The Effect of processing on the content and composition of free sterols and sterol esters in soybean oil

Abstract

The content and composition of free sterols and sterol esters in crude soybean oil and in oils from different stages of two continuous refining systems were determined. The sterols were isolated by preparative thin layer chromatography and analyzed by gas chromatography with cholesterol as an internal standard. The free sterols in one of the degummed oils amounted to 3.1 mg/g and were diminished to 1.8 mg/g oil by the De Laval Short-Mix refining process. The content of free sterols of the other degummed oil was reduced from 3.4 to 1.6 mg/g oil by the Zenith ]grocess. The greatest reduction of sterol content was caused by the treatment with bleaching earth. Th_e stero_l esters accounted for 0.6 mg/g of the degummed oil, and only very small changes were observed during the processes. However, changes in_ the composition of fatty acids of the sterol esters were found. These changes might indicate a selective deacylation of sterol esters or an interesterification during the refming processes. The composition of sterols in free ancl esterified form were different. Campesterol, stigmasterol and sitosterol were obtained in both free and esterified form, but A7 stigmasterol was only found in esterified form. Only small changes in the percentage distribution of the sterols occurred during the processes.

Free and Esterified Sterol Composition of Edible Oils and Fats

“…The average values of 76% of total free sterols and 24% esterified in refined soybean oils agree between the present study and that of Johansson (1979b). The average results for olive oil in our analysis agreed remarkably well with the average proportion of free and esterified sterols in eight Italian olive oils as determined by Grob et al (1990) using LC-GC (Table 3).…”

“…For example, refining has been reported to decrease the total sterol content of crude oils and to increase the proportion of esterified sterols (Kochhar, 1983). Data on the free and esterified sterol content of refined and/or commercially distributed oils have been presented for soybean (Milkova et al, 1977a;Johansson, 1979b), corn (Worthington and Hitchcock, 1984;Milkova et al, 1977b), olive (Dimitrios and Ioanna, 1986;Grob et al, 1990), and sunflower (Milkova et al, 1977b) oils. Kochhar (1983) compiled data for several crude and refined oils, but many reports are dated and sterol values were from colorimetric, not chromatographic, analysis.…”

Fatty acids and sterols evolution during the ripening of olives from the Moroccan Picholine cultivar.

“…Thus, they have a great importance in adulteration detection (Feinberg etal., 1987;Gordan et al, 1989 andJohansson et a!., 1979). This chemical components are also used for varietal characterisations (Castang et al, 1976 andKiosseglou et al, 1989), and are reported to be indicators of the best period of harvest (Fiorino etal., 1991).…”

Refining of Roundup Ready® soya bean oil: Effect on the fatty acid, phytosterol and tocopherol profiles

“…However, they have been performed several years ago [4][5][6], before the first commercialisation of genetically modified organisms (GMO). As nowadays GMO have been a topic of discussion among the scientific community and consumers, and since GM crops are widely used to obtain edible oils, the oilseeds from RR soya bean were the subject of the present study.…”