Hm. Macdonald et al., PARTIAL-PURIFICATION OF COCOA SEED PROTEINS AND STUDIES INTO THE DEGRADATION OF COCOA STORAGE PROTEIN, Cafe, cacao, the, 38(2), 1994, pp. 119-124
Cocoa seed proteins have been extracted and semi-purified without the
use of mercaptoethanol as mercaptoethanol may cause problems due to fo
rmation of colourless adducts between proteins and polyphenols. A non-
storage protein with molecular weight 21 kDa was purified using conven
tional techniques of gel chromatography and electrophoresis. The stora
ge protein itself proved difficult to purify because of its solubility
and its tendency to aggregate or to form complexes. Partially purifie
d storage protein was hydrolysed using commercial enzymes but this gav
e no cocoa-like aroma on roasting with a model sugar mixture. Incubati
on of cocoa acetone powders containing cocoa proteins and proteinases
resulted in proteolysis of the storage protein. The products of proteo
lysis on roasting with sugars resulted in cocoa-like aromas. This woul
d suggest that specific cocoa proteinases are required to breakdown co
coa storage protein to produce cocoa flavour precursors.