Determinação das concentrações cádmio e chumbo em produtos lácteos contaminados intencionalmente

Abstract

Milk and its derivatives are foods widely consumed by variety of age groups, especially by children and elderly, that is why it is worried about the contamination with the potentially toxic metal surplus, mainly lead (Pb) and cadmium (Cd) due to the adverse effects to health. Several factors can lead to the animals’ contamination, and consequently, to the milk. Beyond the fluid consumption, milk is also widely used as dairy raw material. The aim of this paper is to assess the free and complex concentrations of the metals Cd and Pb, artificially contaminated at concentrations of 0.1 mg kg-1 and 10 mg kg-1, added to the milk and pasteurized sour cream, raw materials used in the processing of Minas Frescal and butter products. The cheese was produced by enzymatic coagulation and the butter by stirring refrigerated sour cream. The analysis of the metals Pb and Cd in the products produced and co-products obtained such as the whey and buttermilk was carried out by opening the sample in a digester block, and then quantified in an inductively coupled plasma optical emission spectrometer (ICP-OES 5800). The interaction preference for the constituents of milk: fat or protein, observing the tendency of partition of metals was assessed by the constant of the formation of the complex (Kf). The detected concentration of Pb and Cd were higher in cheese and butter when compared to whey and buttermilk co-products, indicating greater interaction with the protein network of the cheese and with the continuous phase of the fat in the butter, to the detriment of the aqueous phase of the co-products. The constant studied formation showed the stability of the complexes that were formed with Cd and Pb. The constants varied from 5.67 to 11.85. It was showed the formation constant for butter, with lower initial fortification, which resulted in 11.85 for Pb and 11.80 for Cd. As for the cheese, the concentrations of Pb2+ and Cd2+, complexed in the cheese matrix, was almost 10 times higher than the concentration of these ions in their free form (not complexed with the binding groups of the cheese). Thus, through these analyses, it was possible to understand the interactions in the matrices of products such as butter and cheese, which had greater interactions with the potentially toxic metals. These results have presented effective contribution to demonstrate the partition of metal ions in products of interest, since these potentially toxic metals result in serious problems for human health. In the face of this result, it is also concluded about the necessity of implementation of monitoring practices and quality control to reduce the risk of contamination in the raw material, besides the good agricultural practices, environmental managing and industrial process control. The use of these techniques will collaborate on the constant offer to the final consumer of quality products.