Abstract

The first part of this study evaluated oxidative stability in high-oleic rapeseed oil, palm olein, refined olive oil, low erucic acid rapeseed oil and sunflower oil. The results showed oxidative stability in the order: palm olein > high-oleic rapeseed oil > refined olive oil > low erucic acid rapeseed oil > sunflower oil, as determined by the Rancimat method. Addition of alpha-tocopherol at high levels of up to 0.2% increased the oxidative stability of refined olive oil, whereas the opposite effect was generally observed in the other oil samples. In the second part of the study, high-oleic rapeseed oil, palm olein, refined olive oil and refined olive oil containing 0.2% alpha-tocopherol were heated for 3, 6, 9 and 12 h at 180 C. The peroxide and p-anisidine values generally increased over time in the samples, including olive oil containing 0.2% alpha-tocopherol. High-oleic rapeseed oil contained the highest amount of total sterols and total phytosterol oxidation products (POPs), but during heating the total POPs content increased moderately (similar to 10%), in contrast to the threefold increase after 12 h of heating in palm olein and refined olive oil. Very high levels of 6-hydroxy derivatives of brassicastanol, campestanol and sitostanol and of 7-ketobrassicasterol were observed in high-oleic rapeseed oil samples. Addition of 0.2% alpha-tocopherol during heating significantly decreased POPs formation in refined olive oil (P < 0.05).

Keywords

frying oil; lipid oxidation; oxidative stability; phytosterols; phytosterol oxidation products; POPs; PV; AV; alpha-tocopherol; vegetable oil

Published in

Journal of the American Oil Chemists' Society
2008, volume: 85, number: 9, pages: 857-867
Publisher: Springer Verlag (Germany)

Authors' information