engleski

The effect of processing conditions on the nontriacylglycerol constituents of sunflower oil

In this study the samples of nonrefined sunflower oils, obtained in industrial and laboratory scale by cold and hot pressing and hexane extraction as well as of sunflower oils from single refining steps were investigated. The content and composition of carotenoids and sterols, the content of chlorophylls as well as oxidative stability were investigated. To obtain the data about the acidity and oxidative status of the oil samples, basic quality analyses: free fatty acid content (FFA), peroxide value (PV) and spectrophotometric analyses in UV area (K232, K270 and ?K) were used. The results showed that predominating carotenoid in sunflower oil is lutein, and that the total amount of carotenoids during refining process was reduced to about 15%. The major sterol in sunflower oil (about 70 %), as well as in other vegetable oils, was ß-sitosterol. The other important sterols in sunflower oil were: D7-stigmasterol, stigmasterol, campesterol, D5-avenasterol and D7-avenasterol. The composition of sterols in nonrefined and refined oils was more or less the same, while the content of sterols during refining process decreased for 22%. Among all analysed sunflower oils, the best oxidative stability (e.g. the longest induction period, according to Rancimat method) had laboratory extracted oil, while cold and hot pressed oils were less stable than fully refined one.

nonrefined sunflower oil; refining; nontriacylglicerols

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