Digital duplex versus real-time PCR for the determination of meat proportions from sausages containing pork and beef

According to Swiss law, sausages claiming to be made of veal have to contain at least 50% veal. To control the meat proportion of such products, control laboratories use real-time PCR. The measurement uncertainty of this method is at 30%. As a consequence, only extreme fraud can be reliably detected. To analyse sausages for their beef content with lower measurement uncertainty, a duplex droplet digital PCR was developed. Interlaboratory conversion factors were determined to enable weight-to-weight determination using values gained by real-time PCR and droplet digital PCR. Precision and accuracy were investigated examining reference sausages and sausages from the market. Comparing with real-time PCR, results from digital PCR showed a superior interlaboratory measurement uncertainty of 10% and will enable food control laboratories to determine also minor fraud.