The quest to make the ideal espresso

"The ideal espresso (according to the Instituto Nazionale Espresso Italiano) is a 25ml beverage extracted from around 7g of finely ground coffee, using water at a temperature of 88C, passing through the grains at a pressure of 9 bar. See, dead easy. It should be thick-textured, having emulsified many of the oils, retain most of the volatile aromas and flavours of the bean and be capped with a thick colloidal foam layer - "crema" - reddish, creamy and flecked. Each one of those factors is minutely variable, potentially causing thinness, bitterness, under- or overextraction or - the ultimate humiliation - a thin or patchy crema" (Tim Hayward, The Guardian)

Read more)