Species substitution in the meat value chain by high-resolution melt analysis of mitochondrial PCR products
Food fraud in several value chains including meat, fish, and vegetables has gained global interest in recent years. In the meat value chain, substitution of high commercial-value meats with similar cheaper or undesirable species is a common form of food fraud that raises ethical, religious, and dietary concerns. The presence of undeclared species could also pose public health risks caused by allergic reactions and the transmission of food-borne or zoonotic pathogens. Measures to monitor meat substitution are being put in place in many developed countries. However, information about similar efforts in sub-Saharan Africa is sparse. In this study, we used PCR coupled with high-resolution melting (PCR-HRM) analysis targeting the three mitochondrial genes, cytochrome oxidase 1 (CO1), cytochrome b (cyt b), and 16S rRNA, to detect species substitution in meat sold to consumers in Nairobi, Kenyas capital city. Out of 107 meat samples from seven common livestock animals (cattle, goat, sheep, pig, chicken, rabbit, and camel), 11 (10.3%) had been substituted. Of 61 samples sold as beef, two were goat and one was camel. Of 30 samples sold as goat meat, four were mutton (sheep) and three were beef. One of nine samples purchased as pork was beef. Our results indicate that PCR-HRM analysis is a cost and time effective technique that can be employed to detect species substitution. The combined use of the three markers produced PCR-HRM profiles that successfully allowed the distinction of species. We demonstrate its utility not only in analysis of raw meat samples, but also of cooked, dried, and rotten samples, meat mixtures, and with the use of different DNA extraction protocols. We propose that this approach has broad applications in authentication of meat products and protection of consumers from food fraud in the meat industry in low- and middle-income countries such as Kenya, as well as in the developed world.