At last year’s World Barista Championship, Matt Perger did something incredible: he made filter coffee with an espresso machine. Perger’s invention was dubbed the ‘coffee shot’ and quickly spread to top specialty coffee shops around the world.
The secret to the coffee shot was the Mahlkoenig EK43. Originally designed for spices and grains, this grinder allowed Perger to reach previously unattainable extraction yields i.e. the percentage of coffee that is dissolved into water. Previously the industry standard had been 18-22% extraction yield – anything above 22% would produce bitter ‘over-extracted’ flavours. The EK43 not only increased extraction yield to 24% but resulted in a sweeter, more clarified brew.
Recently Gordon St Garage announced that it would be the first coffee shop in Perth to serve all its filter coffee as coffee shots. They’ve discovered that coffee shots bring out the best characteristics of their Mano a Mano single estate coffees.
So how do coffee shots work exactly? Traditionally, espresso grinders have produced a spectrum of grinder particle sizes – very small particles called ‘fines’, very large particles called ‘boulders’ and everything in-between. When hot water hits those particles, each particle extracts at different rates. The fines ‘over-extract’ because they have a large surface area relative to their size. The boulders ‘under-extract’ because they have a low surface area relative to their size. The resulting spectrum of extraction yields averages out to an overall extraction yield of 18-22%. Anything higher and the over-extraction of the fines will make the coffee overwhelming bitter.
The EK43, on the other hand, produces a more consistent particle size with less fines, which results in a more even extraction. Because we don’t need to worry as much about over-extracting the fines, we can take extraction yield into territory that has traditionally been considered over-extraction (higher than 22%).
How does Gordon St Garage make a coffee shot? Simple. Dose the coffee the same and grind it a bit courser than traditional espresso grind. Lock into the espresso machine and extract around 300ml of brewed coffee. The sight of coffee gushing like a waterfall from the portafilter spouts will make any barista cringe (“under-extraction!”), but the resulting extraction yield is actually much higher and much sweeter than any traditional espresso.
The end product is quite bizarre. It looks cloudy and unappealing, but the taste is very complex and structured (that’s another way of saying the flavours change and develop as they make contact with different parts of your tongue). It has much more body than a conventional filter coffee. Despite looking under-extracted, it’s not sour.
All in all, we’re intrigued. The ‘coffee shot’ is a concept which challenges our conventional understanding of the way coffee works. That’s what specialty coffee is all about, and we love it.
Drop into Gordon St Garage, try one out, and let us know what you think!
Gordon St Garage is located, funnily enough, on Gordon St in Perth City.