I am looking to be able to roast 35 to 50kg and, depending a bit on machinery I find, will decide between convection or drum roaster route. The merits of these have been discussed before here but wanted to ask those with experience here for some basic insights.
Converting Coffee Roaster -- anything being done to modify with regard to interior of drum or speed in order to improve roasting/minimize breakage?
Convection Oven -- aside from just setting up a fan, anyone doing anything fancier to cool down the beans?
Hi There, we have have a coffee roaster and we find it quite good and efficient, soon i will post a review on differences between convection and coffe roasters.
One thing i can say is do not buy a roaster from AMBEX. they have robbed us $6000 and we never saw the roaster!
the previous owners did run away wit all the money from clients (deposit..) and now we have lost the chance to see the roaster.
funny enough we found then the same roaster made in Turkey for a 3rd of the price!!
The trick to using a convection oven for a perfect roast is using perforated trays. This is important to allow air flow up through the bottom, but also over top. The other trick is to not overload the trays with beans.
I honestly don't think roasting in a convection oven would be effective if solid bottom trays were used, as much of the air circulation needed to evenly heat the beans wouldn't be present.
We don't cool the beans other than by using ambient room temperature. Once the trays are removed from the oven, they cool very quickly on baker's racks.
Think about it. Do you want to bake your beans? Or roast them?
Convection ovens have the advantage of being very inexpensive.
That said, in my experience, I have NEVER found a convection oven that heats the entire cavity left to right, top to bottom, back to front, evenly. In practice the result is unevenly baked (not roasted) beans. This is true even if you use perforated pans. You can a) rotate the pans during baking (which has other issues related to recovery time), or b) get an oven that rotates the baking rack during the cook cycle.
One technique you should learn from the coffee roasting community is about variable airflow - changing airflow and temperature enables you to get the most out of different beans. With a convection oven, you don't have precise control over airflow, so your baking profiles in a convection oven do not have the control you need to develop maximum flavor for a variety of bean types.
There have to be compelling reasons why coffee roasters are willing to spend $125,000 for half-bag roasters with digital controls. Now - you might not find that you can make a business with a $125k coffee roaster, but trying to "make do" with a $1500 convection oven is not the only alternative.
Baking vs Roasting?
Please don't take offense to this Clay, but cooking ANYTHING is about heat and airflow, not terminology. In my oven at home I bake brownies, roast a turkey, bake cookies, roast a beef roast., and even roast marshmallows for my s'mores. I can also bake the turkey , marshmallows, and roast as well as roast the cookies and brownies. Why? Because it's the same piece of equipment cooking everything.
It used to be that roasting and baking were different - roasting meant cooking your food over an open flame, with higher temperatures whereas baking implied indirect "ambient" heat, usually at a lower temperature. However, even with the "roast/bake" settings on some ovens today, the bottom line is that the oven uses dry heat to cook its contents.
Due to the evolution in cooking technology (namely in ovens), the conceptual differences of roasting and baking are more or less lost. Case in point: Even coffee roasters today use indirect heat (usually natural gas), and add agitation (turning drum) to roast their contents. However, given that coffee roasters can also cook at lower temperatures common in old school baking, does it "bake" the beans when the temperatures is around 325? Nope. Still roasts them.
In the end, what's the difference between baking and roasting? None.
It's all about heat and airflow.