Flavanol and procyanidin content (by degree of polymerization 1-10) of chocolate, cocoa liquors, cocoa powders, and cocoa extracts: first action 2012.24

An international collaborative study was conducted on an HPLC method with fluorescent detection for the determination of flavanols and procyanidins in chocolate and cocoa-containing materials. The sum of the oligomeric fractions with degree of polymerization 1-10 was the determined content value. Sample materials included dark and milk chocolates, cocoa powder, cocoa liquors, and cocoa extracts. The content ranged from approximately 2 to 500 mg/g (defatted basis). Thirteen laboratories--representing commercial, industrial, and academic institutions in six countries--participated in this interlaboratory study. Fourteen samples were sent as blind duplicates to the collaborators. Results for 12 laboratories yielded repeatability RSD (RSDr) values below 10% for all materials analyzed, ranging from 4.17 to 9.61%. Reproducibility RSD (RSDR) values ranged from 5.03 to 12.9% for samples containing 8.07 to 484.7 mg/g material analyzed. In one sample containing a low content of flavanols and procyanidins (approximately 2 mg/g), the RSDR was 17.68%.