The Effect of Processing Conditions on the Nontriacylglycerol Constituents of Sunflower Oil
2004
Rade, D. | Mokrovčak, Ž | Štrucelj, D. | Škevin, D. | Neđeral, S.
In this study samples of non-refined sunflower oils, obtained in industrial and laboratory scale by cold and hot pressing and hexane extraction, as well as sunflower oils from single refining steps were investigated. The content and composition of carotenoids, sterols, and 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 of free fatty acid content (FFA), peroxide value (PV) and spectrophotometric analyses in UV area (K232, K270 and ?K) were used. The results showed that the predominating carotenoid in sunflower oil is lutein, and that the total amount of carotenoids during refining process was reduced to about 15% of the initial amount. The major sterol in sunflower oil (about 70%), as well as in other vegetable oils, was b-sitosterol. The other important sterols in sunflower oil were ?<sup>7</sup>-stigmasterol, stigmasterol, campesterol, ?<sup>5</sup>-avenasterol and ?<sup>7</sup>-avenasterol. The composition of sterols in non-refined and refined oils was more or less the same, while the content of sterols during refining process decreased by 22%. Among all analysed sunflower oils, the laboratory extracted oil had the best oxidative stability (e.g. the longest induction period, according to Rancimat method), while cold and hot pressed oils were less stable than the fully refined one.
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