Abstract:

In this paper, it reports the use of one-factor-at-a-time and orthogonal array design methods to optimize the ultrasonicassisted extraction of polyphenols from peanut seed testa (PTP), followed by the evaluation of their antioxidant effects by reducing power assay and Rancimat assay. The results indicated that the optimum conditions for the extraction of polyphenols were determined to be: material-to-liquid ratio 1:16 (g/mL), ethanol concentration 80%, ultrasonic power 240 W and length of extraction time 10 min. The above conditions exhibited different effects on polyphenol extraction in the following order: material-to-liquid ratio ＞ ethanol concentration ＞ length of extraction time ＞ ultrasonic power. Under the same concentrations, the reducing power of the purified PTP was superior to that of VC. The concentration of the purified PTP providing the best protective effect against lipid oxidation in lard was found to be 150 mg/L. Addition of the purified PTP at 150 mg/L resulted in longer induction time of oxidation of lard than that of VC or gallic acid, but was inferior to that of BHT. In conclusion, PTP appears to provide a promising natural antioxidant.

Key words: peanut testa (PT), polyphenols, ultrasonic-assisted extraction, antioxidant effect