Abstract: The adulteration of meat products happened frequently in recent years, and authentication of meat products is necessary to protect consumers from an inferior product with a false description. Although at present, there are numerous qualitative methods for meat species identification, fewer quantitative detection methods have been reported. Herein, a droplet digital PCR method for the quantitative determination of pork incorporated in mutton products was developed. The single copy house-keeping gene encoding replication protein A1 (PRA1) was chosen as the target to design species-specific primers and probes for mutton and pig, respetively. Each assay was proved specific to the target species, respectively. The ratio constants between copy numbers and unit mass of pork and mutton were obtained by theoretical analysis and then verified by experiments. Consequently, the relative mass fractions of pork and mutton in the sample were measured based on the DNA copy numbers. The limit of quantitation (LOQ) of the method was confirmed to be 1%. The results showed that the absolute error was less than ±1.3%, and the relative error was less than ±10% in the range of pork proportion from 5% to 80%. The method developed in this paper was successfully applied to quantitate pork content incorporated into commercial mutton products and it may be useful for food administration laboratories to carry out meat species quantification in raw and processed foods.

Key words: mutton, pork, quantitative determination, droplet digital PCR (ddPCR)