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Inside The Coffee Roaster

Inside The Coffee Roaster

Mention to people that you are a coffee roaster and more and I am inclined to hear “So you like grind it and stuff?”, “You just bring it from Jamaica and then put it in a bag and sell it, right?”.  The answer that works best for me is ” No more than a restaurant doesn’t put a raw steak and an uncooked potato on your plate.” That usually draws enough silence to let me explain what goes on at Reggie’s Roast Coffee. Yes, we bring our own coffee in From Jamaica, and yes we do put in bags & cans. However there are some very big and important steps that are involved in between.

First, we start with the processed fruit of the coffee tree;  raw or green coffee as it is known and also the same type of green coffee heard of recently in so many diet solutions. This coffee has been hand picked and processed and is ready to be roasted. If you take into consideration as you read that we are essentially “cooking” the coffee beans, this will come together by article’s end.  We are taking an unfinished product and with temperature, time, patience and skill we are opening the eyes of people all across the globe.

The green coffee beans are heated in a large, rotating drum using natural gas to reach temperatures of about 550 F (288 C). The drum continuously spins as the tumbling motion of the drum keeps the beans from scorching as they roast . Once the correct temperature is reached in side the drum, it is now time to charge, or fill  the drum inside the roaster. The first stage is endothermic as the green beans are slowly dried to become a yellow color and the beans begin to smell like toast or popcorn.

The second step, often called the first crack, occurs at approximately 360-370 F  in which the bean grows in size, becomes a light brown color, and experiences a weight loss of approximately 5%. As coffee roasts, it will lose weight from moisture content loss which is why we need to account for a 16% overall loss before roasting. So if we want to produce 100 lbs of roasted coffee, you need to roast 116 lbs of green coffee. The chemical reaction of the heat and coffee essence in this stage of roasting is called pyrolysis, and is what produces the flavor and aroma of coffee.

As the internal temperature increases inside the coffee roaster, the heat source of the coffee roaster must be decreased so the coffee doesn’t roast too quickly or scorch. There are machines that can be calibrated to monitor these temperatures, but nothing is more perilous than not paying attention to your coffee as it’s roasting,  so monitoring by hand is our preferred method. After the first crack is when the beans are developing their true flavor. It is said that some professional coffee cuppers will cup the beans immediately after the first crack to experience the flavor as this step is where it is best represented. This is the range that most roasters will use to produce a light roast, or the now very common “Blonde” roast. All of our Jamaica Blue Mountain Coffee is finished roasting during this stage to allow the bean’s natural, sweet and mild flavors to come through

The beans continue to roast as the bean temperature increases and the beans will begin to reach the next stage. The second step is followed by a short endothermic period which is followed by another exothermic step called the second crack.  This second pyrolysis occurs between 225-230°C, and the roast color is defined as medium-dark brown. These stages will bring the oils from inside the bean outward to the edges of the bean. These are the beginning stages of what is known as French Roast as the bean’s temperature rises and the oil breaks through the bean’s surface after the second crack and the beans have  a dark brown, oily color.  At this point, any further roasting will leave you with a burnt and bitter tasting coffee since all the pronounced flavor is that of the roaster and not of the bean.

Another point that should be noted is that as coffee is roasted longer, it loses caffeine as when you cook with alcohol; it gets “cooked off”.  From the Wikipedia Definition of coffee roasting  “Caffeine diminishes with increased roasting level: light roast, 1.37%; medium roast, 1.31%; and dark roast, 1.31%” Since most will dispute this fact when they see or hear, but none the less it is true. There are also some good photos of different roasting stages and of course a lot of information about what goes on inside the coffee roaster.

Hopefully there has been some light shed without being too confusing in what goes on inside the coffee roaster.  If you have done your homework, and are up to it, for those that may have the knack  here are some home roasting tips from Seven Bridges Cooperative with more detail, and some great tips if you want to roast your own coffee at home!