PCR-based detection of cow and goat milk in sheep milk and dairy products marketed in Mashhad city of Iran

The extensive consumption of milk and dairy products makes these foodstuffs targets for potential adulteration with financial gains for unscrupulous producers. The aim of this study was using PCR assay to detect cow milk in labeled sheep milk، sheep yoghurt، and Lighvan cheese (a traditional ripened cheese produced from sheep''s milk). The assay utilized primers targeting the mitochondrial 12s and 16s rRNA gene. In this study، 35 samples of sheep milk، 35 samples of sheep yoghurt، and 35 samples of Lighvan cheese were purchased from different supermarkets in Mashhad city with different batch numbers. The results showed only 21 out of 105 (20%) samples contained pure sheep milk. Undeclared presence of cow and goat milk was detected in 33 (31. 5%) and 68 (65%) of the 105 samples، respectively. It seems the PCR based analytical method is an applicable technique to monitor adulteration in dairy products.