COMPOSITION AND QUALITY CHARACTERISTICS OF SESAME SEED (SESAMUM-INDICUM) OIL ROASTED AT DIFFERENT TEMPERATURES IN AN ELECTRIC OVEN

The quality characteristics of sesame oils prepared at different roasting temperatures (120-250 degrees C) from sesame seeds using a home electric oven were compared with an unroasted oil sample: only minor increases (P < 0.05) in characteristics, such as acid value, peroxide value, anisidine value and thiobarbituric acid value, of sesame oils occurred in relation to increasing roasting temperature between 120 and 180 degrees C, but colour increase was more pronounced. In the oil prepared using a 250 degrees C roasting temperature, the glycolipid content per 1000 seeds increased markedly (262.9 mg) compared with unroasted oil (6.9 mg) and phospholipids were no longer detectable. The fatty acid content of the oil was reduced, reflecting an increase in glycolipid content and triglyceride oxidation/polymerisation when the roasting temperature was over 220 degrees C but fatty acid composition was unchanged. The amounts of gamma-tocopherol and sesamolin still remained over 900 g kg(-1) of the original level after roasting at 180 degrees C, but were almost depleted at 250 degrees C. Sesame oil prepared using a 180 degrees C roasting temperature had the best flavour score when compared with the other samples.