Effect of γ-oryzanol on oxygen consumption and fatty acids changes of canola oil

Abstract

γ-oryzanol has been well studied for its hypolipidemic, antidiabetic, antiallergic, and anti-inflammatory abilities. However, its ability against lipid oxidation has not been thoroughly explored. The present study examined the effects of γ-oryzanol against canola oil oxidation under Chinese cooking temperatures compared with that of butylated hydroxytoluene (BHT). Changes of oxygen consumption and fatty acids of canola oil with addition of 2–8 mg/g γ-oryzanol were conducted under 60, 90, 120, and 180 °C, respectively. Results showed although γ-oryzanol was not as effective as BHT against lipid oxidation of heated canola oil, it showed an inhibitory effect on the headspace oxygen consumption dose-dependently. Besides, γ-oryzanol significantly prevented the decrease of total polyunsaturated fatty acids in canola oil heated at 60–120 °C, while such effect was not observed in canola oil heated at 180 °C. β-sitosteryl ferulate, one of the major components constituting γ-oryzanol, degraded faster than cycloartenyl ferulate, 24-methylene cycloartanyl ferulate, and campesteryl ferulate at all treatment conditions. In conclusion, γ-oryzanol might have a potential application against lipid oxidation in foods as a functional antioxidant.