Browning reaction in drying cacao

The polyphenol oxidases of fermented and unfermented cacao have the same pH optimum and the same response to the inhibitors diethyldithiocarbamate, cyanide and ethylenediaminetetra‐acetic acid. Temperature optima and activation energies differ, the oxidase of fermented cacao having a higher temperature optimum and a lower activation energy than that of unfermented cacao. Activity is unrelated to total copper content and the conclusion is drawn that the activity of the fermented seed is not due to inorganic copper or unspecific copper‐protein complexes but to a modified form of the original enzyme. Some data on heat inactivation are given and the relevance of the findings to drying temperatures for cacao is discussed.