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The Art of Roasting Cocoa Beans

By Cocoa Runners  ·  24th October 2021  ·  How is Chocolate Made?

Contrary to common belief, the building blocks of chocolate’s final flavour profile are established well before the cocoa beans meet any other ingredients. The chemical reactions that do, or do not, take place within the bean can make a world of difference to the chocolate we eat.

Some of these reactions take place during the fermenting and drying stages, but it is roasting which truly transforms fermented beans into recognisable yet unique cocoa.

Often overshadowed by the contemporary health-food craze of deceptively named ‘raw’ cacao (we’ve written about this previously), roasting is a varied and vital step in chocolate production that deserves justice.

To Roast or Not To Roast

Roasting is not just a matter of flavour, but safety and practicality.

Due to the hot and humid conditions of fermentation, the beans can be exposed to a vast range of mould, fungi and bacteria, including E-coli and salmonella. Insects and bugs have also been known to invade cocoa batches during drying. The high temperatures of roasting kills off all these nasties, leaving us with sterile and safe cocoa.

Furthermore, roasting reduced the chances of running to trouble further down the chocolate production line. For example, as the heat dries out and embrittles the beans’ husks, the process of cracking and winnowing becomes considerably smoother.

The overall texture of chocolate also benefits from roasting. Even after drying, cocoa beans are still composed of around 7% water. If this water is not extracted, the cocoa cannot reach the desired consistency during grinding and conching. The dry cocoa masses and wet cocoa butter will be unable to emulsify and form a grainy mess rather than chocolate’s desired silky consistency.

Cocoa Roasting: A Sensuous Science

When chocolate craft is at its best, the chemistry taking place within the roasted cocoa bean can be detected with all five of our senses.

The unroasted bean starts off with an, often unpleasant, astringent tang and bitter nuttiness from the volatile acids created during fermentation.

But all this changes once the beans are fired up!

The Millard Reaction takes place as the amino acids and natural sugars react and transform into a range of new, flavorus compounds, visibly deepening and evening out the already rich shade of brown the beans took on during fermentation. Meanwhile the acrid smell of boiling vinegar is replaced with the first joyous wafts of that familiar aroma of warming chocolate.

Things heat up further, and; snap! The excess moisture evaporates, erupting from the surface of the cocoa bean with a series of satisfying crackles, indicating they are almost ready to be taken out.

When the chocolate maker is satisfied with their work, they must rapidly snuff out the reaction by cooling down the beans to room temperature. Cooling racks, fans and air conditioning are often commandeered for the best results.

Once cool enough to handle, the whole beans should be brittle enough to break apart. The exterior ‘husks’ should give way easily, revealing the coveted nibs within.

Then, the ultimate test; taste. Some chocolate makers take the opportunity to check out their creation for themselves by sampling a nib or two; the perks of the job!

Finding the Perfect Roast

There is no one way to roast a cocoa bean!

Whereas a mass-market chocolate producers take a one-size-fits-all approach, craft chocolatiers know better: No two batches of beans are the same, therefore nor should the roast be.

A craft chocolate maker will vary their approach depending on the batch of beans, taking into account their type and origin, estimating their moisture level, weeding out damaged beans and sorting them into their sizes for an even roast and optimum flavour enhancement.

They must also choose whether to extract the cocoa nib from its husk before or after roasting. Whereas mainstream companies such as Nestlé and Lindt opt to roast only the nibs, in craft chocolate it’s more common to find the beans roasted whole, allowing the nib to absorb more flavour from its surrounding husk.

A ‘perfect’ roast can be achieved using a number of heat sources, including ovens, drum roasters, a pan over a stove, hot air guns and even coffee roasters. Some methods, like the drum roaster, may create a more consistent roast, but in the right hands there is no best equipment!

Though the roasting temperature of cocoa beans usually ranges between 120-160oC for anywhere from 5 to 35 minutes, each slight tweak to the roasting formula will cause different chemical reactions to take place, creating an entirely different flavour.

Finding new flavours through roasting is often a matter of trial and error, with established roasting formulas often kept under lock and key by secretive chocolatiers.

Ultimately, as long as the beans are roasted enough to be safe for consumption, but not burnt, the ‘perfect’ roast is as subjective as claiming a perfect shade of red!

Taste the Difference

Fresco Chocolate have come up with some different takes on roasting, and we’ve bundled together some bars which show how different roast profiles can result in different chocolate flavours. Each pair of chocolate bars contains the exact same ingredients, down to the crop, drying and fermentation time of the beans, but with different roasting times. See if you can distinguish your dark roasts from your light!

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