Electrical Bioimpedance Scanning in Bacterial Diagnosis and Mastitis Detection

The Electrical Bioimpedance Scanning is a technique based on the electrical properties of biological materials and it can be applied in food analyses in order to perform bacterial diagnosis. This paper presents a bioimpedance measurement system to detect the presence of Staphylococcus aureus in milk samples. In an ABS structure, the frequency of the electric current was varied between 10Hz and 1MHz. The impedance measurement has been performed by four electrodes. Crude milk (autoclaved) and UHTintegral (I), semi-skimmed (SN) and skimmed (DN) - at different dilutions (12.5-100%) were with and without Staphylococcus aureus. The presence of S. aureus in the samples of UHT-integral milk has been suggested from the reduction in impedance values (pure=145.0Ω; 101 CFU/mL = 120.9Ω; 107 CFU/mL = 118.2Ω). In the frequency 1 MHz it was possible to verify a greater influence of the concentration of bacterial cells on the electric current. The higher the cell density, the lower the impedance. There was a difference in impedance values between raw milk (157.9Ω), crude autoclaved (120.0Ω) and UHT-integral (145.0Ω). The proposed measurement system response resembles a resistive and capacitive electric model, as expected, proving to be a promising tool in bacterial detection and food analysis.