Phytochemical compound yield and antioxidant activity of cocoa pod husk (Theobroma cacao L.) as influenced by different dehydration conditions

Abstract

The aim of this study was to investigate the influence of different dehydration conditions (sun drying; hot-air drying at 60, 80 and 100 °C; vacuum drying at 60 °C, 80 and 100 °C; infrared drying at 35, 40 and 45 °C; microwave drying at 270, 450 and 720 W) on the retention of phytochemical compounds and antioxidant activity of cocoa pod husk (Theobroma cacao L.). The finding shows that microwave drying at 720 W took shortest drying time (0.83 h) and retained the highest levels of total phenolics (12.22 mg GAE/g dried sample) and total saponins (31.51 mg EE/g dried sample), which exhibited the greatest antioxidant capacity in terms of ABTS radical scavenging capacity, DPPH radical scavenging capacity, cupric ion reducing antioxidant capacity and ferric reducing antioxidant power (12.30, 5.81, 12.40 and 8.57 mg TE/g dried sample, respectively). HPLC analysis of methanol extract from cocoa pod husk prepared by microwave drying at 720 W found seven phytochemical compounds including gallic acid, theobromine, theophylline, (+)-catechin, (-)-epicatechin, (-)-epigallocatechin and (-)-epigallocatechin gallate. The outcomes obtained from this study reveals that cocoa pod husk is a rich source of phytochemical compounds for further application in the nutraceutical or functional food industries.