April 22/Life Science Weekly -- "Yak milk contains a greater percentage of protein and has better quality than bovine milk. There has been an increasing focus on yak milk and milk products during the last few years," researchers in Shenyang, People's Republic of China, report.

"In the present study, a PCR-based assay was developed for the specific identification of bovine milk in yak milk by designing three primers targeting the mitochondrial ND1 gene. The use of three primers in a single PCR reaction set yielded two amplification fragments of 293 and 190 bp from bovine milk DNA, whereas only one amplification fragment of 293 bp was obtained in yak milk DNA. The technique was applied to raw and heat-treated binary mixtures of yak and bovine milks and enabled the specific detection of bovine milk with a detection limit of 0.1%," wrote W.L. Bai and colleagues.

The researchers concluded, "The assay developed is sensitive, fast, and straightforward and it might be useful in the quality control of yak milk and milk products."

Bai and colleagues published their study in the Journal of Dairy Science ("Rapid detection of bovine milk in yak milk using a polymerase chain reaction technique." Journal of Dairy Science, 2009;92(4):1354-1360).

For additional information, contact G.B. Luo, Shenyang Agriculture University, College Animal Science & Vet. Medical, Shenyang 110161, People's Republic of China.

From the April 27, 2009, Prepared Foods E-dition