Drying Phase

[Mr.Peaberry]

Here's a question I'd like to pose to the roaster members here. I have studied the patent filing for Michael Sivetz' continuous roast fluid bed roaster. The basic design has a separate chambers and heat source/blower for the drying and roasting phases of the process. A third chamber is provided for cooling the roasted beans.

My question is if anyone has done anything similar with these SC/TO builds...i.e., use one setup for the drying process, and another for the roasting process? If so, did it make any difference at all in terms of ease of flow, more throughput, or a better/more consistent roast?

 

[peterjschmidt]

You don't need separate chambers, just separate sections or phases in your roast profile.

When I'm using my SC/TO's, right around 280*, I'll cut the heat and let it coast up to ~300* - that takes 90sec - and turn up the heat, which takes another minute before the temps start rising again. So that's my drying phase. You'll want to visually check the color of the beans and you can also smell an aroma shift. The beans should turn from a green to a light yellow, which signifies they've dried. You don't want to leave excess moisture in the beans as the moisture interferes with certain desirable chemical changes.

 

[Mr.Peaberry]

Thanks Peter. That makes a lot of sense. On a continuous flow machine, isolating the phases allows the process to run with minimal operator input, which is an ideal situation for large commercial roasters, but I wasn't sure if there were any advantages to this on a micro scale roaster. Good information!

 

[ellatas]

The concept of different chambers in a continuous roaster has to do with different environments in each chamber. Since you need to maintain constant conditions of each chamber for extended periods of time (such as weeks), the way to change the heat applied to the coffee and create a particular time/temperature profile is by creating separate chambers and keeping the chambers constant.
On a batch roaster, you can easily modify the heat applied during the roast and not affect the coffee in the batch after. In fact, you can modify the heat multiple times throughout the roast. So the separate chambers on a continuous roaster is an attempt to mimic the capability of a batch roaster in creating a particular time/temperature profile. However, since there are a limited number of "chambers" on a continuous machine, it can't match the capabilities of creating a time/temperature profile on a batch roaster.
On the other hand, the throughput from a batch roaster can't match that of continuous roaster ...if it is roasting the same thing for a number of weeks.

 

[Mr.Peaberry]

Thanks for your insight ellatas. I understand that continuous commercial roasters make sense when a large quantity of the same bean and roast level are needed, On an SC/TO home roaster, the issue is the micro batch size. PJS was using two of these and staggering the drops to achieve "continuous' roasting, and increase throughput. I was just toying with the idea of doing the same, but setting one up to dry the beans, and another to roast. May be the worst idea ever, but I'm new and can always blame these crazy thoughts on a poor upbringing...

 

[peterjschmidt]

Yo mama needs to slap you. <wink>

 

[Mr.Peaberry]

What mama don't know, mama can't worry about. <wink>