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The Science of Chocolate

By Cocoa Runners  ·  5th August 2021  ·  Science

This is our section on the science of chocolate making. For the science of chocolate eating (!), see our section on Taste & Flavour.

There is no one right way to make chocolate. (Though there are plenty of wrong ways, of course!) Since the recent boom in craft chocolate making, we’ve seen our makers push the boat out further and further from shore, discovering new techniques, ingredients, and controversies along the way.

So here’s a brief overview of the science of making chocolate. Feel free to use the table of contents below to jump around.

How Chocolate is Made

The process of turning a cocoa bean into a chocolate bar is a long and complicated one, with every step of the way having an impact on the final flavour of the bar.

There’s a lot to cover, from fermenting and drying to roasting and grinding, from conching and tempering to moulding and wrapping. In fact, there’s so much to say that we’ve dedicated a separate piece to it, with further articles exploring each of the steps in the process. You can read all about that here, in How is Chocolate Made?

Chocolate’s Ingredients

Craft chocolate should only have two main ingredients: cocoa beans and sugar. (Make that three if it’s milk chocolate.) There might also be an emulsifier involved, especially if the chocolate is made in a hot climate (read on for more).

Often “cocoa beans” are separated into cocoa mass, which is essentially unsweetened cocoa powder, and cocoa butter, which is just the natural fat of the bean.

Cocoa beans

Cocoa beans are where the magic starts. Having been harvested, fermented and dried, they are shipped to the maker who starts the process of turning them into chocolate bars.

On labels they are often distinguished into cocoa mass (the brown powder used to make cakes and instant hot chocolate) and cocoa butter, the white fat of the bean.

Cocoa butter

Cocoa butter, or the natural fat of the bean, is where the true magic happens. This is the substance that melts at just below human body temperature, which means chocolate stays solid on the table but melts in your mouth. It is undoubtedly the reason why chocolate has become such a significant food around the world.

It is also used heavily in the cosmetics industry (it’s a fantastic moisturiser), and is the primary ingredient of white chocolate.

Read more: Cocoa butter

Sugar (and other sweeteners)

Technically speaking, for chocolate to be called “chocolate” it has to include sugar (or a sugar substitute). Some hardcore enthusiasts like to stop at the cocoa bean and opt for 100% cocoa bars, with no sugar added whatsoever, but most of us need some amount of sugar to take the edge off the cocoa beans’ natural intensity and astringency.

If cocoa butter is what makes chocolate so special, sugar is why it’s so widely adored – and usually not for the right reasons.

The primary ingredient in mass-produced chocolate is sugar. When we crave chocolate, we’re actually craving sugar. This addictive substance is often combined with fat and salt to override our brain’s satisfaction response and make us eat far more than we should (or want to).

Craft chocolate makers enjoy experimenting with sugar alternatives, such as date sugar, coconut sugar, or maple sugar. It’s also possible to forego the sugar altogether, and instead get all the sweetness from another common ingredient: milk.

Milk

Milk is – unsurprisingly – an ingredient used in the creation of milk chocolate. (It’s also used in most white chocolates.) It is added in powder form (liquid and chocolate do not go well together!) during the conching stage, which typically gives the finished chocolate a smoother melt and sweeter taste.

Although milk chocolate is often sweeter than dark chocolate, there isn’t always more sugar involved. Instead, the milk caramelises in the heat of the conche, which makes it sweeter and gives milk chocolate its common caramel flavour.

Thanks to this caramelisation, some milk bars can be made without any added sugar at all, such as these 70/30 and 80/20 “dark style” milk bars from Zotter:

And with the growing popularity of veganism, there’s been a recent proliferation of alternative milks, such as coconut milk or oat milk.

And a final word to the wise: some mass-produced dark chocolate confectionery actually lists “milk” in the ingredients. How these bars can get away with calling themselves “dark chocolate” is beyond us. Needless to say, true dark chocolate should NEVER contain milk.

Lecithins

An interesting point of contention within the craft chocolate world is the acceptability of the use of lecithins. Lecithins – usually soy or sunflower – are used as an emulsifier, which reduces the viscosity of melted chocolate and makes it much easier to work with.

They are often used by makers who craft their chocolate in the country of origin, where it tends to be hotter and where there are bigger challenges to pull off a making process so dependent on precise temperatures. But it is also used by makers in cooler climates to reduce waste, lower costs, and shorten the time it takes to clean machinery.

Others argue that lecithins impact the pure flavours of craft chocolate, so shouldn’t be used. We don’t take a stand either way – some bars in our library contain lecithins, others don’t. But none of them contain ingredients such as palm oil, which is often used in mass-produced chocolate.

A vanilla orchid.

Vanilla

One ingredient in mass-produced chocolate that can hide all manner of sins is vanilla. Sometimes listed as “vanillin” on labels (or “Madagascan vanilla pods”, if they’re trying to be fancy), it’s an ingredient that’s used to obscure poor quality beans.

Treat it as a warning sign if you see (unflavoured) dark chocolate that contains vanilla. It means the maker isn’t trying to spotlight the cocoa beans, so they’re less likely to have been sourced well and the bar won’t have the depth of flavour you should expect from good chocolate. (Some bars, such as Forever Cacao’s Lucuma & Vanilla or Ethereal’s Blood Orange & Vanilla Bean, are intentionally flavoured with vanilla – so these should of course be an exception!)

It’s a little more acceptable to see vanilla in milk or white chocolate, though purists would still see this as an unnecessary inclusion.

Interested in learning why vanilla is the ingredient of choice for obscuring bad cocoa? Read more in our post on cross-modal perceptions of vanilla.

Inclusions

So that’s a breakdown of chocolate’s most common ingredients, but chocolate makers don’t stop there. On the contrary: there’s a whole world of weird and wonderful chocolate flavours (what we call “inclusions”) to explore.

First are the classics: caramel, sea salt, coffee, coconut, fruit and nuts. They’re often inspired by mass-market confectionery brands, and are attempts by our makers to show you what these childhood favourites should taste like.

Next are the spiced chocolates. Peppers and chillies are a popular inclusion in chocolate, as the sensation of heat combines nicely with chocolate’s cooling properties. They range from the extreme heat of the Carolina Reaper Chilli, through Madagascar’s Black Pepper and Pink Pepper, to the nice and cool Peppermint.

And finally we come to the downright weird. These are flavours you would never think to combine chocolate with, but somehow it works. These are often inspired by the maker’s local culture, such as Reindeer Moss & Lingonberry from Norway’s Fjak, Quinoa from Cacaosuyo, Shattell and Minka in Peru, Salted Egg from Singapore’s Fossa, and Seaweed & Gorse Flower from NearyNogs on the Northern Irish coast.

Read more: Beyond Sea Salt

Types of Chocolate

There are four main types of chocolate. Most of us have a favourite, but they all bring something different to the table, and require slightly different steps in the making process.

Dark chocolate

Often considered the “pure” form of chocolate, dark chocolate contains only cocoa beans and sugar (at its simplest). The sweetness of the sugar counteracts the cocoa beans’ natural astringency, which allows us to enjoy the flavours of the beans without having to fight through the bracing intensity.

Milk chocolate

Milk chocolate is simply dark chocolate with some form of milk powder added during the conching stage. It tends to have slightly less cocoa and slightly more sugar, though not as much more as you might think (since the milk also acts as a sweetener).

100% cocoa

100% cocoa is technically not chocolate, since it doesn’t contain any sugar. But that doesn’t stop many chocolate fans loving it, admiring it as the purest expression of the beans’ natural flavours. It takes some getting used to, though, with the intense astringency often overwhelming first-time (and second-time, and third-time!) eaters.

White chocolate

White chocolate is the most contentious of the four types of chocolate, with some people going so far as to say it’s “not real chocolate”. But we disagree.

White chocolate is made from cocoa butter (the natural fat of the cocoa bean), milk, and sugar. As we’ve said before, cocoa butter is the most amazing part of the cocoa bean. It’s the reason chocolate melts when you put it in your mouth, for example. Can you think of any other food that stays solid at room temperature but melts in your mouth? (There might be a few, but it’s a challenge!)

White chocolate tends to be the sweetest of the chocolates, and therefore carries the least of the beans’ natural flavours. But that doesn’t mean it has no variation, as this selection perfectly demonstrates.

Ruby chocolate

In 2017, Barry Callebaut announced that they had created a brand new type of chocolate: ruby chocolate. Its attractive appearance and sweet taste has captured many people’s imaginations, but it is unfortunately little more than a marketing ploy.

Read more: Ruby Chocolate: Hype or Hero?

Raw chocolate

And on the topic of marketing ploys, some of our most asked questions at Virtual Tastings are on the topic of raw chocolate.

Raw chocolate claims to be made from raw cocoa beans, bringing with it a host of health benefits. But since beans are cooked during fermentation, there is no such thing as raw chocolate.

What makers tend to mean by “raw” is actually “unroasted”. Some makers – such as Raaka in Brooklyn – choose not to roast the beans, which gives a different – and slightly more savoury – flavour profile on the finished product.

As for the health benefits of raw chocolate, we’re yet to be convinced. For more, see our blog post on this and other dubious claims about chocolate and health.

Truffles

And finally, it is worth giving a brief mention to the emerging market for filled chocolates. Whether they can all be called “truffles” or not is a contentious issue, but they are certainly proving popular.

When making filled chocolates, craft chocolate makers carefully select the cocoa beans to create a chocolate that complements the filling. The chocolate is not just a vector for flavour; it’s an equal player in the flavour wave of the truffle.

Read more: The History of Chocolate Truffles and Ice Cream

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