A novel microwave coplanar sensor system for detecting contamination in food products such as milk and oil etc., is designed and developed. The developed system is fully non-invasive and non-destructive, which requires the test liquid to be filled into a disposable container. The sensor placed above the liquid filled container is connected to the network analyzer through appropriate RF connectors to measure the scattering coefficients of the test fluid over a designated frequency band. The dielectric properties of the adulterated specimen are determined in terms of the measured scattering data, and these values are compared with the dielectric data of standard samples in order to find the level of contamination.