Why 9 bar? - Page 2

[endlesscycles (original poster)]

It isn't espresso: no fines, no crema.

This was my experience with mid first crack stopped coffee (not brittle, few fines). Very sweet and clear, but not "espresso-like" in body. I feel like there are a slew of assumptions being made that any one variable could be tweaked and refined. Surely there was a grind setting between gushing and dwelling on the big ditting? And if not, was the brew pressure solution space explored? I'm familiar with Illy's history and significance, but we've got coffee and equipment now that they didn't. Besides, didn't we get over crema in the summer of '09?

I'm coming from the angle that espresso is a fast, concentrated extraction, which I hope to be very delicious. A suspension of fines, CO2, and coffee oils is interesting....but does its presence trump flavor? Is it possible the most delicious shot comes outside of the 9bar, 25sec constrained solution space? Unfortunately I don't have the equipment to find out.

[peacecup]

I have only read little bits and pieces of espresso history, probably only the most popular stuff.

One thing that seems to be often overlooked is that what is defined as espresso has been in some part (a large part perhaps) driven by commercial interests, i.e. the consumer market first in Italy and now worldwide. After all, it was (and still is?) first and foremost a commerical beverage, and retailers must to some extent cater to the public taste. The definition of espresso, therefore, has changed over time, and it will continue to do so. I look a little askance when a given beverage (within limits) is said not to be espresso. After all there was a time not so very long ago that espresso in America meant Starbucks at the cafe and Gaggia at home.

For some 50 years "espresso" was a beverage brewed at steam pressure. When, as I read it, Gaggia developed the piston brewing method, he needed to coin a new word, "crema caffe" to get people to buy it. What's all that foam on the top??? etc.

How much chance was involved in the resulting beverage that came to be known as espresso? Was the pressure of the Gaggia lever machine designed to brew at around 9 bar for the 7g dose that was to make a single. Or was the 58-mm brew group designed to hold the basket, and the resulting pressure merely coincident of the fact that the lever needed to travel a certain distance to make a 30 ml single shot?

To continue on with the story, when the pump replaced the piston, the basket sizes, doses, etc. were more or less carried over. I suppose the public expected their 7g 30 ml espresso, and the machine designers were constrained to this. Did they try to mimic the lever machine pressure, or did they redefine espresso again? Certainly since I've been reading Home Barista these past seven years or so, espresso seems to be being redefined again.

To make a long story longer, I find the espresso I brew on small-diameter home lever exceedingly good, and I suppose the brew pressure is a bit less than 9 bar.

PC

[homeburrero]

More historical stuff (yes, I see now that was not what the OP was after, but is interesting anyway...)

I don't have the Illy "Science of Quality" book, but was able to search an Amazon preview of some of the text around page 284 of the 2nd edition to find this:

The pressure value universally applied [...] is 9 relative atmospheres [...] This value results from a series of 'trial and error' attempts in the early years of espresso machine technology, whose results were measured by customer satisfaction.

Exactly as peaceup said in his post above.

[Peppersass]

Exactly as peaceup said in his post above.

And exactly what Jim said in his post before that.

[endlesscycles (original poster)]

Not really "what he said" at all. There's a big difference between simply accepting a standard for 60+years and having the same be improved upon over said duration. I think there's a lot more of the former going on here.

[chang00]

A few years ago, similar discussion. PM me if you want to read the actual article.

Tamp pressure and brew pressure