HPLC-UV and HPLC-FLD polyphenolic analysis for the discrimination and characterization of dark chocolates

Abstract

The popularity of chocolate has increased greatly in recent years not only because it is considered a delicatessen, but also because the high polyphenolic content of cocoa provides to chocolate some interesting health properties, mainly antioxidant and anti-carcinogenic activities. However, cocoa production has been involved in polemics, as the obtention of this praised food has been related to slavery, biodiversity loss, and deforestation. In order to ensure consumers that the products they buy are environmentally and socially responsible, the development of reliable chocolate authentication methods is required. The aim of this work is to classify and characterize chocolate samples based on their geographical origin, cocoa variety and cocoa content by analysing their polyphenolic composition using high-performance liquid chromatography with UV (HPLC-UV) and fluorescence detection (HPLC-FLD). The chromatographic separation was performed on a C18 reversed phase column with an elution gradient using water 0.1 % in formic acid and acetonitrile as the mobile phases. The chromatographic data of 42 chocolate samples from 4 different bean varieties (Criollo, Forastero, Nacional and Trinitario) and 3 different geographical origins (Africa, America and Asia) were analysed using principal component analysis (PCA) and partial least squares – discriminant analysis (PLS-DA). The obtained score plots were used to achieve the classification and discrimination of the chocolates depending on their variety, origin and cocoa content