Droplet digital PCR (ddPCR) method for the detection and quantification of goat and sheep derivatives in commercial meat products

A highly precise, quantitative method based on the droplet digital polymerase chain reaction (ddPCR) technique was developed to identify and quantify the goat and sheep content in meat products. A formula for calculating raw meat weight based on DNA copy number was established. Exclusive specificity was verified using samples from 24 different animal species, and inclusive specificity between goat and sheep was tested using five different breeds for each species. The limit of detection and the limit of quantitation for both goat and sheep were 1 and 5 copies/mu L, respectively, using a cloned plasmid containing goat- and sheep-specific target DNA fragments as calibrators. The accuracy and applicability of the method were verified using mixed powder samples with known proportions of goat and sheep meat, simulate meatball samples, and commercially available products, respectively. The results confirmed that the developed ddPCR methods are highly precise for identifying and quantifying the goat and sheep meat, indicating their potential applicability in future routine analyses.