Sample Roasting in the Aillio Bullet is a Snap!

The Aillio Bullet R1 is a workhouse for roasting full size batches. But it can be a great sample roaster too.

A key feature of the Aillio Bullet is roast batch versatility, from 2.2 pounds per batch (1 kg.) to small 150 gram sample roasts. Adding a Bullet to your small roasting operation, or for home roasting, is ideal because it won’t outlive its usefulness.

If you start out using the Aillio Bullet R1 as a production roast, doing back-to-back 1 kg roasts, then you upgrade or start co-roasting, you still have a sample roaster and a great backup machine!

The Aillio Bullet R1 is of the few roasters that can truly handle its advertised maximum roast capacity of 1 kg … something that’s not always true even at the commercial level.

You might be saying to yourself, “why would anyone want to roast less than a pound of coffee in a 1kg machine?”

For someone looking to support a small roasting business, the Aillio Bullet presents a unique option of getting a production roaster and sample roaster in one machine. We’ve shown in a previous video how well it does roasting 150 grams of coffee, which is a common size for coffee samples. No need for the added expense a sample roaster brings, which can be quite a lot!

pre-weighed 150 gram batches are stacked and ready for roasting in the Ailio Bullet
Pre-weighed 150 gram batches are stacked and ready for roasting in the Aillio Bullet

But this is also good news for the home roaster left deciding how to approch with small tail ends of different coffees they’ve bought. There’s no need to bulk up a larger batch by blending, as long as you have 150 grams of green. Or maybe you just want to try a few different roasts of a coffee that you only have 1 pound of. Whatever the reason, the Aillio Bullet allows you that option in a very controlled way.

What makes a “sample roaster”?

If you’ve never heard that term before, a sample roaster is typically used to roast small batches of coffee with the purpose of evaluating quality. When I say “small”, I mean 50 to 150 grams of coffee (we roast 100 in our Probat P3). Due to the small size, their use is very specific, and a roaster designed specifically for sample-size roast batches won’t work well as a production roaster too. Another reason why the Aillio Bullet is such an attractive option.

Unlike production roasting, the pinnacle achievement in sample roasting is to consistently reach a light roast in a tight time range across multiple batches. There’s no “profiling” the roast to get the most out of a particular bean. The idea behind this type of roast treatment is that you don’t want to hide any potential faults or flavor defects with roast.

A variety of sample roasters with different numbers of roasting chambers, all made to roast small batches.
A variety of sample roasters with different numbers of roasting chambers, all made to roast small batches.

Some sample roasters are built with more than one roast barrel, allowing you to process multiple batches at the same time. There can be as many as five or six, and are often seen at coffee labs of importers and exporters who roast hundreds of samples each week (we have a three barrel Probat in our lab). But for most small to mid-size roasteries, a single barrel is just fine as long as it can roast consistently.

How to roast 150 grams in the Aillio Bullet

Roasting samples on the Bullet is not all that difficult, and our approach is very similar to how we roast on our electric lab roaster, the Probat P3. We limit changes to thermodynamics, try to stay consistent across roast batches, and avoid getting lost in the weeds. It doesn’t mean our recipe is one-size-fits-all. Variances in the density, moisture, size, etc of green coffee means changing things up in order to stay within the desired roast parameters.

That said, this provides you with a simple baseline to get you started roasting small batches of coffee in a controlled way. A “quick start guide” to sample roasting on the Aillio Bullet, if you will. Once you get the hang of it, adjust the variables as you will to fit your personal preference!

Weighing out each batch to your weight target is an important first step in getting consistent results.
Weighing out each batch to your weight target is an important first step in getting consistent results.

We’re roasting 150 grams of green coffee with a roast target of yellowing in about 3-4 minutes, 1st Crack (“1C”) around 6-7 minutes, ending the roast 1:30 – 2:30 minutes after the start of 1C, and wind up with a moisture loss of 11-13%. I want to leave some space around these numbers because not all coffees handle the same. Coffee with a high moisture content, for example, will lose more moisture weight. And perhaps more importantly, final numbers do not determine the outcome in the cup! You can still tell a lot about a coffee’s quality with a less than perfect roast.

It’s important to point out here that while the IR sensor does a great job of reading bean temperature inside the drum, the accuracy starts to wane a little toward the end of the roast. I think this has to do with the difficulty it has getting a reading off of such a small bean mass that is dwarfed by the large drum size. It’s not really a problem, and can be easily overcome by paying attention to the other variables and cues so that you know how your roast is tracking.

Here's a graph of one of our sample roasts running the profile outlined here on the Bullet.
Here’s a graph of one of our sample roasts running the profile outlined here on the Aillio Bullet.

Here is our roast recipe for a 150 gram sample:

  • Warm up the roaster to a drop temp of 392F
  • Default roast settings are P6, D9, F2
  • 2:00 minutes into the roast, drop power to P5
  • yellowing should happen around 3:00 – 4:00
  • 1C should happen between 6:00 – 7:00, and 380F+
  • I usually pull my batch between 1:30 – 2:30 after the start of 1C

After 30+ roast batches here’s what I’ve learned

My main takeaway from this test is that the Aillio Bullet roasts 150 grams of coffee back-to-back with the same consistency as it does larger batches. The level of roast versatility is unmatched by any other roaster on our list, and is just generally hard to beat. That it can roast both 2 pounds of coffee all the way down to 150 grams places the Bullet in a unique roaster category for someone looking to start a roasting business, since it can perform both production, and sample roasting duties.

If you’re using the Aillio Bullet to roast samples, consider the first batch a warm-up. Don’t just warm up the roaster and drop your one and only 150 gram sample that you need to make a buying decision on. I’ve overlaid my warm-up roast and the one after it below, and you can see that the warm-up ran 1:15 longer. That’s enough of a difference to have an affect on flavor.

This overly of my warm-up batch and the roast after shows a difference of 1:15 overall roast time.
This overly of my warm-up batch and the roast after shows a difference of 1:15 overall roast time.

There are usually a few early snaps that occur before 1C actually gets underway. As you’ll see in the next paragraph, I rely on time more than most other roast cues, so logging an early 1st Crack time is likely to lead to a raw roast from pulling the roast early. I’ve experienced these snaps around 30-45 seconds before the main event, and they tend to be single ‘pop’s that occur in isolation – not in succession. 1st Crack is underway when you hear a successive snaps. You can hear the difference in the video below.

Side-by-side comparison of roast degree between the 4 batches. Detailed close-ups in the video below.
Side-by-side comparison of roast degree between the 4 batches. Detailed close-ups in the video below.

When roasting such a small batch size, I trust regimen over readings. Overall, the Aillio Bullet’s IR sensor does a great job reporting the temperature of your roast. But it has a harder time doing so with 150 grams, evidenced in the wavering line plotted on the graph. It’s important to keep this in mind when you’re seeing temperature swings, especially at the end of your roast. I saw momentary drops and spikes of up to 10F after the start of 1st C, and without knowing this to be normal, may otherwise have caused me to overcorrect or end my roast.

Overlay comparison of the 4 back-to-back sample roasts on the Bullet shows just how closely they tracked.
Overlay comparison of the 4 back-to-back sample roasts on the Aillio Bullet shows just how closely they tracked.

I also let my roaster come down to the original charge temp between every roast. With sample roating, consistency is of paramount importance, so ensuring that you’re repeating variables from one batch to the next can’t be overly stressed! By doing so you can expect very predictable results when roasting multiple batches in a row. Overlaying the 4 batches I roasted during one of my sessions (above), you can see how tightly grouped the yellowing (“Y”), 1st crack (“1C”), and finish times are.

This was a refreshing exercise, and solidifies my belief that the Aillio Bullet makes a great 2-in-1 machine for a small batch roastery who are looking for a roaster that can serve as a sample roaster, and light production machine.

Watch our latest video demonstrating this sample roast profile with four batches of green coffee in the AiIlio Bullet.

Check out an older video of Tom running sample roast tests on the Aillio Bullet, and a whole lot more.

Also see:

Aillio has published an article about Rob Hoos technique for roasting samples in the Bullet as well. We feel as our latest video, and the approach in this new article is a bit more informed than both our older video, and the Aillio article, at this point (9-2023):

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