Effects of microwaves, hot air and freeze-drying on the phenolic compounds, antioxidant capacity, enzyme activity and microstructure of cacao pod husks (Theobroma cacao L.)

The cacao pod husk (CPH) is the primary waste byproduct of the chocolate industry. One ton of cacao beans generate approximately ten times that amount of fresh CPH. The husk is rich in phenolic compounds. The aim of this study is to determine the effects of microwaves, hot air and freeze-drying on the phenolic compound content, antioxidant capacity, enzyme activity and microstructure of CPH. The results showed that fresh CPH contain 323.7±26.5mg gallic acid equivalents (GAE)/100g dry mass (d.m.) of total phenolic compounds, and dehydration had a positive effect on the CPH phenolic content and antioxidant capacity. Catechin, quercetin, and (−)-epicatechin and gallic, coumaric and protocatechuic acids were identified in fresh and dried CPH. Drying the material using a microwave and freeze-drying preserved the husk microstructure. The results showed that microwave drying was a better drying method than hot air and as good as freeze-drying.