Optimization of extraction and antioxidant activity of polyphenols from macadamia green peel

The study focus on the optimization of extraction and antioxidant activity of polyphenols from fresh macadamia green peel.The four factors and three level orthogonal test was carried out on the basis of single factor experiment. The evaluation of antioxidant activity of the polyphenols that extracted from macadamia green peel was carried out by DPPH, ABTS+radical scavenging and total antioxidant capacity in comparison to Trolox. The optimized conditions were determined as follows:extraction time 90 min, solid-liquid ratio 1∶ 50 ( g/m L) , extraction temperature 50 ℃, 40% ethanol.And the polyphenols yield was up to ( 1027.47 ± 10.76) mg/100 g under the optimized conditions.In the DPPH, ABTS+radical scavenging assays, the IC50 value of the polyphenols that extracted from macadamia green peel were 4.13, 112.94 mg/L, respectively. And the total antioxidant capacity was about 1.7 times of Trolox. Moreover, the antioxidant capacity of the polyphenols that extracted from macadamia green peel was very strong and it can be used to prepare natural antioxidants.