Dados do Trabalho

Título

STUDY OF ELECTRICAL IMPEDANCE SPECTROSCOPY (EIS) TECHNICAL AS A PROPOSAL FOR USE AT THE ANALYSIS ROUTINES IN MILK AS COMPLEMENTARY MEASURES

Introdução

Frauds in milk are common in Brazil and an efficient identification are important for a food safety guarantee. However, some adulterations are elaborate aiming to mask the official analysis methods in pre-balanced concentrations. These 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 easy data acquisition, allowing practical analysis methodologies and fast. In this work, a study of Electrical Impedance Spectroscopy (EIS) was carried out with the aim of proposing complementary analysis methodologies.

Material e Métodos

Was studded the impedance module ([Z*]), real part ([Re(Z*)]) and imaginary part ([Im(Z*)], diffusion coefficient ([D]) and electrical admittance ([Y*]). In addition, analyzes of pH also were realized. Samples of genuine raw milk (originals) and purposely adulterer was analyzed. Additions of sodium chloride, ethanol, sodium bicarbonate and sucrose, was studded for being which are substances cited in the literature with potentials adulterants.

Resultados e Discussão

The results showed that the addition of these substances to milk causes changes in the electrochemical characteristics of the samples and consequently, in the profiles of the impedance spectra. Additions of ethanol and sucrose tended to increase impedance values ([Z], [Re(Z)] and [Im(Z)]) while additions of chloride and sodium bicarbonate reduced these values in relation to the original milk. This is due to the nature of the adulterants. Those that dissociate in an aqueous medium, releasing ions, tend to increase the concentration of charge carriers and consequently increase the conductance of the medium, unlike those with a nonpolar nature. This behavior was corroborated by the admittance spectra measured in the work. The work demonstrates that the proposed EIS technical can serve as complementary analyzes to the current methods used in raw milk analysis routines, contributing especially for the detection of substances mask official methods of analysis.

Conclusão

The work demonstrates that the proposed EIS technical can serve as complementary analyzes to the current methods used in raw milk analysis routines, contributing especially for the detection of substances mask official methods of analysis.