January 31, 2010
We’ve been roasting coffee in small batches for nearly six months now, offering samples of approximately one pound to friends and family. It’s unlikely the folks sampling our coffee have ever seen a coffee roaster, and while we will have it in the shop when we open, it seemed like a good time to provide a look at the roaster with you today.
What we have, is a Diedrich IR-3 coffee roaster. With nothing in these photos to provide scale, you may be wondering how big it is? It’s a little over six feet tall and two feet wide. The silver funnel at the top is where we load the green coffee beans. When the drum temperature is right, the silver lever at the top releases the beans into the drum. The nob sticking out the back on the right is an air flow adjustment. The control panel on the lower right allows us to turn everything on. The silver left middle left is used to open to door and release the beans into the cooling tray, which is the circular silver thing at the bottom.
In the photos above, the picture to the far left was taken just before releasing the beans into the drum. In the next two pictures, you can make out the beans tumbling past the sight glass in the center of the release door.
We roast the beans for 13-14 minutes per batch, depending on the darkness of the desired roast, and then the coffee cools in the tray for about 10 minutes before we clear it out and make room for the next batch. We can do the cooling and the roasting simultaneously, so we can do 4 batches an hour, if we work in a full production mode. Honestly, we usually do 3 batches an hour, taking a little more time between batches with note taking and planning.
Although the roaster is rated for 6.6 pounds per batch, we’ve found that this roaster’s realistic capacity is closer to 5 pounds. Beyond 5 pounds we don’t feel there is quite enough heat to achieve our desired roasts in 13-14 minutes, so we keep the batches between 2 and 5 pounds.