Quality of traded raw cocoa: origin specific variation, correlations of quality determining factors and development of a "cocoa quality system"

Cocoa farms around the world export close to 4 million metric tons of fermented and dried cocoa beans (raw cocoa) annually, worth nearly 10 Billion US$. Around sixty countries produce and export cocoa beans. However, differences in quality and quantity of this commodity are immense due to a vast variety of e.g. agricultural practices and post-harvest management. Changes of the market usually occur slowly and are to some extent predictable, since the cocoa tree is a perennial crop. However, quality studies surveying and comparing traded cocoa beans from various countries are rare. In order to display the typical cocoa trade situation two studies, both called "Cocoa Bean Atlas" were carried out, comprising the results of 265 traded, raw cocoa samples from 32 different countries (Rohsius, 2007). The sample set represents bulk and fine/flavour cacao, different regions (e.g., Bali, Sulawesi), special traded qualities and provenances (e.g. Arriba, Maracaibo, Java "A") as well as 5 monoclonal fermentations (e.g. varieties EET 95, EET 103, EET 48, CCN 51, CCN 31) and samples of the related species Theobroma grandiflorum. Around 15 analytical parameters such as content and composition of fat and fatty acids, free amino acids, polyphenols, acetic and lactic acid, methylxanthines etc., as well as physico-chemical attributes (e.g. bean weight) and cut test were analysed. Results from these parameters were correlated within samples from one country, but also between countries using Principal Component Analysis. In order to interpret these correlations the factors "fermentation process" and "origin" were looked at in a separate study (Rohsius, 2007). Therefore, different fermentation stages (single cocoa beans) were collected from the sample set (e.g. from Ghana, Ecuador, Haiti, Indonesia). Polyphenols (epicatechin, catechin, anthocyanins), pH and enzymatic activity (aspartic proteinase, polyphenol oxidase) were analysed. Also free amino acids were analysed in special fermentation and incubation tests. Using all four data sets, a typical processing related biochemistry pattern could be detected ("cocoa quality system"). It provides the possibility to rank even unknown samples from which just a few analytical or cut test results are known. The fermentation status of the cocoa bean could be identified as the most important, but not the only driving factor for the main differences between samples. The variation of the main characteristics of traded raw cocoa quality is described.

Keywords: traded cocoa; cocoa quality system; fermentation stages, Theobroma cacao L.