The definition of authenticity of cheese trademarks by RP HPLC

Abstract

In this paper, the method of reversed-phase HPLC is used to determine the authenticity of real cheeses. To establish the falsification of cheeses two methods were proposed. The first method implies to compare chromatograms of the cheese under  investigation  with authentic sample of  the  fat  known  as  the

«fingerprint» method visually or by direct overlay of the chromatograms. A more rigorous quantitative me- thod involves the selection of the three triacylglycerol (TAG) characteristic peaks the areas of which are used to build a vector model. In this case, the choice of basis depends on the intended type of falsification, and the difference between the samples is characterized by the angle between the vector for the sample and the refer- ence vector. In the analysis of 23 brands of cheese, it was found that most of them are made using natural cow's milk. However, for 7 of the studied cheese grades, large values of characteristic angles were obtained. Comparison of chromatograms obtained for these grades with known chromatographic profiles of seed oils it possible to determine the nature of falsification: by replacing cow fat with palm or linoleic-oleic type oil. In this case area of TAG peaks with equivalent carbon numbers (ECN) 35.6, 37.5 and 47.2 may be explored to build the vector model. The first of them is representative for butyric acid containing TAG: the second – for trilinoleate concentration if some seed oils are used, and the third area is sensitive to palm butter edition. Three another TAG sensitive to exchange of cow milk by goat one were proposed to use in corresponding cases.