Assessment of milk fat based on signal-to-ground voltage

This study proposes an electromagnetic method for assessing fat content by measuring the signal-to-ground voltage in milk. The milk-filled spiral glass tube, acting as the secondary coil of a transformer, under different magnetic fluxes at the same frequency. The measurement system included two connected sample coils in a close-loop configuration and an open-loop configuration. The voltage at the four terminals of two coils was detected. The results indicated that the voltage at these four terminals had differential response characteristics, but their sum was consistent regardless of the configuration. A linear correlation (R2 = 0.845 and R2 = 0.941) was observed between milk fat and signal-to-ground voltage. The root mean square error (RMSE) of calibration (RMSEC) was 0.368 and 0.230 g/100 g fat content, respectively, whereas the RMSE of cross validation (RMSECV) was 0.232 and 0.599 g/100 g (fat content) for the 700 Hz, respectively.