This work aimed to establish a strategy that can identify goat milk adulteration by any form of liquid substances. To realize this, supercoiled pUC-19 plasmid was added to pure goat milk for PCR amplification. The superhelical structure of pUC-19 impeded the progression of DNA polymerase, and the incorporation of dUTP which is not the natural substrate of the polymerase further reduced PCR efficiency. Therefore, a slight change of conditions such as lowering plasmid concentration as the result of adulteration, would lead to failed PCR amplifications (no products). Pure goat milk that was adulterated by four liquids were successfully detected by the PCR-based strategy. Moreover, the authentication can be visualized using ssDNA-functionalized AuNPs that could be re-dispersed by the PCR products from blocked primer. Goat milk adulteration by different adulterants can be detected by the established strategy, providing a point-of-care method for authorities to prevent food fraud concerning milk products.