Giulia Porrini
contact: giulia.porrini31@gmail.com
According to the Swedish Linnaeus’s nomenclature, cocoa belongs to the family of the Malvaceae and to the genus Theobroma, from the Greek “food of the gods”. Theobroma Cacao is the species used to make the well-known and beloved chocolate, but it is not the only species.
There are other 22 known species assigned to the genus Theobroma. Among them, two species are cultivated or wild-harvested on a relatively small scale for human consumption: Theobroma bicolor, also known as mocambo or pataste, and Theobroma grandiflorum, commonlycalled Cupuaçu.
Both native of the Amazon region, they are nowadays spread in Colombia, Brazil, Peru, Ecuador and Bolivia. Cupuaçu is the species which has the largest fruit and is consumed the most in Brazil. The pulp, particularly rich in flavour, is used to make juice or ice cream, whereas the seeds can be used to make chocolate, known in Brazil as Cupulate. This product is commonly commercialized in this country as a particular kind of chocolate, with its own sensorial characteristics. Being rich in fat, it also has found applications in the pharmaceutical and chemical industries.
However, Theobroma cacao is the only species widely cultivated with the biggest economic importance.
Traditionally, two main genetic groups have been defined based on morphological features and geographical origins: “Criollo” and “Forastero”. Criollo, from the Spanish “local”, is native of Latin America. It is considered the best in terms of quality and flavour, is less productive and more delicate. Its beans are white, very aromatic and low in bitterness. Forastero, from the Spanish “stranger”, is the most common in Africa; it represents the 85% of the world production, is highly productive and disease resistant. Its beans are purple, characterised by a strong bitterness and a less complex cocoa flavour. A third group, “Trinitario”, has been recognized as a “Criollo”דForastero” hybrids, probably originated in Trinidad. Furthermore, as a generalization, beans from Criollo or Trinitario cocoa tree varieties are considered fine or flavour cocoa, while beans from Forastero trees bulk (or ordinary) cocoa.
If this is the traditional, most popular classification, this is also a simplification of the reality which takes focus away from the amazing diversity of cocoas. Cocoa is an outcrossing species and, especially in wild individuals, plants carry out the action of self-incompatibility mechanisms[1] in order to stimulate the development of the species (while the cultivated ones are generally self-compatible). This means that every plant is potentially different, and the species is constantly developing. The only way to know with certainty the genotype of every single plant is undertaking a DNA analysis, which is a long and costly process not accessible to cocoa farmers.
In 2010 a research published by Juan C. Motamayor, Ph.D. in Plant Sciences and expert in genetics and agronomy research, proposes a new classification[2] of cacao germplasm identifying 10 major clusters, or groups: Marañon, Curaray, Criollo, Iquitos, Nanay, Contamana, Amelonado, Purús, Nacional and Guiana. This new classification reflects more accurately the genetic diversity now available for breeders, rather than the traditional 3 groups categorization of Criollo-Forastero-Trinitario. Moreover, it is interesting to notice that the highest genetic diversity was found in the Upper Amazon region, which is universally considered the location of the putative centre of origin of Theobroma cacao.
A consideration regarding the term “Criollo” need to be done here. Considering the cocoa tree natural outcrossing mechanism on one side, and the human effort to develop more productive and resistant varieties by artificially crossing the varieties on the other, it appears clear how the pure criollo trees, already a minority, are less and less numerous. As already mentioned, being the most delicate and less productive criollo variety is the less attractive in a global market seeking quantity and uniformity. For these reasons, it appears clear how those completely pure white beans exceptionally aromatic consumed by the Maya and called Criollo are extremely rare. They maybe still exist, but can be found only in remote areas, where trees have no contact with other cocoa genotypes. The terms Criollo itself, which nowadays too often is present on the packaging of chocolate bars on the shelves, is used in a broader and generic sense, describing a local variety, probably descending from the actual criollo of the area, resulting from years of contaminations with other not-criollo varieties.
Cocoa tree is perennial. Evidences show that more than 100-years-old trees can still present vegetal development and fruit production[3]. However, cultivated cocoa trees older than 30 years seem to show a decrease in production. It is considered good practice then to replace the old plant to keep the plantation as productive as possible; and this can be made through two methods. Farmers can plant new seedling (sexual reproduction) or revitalize the old trees through grafting (asexual reproduction). The first option is the longest one since the seedling (a 3-5 months young plant generally raised in the nursery) will take 3 to 5 years to be fully productive. As anticipated, cocoa reproduces through cross pollination, which means that each seed is the result of the mixing of the DNAs of two different plants. Reproducing cocoa trees through seeds or seedlings, then, does not allow farmers to control the new plant genotype and, therefore, the new plant and fruit characteristics. Grafting, instead, is a horticultural technique consisting in joining together parts of different plants by means of tissue regeneration. A young branch coming from a high-yielding plant (scion) is placed in contact with the lower part of an old and strong plant tissue (stock) in such a way that they will continue growing together. In this way, farmers purposefully choose the stock and the scion in order to obtain a productive, disease-resistant plant. The new plants will produce the exact copy of the fruits produced by the selected “parents” trees.
In addition, grafting is a time-saving option since the plant will be ready to produce in few months, compared to the necessary 3-5 years of the seedling. Since in the cocoa market the product consistency is a crucial feature, today the asexual reproduction is the most used method.
Leaves are oblong, leathery and up to 30cm long. Their colour varies depending on the variety, from pale green to rose/purple, and flowers and fruits grow directly from the trunk. Cocoa trees bear fruit and flowers year-round, although for cyclical weather reasons, two crops per year are generally identified: a main one and a smaller one (whose time in the year varies depending on the geographic position).
Cacao flowers are small and star shaped. They measure 1-2 cm in diameter and range in colour from snow white to rosy pink, yellow and red. They emerge fast through the bark of the tree and within less than 24 hours they are fully open and ready to be pollinated. The pollination is carried out almost exclusively by insect, tiny midges belonging to the family of Ceratopogonidae, genus Forcipomya. The synchronicity between the flowering period and the peak in the population development of adult Forcipomya allows cocoa plant reproduction. Is it also possible to pollinate the flowers artificially, by hands. However, through the pollinator Forcipomya cocoa plants were shown to be more productive[4]. This is the reason why some agronomists disapprove the use of agrochemicals, in particular insecticides.
Cocoa flowers stay open from late afternoon to the early hours in the morning, ready to be pollinated. Nevertheless, out of more than the 100.000 flowers an adult plant can produce, only 5% are going to be fertilized and around 0,1% will develop in a fruit. If not pollinated and fertilised during this period of time, they will fall the day after; otherwise the embryo and ovule will start to grow. The pods reach the maximum size after about 75 days and will then mature for another 65 days, making a total of about 140 days after pollination[5].
In general, it is estimated that it takes 4 to 6 months before a fertilized flower becomes a ripe pod, the cocoa fruit. Big and elongated like a football, or small and lemon-sized, cacao pods can vary a lot in shape and colour. From brilliant green to yellow, red, crimson and purple, they present numerous ridges running along its length, more or less pronounced depending on the genotype.
When you open a cocoa pod, you will find typically around 40 beans arranged around the long axis of the pod. They are embedded by a thick, mucilaginous white pulp. It is believed that it is the pulp what first attracted animals and humans to the tree[6], but you would be surprised to discover that its taste has nothing to do with chocolate. It has a sweet and sour taste, similar to some other tropical fruits, jackfruit to mention an example. In some countries the pulp is employed to prepare juice, liquor, beverages, ice cream, and jam but, rich in sugar, it is an irreplaceable ingredient for the fermentation process. This process is the first step of a long series of physical and chemical changes which will transform cocoa in chocolate. Interesting to know, fermenting separately a part of the pulp some people also produce vinegar!
The beans, each about the size of an almond, can be ellipsoid or oval-shaped. Inside each of them you will see the embryo (the precursor tissue of the new plant), which is made of 2 cotyledons, whose colour can vary from white to purple.
Naturally, the cocoa tree can reach 12-15m; it is rare but still possible to find trees in their full, considerable height in some remote places, when it grows wild and untouched by humans. However, when it is cultivated or managed by farmers, it is kept between 3 and 5m of height. By regularly pruning cocoa trees, farmers enhance the plant productivity and ensure an easier harvesting. Standing on the ground, farmers use 3-4m long sticks ending with a hook to cut the ripe fruits from the trees.
Where trees are not pruned, cocoa collectors alone cannot reach the fruits. They climb a 4 to 5m high ladder, sometimes tied up to the tree with a cord for security, and, once on the top of it, they cut the fruits off with the same stick, usually a bit longer[7]. Fascinating practice, but also dangerous and physical at the same time.
In a cocoa plantation, where farmers work to keep the plants healthy and productive, a number of tasks are required. Constant weeding and disease control are of paramount importance and soil management activities are vital to ensure the necessary nutrients availability. We already mention the pruning and we can distinguish here 3 kinds of it, according to the tree age and condition.
Especially in a young stage, cocoa tree needs to receive a regular shape pruning in order to guarantee the development of no more than 3 main branches, according to the available space and light. Afterwards farmers carry out a maintenance pruning and a rehabilitation one when the plants have not been pruned for long time or are affected by diseases or fungus.
The cacao tree is extraordinarily sensitive, known to botanists as the “prima donna” (“first lady” in Italian) of the plant world[8]. It grows best in low-lying areas, up to a maximum of about 1000 m, although most of the world’s cocoa grows at an altitude of less than 300 m above the sea level. It requires rainfall evenly distributed throughout the year, with a range between 1000 and 4000 mm per year, but preferably between 1500 and 2500 mm[9]. Cocoa prefers high temperature, generally within 18–32◦C with 70–80% of humidity during the day and 90–100% at night. Because of its shallow root system, cocoa need protection against strong winds and storms that can damage the pods or the whole tree[10]. This is the reason why, especially in the early stages, they best grow surrounded by other species of higher trees which provide shelter and shade. The soil requirements for the tree are also very specific: it tolerates both acid or alkaline soil but excessive acidity (pH≤4) or alkalinity (pH≥8) must be avoided. A high content of organic matter and the presence of nitrogen and phosphorus are necessary, otherwise nutritional problems are likely. Because of these and other climate needs, especially related to humidity and rainfalls, cocoa trees grow exclusively in a very narrow geographic band near the equator between 20°N and 20°S. You can find cocoa trees in three different continents: Latin America, the native land of cocoa, Africa and Asia.
As mentioned above, cocoa plant is a delicate crop and a long list of harmful fungus and diseases poses a constant threat to the crop. The so-called witches’ broom disease (originated by the fungus Moniliophthora perniciosa) has devastated cocoa production in South America, Panama and Caribbean. Slow through the forest, it spreads extremely quickly in plantation. The most affected area has been the region of Bahia, in Brazil, where in the ‘90s it caused losses of up to 70 percent of production during a period of 10 years. Frosty Pod Rot (caused by the fungus Moniliophthora roreri)is spread mainly in all north-western countries in South America, triggering significant losses in production and even the abandonment of cocoa farms. Pod Rot, also known as Black Pod (caused by the fungus Phytophthora spp), develops rapidly on the pods under conditions of excessive rain and humidity. It generates global yield loss of 20-30% and tree deaths of 10% annually in both Africa and Latin America. Pests are also brought to cocoa trees by insects, like Cocoa Pod Borer (CPB), also known as Cocoa Moth (spread in Indonesia mainly) and mirids whose damage alone, if left not treated for three years, can reduce yields by as much as 75%. These are just some example of vulnerabilities which can destroy the entire cocoa production of a country if not quickly contained. To that, you can add monkeys, parrots, woodpeckers and other animals which, not surprisingly, love cocoa too.
This overview provides a general idea of the complexity of the cocoa production process. After that, through a long chain of transformation activities, chocolate will be ready to be consumed. Chocolate is a treat unrolled in golden paper; this makes it difficult to remember that cocoa is a seed, and chocolate is an agriculture product. As any other agriculture product, then, it is sensitive to many variables like weather, environment and human management. Exactly like wine. In the wine market, though, it is well-known that the origin, the fruit varieties, the climate condition of the year of production, the way the transformation process is carried out, the timing pattern followed during processing process, distribution and consumption, the way the wine is stocked etc. are all variables of massive importance which deeply affect the final product. Chocolate is not yet considered in the same way; the mass diffusion of the conventional cocoa in the market produced the habit to categorize chocolate only in 3 main products: dark, milk or white. This seems a quite simplistic/reductive vision. The three of them come from the same raw materials (the colour of the final product does not depend on the raw material, as happens with wine). Moreover, customers expect to find always exactly the same taste in a chocolate bar, every year, every bar, always. They forget to consider the incredible cocoa varieties, and the number of variables and conditions that hugely affect the cocoa and the chocolate produced with it afterwards.
What is lacking in the world of chocolate
is the contact with its origins. The awareness, knowledge, even culture which
connects and explains a chocolate bar through its varieties, its origin and its
particular transformation process. It is a long and complex consciousness
process, already happening, which will make consumers appreciate a chocolate
bar in the same way they taste and savour a bottle of wine.
[1]Self-incompatibility is a widespread outcrossing system present in roughly half of the flowering plant species. Many hermaphroditic plants utilize this self-/non–self-recognition system as a mechanism to maintain genetic diversity within a population by rejecting self-pollen at the stigma surface (Hiscock et al., 1999; Hiscock and Tabah, 2003; Kusaba et al., 2001).
[2] Motamayor, J. C., Lachenaud, P., da Silva E Mota, J. W., Loor, R., Kuhn, D. N., Brown, J. S., & Schnell, R. J. (2008). Geographic and genetic population differentiation of the Amazonian chocolate tree (Theobroma cacao L). PloS one, 3(10), e3311. doi:10.1371/journal.pone.0003311
[3] Ministère de l’agriculture, élevage de bétail et approvisionnement, CEPLAC. Implantation De la culture du cacao dans des systèmes agroforestriers. 2014 http://www.ceplac.gov.br/paginas/publicacoes/paginas/cartilhas_tecnicas/cartilhas/CT_18.pdf
[4] Forbes, S. J. and Northfield, T. D. (2017), Increased pollinator habitat enhances cacao fruit set and predator conservation. Ecol Appl, 27: 887-899. doi:10.1002/eap.1491
[5] Chocolate Science and Technology – Afoakwa
[6]Brenner G.1999, Inside the secret worlds of Mars and Hershey.
[7] We had the chance to visit a cocoa forest during the harvesting period in the Bolivian region of Beni. There, people leaving in Camiaco and the nearby communities harvest fruits once a year, leaving the trees completely untouched for the rest of the time.
[8] Brenner G.1999, Inside the secret worlds of Mars and Hershey
[9] Afoakwa, E. O. (2010). Chocolate science and technology. Blackwell.
[10] The protection is generally provided by other higher and stronger trees that naturally grow in the rainforest together with the cocoa trees.