Two molecules newly identified by Mass Spectrometry in fermented cocoa beans impact chocolate sensory quality

Polyphenols are a wide and diverse group of plant secondary metabolites found in large amount in cocoa beans. They can be further modified under specific conditions such as fermentation or oxidation. The aim of this study was to characterize this group of molecules and evaluate their impact on chocolate taste. Sixteen cocoas bean samples and the sixteen chocolate samples associated were analyzed. The chocolates were made by a standard process. They were divided into four sensory groups by sensory analysis. The polyphenols have been extracted from the ground and defatted cocoa beans and analyzed by UHPLC-HRMS. Two new series of polyphenolic compounds have been detected in fermented cocoa beans. Two mass signals at m/z 605 and 893 (in the negative ionization mode) have been assigned to compounds known as ethyl bridged flavanols that had never been reported in cocoa. These molecules resulting from condensation of flavanols with acetaldehyde can be formed in planta or more likely during fermentation as acetaldehyde is a microbial metabolite. Chemometrics applied to cocoa polyphenol composition showed that ethyl-bridged flavanols are key molecules to discriminate cocoas according to the sensorial groups of the associated chocolate. Future studies will aim at determining the contribution of these molecules to cocoa and chocolate taste, especially bitterness and astringency.