Easter is nearly here!

For lots of us, Easter is all about eating chocolate in a variety of shapes – mainly egg.

For many people, chocolate is joy itself. But why?

As is often the case, chemistry has all the answers.

Let’s take a look at some of the chemical processes that work to make your Easter a happy time of sweet chocolate indulgence.

Your Brain on Chocolate

Chocolate contains anandamide, a chemical which can improve your mood – indeed, its name is derived from the Sanskrit word for “bliss”.

It was discovered as the natural molecule that binds to the “bliss receptor” that tetrahydrocannabinol (THC) targets. THC happens to be the active ingredient in marijuana.

Although anandamide is produced naturally in the brain, it quickly breaks down. But in addition to the anandamide itself, chocolate contains molecules that prolong the lifetime of anandamide.

And it’s not just marijuana that shares certain chemical traits with chocolate – it also contains similar compounds to those found in morphine, amphetamines, and even ecstasy.

For example, phenylethylamine and tyramine increase dopamine levels, which can cause a racing heart and feelings of excitement. The stimulant theobromine might also contribute to a chocolate eater’s “high”.

Then there’s tryptophan, a molecule that’s linked to the release of serotonin. This is exactly the neurotransmitter you need if you want to induce a mellow mood of contentment.

As if this wasn’t enough, eating chocolate can cause your brain to release endorphins – the beloved happiness hormones that promote overall feelings of well-being.

Chocolate is even considered an aphrodisiac by some.

With all this chemical activity going on, how on Earth is chocolate still legal? How are people allowed to drive and operate heavy machinery while under the influence of chocolate?

The simple explanation is that chocolate only contains trace amounts of these compounds, and any significant amounts can be quickly metabolised by the body.

Still, there’s little debate that your average bar of chocolate can leave you feeling very good indeed. The delicious taste and smooth melting texture only contribute to the pleasure.

What Does Chocolate’s Taste Have in Common with Toast, Steak, and Fried Onions?

The Maillard reaction is responsible for some of the most delicious flavours on the planet. It’s a reaction between amino acids and reducing sugars when heated, and tends to make food brown and tasty.

This reaction occurs in the production of chocolate, but also grilled steak, fried onions, toast, chips, and the malted barley that makes beer and whisky so irresistible.

It is named after French chemist Louis-Camille Maillard, who first described it in 1912. From around 140°C, the reactive carbonyl group of a sugar reacts with the nucleophilic amino group of an amino acid. This generates an unstable intermediate that can lead to various chain reactions.

The result is a complex mixture of molecules which, while difficult to characterise, nonetheless create a range of highly desirable scents and tastes.

The Health Benefits of Chocolate

Another possible reason why chocolate makes you feel so amazing is that chocolate can be good for you.

It contains polyphenols, a class of antioxidants, and in particular the subset called flavonoids. These phytochemicals can neutralise potentially dangerous free radicals.

Cocoa is a particularly rich source of flavanols such as epicatechin, which has been linked to cardiovascular health. Research has found that increased flavanol consumption from cocoa correlates with increased nitric oxide levels, corresponding to good circulation. Flavanols also induce vasodilation, the relaxation of blood vessels, and epicatechin in particular is linked to improved blood flow.

Similarly, a study of almost 20,000 people found chocolate consumption is linked to lower blood pressure and a lower risk of cardiovascular disease. In fact, the data indicated that eating just 6g per day slashed the risk of heart attack and stroke by more than a third.

A recent review went as far as to conclude that “Cocoa consumption could play a pivotal role in human health.”

But tread carefully – studies on the health benefits of chocolate focus on pure cocoa and dark chocolate, while the majority of Easter eggs are made out of sugary milk chocolate.

Chemistry in Chocolate Development

So we’ve looked at how chemicals within chocolate can affect your mood, taste delicious, and even improve your health. Now let’s take a look at the sort of chemistry that’s involved in developing the chocolate creations we all know and love.

We recently raised a toast to Helen Sharman, the PhD chemist who was the first British astronaut. Before her momentous trip to space, Sharman was a research chemist at Mars Confectionery, investigating chocolate flavours and developing the first Mars ice cream bars.

“You had to use your science common sense in a production environment,” she explained in a recent interview.  Sharman loved applying her chemical and materials science knowledge to chocolate development.

One of Sharman’s considerations was crystal structures, and indeed Cadbury have used X-ray crystallography to improve the taste of their chocolate by altering their manufacturing procedures.

The team at the University of Nottingham behind the famous “Periodic Table of Videos” have also explored the “Chemistry of Creme Eggs”.

In this excellent video, they add to the discussion on chocolate crystal structure, but also show the explosive results of heating a Cadbury Creme Egg in potassium chlorate, and use a vacuum pump and vacuum desiccator to mimic a Creme Egg in space – not one of Helen Sharman’s experiments!