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Table 2.4 Matrix of major pest and disease problems faced by cocoa growers. Problem

Capsid

  1. palmivora
  2. megakarya

Swollen shoot virus

Witches' broom

Vascular streak dieback (VSD)

Cocoa pod borer

Average yields

Brazil

Cameroon X XX XX

Côte d'lvoire

Country Ghana XX X XX X

Indonesia X

Malaysia

Nigeria X XX XX

Comments

Ubiquitous though not always serious problem Spreading in Ghana; risk of spread to Cote d'lvoire

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.d%20Cocoa%20Health%20and%20Nutrition/0632054158/files/page_25.html [21.01.2009 23:08:45]

Careful removal of the pods from the trees with a knife is required to avoid damage to the flower cushions; in South America and West Africa pods are usually left on the ground to be gathered together for breaking by a team of workers after a few days' harvesting activity. It appears that this act of so-called 'pod storage' can have a highly beneficial effect on the subsequent development of chocolate flavour, though the precise biochemical pathways, conditions and processes involved are still poorly understood.

It seems that most, if not all, Ghana farmers have unknowingly adopted this technique of pod storage simply by their practice of using family labour to collect the harvested pods into a pile before organizing friends and neighbours to help break open the pods (16). Farmers clearly have to be careful to avoid loss from diseases in these pod piles, which can be a danger if they are left for much more than 10 days.

Research into the poor flavour quality characteristics of much South-East Asian cocoa identified that several days' pod storage could give significant flavour improvement to, for example, Malaysian estate cocoas (17). Unfortunately, there turned out to be insurmountable logistical difficulties in undertaking several days' pod storage on an estate basis, when several hundred tonnes of pods per day could often require to be split while hundreds more were still being stored.

Furthermore an insect pest the devastating cocoa pod borer (see Table 2.4) which burrows around in the pod walls requires that pods in areas affected by the pest (which now include a large percentage of the cocoa growing locations in South-East Asia) are harvested at the latest when pods are just showing a tinge of colour. In the foreseeable future, cocoas from South-East Asia seem set to have poorer flavour quality than West African beans.

Despite a number of attempts, the mechanical removal of cocoa pods from the tree has so far proved impossible, while mechanical pod breaking and extraction of wet beans, despite the construction of a number of prototype devices, still requires to be fully developed. The separation of the beans from the pieces of pod husk of about the same size when both are covered with mucilage has, so far, proved to be a major constraint to success.

Chocolate flavour is developed in two parts: the first on the farm by correct fermentation of the wet beans by the grower, and the second by the processor in the factory at the roasting step. Good chocolate flavour cannot be produced by only one of these stages. In the initial stages of fermentation, much of the pulp drains away and some time between 36 and 72 hours the beans are killed. The processes of flavour development are complex, and still quite poorly understood, though good progress has been made recently through the use of expert analytical and sensory evaluation (flavour profiling) techniques.

Fermentation

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