Roasting @ The Roaster

Where I left off on my trip to Kaldi's Coffee Roasting facility was after the different varietals arrived. Picking up from here, we moved directly into the good part, the roasting. Joe Marrocco, partially pictured to my left, gave me great treatment and shared answers to just about everything I could think to ask, and many things I didn't think of. I'll walk you through some of the more memorable insights.

When I arrived I immediately saw the mammoth Probat roaster- much larger than other operations I have seen- which gives Kaldi's the ability to roast greater volume and sell to a larger market. This is minuscule compared to the volumes of larger companies like Ronnoco or Starbucks, but these companies drop SUBSTANTIALLY in the quality department. The Probat was manufactured in the early 1920s and made out of cast iron at least 1/2" thick, probably much thicker. This substantial construction allows the machine to use less fuel in heating because of shear residual heat buildup. On the opposite side of the Probat, the cycling of the barrel is driven by old-style belts (the belts need no restrictions or guides to keep them aligned simply due to superior construction). The beans are cycled around in the barrel-style bin for very precise amounts of time and in varying levels of heat. As pictured first, I had the opportunity to help track the heat variance on a very small batch of Ethiopia Yigacheffe. This experience really illuminated the process of addition of heat and the process of watching the batch roast develop.

Heat is applied heavily at the beginning to around 410 degrees, the coffee is then dropped into the barrel, and the temperature drops to its lowest point of 200 degrees because at this point the beans have absorbed initial heat. After this absorption period, the temperature begins to rise rapidly back toward the 350s. The "flame" is dropped in proportion to the heat increase within the roaster itself. This may sound paradoxical, but it really does make sense: the coffee begins to roast itself from within- like a miniature candy factory in every bean. The beans increase in temperature on their own during the caramelization process, from the "first crack" (the beans expand and a cracking sound is produced) to the "second crack" where caramelization ceases and carbonization begins (where the sugars produced through roasting begin to burn). After the beans have reached their optimum roast level, they are dropped into a cooling tray. This cooling tray has a reverse fan sucking air from above the beans in the tray, through the beans. At the same time, there are swirling arms that stir the beans, further cooling them and stopping the roasting process within the beans. During this time, the roaster will observe the beans and try to pick out any outstandingly over-roasted beans that may have gotten stuck against one of the iron sides within the barrel.

Kaldi's has another roaster, a smaller San Franciscan, used for small batches like the one I got to work on. It is around 30-50 thousand dollars to buy. This sounds like a lot until I asked what the Probat costs. If you can even find one for sale, the Probat is around 250 grand to start. Wow. Here's a picture of the smaller (more realistically priced) roaster:


Lord, thank you for the great experience and new knowledge. I pray I can do something like this myself. Even if I don't get to have my own roaster some day, I still want to serve You. Keep my head deflated and on straight. Here we go.