Why Is Chocolate So Irresistible? A Chemist Investigates

by Max Harvey

              

(image: Wiki Commons)

With Lent now underway I have no doubt that many of you reading this have embarked on 40 days of not eating particular treats that you would normally turn to at every opportunity. For some of you this may even be the seemingly impossible challenge of giving up chocolate for the Lent period, a task which I have attempted many times myself, and failed on multiple occasions. But what is it that makes this delicious novelty so irresistible and apparently impossible to resist for any sustained period of time?

To understand the lure of this addictive substance we must delve into its chemical composition. Chocolate’s main and defining ingredient is cocoa powder which comes from pods of the cocoa trees. The beans from the pods then undergo a complicated fermentation and drying process before they are roasted and ground to make cocoa powder which can then be used to make the chocolate.

As a result of its ingredients, the average piece of chocolate is known to have over 1500 flavour components which make it one of the most complex foods that we eat regularly. However, just tasting good is clearly not enough to create the irresistible pull that chocolate possesses. Clearly there has to be something else going on!

On the sensory front, we can see how chocolate does not only appeal to our senses of taste, but in fact to all of our senses. The most important, arguable, is indeed the taste but even here the story is not all that simple. The combination of sweet, from the added sugar, and fat, due to the cocoa solids, is well known to appeal to a humans taste buds far more than either sugar of fat independently.

In addition to this however, the other four senses are also stimulated by the chocolate. When looking at a finely prepared piece of chocolate, the chic glossy finish that is observed appeals to our sense of sight as it portrays a perfected product with no flaws. This combines with the snap and crack as you break the chocolate in half which once again denotes a carefully constructed product, made with pride. The reason that both this glossy finish and satisfactory snap can be achieved is due to the manufacturing of the chocolate. When master chocolatiers make their chocolate it is essential that they obtain the correct cocoa fat crystals. All in all there are six different types of cocoa fat crystal that can be formed. Those that are type I-IV crystals create soft chocolate that does not produce a shiny finish or enable a crisp crack when broken and the type VI crystals are prone to allowing ‘bloom’ to form (the nasty white bits when chocolate is left too long). The repeated formation of the type V crystals however is what enables both the auditory and visual senses to be satiated when confronted with a piece of chocolate.

Furthermore, the type V crystals have a further trick up their sleeve. Cocoa solids that consist of these type V crystals have a melting point of around 34ºC. This is a fraction lower than the body temperature of a human but higher than that of room temperature meaning that whilst remaining solid in the packet, once placed into the mouth the chocolate will instantly begin to melt. This coating of the mouth in the melted chocolate adds yet another layer to the satisfaction created.

It is also well known that a high amount of our ‘tasting’ is actually through our sense of smell and hence the smell of and chocolate product is essential to the whole experience. The smell that accompanies the chocolate enhances and preempts the flavours that you are about to experience.

It is not just one of these senses that makes chocolate so delicious and such a wonderful experience, but the amalgamation of all of them combining to create a perfectly balanced yet dangerously tasty product.

At an even smaller scale there are individual chemicals within chocolate that make it yet even more irresistible. For starters, cocoa solids contain caffeine (so this is more prominent for those that eat dark chocolate) which is a natural stimulant and gives your body an instant boost upon consuming it. In addition to the caffeine is a large cocktail of other chemicals including theobromine, a mood lifter, tryptophan, which helps the brain make serotonin (a happiness chemical in the brain) and anandamide, an endogenous cannabinoid which stimulates the same regions of the brain as THC.

All of these chemicals combine together to make chocolate even harder to resist. So for those of you that are trying to not eat chocolate over the coming month, ask yourself, is it just a lack of strength of mind that will cause of you fail, or does the chemical complexity of chocolate mean that you have a predisposition towards being unable to resist it?