Effect of extraction methods on the efficiency of sumac ( Rhus coriaria L.) fruit extract in soybean oil quality during accelerated conditions.

Herbal extracts containing natural bioactive substances with numerous beneficial effects have been recently noticed as appropriate alternatives for synthetic food preservatives. In this study, we aimed to optimize the effects of different sumac ( Rhus coriaria ) fruit extracts (SFE) on oxidative stability of soybean oil under accelerated conditions compared to a synthetic antioxidant. Hydro-ethanolic extracts (70%) of sumac fruits were prepared by three methods of immersion (I-SFE), ultrasound (U-SFE), and microwave (M-SFE). According to the response surface methodology (RSM), 13 runs were considered in the concentrations of 0, 500, and 1000 ppm of each extract that were added to the soybean oil and stored at 60°C for a 20-day period. All of the treatments were significantly ( p  < .05) efficient in preventing the chemical and sensory changes of soybean oil compared to the control in the dose-dependent manner during storage period. I-SFE treatment showed the lowest peroxide value (PV) (0.000063 meq (milliequivalents) O 2 /kg oil), thiobarbituric acid reactive substances (TBARS) (115.06 MDA (malondialdehyde)/kg oil), and acid value (0.0169 mg KOH (potassium hydroxide)/kg oil) among the other extracts at the end of the storage period. Furthermore, I-SFE treatment earned the highest sensory scores (flavor, color, odor, and overall acceptability) of soybean oil in the range of 4-5 in comparison to the other treatments and synthetic antioxidant during storage time. According to the analysis of RSM, I-SFE in the concentration of 999.998 ppm could optimally enhance the shelf life of soybean oil for 11.3614 days under accelerated conditions. It was concluded that I-SFE with the same efficiency as synthetic antioxidants can be considered as a suitable alternative in soybean oil with various health benefits.