Elodie JEAN-MARIE

One of the world's 10 fundamental genetic groups, Guiana cocoa is endemic to French Guiana. Although cocoa is the raw material used to make chocolate and its derivatives, Guiana is still very little studied. In fact, the literature shows that cocoa and chocolate have numerous benefits for the various human systems. These health benefits are thought to be induced by their chemical composition, which is rich in polyphenols and methylxanthines (theobromine and caffeine). However, the chemical composition of Guiana has never been studied and its biological capacities remain unknown. To remedy this, this thesis focuses on the chemical characterisation of Guiana and the determination of its antioxidant and immunomodulatory potential. With the aim of adding value to it, our study determines the impact of fermentation on these different parameters, in order to determine whether these derivatives could also constitute health foods or alicaments in view of their biological capacities.

Initially, the chemical composition of Guiana was characterised by measuring total polyphenols and total procyanidins, as well as by chromatographic analysis using HPLC-DAD. We compared it to a reference cocoa, Forastero, which is produced in the majority (more than 85%) in the world. Our work showed that Guiana has a composition rich in polyphenols, particularly flavanols, condensed tannins, flavones and flavones. It also contains an interesting level of theobromine and less caffeine than Forastero. Subsequently, the antioxidant activity (via FRAP, DPPH, ORAC and NO scavenging tests) and immunomodulatory activity (via murine macrophages whose inflammation was triggered by a mixture of LPS/IFNγ) were confirmed.

Secondly, the impact of fermentation was measured on these different experiments by selecting different degrees of fermentation for the two cocoas (0, 2, 4 and 6 days). Our experiments showed that the process had an influence not only on composition but also on the biological activities correlated with it. Although this work needs to be studied in greater depth, Guianas consumed raw or processed would demonstrate a valuable health potential. Guiana could therefore be used in a variety of fields, including nutrition, cosmetics and pharmacology.

Keywords : Cocoa, Antioxidant activity, Anti-inflammatory activity, Polyphenols, Amazonia

Guiana is one of the ten fundamental genetic groups in the world and it is endemic to French Guiana. Even if cocoa is the raw material in chocolate and derived products confectionery, Guiana is still little studied. Indeed, cocoa and chocolate have demonstrated various health benefits on various human systems. These benefits are induced by their chemical composition which is rich in polyphenols and methylxanthins (theobromine and caffeine). However, the composition of Guiana has never been studied and its biological capacities are still unknown. To remedy this situation, our thesis revolves around chemical characterization of Guiana and the determination of its antioxidative and immunomodulatory potentials. In order to add value to cocoa, our study has determined the impact of fermentation on these different parameters in order to determine if its derived products could be health food in terms of their biological capacities.

Firstly, the characterization of the chemical composition of Guiana was carried out via quantification of total polyphenols and total procyanidins, but also by chromatographic analysis via HPLC-DAD. We compared it to a benchmark cocoa, Forastéro, which is the most produced in the world (85%). Our work showed that Guiana has a polyphenol-rich composition, particularly in flavanols, condensed tannins and flavones. Likewise, it would contain an interesting theobromine content and a lower quantity of caffeine compared to Forastero. Subsequently, the antioxidant activity (via FRAP, DPPH, ORAC and NO scavenging tests) and the immunomodulatory activity (via murine macrophages whose inflammation was triggered by a mixture of LPS / IFNγ) were confirmed.

Secondly, the impact of fermentation was measured through different experiments by selecting different degrees of fermentation for both cocoas (0, 2, 4 and 6 days). Our experiments demonstrated an influence of the process in the composition but also in the biological activities which are correlated. Although this work deserves to be deepened, Guianas (consumed raw or processed) would demonstrate a valuable health potential. Therefore, Guiana could be used in various fields such as nutrition, cosmetics but also pharmacology.

Key-words: Cocoa, antioxidative activity, anti-inflammatory activity, polyphenols, Amazonia