BuckleyT wrote: If someone wants to simultaneously interject other variables such as flow rate and surface area (how about temperature gradient down the puck depth?) and then complain that the system is too complicated to understand, or is too full of contradictions, they are free to do so, but this explanation is the 'Occam's razor' that presented itself to me.

I'm just quoting a bit of your post so you get a notification. Nice post, of course. I think your explanation is the most logical.

With regards to brittleness, lighter roasts are generally less brittle, perhaps due to more moisture content or perhaps due to some other processes. But it's well-documented that light roasts produce fewer fines. That's a major reason why lighter roasts require a finer grind.

With regard to why this benefits lighter roasts, I think it's because they are the least soluble. If we have a technique that lets us grind finer and more uniformly (i.e. fewer fines) for an equivalent flow rate, then we can extract more. With darker roasts, extracting enough is not really an issue, but with a city roast that struggles to extract as espresso, going from 19% to 20% or 20% to 21% is a huge difference that results in dramatically improved sweetness and clarity. This is especially true when you're pulling someone else's roast that wasn't designed to be soluble.

Oh, and I'm not sure why the Mythos keeps getting brought up. Yes, it heats beans, but only as a side-effect and for an entirely different purpose - ensuring grinder consistency regardless of espresso volume. It's a lovely machine, and I'm a big fan of it for cafes, but it really has nothing to do with the sort of controlled heating that we're aiming for.

I have always been confused about light roasts and perhaps I am the recipient of a lot of conflicting information. I have come away with the impression that they are harder and tougher to grind and perhaps I was reading brittleness into the physical characteristics, when I shouldn't. Thank you for the clarification. I'm still confused by light roasts, but it is my job to 'sort my knowledge out'.
BT

I've been travelling a lot for work recently and have also been mucking around with a Ditting for espresso. Today though I went back to the HG one as I am very confident about grind settings for different brew ratios. I had roasted a high quality Yirgacheffe a little lighter than normal and proceeded to use the microwave technique (22 g dose of beans microwaved for 40 seconds) to see how much grind setting variation would result in my normal ristretto shot. I'm a bit of an espresso throwback as I prefer my brew ratio at about 1... my shots are short, thick, syrupy. For me it's predominantly about the mouth feel and I recognise that I give up on some varietal character.

So I progressively moved from standard (non-microwave) grind setting to finer settings. To end up with my preferred shot I ended up having to move the setting a full inch clockwise on the HG one (this is a really significant amount in my experience, my normal movement from a Brazilian SO to geisha is about half that). The result in the cup for this final sample was pretty amazing. It had all of the mouthfeel that I desire and it had remarkable varietal character... the best of both worlds.

That is a cool idea, to try light roast and microwave. I didn't necessarily prefer microwaving the beans for a particular espresso intended coffee. It was different, not necessarily "better". I shall try filter style and microwave... if I can grind fine enough, thanks.

I read an interesting twist on this in the comments section of the Socratic Coffee site here where the commenter tried a 10 minute pre-infusion before brewing and got more sweetness and less brightness. I'm surprised it didn't taste over-extracted.

What's the longest PI you've toyed with? I've gone 30 seconds, but I don't have some deep delicate wine-palate when it comes to tasting & expressing shots; and a majority of my shots are destined to be cortados or macchiatos.

I finally did the microwave trick with my Mythos and even at my near-choking setting for daily hopper use, the shots flowed quite quick & easy. Tuned in quite a bit finer and got the flow to match that of my usual pulls. The faster flowing microwaved shot was plenty tasty though, and noticeably different than the usual pulls.

Dustin at Stanza will occasionally put a stellar Esmeralda Geisha on bar and pull 2 minute lungos, where he just grinds powder fine and pulls the whole shot in pre-brew.

To me it raises an even more interesting discussion, if that's the zenith of the next wave of fine espresso and the main tool used to deal with light underdeveloped coffee, then it's redefining espresso entirely. If crema is rubbish, (and you're certainly not going to get much pulling a shot like this) then "espresso" becomes anything you pull out of a portafilter, I suppose.

I love my Bunnzilla for it's best of both worlds approach, but it will still end up being replaced with an EK for better dosing utility someday. I still like exploring how fine I can grind a pre-warmed dose of beans. The shots are quite impressive.

I have an aversion to microwaving specialty coffee. I am taking the sous vide approach with my steam wand. For over a month I have been scrambling eggs and poaching eggs with my wands. This morning I placed 21 grams of Uganda Peace Kawomera Coop beans (roasted 5 days ago using Rao's 20% past 1st crack method) into a 4 oz canning jar, closed it and put it in a large ceramic cup filled with water. The water reached high heat in a few seconds and I just let the jar sit in the hot water on my Simonelli. When the temp of the beans rose to 170 F I poured them into my Pharos. What's the point? After a 30 second pour to 40 grams, I made the best espresso I have had in months. Lots of red crema, also.

CoruscatingCoffee wrote:I have an aversion to microwaving specialty coffee.

Regardless, did you try microwaving? For the sake of being thorough, I'd suggest you compare two shots; one microwaved and one jar-warmed-in-water; to see how differently or similarly the shots pull and taste. I don't microwave hardly anything unless it's the only sound method of heating/reheating; but when I do it's never on full power. YMMV obviously but I have great success with doing 45 seconds at 50% power or 55 seconds at 40% power, anything longer or higher powered has resulted in a strong/bad odor. Just as it does for others, it made a considerable difference in how much further I can adjust my grinder finer and how fast the shot flows. Much like EK43 shots have been described, my pre-heated doses are lacking a bit in body and sometimes in crema, but the taste has never been poor.

I'm impressed with what nuking can do to an otherwise mediocre coffee.