Ultrasound-Homogenization-Assisted Extraction of Polyphenols from Coconut Mesocarp: Optimization Study

Abstract

Coconut pericarp ( shell fiber ( mesocarp ) and shell ( endocarp )), the main by-product of coconut production, is often discarded and causing serious environmental pollution. To make better use of coconut pericarp, the extraction process of polyphenols from coconut mesocarp (CM) carefully studied by screening seven solvent systems, optimizing the assisted ultrasonic process by response surface methodology, and comparing the four process of Ultrasound, Homogenization, Ultrasound + Homogenization, and Homogenization + Ultrasound. The results showed that using 60% acetone as extraction solvent, solid-liquid ratio of 1:5 g mL-1, ultrasonic temperature of 80 min, ultrasonic power of 225 W, and then homogenizing at 10000 rpm for 10 min, the total flavonoid content of CM reached the maximum 551.99 ± 12.69 mg Rutin g-1 dry weight (dw), while the total phenolic content reached the maximum of 289.48 ± 4.41 mg GAE g-1 dw at 10000 rpm for 5 min, which may be related to the oxidative degradation of polyphenols caused by the increase of polyphenol oxidase with the extension of homogenization time. This study provides a technical guarantee for the further utilization of phenolic substances in CM.