Application of an indirect ELISA and a PCR technique for detection of cows’ milk in sheep's and goats’ milk cheeses

We have applied a polymerase chain reaction (PCR) procedure and an indirect enzyme-linked immunosorbent assay (ELISA) for detecting the presence of cows’ milk in sheeps’ and goats’ milk cheeses. The PCR used a cattle-specific primer set targeting a 223 bp fragment from the mitochondrial 12S rRNA gene. This technique was applied to experimental cheese mixtures, industrial cheeses produced with known amounts of cow's milk, and several commercial cheeses, enabling the detection of low percentages of cows’ milk (1%). An indirect ELISA using a monoclonal antibody (AH4) against bovine β-casein was also assayed in this study for the specific detection of bovine milk in cheese. Results suggested that both ELISA and PCR may provide specific and reliable tools for detection of low percentages of undeclared cows’ milk in sheeps’ and/or goats’ milk cheeses and other dairy products.