Grinding coffee bean-by-bean is up there with cryogenic grinding, double grinding and re-processing as a kind of impractical perfection — all of which are primarily dismissed as inappropriate for the commercial environment. Wet grinding isn’t a thing — it was just a dream of the early third wavers — but let’s throw that in there too. Cryogenic grinding is a thing, but in this article we’re gonna explain how it was that we found a genuine world practical use for bean-by-bean grinding.
To date, the best investigation into bean-by-bean grinding was carried out by astrophysicist-cum-barista Prof Jonathan Gagne. A few years back, some of his subscribers were worried about how the widespread uptake of single-dose grinding (where you throw a pre weighed dose of beans into an empty coffee mill hopper) would alter the way coffee grinders perform, compared to when the beans are fed into the burrs via a full hopper. Jonathan managed to show that the difference was genuine however possibly negligible; i.e. just a couple of beans at the end would experience the so-called popcorn effect and grind a little more coarsely.
There are two terms you need to understand before you read any further.
Popcorning
When coffee beans are driven through the rotating mill burrs, they needs to navigate through whatever gaps present themselves between these burrs which aren’t already occupied by other grinds moving through the system. In contrast, the behaviour of a solitary bean in an empty hopper is markedly different. Without the collective pressure of other beans, a solitary bean bounces around haphazardly, sometimes slipping through largest gaps at the edges of the burrs discussed as the tertiary cuts. Single beans likewise tend to bounce around at the entrance to the blades, resembling popcorn kernels popping and jumping in a hot pan, which is why it is aptly named “popcorning” or “the popcorn effect.”
Outfall Depth
The ‘outfall depth’ in the context of coffee grinding refers to the size of the opening on the side of the burr which is created when the burr’s cutting edges, specifically the tertiary cuts, align. This gap is the exit path for the boulders coffee particles. The outfall depth is significant due to the fact that it directly influences the grinding efficiency and the consistency of the ground coffee:
Larger Outfall Depth: A larger gap allows coffee particles to exit the burrs more quickly, leading to faster grinding. But, this increased speed can result in a wider range of particle sizes, as the beans are not ground as equally. The consequence is a less consistent grind, which can affect the extraction and flavour of the coffee.
Smaller Outfall Depth: Conversely, a smaller tertiary cut at the edge of a coffee burr restricts the flow of ground coffee, slowing down the grinding method. While this might take more time, it typically effects in a more uniform grind, with particles being more consistently sized.
Gagne’s experiment did a good job at quieting concerns that single doses could create inferior grind profiles, compared to full hoppers. He speculated that it’s probably only the last couple beans that experience the popcorn effect and the particle size analyses he ran comparing the two grind profiles from his Niche mill were virtually identical. But, in his blog post he likewise crafted this observation:
‘Grinding bean-by-bean generates a slightly tighter [grind size] distribution, therefore mimicking a higher quality grinder.’
Soon after Gagne’s article, The Hoff likewise had a go at it, combining double-grinding and an ultra slow feed into his grinding machine, and said afterwards
‘I was able to produce what I think was a sweeter, tastier, more delicious espresso.’
Since then, bean-by-bean grinding has sat there as a tempting frontier with quite a lot of unexplored potential. And then, all of a sudden we necessary bean-by-bean grinding — not truly to please the coffee gods, but for actual practical reasons.
The Experiments
As you understand, we’ve been writing about the new generation of filter baskets lately. One thing all the new high extraction baskets have in common is that they require you to grind quite a lot finer. And sometimes, if you happen to utilize an oily dark roast — or you haven’t cleaned your burrs for a while, you might find out that your mill gets totally choked up, with the beans unable to exit the coffee mill at all. It takes place all the time with truly dark roasts. For this reason, makers of commercial grinders — particularly ones like the Mazzer ZM which have a digital grind adjustment mechanism — sometimes create a minimum grind setting to prevent grinders getting choked and likewise to prevent burrs from grinding against each other.
Well, our coffee grinder choked up while we were testing our new Sworks Billet basket. With that particular coffee, we found bean-by-bean grinding was a handy way of guaranteeing beans at any roast level would always feed into the burrs adequately. Plus, in theory, bean-by-bean appeals to us because each individual bean can have the same experience as it enters and leaves the burrs — it never has to wait in the queue. The thing is though, the bean-by-bean approach pushed the essential grind setting a LOT finer. Not just a LOT finer … so much finer that we had to change from Mazzer’s k151I to the k151B 83-mm burr set, which has actually about the smallest outfall depth you can find.
Three 83-mm burr sets with increasingly large tertiary cuts. From left to right, the k151B (espresso coffee burr); the k151I (hybrid burr); the k151F (filter burr)
We asked Lloyd Meadows at Tortoise Espresso coffee to have a crack at bean-by-bean on his EK43 grinding machine, paired with his new Pesado HE% baskets. Lloyd soon found himself on the absolute finest setting his EK would allow and his shot times were gushing through in eight seconds. So we’d now maxed out the fine-grind potential of two of the industry’s leading single-dose grinders, but we weren’t going to quit. (Please note: Lloyd doesn’t work with the Turkish burrs — we’re expecting they would be suitable for bean-by-bean grinding for espresso)
Next step was to override the ZM’s safety features (don’t try this at home). After recalibrating the ZM grinder to grind finer than would usually be possible, we were dialled in for bean-by-bean grinding on a setting roughly twice as fine as the single-dose setting. And the bean-by-bean shots were averaging a full percentage point higher than the full hopper. (If you’re not familiar with measuring coffee extractions, a 1% increase is a lot). We went from an normal of 22.3% up to 23.3%. It’s hard to slow down high extraction baskets much past 16-20 seconds, nevertheless those bean-by-bean shots that took around 31–41 seconds were absolute godshots.
You look at our data set and you can see how much higher and tighter the extraction yield percentage is from bean-by-bean. So, a couple of thoughts here: whilst bean-by-bean may be slow and impractical, it brews unbelievably tasty espresso. It likewise steeps your grinder way quieter, though the motor is on for longer. We can speculate that it will dramatically reduce heat build up in the burrs (that’s a test for another day) and we know it alleviates issues of grinders getting choked, even with evil dark roasts. The automated troubleshoot for this could be as simple as redesigning the auger that brings the beans into the burrs to slow down the feed or putting another auger in the hopper as well. As things stand, this approach may require the beans to go marching one-by-one, nevertheless for sure this is a fast track if you wanna ‘get-down to the grounds.’
The Art of Grinding Coffee: A Deep Dive into Bean-by-Bean Grinding
Ever heard of grinding coffee bean-by-bean? Sounds like a tedious task, right? Well, it might be. Nevertheless let me tell you, it’s likewise a fascinating journey into the world of coffee that could potentially revolutionize your morning cup. So, grab your favorite brew and let’s dive in!
Grasp the Basics: Popcorning and Outfall Depth
Before we get into the nitty-gritty, there are two terms you need to know: “popcorning” and “outfall depth”. These are necessary concepts when it comes to grasp how coffee grinders work.
Popcorning, in coffee lingo, refers to what occurs when a solitary bean is left bouncing around in an empty coffee mill hopper. Image popcorn kernels popping and jumping in a hot pan – that’s exactly what these beans do! They slip through the largest gaps at the edges of the burrs called tertiary cuts.
Outfall Depth, on the other hand, refers to the size of the opening on the side of the burr which is created when its cutting edges align. This gap is essentially an exit path for ground coffee particles. The outfall depth directly influences grinding efficiency and consistency:
- A larger outfall depth allows for faster grinding but can result in a wider range of particle sizes due to less uniform grinding.
- A smaller outfall depth slows down grinding but typically effects in more equally sized particles.
The Bean-by-Bean Experiment
A few years back, astrophysicist-turned-barista Prof Jonathan Gagne conducted an investigation into bean-by-bean grinding. He managed to show that the difference between single-dose grinding (where you throw a pre-weighed dosage of beans into an empty coffee grinder hopper) and grinding with a full hopper was genuine however possibly negligible. However, he also observed that bean-by-bean grinding generated a slightly tighter grind size distribution, mimicking a higher quality grinding machine.
Following Gagne’s experiment, another coffee enthusiast discussed as The Hoff also tried bean-by-bean grinding. He combined double-grinding and an ultra-slow feed into his coffee mill and found that it produced what he believed was a sweeter, tastier espresso coffee.
The Practical Use of Bean-by-Bean Grinding
Now, you might be thinking: “That’s all well and good, but is there any practical work with for this procedure?” Well, as it turns out, there is!
We’ve been testing new generation filter baskets lately. These baskets require finer grinding. But sometimes when utilizing oily dark roasts or if the burrs haven’t been cleaned for a while, the coffee grinder can get completely choked up. That’s where bean-by-bean grinding comes in handy!
With this procedure, we found that beans at any roast extent would always feed into the burrs properly. Plus, each individual bean can have the same experience as it enters and leaves the burrs — no waiting in line! The only catch? This approach pushed the needed grind setting much finer.
The Results
After recalibrating our mill to grind finer than usual, we were dialed in for bean-by-bean grinding on a setting roughly twice as fine as the single-dose setting. And guess what? The shots were averaging a full percentage point higher than those from a full hopper! We went from an normal of 22.3% up to 23.3%. That’s a significant increase if you’re into measuring coffee extractions.
And the taste? Those bean-by-bean shots that took around 31–41 seconds were absolute godshots. Yes, you heard it right! They were unbelievably tasty. Plus, this technique makes your coffee mill way quieter and potentially reduces heat build-up in the burrs.
Final Thoughts
So there you have it, folks! Bean-by-bean grinding might seem slow and impractical, but it can make a world of difference in your cup of coffee. It’s like taking the scenic route instead of the highway – sure, it takes longer, but the view (or in this case, taste) is worth it!
Now, I’m not saying you ought to start grinding your coffee bean-by-bean from tomorrow morning. Nevertheless hey, if you’re a coffee enthusiast looking for new ways to enhance your brew or just someone who enjoys experimenting with tastes – why not give it a shot? Who knows? You might basically stumble upon your new favorite brewing technique!
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