Cooking process evaluation on micronutrient and total mercury content in fish species in Manaus, Brazil

This study evaluated different cooking processes (roasted, cooked and fried) on micronutrient (Ca, Fe, K, Na, Se and Zn) and total Hg content in fish species most consumed by Manaus residents and surrounding communities. Twelve different fresh water fish species were purchased at the central receiving market (CEASA) in Manaus and prepared at the INPA Food and Nutrition Laboratory. In total 64 fish samples were analysed. Analytical determinations were performed by Neutron Activation Analysis Technique (NAA) for micronutrients and Atomic Absorption Spectrometry (CV AAS) for total Hg. All analytical methods were developed and validated for precision and accuracy by means of reference material analyses with certified values for the elements determined. The concentration variation of the analyzed elements was: Hg (2392 to 19 μ kg-1); K (19187 to 1185 mg kg-1); Ca (14590 to 994 mg kg-1); Na (18386 to 12850 mg kg-1); Fe (5580 to 4 mg kg-1); Se (5249 to 129 μg kg-1) and Zn (684 to 15 mg kg-1). The effect of the different cooking processes on the variation of micronutrient composition was quite significant. On the other hand Hg composition variation seems to be more related to fish species rather than the cooking process itself. As was expected, predatory species presented higher Hg and Se levels. (author)