Study to detect mixed adulterations in milk, using electrochemical techniques as a proposal for complementary measures for analysis routines

Abstract

This work presents a study of electrochemical techniques as a proposal for complementary measures to be used in raw milk analysis routines to detect adulterations, especially the so- called mixed frauds. Mixed additions in pre-balanced concentrations in order to mask detections by official methods are common in Brazil. These mixed additions are difficult to discover in the analysis routines of the dairy industries and can bring losses to the producing companies, in addition to risks to the health of the consumer. Therefore, the greater the number of possible complementary techniques to be used in the detection of fraud in milk, the greater the robustness of the analyzes and the greater the guarantee of the quality of the milk produced. Electroanalytical methods have advantages as they are physicochemical properties with easy data acquisition, allowing practical analysis methodologies and fast. In this work, a study of electrical impedance spectroscopy (EIS) was carried out, in particular, addressing the magnitudes, impedance module (Z), real part (Re(Z*)) and imaginary part (Im(Z*), difusion coeficiente (D) and electrical admittance (Y ). In addition, analyzes of electrical conductivity and pH were also analyzed. Genuine raw milk samples were studied and purposely added of sodium chloride (0; 0,05; 0,1; 0,15; 0,2% p/v), ethanol (0; 2.0; 3.0; 4.0; 5.0% v/v), and sucrose (0; 1.8; 3.0; 3.6; 4.8% p/v), in these concentrations, which are substances cited in the literature as used for the preparation of mixed frauds. The results showed that the addition of these substances to milk causes changes in the electrochemical characteristics of the samples and in the profiles of the impedance spectra that were analyzed. Was observad a specific behavior for each adulterant. The behaviors of each technique analyzed were discussed and will be presented. The work demonstrates that the proposed electrochemical techniques can serve as complementary analyzes to the current methods used in raw milk analysis routines, especially for the detection of substances that make up the so-called mixed frauds increasing the robustness of the analyzes.