Effect of Extraction Solvents on Phenolic Compounds of Theobroma Cacao L. By-products Using Ultrasound-Assisted Extraction

Abstract

Nowadays, recent studies focus on plant-derived food additives and plant by-products extract that possess health-promoting properties. Cocoa pod husk is the cocoa fruit's outer layer that is left unused after the cocoa bean processing in the cocoa industry. This by-product (cocoa pod husk) is rich in phenolic compounds due to its antioxidant level. Significant steps in separating the phytochemicals from the plant's cellular matrix are crucial, which is usually carried out by selecting the proper extraction method and choice of solvent. Phenolic compounds from cocoa pod husk were determined by ultrasound-assisted extraction using three types of solvents [aqueous ethanol (ethanol: water, 70:30 v/v), aqueous methanol (methanol: water, 70:30 v/v), and aqueous acetone (acetone: water, 70:30 v/v)]. Methanolic extracts contained significantly higher total phenolic content (34.88 mg GAE/g) and ferric reducing antioxidant power, FRAP, (521.73 μg/g TE) compared to other solvents. Meanwhile, ethanolic extracts exhibited higher flavonoid content (62.18 mg/g RE) and DPPH radical scavenging activity (73.67 μg/mL TE) compared to methanolic extracts, which indicated 33.30 mg/g RE and 65.00 μg/mL TE, respectively. Total flavonoid content had a strong positive correlation coefficient with DPPH scavenging activity (r= 0.951), while FRAP assay gave a strong negative correlation (r= -0.851). This finding provides an alternative method to reduce the accumulation of cocoa pod husk to be utilized as a potential antioxidant source.