Detection of falsified fermented dairy products

Abstract

Study objects served 12 samples of kefir and 6 sour milk, placed in the markets of the Chisinau city. The fat mass fraction was determined by the ISO 2450 method

[2]. The composition of the fatty acids in fermented dairy products was determined using the Reichert-Meissl value, which demonstrates the content of short-chain fatty acids, and the Polenske value, which characterizes the content of volatile fatty acids. These two indices are used to find out the content of lactic fat in products. An alternative method to detect the falsification of the lactic fat content in lactic acid products was applied. It was established that in 11 samples of kefir the Reichert -Meissl value varied between 18.4...22.3, respectively Polenske 1.9...2.1, which corresponds to a content of 100% lactic fat. Only one sample had lower values of the Reichert-Meissl index – 16.4 and Polenske – 1.6.; these values confirm an addition of 10% vegetable fat. Out of 6 sour milk samples,

5 have full lactic fat, because the Reichert-Meissl values are between 18.6...23.0, respectively Polenske 1.8...2.2. One sample, however, had lower values, Reichert-Meissl – 16.8 and Polenske 1.7. The principle of detecting the addition of vegetable oils is explained by the fact that lactic fat contains a much higher percentage of short-chain fatty acids, which are also volatile, compared to sunflower, soybean, and rapeseed vegetable oils. Detecting dairy product falsification regarding the addition of vegetable oils can be achieved by the method that establishes reduced values of the Reichert-Meissl and Polenske indices. The application of this method has shown that counterfeit samples of kefir and sour milk are present in the markets.