Microbial detheobromination of cocoa pod husk

Abstract

Cocoa pod husk, when used in animal feed, exerts certain detrimental effects on animal health at high dietary intake, due to the high concentrations of theobromine. The chemical methods for detheobromination are not feasible in conventional agricultural practice and, therefore, are not used by local farmers. This study investigated the biodegradation of theobromine in cocoa pod husk (bio-detheobromination). Milled cocoa pod husk samples, sterilized and unsterilized, were treated and incubated for 7 days and the theobromine content followed during the period titrimetrically at 24 h intervals. A 54.7% reduction in theobromine content (p<0.05) was observed after 5 days. The microflora of the cocoa pod husk was analyzed to determine the microbial species associated with the detheobromination. Using a 4% selective theobromine medium, in which theobromine was the sole carbon and nitrogen source, Aspergillus niger was identified as the only microorganism present capable of metabolizing theobromine. Treatment of sterilized cocoa pod husk with A. niger for 7 days resulted in a 71.8% reduction in theobromine content (p<0.05). The observations suggest that fermentation of cocoa pod husk may be a useful procedure for reducing the theobromine content of cocoa pod husk to levels safe for livestock consumption.