There are moments in life where time stands still, the body is pumping with adrenalin and all your senses are working together. Many people say that is exactly what happens the moment a delicious chocolate square touches their tongue. In my opinion, good chocolate is indeed a pure pleasure and a celebration of the palate - who would dare disagree with me?
Chocolate, in its final form, is a colloid (suspension) made of several different components, each of which plays a different and important role in its creation. Many factors influence a chocolate’s quality, taste, texture and color, all of which are strongly affected by the chemical character and physical properties of the various components. So how exactly is this wonderful delicacy so popular all over the world and what factors should we consider if we want to make the perfect chocolate?
Cocoa beans| Shutterstock
How it all began - a taste of chocolate history
The story of chocolate begins in the rainforests of Central and South America and West Africa - the home of the Cocoa tree (Theobroma cacao). Cocoa pods, found on the cocoa tree, grow for about four months until they reach their maximum size, similar to that of a melon. And then about one month later they are considered ripe. But what interests most people is not this spectacular pod but rather the 40 cocoa beans inside it.
The taste of cocoa beans is very bitter, which raises the question of who was the first to consider using them and why it even occurred to them? Experts believe that the Olmecs, an ancient nation that lived in Mexico between 1500 and 200 BC, used to dry, crush, and mix the cocoa beans with hot or cold water to create the first chocolate drink. This drink must have been very bitter (the translation of chocolate is actually bitter water) and also extremely in demand, so much so that cocoa beans were used by the Olmecs, Mayans, and Aztecs, all hailing from Central America, as a substitute for money.
The cocoa bean only arrived in Europe in 1502, after Christopher Columbus travelled to the American continent. In those days in Europe, the cocoa drink was only consumed by the upper class, but unlike the Olmecs, the Europeans did not like its bitterness and therefore added sugar to it. It was not long before the cocoa drink spread throughout Europe and migrated with the European settlers to North America as well.
The industrial revolution led to a sharp decline in the production costs of chocolate, which soon became property of the commoner. From this moment on, the chocolate industry prospered - new factories opened and novel, varied and tastier chocolates began to appear. Today there are countless types and forms of chocolate and cocoa products, which are consumed almost everywhere in the world and at any age.
Most chocolate lovers treat it as a delicious sweet, but in fact chocolate is a fascinating chemical system that contains many ingredients that affect its taste, color and texture. To know how to make really good chocolate, we must first understand the chemical properties of the various molecules contained within it.
The science behind chocolate
Who is not familiar with this experience? You take some chocolate, full of anticipation and longing, and just before you put it in your mouth you discover that it has already melted and is smothered over your whole hand. This chocolate is not considered high quality, and neither is granular chocolate, or one that does not melt on your tongue as soon as you put it in your mouth.
Simply put, high quality chocolate has a defined and particular texture, meaning it is not granular and only melts at mouth temperature (36.7 degrees). To make high quality chocolate, we need to know its chemical composition and the various stages of its preparation. Only by breaking down the chocolate into its constituents and recognizing each of their chemical properties can one really understand chocolate, and how its ultimate taste and texture can be controlled during its preparation process.
The chemical composition of chocolate
The process of preparing chocolate includes several stages, each contributing separately to taste, texture and color. But before that, the story of chocolate actually begins in the rainforest, the moment the cocoa beans are formed in the cocoa pod. Their growth takes about five months, and this is also the period when their chemical composition is determined.
Cocoa beans are made up of cocoa butter (54%) and cocoa solids (46%).
Cocoa butter is a collection of fat molecules called triglycerides. Although these molecules do not give chocolate its bitter taste, they are responsible for its texture so we cannot make chocolate, as we know it, without them.
Cocoa solids include all the ingredients found in cocoa beans that are not cocoa butter i.e. proteins, vitamins, antioxidants, caffeine, theobromine, fiber, a small percentage of sugars (sucrose and fructose), minerals like potassium and magnesium, and more. These ingredients are responsible for the bitter taste of chocolate (caffeine and theobromine) and its health value (antioxidants, vitamins, minerals, etc.).
During the preparation of chocolate, the cocoa butter is mixed with the cocoa solids until there is a uniform distribution of the cocoa particles in the liquid cocoa butter, creating a colloidal system otherwise known as a suspension. When the suspension cools, the cocoa butter hardens and traps the cocoa particles inside it, creating the chocolate we know.
Sounds simple? Not quite. Making the chocolate itself is not a complicated matter, but making a delicious chocolate with a precise and high quality texture is much more complicated business.
How does one make the perfect chocolate?
1. Preliminary phase - Determination of the chemical composition of the chocolate
In making the perfect chocolate, one must start in the thick rain forests to handpick the right cocoa pods. Before the chocolate preparation process, three main steps are taken to extract the cocoa beans from the pods and use them as the raw material for making the chocolate.
Fermentation is the primary and critical stage in making chocolate. In this process, the cocoa beans are put into a bucket and covered, usually with banana tree leaves. The function of the leaves is to maintain the heat generated during fermentation. The process of fermentation occurs when microorganisms, especially yeast, naturally develop on the external case of the beans and begin to dissolve sugars into ethanol and eventually to carbon dioxide through oxidation reactions. As part of this process the beans peel open and the microorganisms enter inside. At this stage many chemical processes take place that lead, among other things, to creating the taste and aroma of the chocolate along with its brown color. At the end of the fermentation process, the beans are dehydrated in the sun to reduce moisture levels.
Once the beans are completely peeled, the next step is roasting them at a temperature ranging between 90-170 degrees. In the roasting process, the percentage of water in the beans falls below 3 percent, while other chemical reactions are occurring between amino acids and sugars (the Maillard reaction). These reactions occur due to the heat and produce odor and taste molecules that contribute to the final chocolate product. Therefore, if we change the roasting temperature and duration, we will get chocolate of slightly varying flavours and odors.
Grinding of the peeled beans releases the cocoa butter and creates smaller particles of cocoa solids. During this grinding, the cocoa butter becomes liquid, allowing the particles of cocoa solids to disperse evenly, creating a suspension. Often these two ingredients undergo a separation process – into the cocoa butter and cocoa solids. Compressing the suspension under high pressure while heating encourages the separation, where about 85 percent of the cocoa butter is collected. In this process the cocoa butter drips out and only the cocoa solids remain.
Roasted cocoa beans| Shutterstock
Now that we have all the raw materials, we can delve into the actual chocolate preparation.
2. The process of making chocolate
The process of preparing chocolate consists of three main stages: mixing the ingredients, grinding (Conching) and crystallizing the cocoa butter in a process called tempering.
“Mixing the ingredients” is the stage that determines the type of chocolate we will get at the end of the process: dark chocolate, milk or white.
Dark chocolate is mainly cocoa butter, cocoa solids and sugar, so its color is dark and its taste is relatively bitter, but it is the most “real” chocolate you can get because it is closest to the raw composition of the cocoa beans.
In the preparation of milk chocolate, sugar and milk (usually milk powder) are added to cocoa butter and cocoa solids. Adding milk reduces the concentration of the cocoa solids and therefore creates a less bitter taste with a lighter color, which greatly increases its demand among both children and adults.
White chocolate is the stepbrother, or if you will, the “black sheep” in the chocolate family, because it contains no cocoa solids, only cocoa butter, milk and sugar. The cocoa solids give chocolate its unique taste, color and health benefits. So despite the appeal of white chocolate, I myself and many others do not consider it real chocolate.
After mixing the various ingredients your chocolate is now ready. But the story isn’t over, since perfect chocolate is not just chocolate, and in order to prepare it one must control its physical properties, such as viscosity, texture and melting temperature.
The secret to perfect chocolate - controlling its physical properties
The grinding process is responsible for determining the viscosity and final texture of the chocolate. In this process, the mixture is grinded to reduce the size of the cocoa particles that are stirred in with the liquid cocoa butter. The smaller the cocoa particles, the less granular the final chocolate product. This also decreases the viscosity meaning less of a “bubble gum” sensation while chewing.
The process of crystallization is the final stage in which the melting temperature of the chocolate is determined - whether it will melt in your hands or only once you put it in your mouth. In fact, the only ingredient that determines the melting temperature of chocolate is cocoa butter, which is made up of fat molecules called triglycerides. One of the interesting chemical properties belonging to triglycerides is their ability to be packed in several different crystalline structures while the cocoa butter solidifies. This phenomenon is called polymorphism (many shapes).
Triglycerides can be packed in six different crystalline structures, each of which has a different melting temperature. The temperature at which the cocoa butter solidifies determines the main crystalline structure of the triglycerides, thus dictating the melting temperature of the chocolate.
The average temperature in our mouth is about 36.8 degrees Celsius. In order to produce the perfect chocolate, it is important that it be mixed in the mouth immediately after insertion, so that its texture will be uniform and its flavours will merge into one strong and dominant taste. The melting temperature of structures 1-4 are fairly low, where the best case is them melting in our hands and the worst case they will melt in their wrapping with only a sticky, dirty chocolaty liquid remaining.
Structure 6 has another problem. Its melting temperature is 36 degrees, so it will not get your hands dirty, but it will also take a relatively long time to completely melt in your mouth, which will require our assistance using our teeth or tongue. This preoccupation affects our eating experience so this crystalline form is not particularly desirable. That leaves us with the fifth crystal structure. The melting temperature of structure 5 stands at 34-35 degrees, which ensures rapid melting in the mouth, but not when we hold it in our hand. Perfect!
To ensure that the cocoa butter crystallizes and forms the desired crystalline structure (structure 5), a controlled process called tempering should be used. The two main parameters of this process are the chocolate temperature and the mixing rate.
The following steps will ensure a chocolate product with crystal structure 5:
A. Heat the chocolate to 50 degrees. This ensures all current crystalline structures will be melted.
B. After all has been melted, the chocolate is re-cooled to 32 degrees: this temperature is higher than the melting temperature of crystal structures 1-4, so only crystals of structures 5 and 6 can form. At this temperature, mostly small crystals are formed, mainly in structure 5, and are called “seeds”.
C. The temperature is lowered to 27 degrees: the rate of crystal growth increases.
D. Heat again to 30 degrees. This stage ensures that if crystals are formed in structures 1-4, they will melt and disappear.
Controlled use of the tempering process will eventually produce chocolate with the desired melting point. If we combine this with the accurate grinding of cocoa solids we will get a chocolate product with a smooth, non-granular texture that will melt as soon as we put it in our mouths, resulting in a delightful celebration of flavours - this is the perfect chocolate!
There is no doubt that you have come across chocolate with a kind of fatty, white layer that looked like something had grown on it. Before you get rid of such chocolate, stop - your chocolate is not spoiled! The worst case is its just not tasty.
This white layer is actually the cocoa butter. If the chocolate is exposed to significant temperature changes, for example, when moving from a shady place to a warmer place, some of the cocoa butter crystals temporarily liquefy and then solidify again. If the process repeats itself several times, the cocoa butter slowly climbs from the cocoa solids to the chocolate surface creating these white spots, in a process called “Blooming”.
To minimize the risk of this process occurring, it is important to ensure that the cocoa butter crystallizes in structure 5 - the most stable structure. It is also advisable to store the chocolate in a shady place that is not exposed to the sun therefore preventing exposure to changes in temperature.
Now you can understand that chocolate is not just a simple and delicious sweet. Creating the perfect chocolate is fraught with obstacles, and to prepare it properly one must understand its chemical and physical properties. So next time you eat chocolate, remember to appreciate every bite!
chocolate after "blooming"| photo by Narisa