Comparison of Conventional and Ultrasound-Assisted Extraction Techniques for Extraction of Phenolic Compounds from Coconut Husk

Abstract

In this study, ultrasound-assisted extraction (UAE) was compared with conventional extraction methods, including conventional solvent extraction without agitation (CSE), conventional solvent extraction with agitation at 50 rpm (CSE50) and 150 rpm (CSE150), for the extraction of phenolic compounds from coconut (Cocos nucifera L.) husk. The extraction yield, total phenolic content (TPC) and total flavonoid content (TFC) were examined. The antioxidant capacity of C. nucifera extracts was determined by using 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. Experimental results showed that UAE gave the highest extraction yield, TPC, TFC and antioxidant capacities (ABTS and DPPH), followed by CSE150, CSE50 and CSE, respectively. UAE was found to be more effective than conventional extraction methods. Conventional solvent extraction with higher agitation speed exhibited higher extraction efficiency than those with lower agitation speed and without agitation.