Determination of fatty acid profile and some sterolic (cholesterol and beta-sitosterol) fractions in dairy products using an apolar column

In this study, two opposite components of milk lipids (saponifiable part: glyceridic fraction [cis fatty acid isomers] and unsaponifiable part [stereolic (cholesterol)] were analyzed by of an apolar capillary column (HP5 column) using gas chromatography flame ionization detector (FID). Cis fatty acid profile and sterolic components (cholesterol and ß-sitosterol amount [indicator component for determination of vegetable (palm) oil in dairy products]) of various dairy product samples collected from local markets in Afyonkarahisar [n=25] (5 butter, 5 kashar cheese, 5 tulum cheese, 5 string cheese and 5 process-toast cheese) were examined with a GC-FID capillary column method. In the analyses performed, in some of the samples (2 butter [4.71% - 6.44%], 3 kashar cheese [3.23% - 8.62%], 2 processed-toast cheeses [5.84% - 11.13%] and 2 tulum cheeses [3.53% - 7.79%]) were found to have ß-sitosterol levels above the limit values (maximum 2%). The ß-sitosterol levels in string cheeses were below the limit value. The major sterol component in all dairy product samples was cholesterol (88.87% -98.74%). In dairy product samples, 19 cis form fatty acids (including CLA and EPA) were determined with the apolar HP5 capillary column (from butyric acid to lignoceric acid), but it was not possible to determine trans fatty acids –its presence is definitely known- in dairy products – in this column. In addition, it was not possible to separate linoleic and linolenic fatty acids for the apolar HP5 column, and these two fatty acids were obtained as a single peak on the chromatogram. For dairy products samples, the distribution of cis major-minor fatty acids in the involved HP5 capillary column from most to least was palmitic, oleic, stearic, myristic, lauric, caprylic and butyric acid. It was also observed that some parameters (linoleic/myristic, palmitic/myristic, lauric/myristic, stearic/lauric, palmitic/lauric, myristic/oleic and iodine number) calculated based on fatty acids could be used in the detection of adulteration and fraud for dairy products. In addition, chromatographic data (fatty acid components/parameters and cholesterol levels) could be useful in the characterization and classification of dairy products in multiple data analysis (PCA) was seen.