessible Cr and Pb concentrations. From the health risk point of view, cooking rice in stainless steel containers could represent a certain hazard in the case of Cr but not in the case of Ni. Regarding Pb, rice consumption represents a certain hazard as a good natural source of this heavy metal.