Roast optimization for group size and other variables

#1: Post by **yakster** » May 6th, 2013, 8:26 pm

I ran across the following blog post on the Londinium Espresso site mentioning that Reiss noticed that espresso that tasted great on smaller, 50 mm lever groups tasted bland on larger 58 mm lever groups, and that he's recently reformulated the roast to perform better on Londinium 58 mm machines.

Roasting for 58mm group espresso machines from Londinium Espresso

I found it interesting, especially since a bit over two years ago I'd heard from Orphan Espresso about Evocation Coffee Roaster's 49mm Espresso roast that's optimized for smaller lever groups and started a thread about it.

49mm Espresso Blend for Lever Machines - Coffees • Home-Barista.com

I didn't see any exciting details about what changes were made, but it's interesting to see that the equipment that the roaster uses has that much effect on their roast profile. Maybe it would be good to know from a roaster what equipment they use to dial in their roasts to see if it's a good fit for your home machine. Besides group size, I can see lever versus pump as another variable that could make a difference in the development of your roast profile. I ever remember reading somewhere of a Nordic roaster that discovered their roast had been optimized for their water and didn't play all that well in other regions.

I think I just unintentionally made a case for home roasting there.

#2: Post by **jonny** » May 6th, 2013, 9:15 pm

I bet it has more to do with the machine as a whole than just the group. Temperature profile, pressure profile, optimum dose size, etc. All of these are related to the group head of a lever machine of course.

Of course you just made a case for home roasters! No home roaster uses anything other than their own machine and their own tongue for dialing in their roasts. I would say, most roasters are dialing in their espresso beans using La Marzocco or similar machines.

#3: Post by **another_jim** » May 6th, 2013, 9:48 pm

Actually the answer is dead simple -- the 58mm levers, at least every one I've ever used, have tremendous punch. If you use a regular dose, you'll grind so fine that the shot will be all caramels. Commercial levers need to be updosed dramatically to avoid overly fine grinding.

Of course, that's the "magic" of espresso. You can loudly repeat the grinder is the most important thing, and then never pay the slightest attention to actual grind settings. Instead, you will harness your awesome expertise to changing coffees, roast profiles, group designs, and whatever else you catches your fancy

The VST basket is designed with extra hole area, so you can dose higher than normal and still grind fine. Someone needs to design the exact opposite type of basket for commercial levers; a basket with fewer holes, so that you dose normally without having to grind so fine.

#4: Post by **the_trystero** » May 6th, 2013, 9:52 pm

another_jim wrote:Someone needs to design the exact opposite type of basket for commercial levers; a basket with fewer holes, so that you dose normally without having to grind so fine.

Hah, that's what I'm talking about. I've been thinking about ways to plug up some holes in my EP HQ 21gm ridgeless baskets.

May 6th, 2013, 10:25 pm

A brute force method would be to put a fender washer in the bottom of the basket to plug the holes on the outside like a single basket. Of course, this would wreck the flow for the grounds at the edge of the basket, but it might be a fun trick to try at least once.

May 6th, 2013, 10:31 pm

If you are going to get that crude, why not a piece of aluminum foil cut to shape? That would be much less disruptive

#7: Post by **another_jim** » May 6th, 2013, 10:43 pm

Back in the alt.coffee days, before Scace devices, we made baskets with all but one hole blocked for temperature measures. We used epoxy, but I'm not sure if that's foodsafe or not. In any case, it can be applied from the bottom, so it doesn't add anything to the inside of the basket.

May 7th, 2013, 12:01 am

Funny, it almost sounds like we're making pressurized baskets here.

#9: Post by **zeb** » May 7th, 2013, 2:54 am

another_jim wrote:Actually the answer is dead simple -- the 58mm levers, at least every one I've ever used, have tremendous punch. If you use a regular dose, you'll grind so fine that the shot will be all caramels. Commercial levers need to be updosed dramatically to avoid overly fine grinding.

The VST basket is designed with extra hole area, so you can dose higher than normal and still grind fine. Someone needs to design the exact opposite type of basket for commercial levers; a basket with fewer holes, so that you dose normally without having to grind so fine.

You should not say "need" ... a double espresso is 14gr, 9 bar for 2x25ml in 25sec and therefore, only one possible correct size of grinding.
If you like your coffee weaker you can grind less fine and updose "dramatically", but this is no more espresso

May 7th, 2013, 10:56 am

Ahem. The correct grind for espresso is the particle size that extracts correctly in a 30 second percolation at the correct temperature. That is all there is to it.

It does not matter what the pressure throughout most of the shot since most of the pressure drop happens at the bottom of the puck. An initial pressure ramp up to 9 bar (+/-2) allows for the finest grind and fastest shot possible; which is why it was chosen (espresso is fast food coffee in Italy). The pressure for the rest of the shot is somewhat less critical (which is why you can have lever and pump machines)

Italian espresso machines and their matching baskets are designed to work at the correct grind setting for 7 and 14 grams. Since bar grinders fill the doser for the next 12 shots or so, adjustments are not made to grind settings (which would not have an immediate effect), but to the dose (via the doser adjustment). The grind settings are kept the same.

If your machine/basket combo requires 12 to 15 grams for the proper range of grind settings; you use that. If it requires 16 to 20 grams, you use that.

Bottom line. It is wrong to chose an arbitrary dose, and then to find the "correct" grind setting for that dose. You need to know the correct range of grind settings first, and then set the dose accordingly.

Admittedly, this is very tricky business for a newbie; and I advise you take your grinder to someone who knows about making espresso.