Optimized microwave-assisted extraction of phenolic acids from citrus mandarin peels and evaluation of antioxidant activity in vitro

An efficient microwave-assisted extraction (MAE) technique was developed to extract phenolic acids from citrus mandarin peels. The operating parameters were optimized using central composite design combined with response surface methodology. The optimum extraction conditions were as follows: microwave power, 152 W; extraction time, 49 s; liquid to solid ratio, 16; and methanol concentration, 66%. After method development, the extraction yield of phenolic acids (divided into four fractions: free, ester-bound, glycoside-bound and insoluble-bound) and the antioxidant activity of the extract were compared with those of the extracts obtained from the conventional methods including ultrasonic extraction (USE) and rotary extraction (RE). MAE showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. The results demonstrated that MAE could be a fast and reliable method for quantitative analysis of phenolic compounds in citrus mandarin peels.