Monitoring fatty acid and sterol profile of nizip yaglik olive oil adulterated by cotton and sunflower oil

Abstract

In this study virgin olive oil obtained from cv. Nizip Yaglik (NY) was adulterated with different proportions (5 and 10%, v/v) of cotton (CO) and sunflower (SO) oils. Fatty acid and sterol profiles of olive oil were analyzed by using gas chromatography (GC). Also, difference of Equivalent Carbon Number 42 values (ΔECN42) of oil samples were determined by using GC and HPLC. Due to results of fatty acids analysis, the percentage of oleic acid was decreased when CO and SO were added. Palmitic acid was increased over the addition of CO, and decreased with the addition of SO. The ΔECN42 values were increased in adulterated oils. These values showed further increase in adulterated oils with SO. Beta-sitosterols decreased to 91.06 and 88.54% when mixed with 5 and 10% SO, respectively. On the other hand, decline was negligible when mixed with CO. According to principal component analyses (PCA), pure NY and adulterated oils were clearly separated in different parts of screen plot according to fatty acids, triacylglycerol (TAGs) and sterol profile. The outcomes of this first investigation provide valuable information for about the differences of fatty acids, ΔECN42 values and sterol compounds between Turkish olive oil from Nizip Yaglik cv. and its adulteration with cotton and sunflower oil. It was observed that fatty acids are not very effective in detecting adulteration of NY oil, but ΔECN values, sterols and Rmar values can be used to detect adulteration of NY olive oil.