Cocoa transformation: how many steps does a cocoa pod undertake to become a chocolate bar?

Giulia Porrini
I have been introduced to cocoa during my MBA in Development Economics, when I was doing a research about indigenous small cocoa farmers in Costa Rica and Panama. Addicted to cocoa, I have been travelling and studying plantations in South America, always eager to learn more. Graduated at the Italian Master Chocolatier Academy (who knew?), still working with cocoa producers, founder of CocoaConnection.

Everybody knows what chocolate is and that it is made of cocoa beans, but if you happen to find a bag full of beans, would you be able to make some chocolate out of them? Let’s analyse step by step what the whole process is, following the long journey of the cocoa beans from the plantation to the moment in which we find it in the shop in the form of chocolate.

The long chain of processes that transform any commodity into the final product is called “supply chain”.  The supply chain is often compared to a river, where each activity is connected to the following one as the flowing water. As in a river, the long chain of transformation activities can be divided into two main phases: Upstream activities and Downstream ones (which, within the cocoa industry, coincide with the so-called Primary and Secondary Processing). In the cocoa supply chain, the upstream activities relate to everything that happens in the farm or in small shelters nearby and is operated by the farmers. This first phase includes land selection, soil preparation, weeding and pruning, pest and disease control, harvesting, pod opening, shelling and the so-called post-harvest process or, in Spanish, beneficio which consists of fermentation, (washing), drying and selection.

The Downstream phase covers, instead, the industrial processing of the beans to obtain semi-finished and finished products. These are nibs, cocoa paste (or liquor or cocoa mass), cocoa butter, cocoa powder, chocolate and confectionery containing chocolate. These activities are generally carried out in factories by cocoa processors, chocolate manufacturers and confectionary industries; or they can be made in a more artisanal way by chocolate makers through the nowadays well-known beans to bar process. At the very end of the chain we can find also little chocolate producers or chocolatiers who buy cocoa mass from cocoa processing factories and make chocolate, pralines or other sweets out of it, avoiding the big investment in cocoa processing machines that would otherwise be necessary.

During the aerobic phase of the fermentation process, beans are moved regularly by the farmers to guarantee the uniform contact with oxygen. Photo by Matteo Pietrobelli

According to some supply chain analysis, we could add the Middlestream activities which concern the beans commercialization both at the national and international levels, involving wholesalers and traders.

This categorization will be useful to describe and localize the different activities along the chain. Skipping the technical analysis of the cropping management, in the next paragraph we will following the chain starting with the harvest.

When the harvesting time comes, cocoa farmers collect the ripe and healthy fruits with long handled knives, hooked sticks or machetes and put them together in small stacks. In order to pick fruits at the correct stage of ripening, recognizable by the change in colour, it is recommended to harvest every 15 days. Cocoa pods are sometimes left in the field for few days (pod storage), a practice which allow to assemble enough fruits in order to break them all on the same day. Cocoa harvesting is a long process that can last up to 3 months; however, it is important to avoid exceeding three days of storage of collected fruits  to prevent the germination of the beans which would affect their quality. Farmers usually sit in couple on the opposite sides of a fruits stack and start the break of the husk, “la quebra de las mazorcas”, how they call it in Spanish, in a regular and continuous rhythm. One cuts the external husk with a machete or a rock, the other opens the fruit, discards the husk and collects the wet cocoa beans separating each bean with his fingers. In this stage, it is crucial not to damage the beans while opening the fruit, since they would be likely harmed by the fungus or insect affecting the quality of the harvest.

Different methods are used to ferment cocoa; these wooden barrels can be turned with a handle, making easier the moving process otherwise implemented by hand as shown in the previous photo. Photo by Andrea Onelli

The wet beans are put into timber boxes or heap into piles covered with mats or banana leaves, ready for the fermentation process. Cocoa beans naturally begin to ferment when they come into contact with the micro-organisms present in the environment. These micro-organisms proliferate decomposing the pulp around the beans which, in turn, sets off biochemical and physical processes lasting three to seven days. We can distinguish two phases in the fermentation process: anaerobic and aerobic. In the first one, with no need of oxygen, yeasts start to process the mucilage sugars producing alcohol and carbon dioxide (CO2) in 24 to 48 hours. In the second phase, the temperature increases up to 45° C, yeasts decrease and acetic acid rises. Now the oxygen plays a big role: it is crucial then to regularly move the beans in order to guarantee that the beans get in contact with it uniformly. This process is very complex and always slightly different in timing depending on  a long list of variables: from the geographic area, weather and humidity, to the beans characteristics (like size, fat and polyphenols content); from the conditions which depend on humans (like the state of cleanliness of the fermentation boxes; the regularity in the beans stirring), to some environment conditions (like the presence of extra yeast, for example, in the banana leaves).

Formerly used to kill the embryo and avoid its germination, it is today well-known that the fermentation process is responsible for the development of the precursors of aromas and flavours that will be present in the chocolate. This makes this delicate stage extremely important for the production of good quality cocoa. After a year of work in the plantation, despite the fact this is just the beginning of the cocoa transformation, something going wrong in this stage would permanently affect the taste of the final product .

After the fermentation, the drying process takes place. During this process the beans’ moisture content drops from about 60% to 6-7%. It is a delicate phase and lasts for several days: it should occur slowly, to prevent the development of bitter flavours, but not too slow, to avoid the emergence of moulds and off flavours. The final moisture percentage is very important because it determines the beans’ shelf life: with a humidity higher than 8% mould can originate, below 5% the beans will become too dry and brittle. The drying process relies on the air movement and can be done naturally, operated by the sun, or artificially with the help of other heat sources, generally fire. Sometimes the process is made by the combination of the two.

Beans drying in the sun in Bolivia. Photo by Matteo Pietrobelli

When the sun drying option is selected, beans are spread out on a flat surface. In Africa, farmers use mostly mats, trays or directly the concrete floors; in the West Asia and South America, odourless wooden platforms are more likely to be seen. Sometimes wooden floors are covered by moveable roofs which protect the beans from the rain or from excessively strong sun in the central hours of the day. The beans are normally turned or raked in order to keep the beans separated and make them dry uniformly. Sun drying is used in countries where harvesting occurs in a dry period, like West Africa or the West Indies. In those countries where there is a lack of pronounced dry periods after the harvesting time,a  few alternatives are used by farmers who can afford it. This is a problem faced by cocoa producer countries in South America, South East Asia and sometimes in West Africa. One option is the use of greenhouses where they can achieve very high temperature and protect beans from the rain at the same time. Another option is related to more structured driers like a convection one: “the simplest forms of artificial driers which consists of a simple flue in a plenum chamber and a permeable drying platform above. Air inlets must be provided in order to allow the convection current to flow without allowing smoke to taint the beans”. Slightly different artificial driers have been developed in different regions but, in general, the most important requirement for a cocoa drier to be good is to avoid the beans contamination from the smoke produced and prevent a too fast process (which would results a high acidity in the cocoa flavour). The weather itself, in terms of temperature and relative humidity, strongly affects the timing: the drying process normally takes about 5 to 7 days with adequate sunshine and little rainfall, but much longer if the weather is dull.

Unfortunately, in certain regions it is quite common to see cocoa beans drying in patios, on the soil, in the same area where animals are free to walk and graze. Cocoa beans, rich in fat, absorb odours very easily, so it is of paramount importance to provide a clean environment free from bad odour and animals (sadly, this is a fact that farmers are not always aware of).The primary processing activities are extremely important to obtain a good flavour profile and guarantee the cocoa conservation and transportation. Without them, in fact, beans would be too acidic and sour to make chocolate out of them. Moreover, if properly dried, cocoa beans can be stored in bags for months, provided the necessary environment: a fresh and cool place, and a controlled relative humidity of 60-70%.

Dried cocoa is then brought into designed warehouses in the biggest town near the plantation to be sold. Some of it will stay in local market whereas the majority will be bought by wholesalers, traders or directly by big multinational companies. The last step before the start of secondary processing is the selection process. Fermentation degree, moisture content, number of defects and broken beans, mouldiness, beans size, colour and flavour are some of the evaluated variables necessary to determine the beans quality. Imperative is the “cut test”, the evaluation process in which a sample of beans is cut lengthwise to infer about its internal coloration and the percentage of defective beans (mouldy, slaty, insect damaged, germinated or flat). These characteristics are related to the chemical composition of the bean and derive from the fermentation and drying process, determining the quality of the beans and their price.

Once selected and divided into categories according with their quality, beans undergo the secondary processing phase. At the very end of this phase cocoa will be turned into chocolate, the main commercialized product obtained by cocoa beans, but not the only one. The cocoa bean can in fact be divided into two components, each of which represents roughly half of the weight (depending on the variety): the fat and the dry cocoa solids. The first is the cocoa butter and is the most expensive beans component. It is used in the pharmaceutical and cosmetic industry or bought by chocolate manufacturer companies to be used as an ingredient. After the extraction of the butter, the dry cocoa solids are gradually refined until cocoa powder is produced. It is a fundamental ingredient in the confectionary industry, used for liquid drinks or sold to the final consumer. We will analyse the cocoa processing activities to make clear when and how these different products are produced. They can be made in many different ways, in industrial or artisanal methods, but the necessary steps are generally the same.

Before everything else, the receiving processing factory carries out a cleaning process in order to eliminate any contaminations such as rocks, nails or wood. It could look weird, but it is very usual to find an interesting mix of extraneous materials among the cocoa beans which, if anything, makes that cocoa bag heavier.

Artificial drying machine, heating the beans with the heat produced by the fire.
Photo by Giulia Porrini

A disinfection process also is necessary to make the beans completely clean and safe. Through a high temperature steam any microbial activity on the bean stops and they are ready for the roasting. In this process the cocoa beans are exposed to high temperatures with a variety of schedules in terms of timing and temperature. Often, though this is not the rule, people responsible to tailoring the ad hoc “recipe” for each received stock carry out an initial beans tasting, in order to obtain the best result according with the specific beans’ characteristics. After the fermentation, the roasting is the second crucial step for the beans to develop their potential flavours and aromas. During this process, in fact, the aroma precursors arisen during the fermentation change chemical and physical structure giving the way to the aromatic compounds that will remain in the cocoa until the final product.

Then, the cocoa beans are broken and grinded through a mechanical process and they are now called “nibs”. During this phase, the “testa” or “tegument”, which is a subtle shell which naturally covers the beans, comes off once the beans are broken down. The bean’s shell is much lighter than the nibs and is mechanically sucked. This process is called winnowing and is necessary since the shell is the part where harmful pathogens or heavy metal like cadmium are stocked. Moreover, it is suggested to remove the testa also for tasting reasons: it gives extreme astringency to the chocolate.

There is an additional process undertaken only in processing factories which handle a large amount of beans. It is called alkalinisation or Dutching process, since it has been developed in the 19th century in Holland by Van Houten, and entails a chemical treatment of the cocoa nibs with potassium carbonate to develop flavour and colour.

In the selection process, beans undertake the cut test.A sample of beans is cut lengthwise to infer about its internal coloration and the percentage of defective beans.
Photo by Andrea Onelli

In fact, by raising the pH, it reduces the acidity and sourness of the beans, increasing the solubility and dispersibility of cocoa in water (a key feature in chocolate beverage). Moreover, having discovered that the consumers are influenced by the cocoa colour in their purchasing preferences, big processing companies differentiate the treatment in order to obtain different colour from the same cocoa beans. Through this process they are able to make a darker/black powder to gradually lighter/brown ones, depending on the final product they are intended for. Needless to say, it strongly affects cocoa natural flavour and characteristics, deleting all its aromas. This means that this process offers the opportunity to cover all the defects and off-flavours of low quality beans generally used by big companies to produce chocolate mass products.

Alkalinised or not, the nibs are then refined, and their size is progressively reduced until each particle is so small to be imperceptible on the palate. Our mouth is able to perceive particles bigger than 30 microns, so usually cocoa is refined in order to be smaller than that, measuring on average around 25 microns. However, this is not a rule; the particles size varies a lot depending on the chocolate makers choice and the desired result. Moreover, the quantity of cocoa butter strongly affects the mouthfeel, defined as the way a food or drink feels in the mouth, as distinct from its taste. The refining process can be carried out with different machines: in artisanal factories melangeur or ball mills are mostly used, whereas in bigger industries cocoa nibs travel through a series of roll refiners. Through this machine, because of the friction between the cocoa particles and the machine components in constant motion, the fat present in the beans warms up. The temperature raises and the warm compound gets increasingly similar to the chocolate texture. When it reaches a smooth and homogeneous consistency, it is called “liquor” or “cocoa mass”, but it is not yet chocolate.To be called chocolate in fact it must contain at least 1% of sugar, while the cocoa mass is still 100% cocoa.

At this point, different procedures can be undertaken depending on which product need to be produced. Cocoa butter can be now extracted by pressing the liquor, obtaining a solid mass called cocoa presscake with the remaining part of the cocoa beans. Cocoa powder is produced breaking the presscake, and industrially refining its pieces. Finally, adding sugar and other ingredients in the refining machine, we will obtain chocolate.

At this point, the list of ingredients necessary  to make chocolate should be considered.  As mentioned before, all you need to make chocolate is cocoa beans and sugar. Everything else is added by chocolate makers with special purpose in mind. Generally, cocoa butter in variable proportion is added to make the chocolate richer and shiner, improving also its meltiness. Powdered milk is added to obtain milk chocolate (whereas to make white chocolate it is an entirely different process). The list of ingredients could stop here; especially if the beans are of good quality, chocolate makers do not want to cover the natural cocoa flavours. Often, among the ingredients we can find natural vanilla aroma, a natural aroma that combines well with cocoa, and soya lecithin, which helps sugar and fat to emulsify and mix harmonically.  When other ingredients are added, it is worth to wonder why; it is often the way to cover cocoa off-flavours and defects.

Once all the ingredients are properly mixed, chocolate just needs time to get to the desired consistency moving and turning in the refining machine. According to the chocolate characteristics, sometimes chocolate undertakes an additional step in a machine called “conche”. Invented in the 1880 by the chocolate maker Rudolphe Lindt, the conching machine contributes to correct chocolate flavour and affects its final texture. By agitating chocolate at more than 50◦C for few hours, the continuous mixing movement allows volatile undesirable compounds such as acetic acid to get dispersed and promotes flavour development, reducing the viscosity by further refining the particles. On the other side, if the conching is crucial to get rid of undesirable volatile elements, too much time spent in the conche could result in the loss of other positive aromatic notes. The speed, duration and temperature of the conching affect the chocolate taste and need to be adjusted according to the cocoa beans characteristics.

Winnowing process: cocoa nibs are separated by the testa, a thin shell surrounding the bean. Photo by Andrea Onelli

Now the chocolate is ready, but it is still hot and in a liquid state. Unfortunately, the way it solidifies is not negligible and only the chocolate solidified in a certain “shape” will be considered well done. The method that makes this possible is called tempering, which affect in particular the cocoa butter behaviour.

The fat contained in the beans can crystallise in a number of polymorphic forms, precisely six, each of which has different characteristics. The 5th form is the most stable and the only one able to give the chocolate those characteristics that determine a good quality bar. Good quality chocolate has a shiny, uniform aspect, and a distinctive sharp sound when the it is broken – the so-called “snap”. It is a stable product – harder and more heat-resistant- with a longer shelf-life and prevents the fat bloom phenomenon, the appearance of a white patina on the chocolate surface caused precisely by the cocoa butter migration. Finally, a well-tempered chocolate will melt in the mouth in the most harmonious way providing the best tasting experience.

The tempering process, then, guarantees a stable cocoa butter crystallization at its 5th form and can be done in several ways. Generally, it is carried out by a series of controlled thermal shocks. Once the chocolate is tempered, avoiding any further change in temperature, it is usually poured in moulds and let cool down through a refrigerated tunnel. At the end of the tunnel, the solid chocolate is taken out from the mould and ready to be packed.

Cocoa mass poured from a melangeur, a refining machine which gradually reduces cocoa solids up to 25 microns.
Photo by Andrea Onelli

At this point, chocolate will start a journey through ways of transport and shop shelves, ending in the consumer’ hands. During all this time, it is of paramount importance to prevent any further thermal shock: if a sudden temperature change wider than 10°C occurs or the temperature exceed 12°-16°C (the suggested conservation range temperature) it will be necessary to re-temper the chocolate again .

This was on overview of the long chain of transformation processes which the great majority of cocoa bean produced in the world undertakes. As you can see, within every single step there is a list of variables that permanently affect the final result. On the other hand, there is not a recognized set of rules describing the best practices, applicable everywhere to handle every kind of cocoa, with no exception. In respect of the raw material, every cocoa variety growing in every single area of the world presents peculiar characteristics and needs. In the same way, within the chocolate making process, every chocolate maker applies his own recipe, using different timing, temperature and machines. It is incredible to think how many different outcomes can be produced starting from the same cocoa beans.

The whole process is very complex, but it is crucial to understand that the quality is determined in the plantation, during the harvesting and the post-harvesting activities. Through the choice of the ripe fruits, the fermentation and the drying process, farmers are responsible of the cocoa quality and, consequently, of the final product. Chocolate makers can emphasize the aroma precursors present in the beans and produce the best chocolate according with the beans’ characteristics. They can moderately correct or make smoother the presence of some little undesired elements, but they will never able to change the taste.  They cannot create high quality chocolate without using high quality beans. This is something that escapes the mass understanding, the average consumer does not think about the role of the farmers when buying some chocolate. All the attention is focused on the art of a specific chocolate producers or famous chocolatier.

Knowing the cocoa supply chain better , the actors, and each of their role ,is definitely a way to better understand the treat everybody loves. Making chocolate is an art the starts much earlier than the laboratory where hands covered by white gloves work on it; it starts in the plantation, on the trees, around palm leaves and under the sun. Being aware of this gives us the power to understand the quality of chocolate products we consume and to give them the right value.

Giulia Porrini

MBA development economics

Contact: Giulia.porrini31@gmail.com