Learn Coffee Roasting

tips, tricks, and advice to get you stated

Coffee roasting is complicated, but it doesn’t have to be hard. Let me help you cut through the noise and take steps to get up to speed on coffee roasting quickly. I've got some great resources, links, and advice for new roasters here!

If you’d like a few shortcuts to learning about coffee roasting, I’ve got you covered.

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First steps of Learning Roasting

  • When you first start roasting, there is going to be a lot of information you’re presented with which may not make perfect sense to you at the beginning. That’s OK! It is important, however, to make sure you have that information to look back on when you are ready to take it in and digest it. For that reason, you need to keep diligent notes about everything that you do when you’re roasting coffee.

  • When you buy a new coffee, you’ll want to record the following important information.

    • Country of Origin

    • Cultivar(s)

    • Processing Method

    • Altitude

    • Bulk Density / Water Displacement Density Reading

    • Moisture Content

    • Aw (if possible)

  • When you’re first learning to roast, you may not have access to a data-logger (a computer program that records temperature over time during roasting). That said, you can accomplish a lot with your powerful Coffee Journal / Notebook

    Record the following:

    • Date, time, and batch number for the day.

    • Beginning weight

    • Preheat temperature (if you have multiple thermocouples, I would write them all down for preheat… I rely more heavily on exhaust air temperature… but watch all of them).

    • Temperature and Time of Turn Around Point (TAP).

    • Temperature of at least the bean temperature probe every 1:00.

    • Time and temperature of the coffee turning > 70% yellow in color (Yellowing)

    • Time and temperature of the first crack (FC)

    • Time and temperature of the second crack (SC) if applicable.

    • Time and temperature of the end of the roast (EOR).

    When you’re done roasting, take the time from FC to the EOR to determine your “post-crack development time” (PCDT - formerly Development time).

  • When you’ve finished roasting the coffee, record the following.

    • Time it takes to cool the coffee to human body temperature or below.

    • The final weight of the roasted coffee.

    • Use the initial weight (GW - Green Weight) and the final weight (RW - roasted weight) to calculate the weight loss percentage.

      ((GW-RW)/GW) x 100 = WL as a Percentage

    • Record Whole Bean (WB) and Ground (GR) Color if possible.

  • If possible, keep room on the same notebook page for you to write your impressions of the coffee as you taste it over time.

    Make sure to put a date next to your flavor notes so you can see how the coffee changes while it is aging.

FAQs
for new Roasters

How do I figure out an appropriate charge temperature?

Determining which charge temperature to use can be tricky. On some machines, ~200 °C (~400°F) will work well for a large batch size, while on others, you’ll need to charge to nearly 260 °C (500°F). How can you determine where you ought to go? You’ll know if you’re charging too hot because you’ll see roasting defects like scorching and tipping on the beans during the early roast (more info on those here: https://hoos.coffee/blog/defects). On the other hand, if you’re charging too low, you’ll experience significantly longer-than-desired roast times. The key is to find the right balance between batch size (generally aim for 60-80% of the manufacturer's rating) and charge temperature (use the manufacturer's recommendations as a starting point).

Why does my Turn Around Point (TAP) look so different from other people’s?

The TAP will vary greatly depending on how your roasting machine has been set up. Thermocouple type, thickness, and placement will all have a large impact on when and at what temperature the turnaround point happens. If yours looks different than someone else’s, don’t sweat it. In the world of coffee roasting, we use it more as a metric of internal consistency than as a demarcation of quality.

With TAP, you are measuring how quickly the coffee can cool the preheated thermocouple to its temperature before the thermocouple stabilizes and begins to rise with the coffee as it is heated from room temperature.

What is soaking, and should I do it?

Soaking is the practice of leaving the flame low or off at the very beginning of the roast to allow the coffee to absorb some of the heat already in the system before adding more heat energy to that system. Generally speaking, it is necessary to do so in some more thermally retentive systems and counterproductive in others. To my current understanding, it is a way to control heat transfer in the roasting system and will not “create” flavors. It can, however, help you avoid certain negative flavors associated with roasting defects. In particular, this could be a way to avoid scorching (more info here: https://hoos.coffee/blog/defects).

What is the difference between light, medium, and dark roasted coffee?

The final temperature is generally indicative of whether the coffee is light, medium, or dark-roasted. However, because everyone’s thermocouple is different, it can be more helpful to denote roast degree based on color (as measured by a colormeter - see coffee review’s guide here) or weight loss percentage. I’ve got a nice guide to weight-loss percentages here.

We can also denote the degree of roast by where it falls in relation to the first and second crack. Generally speaking, I would suggest that a light roast occurs when the first crack is still happening. A medium roast occurs after the end of the first crack, but before the beginning of the second crack. A dark roast occurs after the beginning of the second crack.

However, each of the roast levels is also connected with a certain length of development time. Generally, light roasts are 1-2 minutes in development time, medium roasts are 2:00 - 3:30, and dark roasts are 3 - 4 minutes.

What is the best kind of coffee roaster?

There is really no right or wrong sort of coffee roasting machine. They are simply tools we use to transform coffee physically and chemically. That said, some machines are easier and others harder to use.

Look for a machine with a good balance of convection and conduction. Most coffee roasting occurs through convective heat transfer (~70 percent), with some conduction between beans and less between beans and metal, and an unknown amount of radiative heat transfer.

Fluidized bed roasters are quite easy to use, but can lack some of the control and flexibility of a drum roaster. Drum roasters, while slightly harder to learn, can offer you significantly more finesse when roasting.

Where can I learn more?

There are so many places you can learn more about coffee roasting.

Check out my blog: https://hoos.coffee/blog/

Subscribe to my email list:
https://hoos.coffee/signup/

Get your hands on my books:
https://ebooks.hoos.coffee/

Have a meeting with me:
https://calendly.com/robhoos/

Join the Roasting Lab Community:
https://forum.hoos.coffee/roastinglab