Comparison of Antimicrobial and Antioxidant Effects of Sesame Oil Produced by Traditional, Industrial, and Cold Press Methods

This study aimed to compare the antimicrobial and antioxidant effects of sesame oils produced by traditional (Ardeh method), industrial, and cold press methods.

30 samples of sesame oil (12, 12, and 6 samples by traditional, cold press, industrial methods, respectively) were collected from Isfahan, and Ardakan cities in Iran. The antimicrobial effect of the samples was measured by agar diffusion method, and then by minimum inhibitory concentration. Antioxidant capacity of oils was measured using 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) method. Moreover, data analysis was performed using ANOVA, one-sample t, Kruskal-Wallis, and Mann-Whitney tests.

Zone of inhibition was caused by 100% of the samples, and the highest antimicrobial effect was observed in the traditional method on Bacillus cereus. The zone of inhibition of all samples showed statistically significant difference compared with positive control (kanamycin antibiotic) (P < 0.050). The results of minimum inhibitory concentration (MIC) against Escherichia coli and Bacillus cereus showed that the MIC level against Bacillus cereus was 500 μl/ml in cold press and traditional sesame oil, and more than 500 μl/ml in industrial sesame oil. The lowest MIC was obtained from the cold press sesame oil in 125 μl/ml on Escherichia coli. Antioxidant capacity was observed in all oil samples. However, three of the oil production methods did not show a significant difference.

All sesame oil samples with different production methods have antimicrobial effect on important microorganisms in food hygiene, and have antioxidant effects as well.