Those tiny balls of boutique mozzarella cheese with the sticker-shock price tag beckoning from the dairy case -- are they the real deal, mozzarella di Bufala Campana DOP, crafted from the milk of water buffaloes? Or are they really cheap fakes made from cow's milk? A new method described in ACS' Journal of Agricultural and Food Chemistry promises to provide the answer for mozzarella and other dairy products.

Barbara van Asch and colleagues explain that premium dairy products, such as imported specialty cheeses labeled with a designation of origin, are most vulnerable to adulteration. Unscrupulous manufacturers may substitute a less costly ingredient for an expensive one or skimp on high-quality ingredients. Previous studies show that the problem is widespread, with bogus dairy products surfacing in Italy, Spain, China, India and other countries. Current methods of detecting fakes can't simultaneously detect cow, goat, sheep and buffalo milks -- the ones most likely to be involved in adulteration -- and have other drawbacks. The scientists thus set out to develop a better test.

They describe development and successful laboratory testing of such a test on 96 dairy products commercially available in Europe, including cheeses, milks, yogurts and butters. About 12 percent of the products did not contain ingredients listed on the labels. For example, one product label indicated that it was made from 100 percent sheep milk. The test, however, showed that it also contained ingredients from cows and goats.