Divine Chocolate

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Search the world over and it is difficult to find anyone who does not like chocolate. But the sweet, smooth, melt in your mouth experience of today is a million miles from the maze thickened, chilli-flavoured, savoury drink of its origin.

Theobroma cacao, literally meaning, the food of the gods is the Latin name of the cacao tree, the source of chocolate. It is a member of a tropical family of plants called the Sterculiaceae, which are named in honour of the Roman god of toilets, Sterculius, as they possess malodorous flowers. Cacao is a tree, about the size of an apple tree, which grows wild in the gloom of the Amazonian rainforests of South America. These truly wild trees are of a kind referred to as Forastero. They are vigorous, high yielding, and disease resistant. Their pods are large, containing between 20 and 30 dark purple beans, which are surrounded by an acidic sweet sticky pulp. The beans produced from Forastero trees are known by the trade as ‘bulk’ and this forms the basis of milk chocolate. Deep in the upper Amazon rainforest the sex-life of the cacao tree is most exotic. A curious physiological process within Forastero trees ensures that, if by chance, the midges which visit their flowers bring about self pollination (fertilisation with pollen from the same tree) then, the tree will abort the developing pods, rather than produce inbred offspring. If cross-pollinated, the pods take six months to mature and ripen, turning from green to yellow.  Once ripe the pods which in addition to being found in the canopy, also grow directly from the trunk of the tree are readily accessed by monkeys and squirrels which gorge on the sweet pulp and discard the bitter tasting beans. As a curious aside, the carob tree, (well know chocolate taste-alike) also produces its bean-like pods on its trunk, one of only two European trees to do so.

For at least 2000 years before the Spanish conquest of the New World, the Aztec Indians of Mexico had been consuming cacao. They also used cacao beans as a form of currency, forcing their Mayan subjects to cultivate cacao to be able to pay tax. Alternatively, as few as ten cacao beans (less than a Mars bar’s worth) would hire the services of a whore. The custom of using cacao beans as cash apparently survived until at least 1840. Surprisingly for a ‘money tree’ the yield of these cultivated trees, known as Criollo is lower than those of the wild Forastero. Although, it may be possible to argue that agricultural improvement in such a crop is as unsustainable as printing bank notes, it is very strange that cacao is unique amongst crops in that the cultivated form is lower yielding than its progenitor. Criollo trees also differ in being more disease susceptible, producing small red pods with large pale violet beans. The beans are however, easier to process and considered of finer flavour. The greatest single difference between the cultivated Criollo and wild Forastero cacao is their sex-lives. Possibly related to the fact that the Mayas tended to grow cacao as solitary trees, Criollo trees indulge in self-pollination (what choice did they have). Their lower yields and higher disease susceptibility may therefore be a consequence of generations of inbreeding.

The Spanish rapidly acquired the chocolate addiction from the Indians of Central America, but preferred to add sugars rather than chilli. They established estates of the Aztec’s Criollo type cacao throughout their new colonies in the Caribbean. This young industry flourished for nearly 200 years supplying a growing demand from the cocoa houses of Europe. Then in 1725 a mystery phenomenon known as the ‘blast’, devastated the cacao farms throughout the entire region. Criollo cacao, which produced a fine flavoured dark chocolate, never recovered from what was probably a fungal epidemic or alternatively, but less likely, was hurricane damage. Criollo cacao in its pure form is probably now almost extinct.

Following the blast, the Caribbean rejuvenated its cacao industry by replanting with stock of the more vigorous Forastero type, imported from mainland South America. The newly imported Forastero trees then hybridised with the remnants of the old Criollo material. The populations, which arose, became known as Trinitario cacao, and are grown to this day for their bitter dark chocolate taste. As hybrids, Trinitario types are intermediate between their two parents for all characters including sexual preference. Thus, some Trinitario trees abhor inbreeding while others are content to self-pollinate.

By the time of the blast, the Spanish domination of the region was broken and the Caribbean was divided between several colonial powers and trading blocks. British islands, such as Jamaica, did not have free access to the rainforests of South America which where still held by the Spanish. Exactly how and from where the individual islands managed to obtain new stock to replant their estates remains a mystery. What is clear, however, is that through this quirk of colonial history the region gave rise to a wonderful range of dark chocolate varieties with exotic flavours unique to each island.

To this day the trees which are responsible for the distinct flavours of milk and dark chocolate differ in their sexual habits. There is, however, one final twist to this story of sexual intrigue. Much of the world’s milk chocolate is now grown in West Africa in Ghana, Nigeria and Côte d’ Ivoire. In the days of sail, when the first Old World cacao plantations were being established, seeds were imported from the nearest possible source, from trees growing along the coast of South America. These coastal populations of cacao are at the very edge of the natural range of the species. These trees while of Forastero type are of a sub-type known as Amelonado (because of their melon like pods). The natural population density of these cacao trees is extremely low, consequently the trees have evolved the ability to self-pollinate.

The outcome of all of this historic movement of cacao trees around the world is, that while potentially dark chocolate is inbred and milk chocolate more promiscuous in its habits, the reverse is more likely to be true. The cacao tree of today remains very close to its uncultivated origins and every piece of chocolate you eat can probably trace its ancestors to the forests of Amazonian in two or three generations.

So how do you get from the bitter tasting, slimy purple cacao beans to a chunk of chocolate? The first stage, surprisingly enough is fermentation. The harvested beans are piled in heaps on banana leaves or in wooden boxes. Here attracted to the slimy pulp which surrounds the beans, fruit flies gorge themselves. The flies deliver the yeasts which start the fermentation reactions. Over several days (longer for Forastero chocolate than Criollo) the fermentation generates heat which kills the beans and brings about a host of chemical changes which are important in the producing the complex chocolate taste. Once fermentation has finished the beans are dried in the tropical sun before being exported. The beans are then roasted to produce the final chocolate aromas. Fifty percent of the weight of these roasted beans is a fat called cocoa butter. This fat has the very special property that it melts in your mouth,  (it also melts in other places, which is why it can also be used in suppositories). Once the cocoa butter has been extracted from the beans, the dry powder that remains is then cocoa powder. Chocolate is then made my blending many different cocoa butters and cocoa from different countries, with sugar and milk solids. Good chocolate should snap rather than tear, but because most British chocolate contains more milk than does continental chocolate, it would be rather soft without the addition of other vegetable fats. This works because these fats have higher melting points than does cocoa butter, and as it happens, they are cheaper.

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2 thoughts on “Divine Chocolate

  1. Pingback: #Advent Botany – the full story! | Dr M Goes Wild

  2. Pingback: 2014 Advent Botany – Day 16 – Chocolate (Theobroma cacao) | Culham Research Group

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