Three years later, the Aillio Bullet is still our top choice for roasting large volumes of coffee back-to-back.

We’re dusting off this post from 2020 to double down on why we think the Aillio Bullet is at the top of its class for roasting large volumes of coffee consistently.

[UPDATE: August 24, 2023]

In a recent Instagram post, we asked our customers how many batches they roast in a row. The responses were astounding, topping 85 pounds in a single roast session! It’s no wonder the Bullet’s become a popular stepping stone for commercial roasting startups.

When we originally published this blog post, we knew the Bullet could roast a lot of coffee by design, but didn’t have a lot of data to point to other than batch size. In terms of sheer volume, the Bullet’s advertised 1kg (2.2 pounds) roast capacity out-roasts our other machines by quite a lot.

Since then, we’ve seen quite a few roasting businesses built on the Bullet’s large capacity, processingThe removal of the cherry and parchment from the coffee seed.: Coffee is either wet-processed (also called washed or wet-milled) or dry-processed (also called wild, natural or natural... 10’s to 100’s of pounds of coffee a week, supporting subscription services, and even small cafe’s. Despite the Bullet’s “100kg/month” recommendation, it’s proven to have no problems being put through more strenuous paces.

Volume is only part of the equation to consider when looking for a high volume roaster. Another major strength of the Bullet is the ability to track consistent roast profiles from one batch to the next. Outside of these two touchstones of production roasting, the only other considerations are maintenance, and your time at the roaster!

Check out our original piece below, where we share our own experience roasting 20 x 1 pound batches in a row on the Aillio Bullet, and what we learned from that experience.

---

Article originally published October 2020

Roasting 20 Batches in a Row on the Aillio Bullet R1 Coffee Roaster …here’s what to expect

The reason we tout the Aillio Bullet R1 Coffee RoasterA machine for roasting coffee. Or the person operating it! The basic requirements for a coffee roaster are a heating element that gets suitably hot and a mechanism... as a potential shop roaster is because it can manage 2 lb roast batches with relative ease and roasts while cooling coffee simultaneously, making it an ideal candidate for roasting back-to-back. But we hadn’t really tested how consistent the roaster is from one batch to the next. So when the opportunity to provide 30 bags of coffee for charity came up, I knew it was time to see how well-suited the Bullet R1 is for a big job like this.

OK, exactly how much coffee is 20 batches? That all depends on how much coffee you roast and how dark your roast level is. Darker roasts lose more weight than light roasts and will require more 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,... to reach your desired output weight.

For my project, I needed 30 x 325 gram bags of roasted coffee, or roughly 22 lbs. I tend to gravitate toward lighter roasts, and for the ColombiaColombian coffee is highly marketed and widely available in the US. They have been largely successful at equating the name Colombian Coffee with "Good" Coffee. This is half-true.... I chose to roast for this, I was shooting for something like 15% moisture loss green-to-roasted coffee. Some quick napkin numbers helped me deduce that I needed at least 26 lbs green, which led me to settle on 20 x 600 gram batches of coffees to hit my mark.

I know the Bullet can handle 800 grams+. But running any roaster at max capacity tends to slow down roast progression. I prefer the complexThe co-presence of many aroma and flavor attributes, with multiple layers. A general impression of a coffee, similar to judgments such as "balanced" or "structured" acidityAcidity is a positive flavor attribute in coffee, also referred to as brightness or liveliness. It adds a brilliance to the cup, whereas low acid coffees can seem... that comes with hitting 1st 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... (“1C”) around 8 minutes in the Bullet, and in my experience with my particular R1 that is still running the old PCB, 800 gram roasts stretch 1C well beyond that mark.

The roasting is done and so I’ll get right into performance and a few observations. All in all, I was very pleased with how consistent the Bullet performed across all 20 roasts. Save the warm-up batch and any “operator errors”, replicating my initial roast parameters was easy, the roast legs close, as long as I remembered to make my changes in heat and airflow at the same times.

I kept my profile simple so there weren’t too many twists and turns to remember (or forget!) making replication easy.

The gist: I started with heat high, slowly tapering off before 1C. Drum and airflow are low to begin with, ramping up toward the end as to slow down the rate of rise and pull chaffChaff is paper-like skin that comes off the coffee in the roasting process. Chaff from roasting is part of the innermost skin (the silverskin) of the coffee fruit... off the roast.

The specifics: I started with settings P9 (power), F1 (fan), D3 (drum speed). At 4 minutes in, I increased fan and drum speed to F2 and D4. Once I was 20F degrees from 1C (350F – 1C happens around 370F on my roaster), I decreased power to P8 in order to start slowing roast progression. At 1C, I increased fan and drum speed to F3 and D5, and 1 minute later increased fan speed to F4 and decreased power to P7.

I replicated this roast as best I could across all 20 batches. You can “replay” a roast on the Bullet, but that’s not what I did for this test.

I should also note that I’m roasting back to back without letting the roaster cool down to the pre-heat temperature that I have set to 400F. This meant that after dumping a roast in the cooling tray, closing the roaster door, starting the charge sequence and weighing out my next roast batchOne of the most important variables in roasting coffee, the weight or volume of the coffee being put in to the roaster will dramatically affect the outcome of..., the roaster temperature dropped to about 440F. If I were roasting a softer, less dense bean, I would likely let it cool down much closer to the pre-heat temp to keep from scorchingPatches of discolored burn marks on the coffee bean, due to a high-heat roast environment or other roast error.: Scorching refers to a roast error that can be... the coffee. But the Colombia is very dense and has a slightly higher moisture content than most, absorbing a lot of that extra energy after entering the roast chamber.

So how consistent were my roasts? Very consistent. Below is an overlay of three roasts at different intervals to illustrate, roasts #6, #12 and #20.

What stands out to me in this graph overlay are the fact that the drum (green) and IBTS/bean (purple) temps are nearly identical across all three roasts. Though rate of rise (“ROR” in pink) is somewhat erratic, that’s to be expected. I have ROR set to update every few seconds and the temperature is bound to vary slightly depending on where in the bean mass the IBTS sensor is reading. It’s also worth noting that 1C time for all of the roasts was right around 7:45.

Key takeaways from the experience and recommendations for roasting multiple batches back-to-back:

• Start with a clean roaster. Don’t set off on a lengthy roast session like this with a dirty roaster as you’re likely to damage the machine and can even start a fire.
• A warm-up batch is HIGHLY recommended as they tend to run  longer than the successive batches and will taste different.
• I vacuumed the chaff from the access hole on the bottom of the chaff collector every 5 roasts. I would recommend more frequent cleaning if roasting a natural or honey processThe honey process has nothing to do with honey other than the fact that they're both sticky! It's a term that became popularized in Costa Rica as another... coffee since they produce more chaff than washed. Failing to do this will likely cause a fire.
• Check the cooling tray filter and vacuum between each roast. See the photo of mine below after roasting 20 batches. I was able to clean it up enough to continue using, but it’s good to have a few of these on hand to make sure air is flowing freely.
• Don’t try to fit too much in a single day. 20 roasts took about 3.5 hours. While this isn’t a terribly long time, I worry that too much coffee through the roaster without a deep cleaning in between is dangerous.
• Perform a deep cleaning after the roaster has cooled.

All in all, this was a very informative exercise. We know the Bullet R1 is a capable and consistent 2 lb. roaster, but the test helped put into perspective just how well it performs across a marathon of roasts. As with any roaster, the Bullet should be cleaned regularly between roasts, and in the case of roasting several batches in a row like this, you should vacuum the chaff drawer every few roasts to avoid a potential fire. None of this is unique to the Bullet and just part and parcel with roasting large volumes of coffee, which the Bullet R1 is certainly capable of.

Other Aillio Bullet Coffee Roaster Information

Our Aillio Bullet R1 Resource Page

Our Bullet basic cleaning guide

Aillio Bullet Sample Roasting Video

Our Video of the .pdf in action