Design of a low-cost non-destructive system for punctual measurements of salt levels in food products using impedance spectroscopy

The measurement of salt content in processed products still remains a problem to solve in the food industry due to the destructive nature of the conventional measurement methods. In this paper a method to assess salt content in food products such as cured ham or pork loin using impedance spectroscopy is presented. A low-cost system to carry out a punctual measurement of the impedance inside the food sample based on a non-destructive sensor was developed. The system includes an electronic equipment that allows the implementation of impedance spectroscopy and an electrode consisting of a coaxial needle. In order to validate the equipment, solutions with different salt concentrations were measured. The impedance modulus and phase values obtained for each frequency were processed using PLS; the results show a very good correlation between predicted and observed data. The same process was carried out on minced meat samples and again a good correlation was obtained. The PLS tool generated a model that permits prediction of salt levels in new meat samples.