Refining of high oleic safflower oil: Effect on the sterols and tocopherols content

Abstract

The purpose of this work was to study the influence of the industrial process steps on free fatty acids, peroxide value (PV), p-anisidine value (PAV), trans fatty acids, tocopherols and sterols (free, esterified and total) in high oleic safflower oil. Degumming, bleaching and deodorization steps removed 91.4% of free fatty acids, 96.31% of oxidation primary products (PV), and 54.57% of oxidation secondary products (PAV), from crude high oleic safflower oil. Degumming neither affected the content of sterified sterols nor its proportion with respect to the crude oil. A significant increment (p<0.05) in the content of free sterols was observed during degumming and bleaching due to the acid-catalyzed hydrolysis of steryl esters. A significant reduction (p<0.05) in the content of total sterols during bleaching was observed, which is attributed to a reduction in the sterified sterol fraction. During deodorization, free sterols were distilled from oil, with a gradual reduction in the total sterol content as a function of the deodorization temperature. α- and γ-tocopherols represented 93.3% of the total tocopherols in high oleic safflower crude oil. The refining process removed 28.5% of the tocopherols. Deodorization was the main step which increased the level of trans fatty acids as an effect of temperature and heating time.