Effect of drying on acidity and volatile fatty acids content of cocoa beans

The objectives of the study were to evaluate the effect of drying on the pH, titratable acidity and volatile fatty acids (VTA), ie acetic, propionic, butyric, isobutyric and isovaleric acids content of cocoa beans, and on the flavour of the resultant chocolate. Freshly harvested cocoa pods from clones of PBC 123 and 128 (1 :1 ratio) were stored for 9 days and fermented for 5 days with a single turning at 48 h. Four drying treatments, ie oven-drying at 60°C, air-blow drying, shade-drying and sun-drying were carried out. Samples were taken periodically for pH, titratable acidity, and VFA analysis. Physical characteristics were also recorded. The resultant beans were made into dark chocolate for flavour evaluation. The results showed that wet beans held in shady areas for 120 h will not dry quickly enough to inhibit mould and yeast and other putrefactive activities; rapid oven-drying of these still wet beans did not improve their flavour profile. There were no significant differences (P ⩾ 0.05) between samples that have undergone sun-drying and air-blow drying in the acidity and C3-C5 VFA content; both were evaluated favourably by taste panellists. Oven-dried beans contain a high concentration of VFA and produced chocolates with a high intensity of off-flavour.

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