Ultrasonic microwave-assisted extraction coupled with macroporous resin chromatography for the purification of antioxidant phenolics from waste jackfruit (Artocarpus heterophyllus Lam.) peels

An efficient ultrasonic microwave-assisted extraction (UMAE) coupled with macroporous resin chromatography technique was successfully used for the extraction and purification of antioxidant phenolics from jackfruit by-products (peels). After optimization by single factor experiments and response surface methodology, the optimum extraction conditions for UMAE were: ethanol concentration 63%, solvent-to-solid ratio 34mL/g, microwave power 160W and irradiation time 20min. Under the optimal condition, the phenolics extraction yield was 8.14mg GAE/g DW. After the purification by macroporous resin AB-8, the purity of antioxidant phenolics from UMAE extracts improved from 13.59 to 49.07%. Furthermore, ABTS radical scavenging activities were also significantly increased from 35.95 +/- 2.21 to 162.36 +/- 10.26mg TE/g. HPLC analysis revealed that gallic acid, chlorogenic acid, and catechin were three dominant antioxidant phenolics in jackfruit peels. All of the results demonstrated that waste jackfruit peels could be utilized as a good source of phenolics with strong antioxidant activities in food and pharmaceutical industry.