Bioactive compounds of organic goji berry (Lycium barbarum L.) prevents oxidative deterioration of soybean oil

The protecting ability of the organic goji berry extract as an alternative to synthetic antioxidants against oxidation of soybean oil was investigated. For this, the extraction of phenolic compounds with high antioxidant activity was optimized. The main bioactive compounds of the optimized extract were identified and quantified. Different solvents were used in the extraction process. The effects of temperature (25-45 degrees C), time (60-180 min), and solid:solvent ratio (1:10-1:30, w/v) in the extraction were evaluated by a Box Behnken experimental design. Analyses of phenolic acids and flavonoids were performed by Ultra Performance Liquid Chromatography (UPLC), in optimal extraction conditions. The effect of the organic goji berry extract on improving the soybean oil oxidative stability was evaluated using the Rancimat test. A solution of ethanol/water (70/30, v/v) was the most efficient in the extraction of phenolics with a high antioxidant activity. The optimum conditions for the extraction is obtained by the experimental design were 45 degrees C, 162 min and a solid:solvent ratio of 1:30, resulting in an extract with 1338.80 mg/100 g of phenolics, and antioxidant activity of 0.73, 3.66, and 2.81 mmolTE/100 g for FRAP, ABTS, and DPPH, respectively. The phenolic acids identified were as follows: syringic, chlorogenic, gallic, caffeic, p-coumaric, 4-hydroxybenzoic, ferulic, and trans-cinammic. The flavonoids were as follows: rutin, naringin, quercetin, catechin, and kaempferol. The protection factor (PF) values of soybean oil with organic goji berry extract (500-3000 mg/kg) were significantly higher than that of oil with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) (100 mg/kg). These results suggest that the organic goji berry extract may be a substitute for synthetic antioxidants in stabilizing oil against oxidative deterioration.