In 2010 the Speciality Coffee Association of Europe embarked on a study to ascertain coffee extraction preferences exhibited by consumers of filter coffee. This was the first public study of its kind since the publication of data in the United States of America in the 1960’s, under the auspices of the Coffee Brewing Centre. The data from the Coffee Brewing Centre indicated ideal coffee extraction is when between 18% and 22% of ground coffee is dissolved in hot water, yielding between 1.15% and 1.35% solubles concentration, or strength, in the final brew.
This specification of correctly brewed coffee has been adopted by various international coffee associations since, amongst them the Norwegian Coffee Association (NCA) formed in 1975, the Speciality Coffee Association of America (SCAA) formed in 1982 and the Speciality Coffee Association of Europe (SCA) formed in 1998.
While the definition of correct strength, being the concentration of dissolved coffee solids in the final brew, differs by association, all teach the common specification of correct extraction being achieved when between a minimum of 18% and a maximum of 22% is extracted from the bean and dissolved in the coffee brew. To yield below 18% was deemed an underdeveloped coffee and to yield more than 22% was deemed to overdevelop the coffee.
The objective of the SCA study was to establish extraction preference through blind tasting. This was achieved by fixing the coffee strength of five samples of the same coffee and presenting five different extractions.
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