Most cocoa beans that you will encounter for chocolate making are fermented, but are not roasted yet. Regardless of how hot the fermentation was, these are still refereed to as raw cocoa. The fermentation process does darken them up considerably and you may think they are already roasted, but the lack of an evenness in color and texture is the key to telling when they are unroasted. Roasting accomplishing a number of things.
It helps separate the outer husk from the inner bean and makes cracking and winnowing much easier.
It also virtually sterilizes the cocoa bean. This is rather important as the conditions in which cocoa beans are fermented are naturally full of bacteria, fungi and molds. There is a "quantifiable" risk of infection from unroasted cocoa beans. Roasting reduces this risk.
Various chemical reactions occur when cocoa beans are roasted and proper roasting is integral to good flavored chocolate. The vinegar smell from fermenting is driven off. Raw beans don't taste like chocolate. Roasted beans do.
Finally, for those of you who have read about the nutritional value of chocolate and cocoa beans, and worry that roasting destroys these nutrients, please remember that all of the research (to the best of my knowledge) has been done on fully roasted, fermented cocoa beans and chocolate. Sure, if you over roast or over process it, you may well loose some nutrients, but I personally take the nutritional benefits of chocolate as a benefit, not a goal. The flavor is my goal at Chocolate Alchemy.
Whole beans or nibs? Ignoring the fact that no roaster out there will roast nibs, the biggest issue with roasting nibs is the danger known as tipping in coffee. The uneven nature of the nibs can lead to over roasting the edges because they dry out so fast and introducing defects that can lead to harsh acrid flavors. Whole beans roast a whole lot more predictably. Stick to those if you can. Plus, we are mostly discussing how to use cocoa like coffee, and as we will get to, using the whole bean (ground up) makes a better beverage the just nibs.
That said, if you do want to roast you own nibs, you’ll have to stick to roasting in an oven and treating them a bit more gentle that you normally would lest you damage them.
Options for Home Roasting Cocoa Beans
There is a ton of information out there on the web about roasting coffee at home. If you can roast coffee at home (I do), you can roast cocoa beans at home. Sweet Maria's is a great source for coffee roasting information and some supplies.
Unlike coffee, which roasts anywhere from 400-460F, cocoa beans need more gentle treatment. In that there are no hard or fast coffee roasting rules, the same holds true for cocoa. In general though, they can be roasted from 5-35 minutes anywhere from about 250-325 F. To do this, there are four options, but only two are feasible:
Coffee roaster (the Behmor 2000 is our pick)
Oven roasting
Air roasting (not feasible)
Drum roasting with a gas grill (not feasible).
With all of the methods, the basic technique is the same. Subject the cocoa beans to a high temperature initially, slowly reduce the temperature and stop the roast when the beans are "cracking", but well before they start to burn.
The initial high heat lets the beans gain some thermal momentum and allows for a good separation of the husk and nibs as the beans expand. You lower the ambient temperature so as not to burn the outside of the bean, but let the interior continue to roast. Finally, the cocoa beans will start to pop and crack as water vapor is explosively released. This happens when the cocoa bean temperature is around 250 F. This is your sign you are just about done roasting. Experience and smell (you don't want any burned smell) are the key indicators when the beans are roasted. Once the cocoa beans are roasted and cooled, try separating the husk from one. If it comes off easily, you did well and the beans are fully roasted. Likewise, taste some. They should have a nice cocoa flavor, with no raw or burned flavors.
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.
Drum Roasting
If you are going to be serious about roasting cocoa beans at home, and/or making chocolate, this is the method I recommend. It has the most flexibility, the most consistency and gives the best overall product for the least amount of work.
In this category there are three ways you can go. Going from simply to complex they are:
Home made, using a gas grill.
Stand alone home coffee roaster
Commercial coffee roaster.
All have their advantages and disadvantages.
Gas Grill
In the early years I used and recommended this method. It worked well enough but takes quite a bit of user competence and is difficult to make solid recommendations since you basically have to construct it yourself. Many home coffee roasters use the RK Drum but I’ve found they don’t do great with cocoa due to the large mixing vanes. Unlike coffee that has predictable audible cues, 1st and 2nd crack, cocoa doesn’t have this so unless you go through the not insignificant job of modifying the RK Drum you will be roasting mostly blind. I mention this mostly out of posterity.
Home Coffee Roasters
There are only two off the shelf coffee drum roasters that I know of that can do a reasonable amount of cocoa beans on a small scale. The Behmor 2000 and the Hot Top.
Between the two, there is just really isn't any contest. The Hottop will do 6-8 oz of cocoa, maybe 12 oz if you push it. I don’t recommend it.
The Behmor 2000 roasts 2-2.5 lb. I suggest not trying to roast less than that. Using it is very simple.
Load 2 - 2.5 lb of cocoa
Roast on Profile P1 for 18-22 minutes, stopping when you smell the characteristic chocolate brownie smell.
Cool
In the same way you can use a Behmor 2000, you can use pretty much any commercial drum coffee roaster if you have the use of one. There is no cross contamination of taste either. I roast coffee and cocoa in the same roaster and both taste as they should. I personally use an old Royal #5 which runs off propane and can handle 15 lb of coffee. But because cocoa roasts so much cooler than coffee, I routinely roast 30-35 lb of cocoa.
As a rough guide pre-heat to 350-400 F, and drop in the cocoa. With a thermometer in the bean mass, the temperature usually drops to the low 100's. I typically roast, adjusting my heat input, to reach 250-260 F over about 13-18 minutes. Yours of course may vary, but as a bench mark, for me, the beans just start to crack in this temperature window.
How to use a Professional Coffee Roaster for Cocoa
None of that above really tell you how to roast cocoa, only the equipment that can be used.
Let’s get into the weeds of how to roast. I’ll grant it is a learning curve, but the benefits are numerous.
Profile Drum Roasting
I have developed a method of Profile roasting cocoa that is remarkable similar to the profiles used by coffee roasters. You have a drying, flavor development and finishing phase.
In lieu of repeating (for now) what I have written in great detail, I recommend you go read Ask the Alchemist 200 through 206. I go into each phase in great detail and how you can adjust each one to reliably alter the flavor profile of your chocolate to suit your tastes.
I want to make it VERY CLEAR this is about DRUM roasting and can NOT be applied to oven (even convection) roasting.
Oven Roasting
That I am aware of, virtually everyone has an oven in their kitchen, and you can roast cocoa in it. Unfortunately it is not quite as simple as baking a batch of brownies.
Over the years I have written a lot about the difficulty of roasting in an oven. I’ve settled on two moderately robust methods that I outline below as Option 1 and 2. If you care to see why I recommend drum roasting, feel free to dive in.
Issues with long and low roasting.
In general, if you try oven roasting, you will start hot (350-400 F) for a short amount of time and slowly lower it to your target temperature (275-300 F). This is for about 2 lb/1 kg of beans. The more you are roasting, the higher your initial temperature can and has to be and the time will probably be a little longer.
Option 1
Remember, you want to roast the cocoa beans, not bake them. This is how that looks:
Whole cocoa beans
375-400 F 5 minutes
350 F 5 minutes
325 F 5 minutes
300 F for 10-15 minutes or until done*. Look for the aroma of baking brownies and/or pops. Both are good indicators you are there.
*For an even better indicator of a complete roast, use an infrared thermometer and roast until the beans show 250-260 F. Make sure you stir the beans before taking your reading so you don't have a high bias.
If you have nibs, you both can and need to take them a little more gentle.
350 F 10 minutes
325 F 5 minutes
300 F 5 minutes
275 F for 5-10 minutes or until done (again 250-260 F IR thermometer reading)
That is really it. Of course, there are LOTS of other ways you can do this. I know some people roast at 250 F (or even 220 F) for 45 minutes to an hour or even two. I am personally not a fan of this style, but you may be.
Option 2:
I find this procedure works pretty well and is a little simpler than the method above, having fewer adjustments. It is moderately predictable, repeatable and although not as dynamic and controllable as a drum roaster, does a good job.
You will need an IR thermometer.
Roast 2 lb of beans.
Preheat your over to 350 F.
Place your cocoa beans in a single layer on a baking sheet and into the oven.
Stir the beans at 5 minutes and check the temperature.
Continue roasting until the surface temperature reads 205-215 F (it may well vary across the beans).
At that point, turn your oven down 10-15 F above your target end roast temperature (EOR)
If it is 255 F then add 15 and set your oven to 270 F and continue to roast without stirring every 5 minutes until approximately 255 F.
Again, there will be variation but the beauty of this method is having turned the oven down it is difficult to over roast. If you do find your roast is progressing too fast, adjust accordingly, starting at 325 F and/or changing your target to 265 F. Overall you may well roast 30-40 minutes. The important part here is to get good momentum going in a hot oven and then basically coasting to finish.
What about <insert name> roaster?
There are a number of small home coffee roasters out there and I mention them here for completeness. Spoiler, none really work for roasting cocoa.
All Fluid bed Air roasters including but not limited to the FreshRoast, Poppers, Sonoffresco, etc.
Pros: None
Cons:
The won’t lift and fluidize cocoa beans.
Nibs tend to ‘tip’ or have their ends scorched.
Nibs can fall through the holes at the bottom.
Capacity tends to be quite small. In some cases if you have temperature control (most don’t) you can control tipping but the small amount you can roast isn’t usually worthwhile other than for novelty sake.
GeneCafe:
Pros:
Not many. Beans tend to not mix well due to their size.
Nibs are ok.
Cons:
Capacity is low
The airflow tend to strip flavor from the nibs and beans.
Mixing is subpar.
No bean temperature probe
Hottop
Pros: None
Cons: Beans tend to jam and nibs fall through the drum
Allio Bullet
Pros:
Has temperature probe
Cons:
Whole beans jam and nibs sound crunchy and might damage the roaster
Expensive
Cooling your cocoa beans?
Whatever method you use for roasting, it is important to cool your beans in a reasonable amount of time so they don’t keep developing. Anywhere from 5-15 minutes is just fine.