Roast Profiles in Popper Coffee Roaster

A simple heat profile in Popper can yield some nice results, and a more balanced cup flavor.

After you have been using Popper is a Coffee Roaster a while, you might wonder if there is anything you can do with the settings to get different roast results, to change the heat or air settings to create “roast profiles.”

I have been doing a lot of tests lately to produce a varietyA botanical variety is a rank in the taxonomic hierarchy below the rank of species and subspecies and above the rank of form (form / variety / subspecies... ...more of roast profiles and evaluate what the differences are when cuppingCupping is a method of tasting coffee by steeping grounds in separate cups for discrete amounts of ground coffee, to reveal good flavors and defects to their fullest.... ...more the coffees side by side. With these tests, I am logging temperatures and energy usage by the Popper to record the path taken to achieve a particular roast level. In other words, you can roast a coffee to a similar roast level (measured by roast color, ending temperature, or weight loss from green to roasted coffee) but the way you got there, the temperature levels and durations, have an impact on the cup flavors. I can roast the same coffee and reach a finishing temperature of 440°F or a weight loss of 13.5% but they can taste quite different.

In short, that’s the importance of a roast profileRoast Profile refers to the relationship between time and temperature in coffee roasting, with the endpoint being the "degree of roast". Roast profiling is the active manipulation of... ...more. All we mean by a roast profile in this case is the time and temperature graph as it is recorded during the roast process, impacted by changes to the roaster settings. (And why is this called a “roast profile”? I have always assumed that the 2 dimensional X-Y axis graph, made by measuring bean temperature over time, forms an outline of the roast, like you might sketch a profile of a person’s face from the side. It is not the person, but it represents them.)

Take note: These tips all pertain to the latest production model of Popper, the “gray” machine. (The main bodyAssociated with and sensed by mouthfeel, body is sense of weight and thickness of the brew, caused by the percentage of soluble solids in the cup, including all... ...more is gray, unlike the black colorway of the first production runs of Popper). The gray model has a numbered heat dial; the black model has no numbers on the heat setting.

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Cut to the Chase: Tips for Popper roast profiles

I want to give you a shortcut on how to approach roast settings on the Popper. You should take time to read the qualifiers and watch the video. But I also want to give a spoiler for those who don’t. (Come back and read to the end if my tips don’t work for you! I’ll probably tell you why…)

Each profile below starts with the same low heat setting of “1” on the heat dial for the first 3 minutes … and then there are options for progressively darker roast levels. ALL these roasts have the fan speed set to HIGH for the entire roast. We will have another article about using fan speed changes at the end of some roasts to raise the roast temperature. But let’s not complicate things with that now…

Start with a low heat level on Popper. Set the heat dial to “1” for the first 3 minutes.

• Air roasting is faster than other methods by nature, since the heat transfer in a rapid air stream is very efficient. But the initial heat bump in an air roaster is a bit of a shock, and the rapid development and bean expansion of an air roast can create a particular flavor distinct from roast processes with a slower hear transfer from the environment in the roast chamber to the green coffeeGreen coffee refers to the processed seed of the coffee tree fruit. Coffee is a flowering shrub that produces fruit. The seeds of the fruit are processed, roasted,... ...more.
• Using the “High” fan setting, start your roast on the lowest heat setting, “1.” It allows for a slower drying phase for the green coffee, setting it up for a more controlled finishSimilar to aftertaste, but it refers to the impression as the coffee leaves the palate. Aftertaste is the sensations gathered after the coffee has left the mouth. We... ...more at the end of the roast.
• All the recommendations below include starting your roast with 3 minutes at heat setting “1,” and then making adjustments.
• All the recommendations below assume fan speed is set to HIGH for entire roast.
• We assume you are weighing your batches and using the exact same amount in each roast, always!

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1. For a lighter City roast, adjust the heat setting to “2” at the 3 minute mark.

• 3 minutes at “1,” 4 minutes at “2”: You might find that changing the heat to “2” is all you need to do… and let the roast play out until it goes into cooling at the 7:00 mark (3:00 on the count-down timer). Yes, it’s not much of a roast curve in terms of being complicated. But what we really want in roasting adjustments is to find the simplest path to the desired cup. Complicating things unnecessarily is just purely affect, and without substance. Let’s keep it real!

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2. For a more aggressive approach to reach City+ level, adjust to heat setting “3” at the 3 minute mark, then reduce to “2” at the start of first crack.

• 3 minutes at “1,” 2 minutes at “3,” 2 minutes at “2”: Depending on your electrical line voltage, and corresponding wattage, this approach might work best for most people. You can use the “3” setting to push the coffee into first crackFirst crack in one of two distinct heat-induced pyrolytic reactions in coffee. It is distinguished by a cracking or popping sound in the coffee, and occurs between 390... ...more. Once you confirm first crackAn audible popping sound heard during roasting. In coffee, one refers to "first crack" and "second crack," which come from two different classes of chemical reactions.: An audible... ...more is under way, back off to “2” to allow for a controlled, prolonged first crack.

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3. For Full City roast level, getting a few second crack snaps at the end, simply extend the time of the previous profile.

• 3 minutes at “1,” 2 minutes at “3,” 3+ minutes at “2”: If you want a darker roast level, you might find than holding the roast longer at the “2” setting at the end gets you where you want to be. Adding 1 minute for a total 8 minutes of roast time works great to get a balanced darker roast profile.

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4. For espresso, extend the roast by 2 minutes or so, using heat level “2” to slowly reach towards City+ or Full City level

• 3 minutes at “1”, 6 minutes approximately at “2”: It’s said that using an air roaster for espressoA small coffee beverage, about 20 ml, prepared on an espresso machine where pressurized hot water extracted through compressed coffee.: In its most stripped-down, basic form, this is... ...more is difficult, but this approach to slowly edge the roast upward toward around 445°F has resulted in some outstanding balanced shots for me. You will be extending the roast time a couple minutes beyond the default 7 minute cycle here.

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Alternative to Heat Profiling: Keep it simple and don’t change anything!

I find the above heat profiles to produce a very balanced cup profile, and one that tastes more like a slower drum roast method than a fast air roast.

But for filter drip coffee and pour-over methods, faster roasts with more initial heat are really delicious. They tend to produce a more dynamic cup, with more “bass and treble” while having less midtones. Plus, it’s less work too. All these roasts have the fan speed set to HIGH the entire time:

1. Heat Level “2” for 7 minutes: This consistently produces a nice City roastCity roast is what we define as the earliest palatable stage that the roast process can be stopped and result in good quality coffee. City roast occurs roughly... ...more that shows the “originIn coffee talk, it refers to a coffee-producing region or country; such as, "I was just at origin." Of course "Origin" for most product we use is not... ...more character of the coffee very well. It should use 810–820 watts, First crack starting at 5:00 to 5:30, with about 1:30 of development time, and an ending temperature of 424°F. The cup character is bright and lively as pour-over, after 2 days of rest!
2. Heat Level “3” for 7 minutes: This setting gets considerably darker, even a couple snaps of second crackAfter First Crack, a roast reaction around 440 to 450 degrees that is distinguished by a snapping sound. Second Crack is the second audible clue the roaster-operator receives... ...more at the end. It’s a Peet’s style roast, Full City+City+ roast is an ideal roast level that occurs roughly between 425 and 435 degrees Fahrenheit in many coffee roasters with a responsive bean probe where First Crack... ...more, and a lively, tangyAn adjective modifying a flavor descriptor, describing a sharp effect; tangy citrus, tangy bittersweet flavor, tangy green apple. ...more dark pour-over cup. Heat level “3” is drawing around 950 watts to get these results. First Crack starts at 4:40 or so, and at 7:00 I am seeing 459°F bean temperature reading.
3. Heat Level “4” for 6 minutes: This is a faster roast, and I need to end it at 6:00 because it’s in Second Crack and getting dark already at that time. This is also something you might find at Peet’s or Starbucks, but fresh, so far better! It’s tangy, a little carbonyA roast-related flavor term, referring to burnt flavors from dark roast levels. For some this is a pleasant flavor if residual sweetness is present, but plain carbon flavor... ...more and dark. First crack can start as soon as 3:30, while drawing 1050 Watts of power. Finish at 6:00 and 469°F with second crack starting.

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Shortcut Recommendations by Roast Level

City Roast (Light): Simply setting to Heat Level 2 and fan on High produced an excellent light roast in 7 minutes. If that roast is too light or barely reaches first crack in 7:00, you might have slightly lower voltage and need to bump it up to level “3” heat.

City+ Roast (Medium): Fan on High, Heat Level 1 for 3 minutes > Heat level 3 for 2 minutes > Heat Level 2 for 2 minutes. This was the best roast for slightly more development then City roast without getting too dark.

Full City RoastA coffee that has been roasted to the brink of second crack.: A coffee that has been roasted to the brink of second crack. The internal bean temperature... ...more (Medium Dark): For brewed coffeeBrewed Coffee refers to all coffee preparations produced by adding non-pressurized water to coffee grounds. Contrasted with espresso coffee, which is produced under pressure, brewed coffee is primarily... ...more, I honestly thought that using Heat Level 3 for the entire 7 minutes was a great, lively FC or FC+ roast! To get this roast level for espresso, I would see the rec. below and just add a bit more heat at the end.

Espresso: We like lighter roasts for espresso, not too ashyThe smell or taste of ash, such as an ashtray, cigarette smoke, or fireplace. Often a roast defect.: A quality in aroma or flavor similar to that of... ...more / dark. We had outstanding shots (that didn’t scream out “air roast” too) with this: Fan on High, Heat Level 1 for 3 minutes > Heat Level 2 for 6 minutes. Easy, with a slow RoR and lots of development time after First Crack. If you want it darker, you can add more heat with level 3 for a bit, or actually reduce Fan Speed to Low after first crack is finished.

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Voltage and Temperature Variables: Why you might need to diverge from my recommended profiles

Some people have different voltage conditions or roast in a colder climate. If that’s applies to you, consider adding +1 to my heat setting recommendations across the board.

Like all roasters, Popper performs a little differently based on the energy it is fed by your outlet.

Every Popper we are shipping has been calibrated before we send it out. We test each one with 90 grams of a standard washed coffee to be sure we are seeing the same bean movement. But this has made us very aware of a factor that results in different people getting slightly different roast results: your electrical outlet.

We always check the voltage, the voltage drop (what is measured after the roaster is started), and the watts consumed at various settings. Even in our warehouse, we see a variation between the upstairs cupping lab and our downstairs testing room. Upstairs is closer to the electric panel, downstairs is further away. Although we often measure 122–123 volts before starting the roaster at both locations, upstairs dips to to 119-120 under load, whereas downstairs can go as low as 116 volts.

We think the variation we see within our own facility represents the range that might be experienced in the homes of Popper users. The resulting wattage is quite different for the various roast settings.

What that means is people with electrical supply more like our downstairs outlet should likely increase the recommended settings by +1. So you want to do the initial 3 minutes of roast at setting “2,” not “1”.

Ambient temperatureThe temperature in a given room or space: This term is used to describe the overall temperature in a given environment, and is an important variable in coffee... ...more (including even humidity and altitude) can impact roasting. If your roaster is taking in cooler air, such as an early morning roast versus one in the afternoon, you will likely need to boost your heat settings. We find that the electric supply to the roaster is the number one variable people encounter.

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How do these roast curves compare?

Here is a comparative graph of the “straight roasts” where no heat level changes are applied.

Between the one where heat level “2” (light City roast) and heat level “3” (Full City+ roastA roast slightly darker than Full City. At Full City+, the roast is terminated after the first few snaps of second crack. The main cue that distinguishes the... ...more), there is a dramatic difference in the roast level and style.

Below is a comparison graph of the 3 roasts with heat profiles applied. It is remarkable how they can end at the same final temperature but taste different in the cup.

The roast marked in red cupped lighter and brighter than the roast in purple, but ended at nearly the same finish temperature at the same time. For the roast in brown, which had a delicious darker roast level, simply +1 minute continuation of the roast in purple was the way to achieve this.

For espresso, we had really nice shots from this very simple, gentle roast curve with minimal intervention.

After our slow 3 minute warm up at heat level “1,” we use heat level “2” to gently edge the roast along with a slow ROR (Rate of Rise) to achieve an air-roasted espresso that really tastes more like a slow drum-roasted espresso.

P.S. I really want to provide guidance for getting better good results on the Popper roaster, but this project had a bit too much “nerd creep” and ended up feeling a bit disorganized. If I wasn’t clear enough about anything here, please let me know in the comments.