Determinação de minerais em vísceras de frango cozidas em diferentes panelas e em amostras de sais e temperos por espectrometria atômica

Abstract

Chicken meat and seasonings are important products for nutrition and economy. In this study, the levels of minerals were evaluated in edible chicken tissues, seasonings and kitchen salts. Samples of edible chicken tissues were analyzed raw and cooked with seasonings in different cooking pots commonly used in Brazil: iron, aluminum and hammered aluminum pot. Microwave-assisted acid digestion was used to sample decomposition. The levels of the metallic elements Al, Ca, Cu, Fe, Mn and Ni were determined by Microwave Induced Plasma Optical Emission Spectrometry. The limits of quantification were below 0.52 mg kg-1, showing to be adequate to the analytes levels; deviations were below 13 % showing good precision. The cooking in different pots promoted a decrease of Ca, Ni and moisture contents and an increase in the protein and ash concentration. Liver cooked in both iron and hammered aluminum pots presented similar Fe contents. The concentrations of Ca, Cr, Fe, K, Mg, Na and Zn in 15 samples of seasonings from different brands commercially available in Brazil were determined by Atomic Absorption Spectrometry, after microwave-assisted digestion. The method showed good accuracy with recovery ranges between 91 and 109% for addition to recovery tests and between 93 and 107% for the analysis of a certified reference material. The limits of quantification ranged from 0.061 (Cr) to 69 (K) mg kg-1 . The standard deviations were below 13%, indicating good precision. The ready-to-eat spices showed the highest Na levels among the samples studied. The levels of Ca, Fe, K, Mg and Na were determined in 23 samples of common and gourmet salts by spectrometric techniques after dissolution using diluted nitric acid. No matrix effects were observed when aqueous calibration was compared to the standard addition method. The accuracy of the method was assessed by addition and recovery tests, with ranges from 94 to 109%. The limits of quantification ranged from 3.3 (Fe) to 76 (K) mg kg-1. The standard deviations were below 3% showing a good precision also. Principal component analysis showed that some Himalayan salts had similar Ca and Mg contents among different samples. Blue Persian salts and low-sodium salts had the highest K concentration levels. In addition, the Hawaiian black salts presented similar Na and Fe concentrations. In relation to the concentration of the analytes in general, the results suggest that these types of salts cannot be considered to be a source of Ca, Fe, and Mg, contrary to the widespread statements found in popular media. With respect to the Himalayan samples' authenticity, both UV-VIS spectrophotometry and FT-Raman spectroscopy were used to investigate the presence of ordinary colorants E122 and E124 in commercial samples, and no evidence of adulteration or fraud was observed.