Stability and degradation products of native flavan-3-ols and anthocyanins through fermentation and roasting of Theobroma cacao beans : potential markers for distinguishing white-seeded cultivars
(2017)
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- Authors
- Supervisors
- Collin, Sonia
- Abstract
- Raw cocoa beans account for one of the richest source of phenolic compounds. However, during chocolate manufacture, the amount of antioxidant molecules can suffer a 10-fold decrease, mainly through fermentation and roasting. Belgium is renowned internationally for its chocolate, owning a long history and an important know-how. Yet, very few is known on the fate of native polyphenols through post-harvest processes. In this study, we analyzed beans of Theobroma cacao belonging to diverse genetic origins. RP-HPLC analyses showed that a well-conducted fermentation only leaves trace levels of the two main native anthocyanins. Our acidic incubations proved to mimic successfully natural fermentations in regards of flavan-3-ol variation. In addition to a new glycoside of cyanidin, we evidenced five compounds present only in well-fermented beans (F1 ! F5). The latter is suspected to be an inter-class degradation product, hence absent in white-seeded cultivars. During roasting, we evidenced the creation of “chemical” oligomers but only up to 3 units, contradicting the old belief based on an mDP increasing with oxidation. Epimerization and depolymerization are the two major degradation pathways and when oxidation occurs, it is preferentially within “natural” or “chemical” small oligomers. Procyanidin A2, an oxidation product of B2, is naturally present in unfermented cocoa beans but two A2 epimers appear through the process, one during fermentation and the second at roasting. White beans revealed to exhibit a significantly higher roasted/unroasted catechin ratio (>4). Taken together, these results provide useful information for the chocolate industry, with several new tools for discriminating well-fermented beans and for distinguishing white-seeded cultivars after fermentation and roasting.
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Citations
De Taeye, C. (2017). Stability and degradation products of native flavan-3-ols and anthocyanins through fermentation and roasting of Theobroma cacao beans : potential markers for distinguishing white-seeded cultivars. https://hdl.handle.net/2078.5/45926