Optimization of mountain watermelon fruit extract extraction process by response surface method and evaluation of its antioxidant effect on the stability of soybean oil during shelf life

Oxidation of fats and oils leads to the production of harmful substances that endanger the health of the consumer. In the present study, the antioxidant activity of mountain watermelon fruit extract was investigated. Extraction was performed by ultrasonic extraction with the help of solvent (ethanol). In this study, the extraction process was performed by ultrasound technology with 3 levels of 20 tests, by the response level method. The results of statistical analysis were reported in optimal conditions, time of 18.62 minutes, sound intensity of 84.56 khz and temperature of 49.52 ° C and extraction efficiency of 34.456 8456%. Under these optimal conditions, the amount of phenolic compounds and free radical scavenging power of the extracts at concentrations (100, 200, 200, 400, 800 ppm) were measured by Folin and DPPH tests, and then the extract was concentrated at concentrations (100, 200, 400, 800, 800 ppm). Samples of soybean oil without added antioxidants and parameters of peroxide index, thiobarbiotic acid index (TBA) were compared with samples of soybean oil containing 200 ppm synthetic antioxidants (BHT) and control sample. The results showed that with increasing the concentration of mountain watermelon extract in soybean oil from 800 to 100 ppm, the index of peroxide, thiobarbiotic acid index (TBA) decreases and the concentration of 800 ppm of the extract due to higher levels of antioxidant compounds is more effective in inhibiting free radicals.