The content of protein and non-protein (free and protein-bound) tryptophan in Theobroma cacao beans

The contents of protein and non-protein (free and protein-bound) tryptophan and of proteins in cocoa beans of various origin were determined. Protein concentrations varied from 11.8 g/100 g in beans from the Dominican Republic to 15.7 g/100 g in roasted beans from the Ivory Coast. The highest protein tryptophan content was found in cocoa beans from Ecuador. Madagascar beans had the highest value of free tryptophan and Echeandia the lowest (17.26 and 6.39 mg/100 g, respectively). Tryptophan was bound to water-soluble proteins as well as to proteins soluble in buffer solution (pH 8.9) and in 70% ethanol. In particular, Dominican Republic cocoa contained the highest amount of tryptophan bound to water-soluble proteins. Very little tryptophan was linked to proteins soluble in alkaline or ethanol solutions, and values ranged from 0.96 to 3.04 and from 0.24 to 1.21 mg/100 g of dry defatted cocoa sample, respectively.