Detection of vegetable oils in industrial dairy products of Kermanshah using chromatography methods

Widespread use of milk and dairy product has caused to increase adulteration especially by manufacturers, aimed to gain more profits. One of the most common adulterations in this context is the addition of vegetable oils with low price for increasing profitability. In this study, 73 samples of dairy products including milk, yogurt, butter and ghee was bought randomly from 23 supermarket of Kermanshah city. To detect adulteration, the sterol and fatty acids profile of samples was determined after fat extraction, by liquid and gas chromatography techniques. After the chromatography, the existence of plant sterols like as β- sitosterol and stigma sterol was established in 33% of yoghurt, 26% of butter, 25% of ghee and 13% of milk samples. Yoghurt samples contained the highest β- sitosterol and stigmasterol and ghee samples showed the lowest amount of phytosterols. Also, fatty acid profiles of yoghurt and butter samples showed high amount of polyunsaturated fatty acid like as linoleic acid and low amount of myristic acid in these samples, respectively that confirm the presence of vegetable oil in traditional dairy product. It can therefore be concluded that sterol and fatty acids measurement are appropriate tools to verify the authenticity of the milk fat in dairy product. The results showed that almost 25% of 73 samples (milk, yogurt, butter, ghee) had vegetable oils.