Optimisation of ultrasonic‐assisted extraction of polyphenols from apple peel employing cellulase enzymolysis

Summary Cellulase enzymolysis extraction with ultrasonic‐assisted technology was applied for polyphenols extraction from apple peel, and response surface methodology was used to optimise the conditions of polyphenols extraction. Efficiency of extraction was optimised by measuring total polyphenol content and three individual polyphenols. Three independent variables that were taken into consideration were extraction time (X1), extraction temperature (X2) and enzyme amount (X3). The statistical analysis indicated that extraction time and the quadratic of X1 had significant effects on the yields. The mathematical model had been developed adequately describing the ranges of the experimental parameters studied and provided a statistically accurate prediction of the optimum yield. A high correlation of the quadratic polynomial mathematical model was gained. The optimal extraction conditions of polyphenols were determined as follows: extraction time of 37 min, extraction temperature of 37 °C and enzyme amount of 2500 U g−1, which was agreed closely with the predicted value.