Improving oxidative stability of peanut oil under microwave treatment and deep fat frying by stearic acid–surfacant–tea polyphenols complex

In this work we present a study of the influence of a stearic acid–surfactant–tea polyphenols complex (SSTC) on the oxidative and thermal stability of peanut oil under microwave heating and simulated deep fat frying. Changes of the quality parameters of all oil samples containing different SSTCs were very obvious, compared with those of pure peanut oil. Especially for the oil sample containing SSTC‐P, the p‐anisidine value decreased 48.89% and 14.90% after microwave heating and simulated deep fat frying. For K 232 , it decreased 36.90% and 33.18%, respectively. By GS–MS analysis, the content of unsaturated fatty acids in peanut oil containing SSTC‐P was 8.7 times more than that in pure peanut oil after microwave treatment. As an efficient food antioxidant, the self‐assembled complex of tea polyphenols in edible oil prepared by this novel method may have great market potential. Practical applications: Oxidation processes are one of the major problems encountered in oil consumption and storage. The addition of natural antioxidants is a major way to inhibit oxidation processes in edible oils. Tea polyphenols are excellent source of phenolic compounds, which have been reported to show good antioxidant activity. The results of this study suggest that oil‐soluble tea polyphenols can be prepared based on a stearic acid–surfactant–tea polyphenols complex. The dispersion of SSTC into peanut oil can improve oxidative and thermal stability of edible oil. Therefore, the complex of tea polyphenols in edible oil may have great market potential of food antioxidant. Tea polyphenols solution was used as the aqueous phase. Stearic acid containing appropriate amount of surfactant were poured into a 50 mL centrifuge tube, and kept in a water bath maintained at 80°C and stirred at 500 rpm until a homogeneous clear solution was obtained. Then, the aqueous phase and the oil phase were mixed using a homogenizer at 26 000 rpm for 2 min to form a stable W/O emulsion. The resulting emulsion was frozen rapidly in liquid nitrogen, and lyophilized using a freeze‐drying machine for 48 h. Finally, all of the stearic acid–surfactant–tea polyphenols complexes (SSTC) were obtained. The SSTC was dispersed in peanut oil. Oxidation products of the oil sample were analyzed by GC–MS under microwave heating.