RESUMO
Species identification in dairy products has a notable importance in food traceability and adulteration control and consequently has a significant effect on the final economic value of foods. In the present study, we developed a method based on real-time quantitative PCR (qPCR) for detection and quantification of cow DNA in DNA samples from milk and dairy products from buffaloes, goats, and sheep. The qPCR reactions showed high specificity, and the amplifications only occurred to species-specific primers. The calibration curves allowed for the quantification of the amount of DNA of each species-specific primer, and the established detection limit was 0.016 ng for the four species. The detection limit of cow DNA in buffalo, goat and sheep DNA samples was 0.1% (0.01 ng). Although the present study aimed to detect and quantify cow DNA in buffalo, goat, and sheep dairy products, we believe that the qPCR assays can also be directed to differentiate and quantify goat × sheep, and/or buffalo × goat/sheep.
RESUMO
The rising consumption of A2 milk and its derivatives in recent years has garnered attention from both consumers and producers, mainly due its possible health benefits, such as enhanced digestion and easier absorption. Thus, a novel real-time PCR using a combination of locked nucleic acid modified (LNA) conjugated probes was developed to genotype A1 and A2 alleles of ß-casein gene (CSN2) and to detect and quantify the A1 presence in A2 samples. The limit of detection for each probe (A1 and A2) was evaluated using decreasing serial dilutions. Besides, the sensitivity of A1 allele detection in the A2 samples was also tested. The limits of detection of A1 and A2 alleles were 6 copies, while for A1 allele detection in A2 samples was 7.5 copies (1%). The LNA-probe based method was found to be rapid, robust, highly sensitive, cost effective, and can be employed as screening test to certificate the A2 dairy products.
