Influence of roasting conditions on the chemical properties and antioxidant activity of perilla oils

Chemical properties of perilla oils under a variety of roasting conditions were evaluated. Roasting was performed in a hot-air roaster, with inlet air temperatures of 150 - 240 Celsius. The major fatty acid contents in perilla oil were a-linolenic, oleic, and linoleic acid. Trans-fatty acid content was 0.10 - 0.31 % from perilla oil under different roasting conditions. Maillard reaction products increased significantly from perilla oils exposed to higher temperatures for longer times. In particular, 2-methylpyrazine and 2,5-dimethylpyrazine were highest in the P210/30 (roasting temp. 210 Celsius, roasting time 30 min) and P210/30 treatments, respectively. Total benzo[a]pyrene of 0.21 microgram/ kg was detected in perilla oil under different roasting conditions. Evaluation of radical scavenging activity revealed that antioxidant function of perilla oil was promoted by increasing the roasting temperature of perilla seeds. As roasting temperature and time increased, the oxidative stability of perilla oils increased. The average iodine value of perilla oil under different roasting conditions was 154.23. Oxidation stability increased in the P240/20 group.