How to Roast Cocoa Beans

It is a long process to produce chocolate from cocoa beans, and possibly the most important stage is roasting. Cocoa beans are roasted to develop the flavour, kill bacteria, reduce the moisture and loosen the outer shell. Getting the roast right is the difference between making run of the mill chocolate to creating incredible chocolate. The best part of it is, there are many ways to roast cocoa beans and there is no right or wrong way, it is totally dependent on the preferences, taste and recipe of the chocolate maker. But how and why exactly do we need to roast cocoa beans?

Cocoa Roasting for Beginners

It is not only professionals that can make chocolate, but it is also perfectly easy to make chocolate at home. That can also be said for roasting the cocoa beans. There are a variety of ways to roast the beans, such as in a pan on a stove, in a standard kitchen oven, in a coffee roaster or in a rotating drum overheat.

As a beginner, there is no need to get intimidated over the vast amount of information about roasting cocoa beans. Every chocolate maker has their own way of roasting beans and as such, can determine the tools used, the temperature and the length of time of each roast. There are many variables that contribute to the final flavour of the chocolate and so it is up to the maker to experiment and taste different roasts until they find a formula they are happy with.

There are a few important factors to consider when roasting the beans: the size of the beans, the moisture content, the smell during the roast and the development of flavour. When it comes to how long to roast and at what temperature, this is up to the maker, what type of beans they use and whether they prefer a light or a dark roast. The only way to find out what they are is to get roasting and keep notes to ensure you remember what works and what doesn’t.

Why cocoa beans are roasted?

Killing the bacteria

Cocoa beans should be roasted for a number of reasons. The most important of which is to make sure that the beans are safe to consume. The conditions in which cocoa beans are fermented are ideal for the growth of bacteria, fungi and mould.

On top of that, the beans are usually dried on the ground, which gives the opportunity for bugs and other biological hazards to contaminate the beans. Therefore, the beans should be exposed to heat to destroy any harmful bacteria and to remove any external contaminants.

It is important to roast the beans sufficiently and to expose them to a high enough heat to significantly reduce the harmful bacteria, such as salmonella and E. coli. If any manage to survive the roast, the heat from the refining stage should help to ensure that the chocolate is safe to consume.

Flavour development

Roasting the beans is vital for the development of good flavoured chocolate. During roasting, various chemical reactions occur inside the bean where the amino acids and natural sugars are converted into flavour compounds. Cocoa beans that are not roasted have a bitter, acidic, astringent and nutty flavour, however, when the beans are roasted,  the acidity is decreased by reducing the concentration of volatile acids.¹ The acidic, vinegary smell that is formed during fermentation is driven away and replaced with the far more pleasant chocolatey aroma and taste that we all know and love. The different flavour profiles that can be achieved depends on the type of bean that is being used and how they are roasted.

Michael Laiskonis from Ice’s chocolate lab explains the reactions:

“Most importantly, all of the complex chemical reactions (Maillard reactions and Strecker degradation) take place during roasting, transforming the flavor precursors created during fermentation into hundreds of individual compounds that give chocolate its alluring color and taste.”²

Reducing the moisture

Cocoa beans still contain around 7.5% moisture and it is important to lower this as water and chocolate do not mix well. Roasting the beans will significantly reduce the moisture content and make the grinding process so much easier. It is easy to notice when the water is being expelled from the beans as it is responsible for the loss of weight and the popping noise during roasting.

Separating the husks

Roasting also helps separate the husk of the bean from the nibs. It is a good indicator that the beans have been roasted well when the husk comes off easily using your fingers. Roasting well makes the cracking and winnowing stage far more easy-going.

Consider the beans

When roasting cocoa beans, it is necessary to consider the type of beans being used, as it will determine the best way to roast them. As an example, bulk cocoa or Forastero beans are usually roasted at higher temperatures than the more flavourful Criollo or Trinitario cocoa beans.

After that, it is important to sort and roast the beans according to size in order to ensure that they are roasted evenly. The beans should be separated into large, medium and small beans and then roasted in batches, which will, of course, govern the length of the roast and the temperatures used.

The moisture content of the beans is also crucial. The beans need to be roasted enough to sufficiently evaporate the moisture, but without over roasting them. There is the risk that drier beans will break during roasting.

Then, of course, chocolate makers will determine the roast based on the roasting profile they want to follow and the flavours they want to develop. The raw cocoa beans can be tasted to recognise what flavours to develop and then different roasts can be tried to see what works best.

Create a Roasting Profile

A roasting profile is the set of temperatures used when roasting cocoa beans to fully enhance their flavour and condition for making chocolate. A good roasting profile will meet all the requirements discussed above, such as sterilising the beans, loosening the husks and developing the best possible flavours and aromas. Of course, flavour is very subjective, so the best roasting profiles are wholly dependent on the tastes and preferences of each chocolate maker. So, the way to create a roasting profile is to do small test roasts on new beans, periodically taste them and then compare the results.

Many chocolate makers start the roast at a high temperature, 150-190°C (300-375°F), to kill the bacteria, release the moisture and to expand the bean for easy separation of the husk. The temperature is then lowered to continue roasting the centre of the bean without burning the outside. When it comes to the length and time of the roast, there are no official standards and so it is up to the maker to figure out what they feel is right. They should smell and taste the beans until they find the flavour notes they are happy with. The beans making popping or cracking noises is a good indicator they are nearly there.

Here is the result of a study and the advice of some well-respected chocolate makers:

A study conducted by the Food and Science Technology, Campinas revealed that:

“Higher scores of sensory acceptance were obtained from roasting temperature range 90 to 110 °C (190-230 °F). On the other hand, the sensory acceptance was significantly lower for the samples obtained from higher roasting temperature 150 to 160 °C (300-320 °F), for the aroma, flavor, texture and overall quality attributes.”³

John Nanci from chocolatealchemy.com says:

“In general though, they can be roasted from 5-35 minutes anywhere from about 120-160 C (250-325 F)… Generally, I like to have a roast take 15-20 minutes, regardless of method. Under that amount of time and the beans seem to retain a raw unfinished flavor. Over that and they start to taste baked and sort of flat.”⁴

Xtcchocolate.com recommends:

“I have found that having a ‘starting point’ of a default roast is a good place to start. Using my own countertop drum roaster, that’s 20 minutes at 140℃ (280°F)… With practice, you can tell if a bean is under-roasted (often exhibiting grassy or earthy flavour notes) or over-roasted (smoky or burnt notes).”⁵

Thus, finding the right roasting profile for a batch of beans is all about experimenting with different temperatures and timings. When checking the temperature, it is important to check the temperature of the beans, not just the roaster. This can be done with a thermocouple probe buried into the beans during the roast or with an infrared thermometer after the beans are taken out. When trying out different roasts, record the results, the type of beans, the roasting details and any suggestions for improvement. Following this advice, you will learn the ideal roasting profile for each variety of beans, find your own recipes and produce some fantastic artisanal chocolate.

How to know when the beans are roasted

There are a few ways to tell when the beans are optimally roasted: the colour, smell, taste and popping noise. Cocoa beans are already darkened during fermentation but they will darken slightly more during the roast. The colour change is noticeable if a bean is opened before, during and after the roast.

The aroma and taste of the beans change significantly throughout the roasting process. The beans will start off smelling slightly vinegary and acidic due to fermentation, which will peter off into a much more pleasurable fresh brownie smell the more they are roasted. It is important to really take in the smell during the experimental stage and to regularly taste the beans to observe the development. Of course, the beans should not smell anyway near burnt as that will impact the flavour.

Then there is the popping or cracking noise which is a strong indicator the roast is nearly finished. However, if you have roasted different sized beans, the smaller ones will roast quicker and therefore start popping a lot sooner than the larger ones.

Equipment for roasting at home

There are many ways that cocoa can be roasted and a variety of different equipment that can be used. First, identify what type of chocolate you want to make, what attributes you want it to have, and then select the roaster. If you ask the question “what is the best roaster to use for roasting cocoa?” every chocolate maker will give you a different opinion. It depends on what exactly you are trying to achieve. The beans can be roasted in an oven, in a coffee roaster, in a pan on a stove or a rotating drum overheat.

Oven

An oven is a popular way to roast cocoa beans and a standard kitchen oven can be used for people at home. Just spread the beans in a single layer on a tray and place them in the oven, setting the desired temperatures. Unless you have some kind of movement in the oven, the beans should be moved around a few times for a more even roast.

The roasting temperatures and time would vary depending on your own preferences, the size and type of bean, the desired flavour and the oven. As we have discussed above, many makers start the roast at a high temperature of around 150-190°C (300-375°F) for 5 minutes and then gradually lower to around 120-160°C (250-325 F) for a further 20-25 minutes. Whereas other makers roast for a longer time and at a lower temperature for a lighter roast. If you are roasting cocoa nibs, the temperatures definitely need to be lowered for a gentler roast. An infrared thermometer can be used to check the temperature of the beans.

However, if you have or are starting a chocolate business, a commercial oven would be far more suitable, to have more control and to be able to roast larger volumes. It would also give your business more flexibility by being able to bake other goods and to offer other products. Some commercial combi-ovens even allow you to program the temperature, times and humidity, so when you find a roasting profile you are happy with, you can set the parameters into the oven. Then the next time you use it, you can place the beans in the oven, select the program and then leave it until it’s done. This will allow you to concentrate on other activities, be more productive and even allow an untrained person to complete the roast.

Drum Roaster

A drum roaster is a cylindrical chamber that rotates horizontally overheat to give all sides of the bean an even roast. There are many types of drum roaster and they come in a range of different sizes, from small table top drums to large industrial machines. They can roast over a gas grill, a heating element or an open fire and can roast anywhere from a few hundred grams to hundreds of kilograms.

Some makers say it offers the most flexibility, achieves the most even roast and results in the best tasting chocolate. There are many on the market, however, it is also possible to make one yourself, so that it can be designed to suit your specific requirements. A huge advantage of a drum roaster is that you could place a probe inside the mass of beans connected to a computer. This will allow you to log and visualise the roast in real-time and to use for comparisons.

To use the roaster, pre-heat it to around 175-205°C (350-400°F), pour the beans into the drum and then start the rotation. Thermometers can be placed below the drum and inside it along with the beans. The temperature should not be allowed to go much over 205°C (400°F), as the beans will quickly dry out and potentially over roast. To tell when the beans have finished roasting, use your sense of smell and judgment as well as listen out for the beans popping. You could also take out a bean occasionally to taste.

Coffee Roaster

Some coffee roasters are also great for roasting cocoa. As they are designed for coffee, they will need to be modified slightly when using cocoa beans. Coffee is normally roasted at a much higher heat and so the temperatures will have to be adjusted to suit the different roasting profiles. Like some ovens, a good coffee roaster can be programmed which will make repeating roasts far easier. Also, some coffee roasters have a rotating drum inside which will give an even roast.

Of course, whenever roasting cocoa, your judgement is vital when deciding temperatures and when to finish the roast.  There are so many different types of coffee roasters on the market, but many chocolate makers recommend the Behmor 1600, which can roast up to 2kg of beans.

In a Pan on a Stove

The simplest way to roast cocoa beans is in a pan on a stove. Probably not the most effective or consistent, but is something nearly everyone can do. I have made plenty of great-tasting chocolate in a pan in my kitchen. Start on high heat to kill off the bacteria for 5 minutes and then lower the heat for a further 20-30 minutes or until you are satisfied with the roast.

But to roast this way, you need to use your judgement more than ever. Use your sense of smell and taste to ensure the beans don’t overcook and listen out for the beans popping. Take the beans off the heat when you are satisfied with the result and when the husks easily fall off the bean when you crush them using your fingers.

‘Raw’ vs. Roasted Cocoa

• Although some products will say raw cocoa, it is not technically raw as it has gone through the process of fermentation. Fermentation exposes the beans to heat, yeast, bacteria, and other microorganisms that break down the sugars.
• It is generally accepted that raw food must not be heated above 118°F (47°C), but cocoa experiences temperatures of up to 122°F (50°C) during fermentation.
• When they say “raw cocoa”, they are referring to beans that have either not been roasted or roasted lightly.
• Unroasted cocoa beans are possibly unsafe to eat and could contain E. Coli, Salmonella, Staphylococcus and other harmful bacteria. Roasting kills off most of the bacteria and pathogens.
• ‘Raw’ chocolate is usually promoted for its supposed health benefits as they say roasting negatively affects the levels of nutrients and antioxidants.
• However, there have been almost no studies conducted on the effects of roasting on phenolic content,antioxidant activity, lipid quality, proximate composition and mineral content.⁶ Therefore, the claims are highly debatable.
• Roasting is not just safer, it is important for the development of the flavour and texture of the beans