The present invention relates to a process of fermenting cocoa beans.
Chocolate and cocoa products are derived from the cocoa tree "Theobroma cacao", whose fruit consists of pods each of which contains about 35 seeds, commonly referred to as the cocoa beans, which are coated with a sweet mucilaginous pulp. In order to prepare the cocoa beans for the manufacture of chocolate and cocoa products, the cocoa beans are traditionally fermented together with the pulp and then dried. Fermentation is a key operation in developing the colour, flavour and aroma of the beans. If the fermentation process is not well conducted, the flavour will be weak in intensity and often spoiled by acidity and/or off-flavours.
Without fermentation, good flavour characteristics are practically non-existent and extreme astringency is perceived.
There are several fermentation systems, depending on the cocoa variety and the country of origin. A standard process existing in Malaysia involves placing fresh cocoa beans with their coating of pulp in stainless steel press-boxes, reducing the pulp content by pressing with a hydraulic press and then storing overnight under pressure. The beans are tipped into a large fermentation box with a shallow bed depth and fermented for one day, then transferred to a smaller fermentation box with an increased bed depth of the beans and fermented for a further day. This transfer between small boxes is repeated and fermentation is continued for 5 or 6 days. The fermented beans are transferred to a circular dryer and dried for 8 hours at 70.degree. C.-80.degree. C., rested for 12 hours and finally transferred to a rotary drier and dried again for 8 hours at 70.degree. C. to give the dried cocoa beans.
However, Malaysian cocoa beans fermented in this way may have some of the following major disadvantages:
1. high acidity
2. high incidence of off-flavours
3. low chocolate flavour
During fermentation, the pulp, containing about 80% water, 18% sugars, 1.5% citric acid, pectin and minor quantities of amino acids and mineral salts, becomes host to a wide range of microbial activities: e.g., yeasts transform sugars into alcohol, acetic acid bacteria will metabolise alcohol into acetic acid, and lactic acid bacteria will change sugars into lactic acid. With the help of pectinolytic enzymes, the pulp loses its mucilaginous nature and much of it drains from the mass as "sweatings". Bean death occurs within two days allowing enzymes and substrates to interact freely inside the nibs. The initial pH within the nibs is about 6.6 but during fermentation the pH falls to below 5 owing to the diffusion of the acids into the nibs. The pH of Malaysian beans is often still below 5 after 5 days of fermentation causing the objectionable high acidity, while prolonging the fermentation beyond 5 or 6 days contributes to a high level of off-flavours in the cocoa bean.
Since the cocoa beans grown in most of Peninsular Malaysia contain a higher amount of pulp than other cocoa beans, e.g., the Amelonado in Ghana, the pulp tends to make the beans stick together so that the fermentation is anaerobic. Various methods have been proposed to reduce the amount of pulp in order to modify the fermentation conditions so that they become more aerobic and more similar to those of other cocoa beans, e.g., Ghana. Such methods include hydraulic pressing, pod storage, sun spreading and a combination of pod storage and sun spreading.
Harrisons Malaysian Plantations Berhad use hydraulic pressing widely in fermentaries but the fermented cocoa beans have the disadvantages indicated above. The pressed beans have a rough exterior with a significant amount of pulp remaining which is unevenly distributed.
Pod storage involves storing harvested pods for periods from 5 to 11 days after which the pods are broken open and although the pulp to nib ratio is reduced substantially, this reduction is inconsistent, resulting in a cocoa with only occasionally improved flavour. In addition, pod storage in the field would leave the pods susceptible to attack from disease and pests such as rats, as well as to theft whereas pod storage in a warehouse is space and time consuming as well as expensive and not feasible on an industrial scale.
Sun spreading involves placing the cocoa beans, fresh or from stored pods, in thin layers (2-3 cm thick) on trays or on a concrete floor in the sun for several hours to evaporate additional moisture. However, the flavour improvements in this cocoa have been found to be inconsistent. In any case, sun-spreading requires a large area and fair weather to be efficient.