‘TOWARDS EVENNESS’, 2012

A conventional cup of coffee is made up from hot water that has passed through ground coffee. That act of passing - whereby a certain proportion of the coffee ‘solubles’ dissolve into liquid - is an extraction process. In order to maintain consistent good practices and optimum calibrations within the chosen brew method, the most fundamental element needed (presuming the coffee itself has been sensitively roasted within the past four weeks) is an even grind of the coffee beans. A reliable approach to different brew methodologies and variations in techniques can only be undertaken and compared with the guarantee of a stable grind.

Coffee must be ground consistently, meaning that when grounds are spread within a basket for an espresso machine or in the bottom of a paper filter for a pour-over extraction, the grounds distribute evenly (although distribution - especially in espresso - is also a key skill of the barista) and the water passes through at a steady and even pace. If a grinder produces coffee grounds of varying size, the speed at which the water passes through the coffee will be inconsistent and the amount of time coffee is in contact with water will vary within the same extraction process. So one cup will contain some coffee that has over-extracted - ie. the coffee has dissolved too much in the water, meaning that the brew takes on flavours of the coffee beyond the desirable acids and sugars that constitute the aromas and tastes we try to develop in the cup - as well as coffee that has under-extracted - ie. the resulting cup has not taken on enough of those acids and sugars.

Over-extraction (broadly we can say this results in a bitter cup) and under-extraction (a sour cup) of course still occur regularly – as testified by most brewing practices in London cafes - even with consistent grinding facilities. I make no apologies for snobbery here and I should also point out that a coffee made without much care or interest in the extraction process can still provide an enjoyable drink, even if the taste is overbearing and basically unpleasant apart from the psychic association that our synapses are firing a little faster with each sip. There is, however, no chance of attaining good practices for reproducible brewing processes within desirable extraction ratios (the common belief is that dissolved coffee solubles in the brewing process should be within the 18-22% range) without evenly ground coffee and it is towards this simple requirement that I emphasise the importance of the grinder itself.

‘TOWARDS EVENNESS’, Page 1 of 4

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