Abstract:

The ultrasonic-assisted extraction of polyphenols from pomegranate peel was optimized through the combined
use of single factor method and response surface methodology. The optimal extraction parameters were found as follows:
ethanol concentration, 40%; ultrasonic power, 250 W; extraction temperature, 60 ℃; material/liquid ratio, 1:27.5 (g/mL);
and extraction time, 39.3 min. The yield of polyphenols was (1.13 ± 0.26) mg/g under these conditions. Polyphenols
compounds were extracted from the peel, pulp or seed of pomegranate under the optimal conditions, and their antioxidant
activities were evaluated and compared. The results showed that the antioxidant activity of different fruit parts of
pomegranate was in the decreasing order: peel > seed > pulp. The present study also found that after treatment with artificial
gastric fluid, the antioxidant activity of pomegranate peel was significantly increased (P < 0.05) but was significantly
decreased after treatment with artificial intestinal fluid (P < 0.05). The results suggested that the changes in the structure and
function of polyphenols in artificial gastric and intestinal fluids were different.

Key words: pomegranate, parts, polyphenol, antioxidation, response surface methodology