Bioactive compounds and antioxidant activity of cocoa hulls (Theobroma cacao L.) from different origins

Abstract

Cocoa hulls are the main by-product of cocoa with a high content of soluble fibres and polyphenols. Cocoa and cocoa-derived products are largely studied because of the antioxidant and antiradical in vitro properties of the polyphenolic constituents. These bioactive compounds have beneficial implications to human health (prevention of cardiovascular diseases and cancer) because of their free radical scavenging capacities. Thus, it is an imperative interest to bring this low-priced by-product into a more profitable utilization as possible source of dietary fibre for functional foods. The focus of this work was to characterize the content of bioactive compounds (polyphenols, hydrocolloids) of cocoa hulls from different geographic origins, i.e. Madagascar, Ghana, Trinidad, Venezuela and Ecuador. The antioxidant activity, measured by electron spin resonance (ESR), showed a high correlation between polyphenol content and antioxidant activity. The analyses showed significant differences between the geographie origins. The hulls of Madagascarian cocoa beans had higher contents of polyphenolic compounds and water soluble pectin compared to all other analysed origins. Moreover, they showed the highest antioxidant activity. In contrast the cocoa hulls from Ecuador contained the lowest values of polyphenols as well as of antioxidant activity. The lowest content of water soluble pectin was determined in cocoa hulls from Trinidad. Beside genotype variations, ripeness and fermentation of the cocoa beans, climate and soil conditions as well as stress are significant factors influencing the content of the bioactive compounds. The geographic origin of the cocoa beans (climate, soil quality) substantially influences their quality. Finally, cocoa hulls polyphenol-rich extracts are very interesting raw products with peculiar colorant and functional properties. The interest in functional foods and the focus on potential health benefits of these compounds, invites the speculation that cocoa bean shell could provide a ready source of inexpensive polyphenol and pectin rich additives to human foods, for example chocolate.