Just saw a vid that might change my opinion (small vs larger espresso machines) - Page 2

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#11: Post by mrgnomer »

I wonder how much better the extractions would be if they were done in a vacuum? They could make great espresso on the ISS if they tried it in a heated oxygen free module. Space suit gloves would make it tough, I think. Making espresso would be like trying to tie your shoes with oven mitts on.

Oh yeah, no air pressure would probably make the machine boiler explode. Guess it wouldn't work. :oops:
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coyote-1 (original poster)

#12: Post by coyote-1 (original poster) »

espressoren wrote:Interesting. I'm a bit skeptical, as usual.

I don't think oxidation works that way. You can take a hunk of copper and leave it in the rain. It might take a day or two to turn green. Then you may start over and cut the copper into bits, and leave it out. You will oxidize more copper, because more surface is exposed, but it will still take a day or two to oxidize.

I think we know beans are permeable, which is why we seal them up in between uses, but at what rate? If we believe that small particles are ruined at 90 seconds, doesn't it follow that the entire outside of a whole bean is also ruined with 90 seconds of exposure? And since it is permeable, is the whole bean is ruined at five minutes? Ten minutes?

I do think there something to be said for release of aroma and possibly CO2 immediately after grinding. However I think when you're talking about scrambling to infuse within 30 seconds rather than a leisurely 60 seconds or whatever you usually do, there are probably diminishing returns. Just use them reasonably soon, don't walk away for 30 minutes or something.
Except this is not oxidation. Yes that is also occurring, but it is not the driver in degassing. Have a look at this:
https://uweb.engr.arizona.edu/~blowers/ ... ffee3.html
If we take a coffee bean to have roughly 1 cm2 surface area, and there to be about 200 coffee beans used to brew a pot of coffee, we find that they have an initial surface area of .02 m2. Coarse powders of the approximate size of a coffee ground tend to have 50 meters m2 per gram. That's about 800 m2 surface area of coffee per pot, an increase of 40,000%!
Consider now that for espresso, we are not creating a coarse grind. We are creating a much finer grind. Just guessing here, but espresso grind might be doubling (or more) the surface area of the coarse pourover grind. That represents an increase of 80,000 times the surface area of an intact whole bean. So if degassing is a function of surface area (just as extraction is), and surface area has increased 80,000 times, we would reasonably expect there to be far more degassing occurring.

It would be an interesting bit of science to deploy highly sensitive CO2 detectors. Put one in a bag of recently roasted beans, put a second in an equivalent weight bag of those same beans ground for espresso. See how much more CO2 is being degassed by the ground beans.

coyote-1 (original poster)

#13: Post by coyote-1 (original poster) »

baldheadracing wrote:Crema is a function of the green coffees used and how they were roasted.

In typical traditional Italian espresso roasts, the quality of the green coffee is relatively poor and the roasting dark. Crema indicates that such a blend hasn't gone rancid.

If you buy specialty-grade coffee and have it roasted to highlight origin, then crema is irrelevant. Some even find that the espresso from high-end coffees tastes better if you skim off the crema before drinking. Similarly, higher grades of coffee that are roasted lighter can 'sit' for longer - much longer - after being ground compared to dark-roasted low-grade coffee.

That's great information. Thanks for sharing it!

But in the modern day, crema is like wine cork. It's part of the ritual. Winemakers have been trying to eliminate the cork for decades, as a screw top provides a better seal! And this holds true especially of the makers of more expensive wines. Who wants a $600 bottle to emerge from the cellar, only to be spoiled? But the cork remains prevalent, because uncorking a bottle is such an ingrained part of the ritual of serving (or ordering) a bottle of wine.

Certainly, if you go to a restaurant or typical coffee house they are using darker ground coffees for the espressos they are serving. So you would want to see some crema.

coyote-1 (original poster)

#14: Post by coyote-1 (original poster) »

Ok, I've been doing this for four days now. I changed my workflow such that I'm WDTing while the flush is happening. It's no more than 25 seconds from end of grind to start of brew.

It makes a difference. Consistently. Every cup since I started this is better than they were before I began. The crema is noticeably more substantial.... and it might be coincidence, but the flavors are better.

Next step is a 'base' on which I can rest my basket while the grinds are coming into it - so that I can grind hands-free, and therefore begin the flush even earlier.

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#15: Post by mrgnomer »

So what grinder and machine are you using to find such an improvement with?
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coyote-1 (original poster)

#16: Post by coyote-1 (original poster) replying to mrgnomer »

Saeco ViaVenezia machine, and Urbanic 070s grinder. Saeco is modified with a dimmer for flow control, along with a direct thermometer read of the boiler. Grinder is modded to stepless.

Everything I see I'm taking as something of a challenge. You're supposed to get great espresso from an ECM or a Decent or LaMarzocco or whatever big-$$ machine and a Niche grinder. But can it be done on gear that is less than 10% of the price of those things? :?:

My answer so far: YES. 8)

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#17: Post by yakster »

Are you using the pressurized filter basket the Saeco Via Venezia came with?

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coyote-1 (original poster)

#18: Post by coyote-1 (original poster) replying to yakster »

No. I'm using an unpressurized, 2 spout portafilter. Nice and heavy, retains the heat from the purge.

Technique-wise, I'm not using a scale. I'm eyeballing the bean load, and counting seconds of brew time.


#19: Post by Pressino replying to coyote-1 »

I believe that machine was designed for and sold with a pressurized portafilter. The rubber disk can be removed, apparently, but the extraction is going to be different, and will certainly require a different grind than it did when extracting with the pressurized portafilter. What grinder are you using?

coyote-1 (original poster)

#20: Post by coyote-1 (original poster) replying to Pressino »

Already posted with a picture, but no harm in saying it again: I'm not using the stock portafilter. I'm using a non-pressurized double spout aftermarket one. The grinder is an Urbanic 070s, modified to stepless. I also adjusted the ViaVenezia's OPV, but that's mostly a non-issue with the dimmer flow control modification.