Method for estimation of proanthocyanidins based on their acid depolymerization in the presence of nucleophiles

Depolymerization of proanthocyanidins in the presence of phloroglucinol or benzyl mercaptan nucleophiles was studied to develop a method for their quantitative determination. Degradation products were separated and quantified by either GC or HPLC and the reaction conditions optimized. The high depolymerization yields obtained with benzyl mercaptan make the method suitable for proanthocyanidin determination. The method is more specific and sensitive than the colorimetric methods classically used. It is particularly well suited for the analysis of samples containing either low amounts of proanthocyanidins or insoluble proanthocyanidins.