Detection of Cow’s Milk, Fat or Whey in Ewe and Buffalo Ricotta by HPLC Determination of b-Carotene

The addition of cow’s milk, fat or whey to ewe or buffalo ricotta is a common form of fraud in the dairy industry because of its economic convenience. b-carotene may serve as an excellent indicator of the presence of cow’s milk in ewe or buffalo ricotta because it has been noted that b-carotene is naturally present in cow’s milk alone. Therefore, a simple and sensitive isocratic reversed-phase HPLC method has been developed for the determination of b-carotene in ricotta. This method involves fat saponification followed by extraction with a mixture of organic solvents. A linear correlation between the concentration of b-carotene and the area response has been obtained over the concentration range of 0.045 to 0.900 μg/mL, which corresponds to about 1 to 22 μg/100 g in ricotta. The detection limit was 0.7 ng of injected sample, and the recovery evaluated in spiked ricotta samples was always higher than 90%.