I field calls on a daily basis. Basic roasting questions are the most frequent ones posed so let’s get down a basic approach. Keep in mind, there are plenty of ways to roast. This is mine, though there are others. Most importantly, what counts is how the cup tastes. That is all that matters.
First, some qualifiers. I offer some ideas based on my 12 years of roasting. I have my own preferences. My ideas for you are suggestions, “roaster preferences.” You will meet other roasters who have their own ideas, their roaster preferences. Learn yours.
Second, I find that there is always something else to learn. That is the hook that holds me with coffee. I invite your comments and responses. On with the show…
Grab Artisan and get it installed on your laptop. You can find it here. It is free and open source software. Don’t forget to download your Phidget 1048 drivers in addition to Artisan.
I will avoid discussion of hard and fast “settings” or numbers from individual gauges and fan settings. We can’t assume that your gauge and potentiometer are calibrated against mine. We can’t assume you have your high pressure regulator is adjusted to the degree to which I would set mine. You may be on propane; I roast on natural gas. What we will have in common in a “roasting in stages” approach. We will focus on:
– end of drying between 5-5:30 minutes,
– 8-11:00 minutes for first crack and then
– 1:45-2:15 minutes after first crack for your first wet processed coffee.
Let’s look at Stages of the Roast: Drying/Caramelization/and First Crack and Beyond
1) Pre-warm the roaster for 30 minutes.
– Make sure your drum is rotating. I set it at medium during my pre-warm.
– Set your airflow at about medium. Learn how to determine airflow settings.
– Open your gas valve about half way. Ignite the burners (“roasting switch”). You will hear the burners ignite.
2) Locate your fire extinguisher and place it between you and the exit door.
3) Charge. Charge refers to the weight of the roast and the beginning temperature. I use the PID temperature reading on the control panel to determine when and at what temperature I will drop the beans into the drum. I vary charge temps between 385 and 410º, based on:
– elevation (as a rough measure of density) at which the bean was grown,
– size of the roast, and
– type of processing (wet processed, dry processed, pulp natural, wet-hulled, or decaf)
First step? Things to consider for charge temp?
a. Elevation/density. (The higher the elevation at which the bean is grown, the denser the bean. Dense beans require higher charge temperatures.)
– High growns, 5000 feet or more (Centrals, Africans, Colombians, Bolivians, Yemens)
– Medium elevation, 2200-4900 feet (Indonesians, Brazils)
– Low Grown, 800-2000 feet (Hawaiian) and Decafs
b. Weight of roast: (My typical charge sizes are: 1 kilo). Note: The North Roaster was designed to roast full charge. Our “sweet spot” is a full measure of machine design, or 100%.
Washed coffees take more BTUs than natural processed coffee (many of the Ethiopians). Charge a natural coffee, a pulp natural, and a semi-washed about 10-15º lower than you would a washed coffee. Decaf? 20-25º lower. Experiment and learn your machine.
4) Charge temperature reading: (“Temperature Controller” reading on control panel). Varies based on elevation and weight. For an example throughout this blog, I am roasting 2.2 lbs of a high-grown Colombian by charging when the PID reading (“Temperature Controller”) achieves around 400º. (Your temp settings may vary from mine.) Vary your charge temp (385-410º) based on:
– elevation of roasted bean (density),
– charge size and
– type of processing.
Let’s start with one word of caution. Don’t get married to Artisan! Engage with, yes. Married, no! I can’t emphasize that enough. Stay on top of your trier. Learn to smell, see, and take in the bean. Learn the sight and smell of the bean as it works its way through the 3 stages. The Artisan software is a wonderful tool to assist you. But get away from the screen and work that trier to death — quick out, view, smell and back in.
– Get your Artisan running by hitting “start.” Buttons will appear on the bottom (charge, dry end, FC start, etc.)
– When you have 2.2 lbs of the high elevation Colombian weighed out, make sure your PID temp reads about 400º.
– Make sure your fan is set to low (how to determine airflow settings?)
– Make sure your drum is turning.
– Dump your beans into the hopper, open the gate then close it, and hit “start” at top of screen, the”charge” on the Artisan.
– Do not turn off your burners if working on 3K and above. On our 1K/2K, I need to turn off the burners for 60 seconds or so because of the BTUs.
– Now, look at the front of the roaster at the sight glass. I like to roast with an approximate 50-55º angle/tumble of the beans. (Our roasters have a variable RPM on the drum speed, approximately 48-72RPMs. The setting does not correspond to RPMs. For example, a 30 dial setting is only a dial setting. It does not correspond to 30 RPMs.)
– At 1:00 of the roast, re-ignite your burners (only pertains to the 1 and 2Ks). I roast with natural gas . Leave your fan on low during this drying phase.
– Our goal is to achieve a band of 32-36º for approximately 1.5-2 minutes. This gives an internal bean temperature sufficient to carry you appropriately through the roast.
– Next, shoot for a “yellow stage” at 5-5:30 min of the roast. What is yellow? All the green hues/streaks are gone. I mark it high, typically at ~340.º
– Many roasters mark “end of drying” around 320º. It doesn’t matter, so long as you do it consistently. It is just a data point to help you anticipate first crack.
– When the roast achieves “yellow stage,” mark “dry end” on Artisan. This is just a goal, nothing more. It can be a moving target. You will get the feel of it.
– At this point, when the beans are yellow, increase the airflow to medium.
– Our next goal is to achieve “first crack” between 8-11 minutes (again, a goal, not a rule). I turn down the gas by 10-15% 30-35 seconds before I anticipate first crack. It is always a guess when you’re going to hit first crack. Look for beginning smoke and the seams beginning to open.
– Keep an eye on the bean mass temp and rate of rise. Don’t let them run away before first.
– Don’t be afraid to meter the gas down.
– One quick word on “rate of rise.” Don’t let it drift below 5º during the roast. We will pick up on “rate of rise” in our next roasting blog, Roasting 102.
– When the beans hit first crack, you will clearly hear them. The first two or three cracks are considered “outliers” and I don’t mark the first crack icon (FC START) until I hear a series of about 3-5 cracks.
– Mark first crack on Artisan. Turn your airflow up to high and check the angle of descent. The volume of beans has increased due to bean expansion. Turn up your drum speed to keep the 50º angle of descent.
– Let’s say first crack is at 8:50. While I keep an eye on the beans in the trier, at 1:30 minutes after 1st crack on a wet processed coffee, I am all over that trier, constantly looking at the bean, smelling it, and determining when to “drop.” The bean will tell you. I am after a uniform coloring of roast on an individual bean (taking in coloring on several beans) and minimal variance, bean to bean.
– The darker you roast, the less variance will appear.
– At this point, Artisan may reflect bean temp of 417º as an example. I consider that a data point but I am as interested in the bean’s appearance. Somewhere between 2:00 to 2:15 min after first crack, I am going to drop that bean as a baseline roast. (Future roasts are adjusted, profiled and determined based on its cupping and whether you intend to use the bean for pourovers or espresso.)
– When you are ready to drop, get one hand on the computer controls, getting read to hit “Drop.” The other hand is busy starting the cooling fan and the cooling arms. Turn them on.
Mark “Drop” on Artisan and ease open the drum door. A partially open door will contain the outflow and prevent beans from flying out of the cooling tray. I leave the drum door open for 20 seconds to let the hitchhikers come out.
– Beans will take ~ 3:30 minutes to cool.
There, you have done it. Four days later, cup your roast. Tweak your roast depending on your results and preferences.
Let’s hear your comments and…
Roast on! Dave, BoldJava