Effect of roasting treatment on the chemical composition of sesame oil

Sesame oil is rich in highly concentrated bioactive components including tocopherols, phytosterols and lignans (e.g., sesamolin, sesamin, and sesamol). The chemical composition and quantification of oil extracted from roasted sesame seeds was investigated and compared with unroasted sesame oil in relation to health-promoting and potentially harmful substances (particularly polycyclic aromatic hydrocarbons, abbreviated as PAHs). With roasting, the peroxide value and color development of oils was elevated obviously while the total tocopherols and sesamolin decreased steadily. The acid values in the current experiment were expected to grow as the roasting time increased at the same temperature, and the acid value decreased in the first 30 min of roasting at 160 °C. Increased roasting temperature or time facilitates sesamol formation in sesame oil. The fatty acid profiles are almost independent of roasting conditions. There was a significant increase in PAHs with elevated temperatures and extended times. In general, favorable sensory qualities accompanied by a beneficial healthy composition of sesame oil may be attributed to the treatment by roasting at a temperature from 160 °C to 180 °C and a roasting time of less than 20 min.