Also, I think we’ve discussed this in here before, but the “drink your coffee within 14 days” thing is old news about dark roasts that people have been parroting forever. With lighter roasts, 14 days off roast might be how long it takes to achieve its peak flavor profile:
Over the course of the last few months, I have conducted a battery of tests using coffees with age ranges from 1 day off roast to 1 1/2 years off roast. The tests were all done blind and all done to taste, no scientific equipment (refractometer et al) was used. The results were startling and made me reconsider my definition of peak freshness. As expected, the coffees that were in the 7-21 day range were delicious. The real surprise, however, were the coffees at a month, 2 months+. Only, after about 3 months did we notice a truly discernible loss of what I would call vibrancy. The coffees still tasted just fine, but had lost the higher acid notes that constitute a balanced cup. Hell, the 6-month tasted fine too. It wasn’t until the year and a half coffee that it was completely evident that the coffee was old.
This is a wire mesh sieve of unknown size. To my eye, it looks smaller than the 800 to 900 micron range that these results suggest, but this is hard to nail down macroscopically. My gut is that the app overestimates grind size slightly compared to sieving due to how the particles lay down on paper for photos (i.e., they tend to not stand up tall like a skyscraper which means the app is biased toward capturing the max dimension of each particle).
*I tested the hot tap water flow rates of the tabbed vs untabbed side by side. Didn’t end up timing it because the tabbed filters are draining way faster. The original untabbed tend to even stall out a bit with about an inch of hot tap water left in the cone (boiling goes through faster). I haven’t tested this with actual coffee though which could be different.
Everyone drinking light roasts should read this first link by La Cabra for sure. They make bolder claims than I’ve seen anyone make regarding resting with provided V60 recipe tips based on time off roast. The second link is a short academic paper that provides some key insights on degassing. The third link is a 188-page dissertation. Choose your own nerd level.
Check out how ridiculously slow light roasts de-gas compared to other roasts (!!!):
Time-Resolved Gravimetric Method To Assess Degassing of Roasted Coffee
The weight loss and degassing rate of the sample roasted at medium speed to a light roast degree was also measured over a longer period of 800 h; after 800 h, a total of 3.4 mg/g weight loss from degassing was measured. The degassing rate at this point was still 2 μg g^−1 h^−1. This shows that even when degassing is conducted at elevated temperatures (35 °C), light roasted whole coffee beans are still degassing 1 month after roasting.
This paper cites what appears to be a 2014 Chinese dissertation on the topic, which can be found here (warning: this is full bore rabbit hole):
Anyway, the experiment I was looking for occurs here beginning on page 83:
The degassing attained equilibrium in 90 h at 81% RH, while only ~60 % of CO2 in roasted beans was degassed at 0% RH, even after an extended degassing period (1100 h).
The increased degassing rate of the beans at elevated RH could be explained by the plasticizing effect of moisture on the cellulose matrix that increased the diffusivity of CO2, whereas, under the dry conditions, cellulose mainly existed in a glass state.
No I haven’t. What are you thinking makes for a good experiment here? Something like separating out anything that goes through the 400u screen and run the rest through the app?
I did try brewing after using the sieve once and it made for really weak coffee so I haven’t tried it again.
Yeah like maybe prepare a sample of 400 to 800 range or whatever and see if the app agrees.
One thing I’ve noticed looking at those laser diffuser plots is that the total surface area of fines from “good” grinders is about equal to the total surface area contributed by the target particle size. I have no idea why, but even that guy in the Hoffman video with the $500,000 machine made an adjustment that produced additional fines somehow that evened out the surface area contributions. So that’s what I’d be thinking about during sieving for an actual recipe.
You can see that shaping the particle distribution has more dimensions than just “getting a unimodal grind” or whatever has been pushed onto us repeatedly. People have pointed out that even the EK43 makes a lot of fines, and that zero fines isn’t really the goal here. In fact, I’m not sure anyone knows exactly what the goal is because it seems rather complicated, but the surface area density plots are quite striking. However, I think one problem is that rather early on in specialty coffee, some of the bigger influencers were “sieving out fines” during competitions, and the idea that fines == bad caught on and never totally died.
I’ve always seen the Kruve more as an affordable way to measure grind distribution (lab grade sieves are expensive) and not as a recipe manipulator, but if I was going to remove fines for brew purposes, my intent would be to even out the surface areas. Based on the laser analysis of the new Vario (i.e., Forte), it looks like the amount of fines you could remove by weight before moving into an uncanny valley territory is ridiculously small, and mostly in the 100 um to 300 um range. Like, look at that first plot: the Vario tracks a $500k grinder almost perfectly below 100 um. You could also arguably lop off a tiny amount of boulders, but again, I think you’d need at least a milligram scale to do it at a meaningful level. Yesterday I was clearing fines out of the J-500 with the bag knocker, and a significant amount of dust / powder landed in the catch cup, yet it didn’t even register on my 0.1g scale.
Another point regarding that last bit: I realized that with this commercial grinder I was DOING IT WRONG. I’d grind directly into my bin and then use the bag knocker to get the rest out. But after cleaning the machine and using RDT, the only thing coming out after cutting the motor or flicking the knocker were fines and chaff dust that clung to the inside due to static. So now I use two different bins to catch it. And again, this was a fair amount of powder in terms of surface area, and the amount of mud in my V60 bed decreased by about half, yet it didn’t register to one tenth of a gram. IOW, this feature of fines manipulation is built into some grinders to some degree, and I suspect that increasing static might hold more fines back.
Right, the only reason I even thought of it is because this thing has a spring-loaded bag clamp that you can use as a knocker. Several consumer grinders like the Fellow Ode and some recent Chinese knockoffs have similar mechanisms, but it’s probably bellows or canned air beyond that.
Still doesn’t solve the mystery of how I was able to grind months-old coffee perfectly to one of the most consistent grinds I’ve ever seen, yet all of this new stuff is creating enough dust to cause black lung. My working theory is that high CO2 → worse grind quality but it’s gonna take a lot of experiments to prove that.
51 minute youtube??? does he talk about grinding? I feel like there’s lots of interest around CO2 but everything I’ve seen has all been from the perspective of brewing and just sort of assuming that grinds are consistent
No grinding but the electron microscope views and how CO2 is stored is pretty interesting. Also a thing at the end where he talks about freezing your coffee: there isn’t enough water in coffee to get freezer burn / crystal structure and can slow ~1 month of normal degassing rate to about one year.
Thanks for that la cabra link. I just started a new bag from black and white - a cinnamon anaerobic. I had been doing my normal recipes using 95c or even 99c water and was mostly getting burnt bean flavor with a hint of cinnamon
After reading that I dropped temp to 90c and have played with two bloom phases or at least one very long bloom phase and it tastes so much better. Not my favorite flavor profile but now it at least has the flavor profile of a classic medium roast with some cinnamon
I still have a dose of that cinnamon anaerobic left. One of the few coffees where I thought the aroma was better than the cup itself, but mostly because the cinnamon toast fragrance was unreal. I wanna say the cup profile definitely improved after a few weeks. Was mostly getting a green apple acidity with slight cinnamon notes and the roasty bitterness finally went away. Probably all along I haven’t been resting most of my coffees long enough.
Something I noticed in the video above that he didn’t have an answer for: he showed grind sizes for roast at 0 days, 10 days, and 60 days, and the change was not monotonic. It went 1.45 → 1.6 → 1.45.
I no longer believe people who say this stuff doesn’t matter for filter and just instead assume they’re simple or trolling. Whatever is happening here probably explains why brewing LRSO V60s is like shooting dice, and dialing in a filter brew at home is nothing like dialing cafe espresso where you keep pulling shots and discarding until it’s right.
Practical recommendation for people who want SIMPLE:
When you order coffee, get at least one true medium roast in your order so you can enjoy it while lighter stuff rests. Anecdotally, I’ve had way more success brewing mediums consistently and [the faster offgassing] is probably why.
And yeah the aroma of cinnamon is much stronger than the flavor in this thing. It’s an ok cup but I’m thinking about abandoning the beans halfway through the bag to move on to some stuff I might like more
to catch it. And again, this was a fair amount of powder in terms of surface area, and the amount of mud in my V60 bed decreased by about half, yet it didn’t register to one tenth of a gram. IOW, this feature of fines manipulation is built into some grinders to some degree, and I suspect that increasing static might hold more fines back.
