Apropos of several current discussions here about extraction measurement and algorithms, SCAA's Science Manager, Emma Bladyka, just posted a short history of where all those guidelines came from. I think this does not require registration, but my apologies if it does: http://www.scaa.org/chronicle/2013/10/0 ... institute/.

Emma Bladyka wrote:Although there were many useful publications from the CBI/CBC, one of the most valuable assets they provided to the coffee brewing industry was perhaps the Coffee Brewing Control Chart. The relationship of strength, extraction, and brew formula gave a quantifiable approach to verifying the consistency of the brewing process. The gold cup ratio was designed by the CBI to fit that "ideal" extraction and strength zone. Through sensory evaluation tests, a range of formulas were developed. Beverages were analyzed for soluble concentration (strength) to determine the percentage of the beverage that was the soluble material from coffee. A range of strength from 1.15 - 1.35 % coffee soluble material in the beverage was determined to be the most enjoyable through CBI testing. Extraction (yield) from the grounds was also analyzed. The desirable extraction limits were determined to be within a range of 18 - 22 % of the original weight used in the brew. The development of the Coffee Brewing Control Chart gave us a clear and understandable tool for plotting or recording the consistency of the brewing process. This work laid the foundation for brewing 'good coffee' and has since allowed us to have this discussion amongst an educated coffee community.

Here is a film released in 1961 by the CBI...

http://youtu.be/KQ4mQVlt-4o

Note copious use of percolators, Chemex just gets a cameo role...not a grinder in sight...

The original chart uses liters instead of kg's. I'm curious what the actual recipe's were for the original taste tests. It probably doesn't matter given the wide range of suggested brew ratio. My own tasting using an excellent grinder and testing using a vst confirms that range, for my palate, coffee, water, and equipment. It's my assumption the coffee I have access to is of significantly higher quality than what was available then, but I don't know. It would be interesting if coffee of all quality always tastes best to most people in the 50-60g/kg and 18-22% range.

There is no wide range of suggested brew ratio in the CBI film, it's purpose seems to be to inform of a golden ratio (one CBC scoop to 6oz of water) that is engineered to get you in the ball park of yield & TDS tolerance.

The take aways for me, from the film, are that to make good coffee (irrespective of whether it meets today's definition of specialty) requires some care. Commodity grade coffee is subject to the same ideals of extraction as your preferred lot/roast level of specialty coffee. This film was obviously aimed at the home user, assuming store bought every day coffee, using the preferred brew technology of the time (home drip machines were not common then) and that the majority of coffee drinkers were not going to grind just before use, or keep a grinder at home. Nowadays, and in other countries, TDS preferences may have varied, but the 18-22% extraction box remains, you just adjust the brew ratio to suit, maintaining the desired yield.

Establishing parameters where coffee brewing could be objectively evaluated was a great legacy, the objectives of which are the basis for our modern perceptions of "quality" in the cup & driving the philosophies behind the SCAA/SCAE/NCA.

Your excellent grinder (EK43) seems to be able to shift that box upwards (no evidence that it extends it as yet), so you are looking at a slightly different box in that scenario. Even if you have a great grinder, great coffee, great brewing kit, you still need to extract that coffee well...there is no coffee, or brewer that does it for you.

New standards?

New brew recommendations by TCC (Copenhagen) wrote: We've changed our recipe a little for these two new blends and recommend the following:

Dose: 19 g.
Brew weight: 37 g.
Time: 27-29 sec.

VST 18 g. ridgeless basket.
Machine temp at 93° C in the group.
Pressure at 9 bars with a 4-5 sec preinfusion.
Water at 100 ppm with 50 ppm bicarbonate hardness.

EBF: 51.4%
TDS: 9.8%
%EXT: 19.1%

But hey... feel free to do whatever you need to make it taste great !

http://coffeecollective.blogspot.dk/201 ... lends.html

Not so much new standards. Over the history of espresso it has been a considerably longer drink (& shorter), with no real set definition re. brew ratio, or at least they were hazy definitions by today's standard, so more of a shift to slightly lower TDS than is typically aimed for (usually 11-12.5% TDS). It may simply be these coffees benefit from more water through the puck to hit the desired yield?

Sorry I meant new recommendation standards, not brew standards!