The appliance of science

Joshua Pattinson dons his safety goggles, puts on a white coat and geeks out over the Chemex

Prufrock Coffee is an internationally respected coffee shop and barista trainer that pioneered the third wave in the UK. With 2009 World Barista Champion Gwilym Davies at the helm, its flagship at 23-25 Leather Lane in Clerkenwell has a reputation for innovation, consistent quality of the highest calibre and for doing things just a little bit differently.

It is in the friendly interior of Prufrock’s London HQ that Andrew Leitch, a recent addition to the team from Australia, talks us through how to brew with a Chemex, which often intimidates the uninitiated with its chemistry-set looks. Happily, I discover that no Bunsen burners or litmus papers are required.

“A really big thing in a coffee shop environment like ours is that we need to follow protocol, for consistency,” Andrew says. “We standardise the method, so day to day all of the baristas can make the same brew for each customer.” That means their method is tried and tested and guarantees a good result. Here goes!

As always, the first step is choosing the right coffee. Andrew uses 45g of natural process Ethiopian Yirgacheffe by Square Mile, which he describes as “a complex coffee with lots of tropical fruit and a nice brightness”.

Next, he grinds the coffee with a Mahlkönig Tanzania, the essential filter grinder for many a speciality coffee shop. The beans are ground quite coarse as the paper filters for the Chemex are a bit thicker than usual and therefore restrict the water flow.

Because of Prufrock’s reputation for being at the forefront of the UK speciality coffee scene, they are often asked to test products about to launch on the market. On the day of my Chemex lesson, we trial a prototype sieve with an aperture of 250 microns. The sieve is used to remove the dust-like particles (“fines”) that are thought to be responsible for any unpleasant, burnt, over-extracted flavours. However, to compensate for the coffee lost to sieving, Andrew recommends adding an extra 10%, and to weigh it as we add it.

After a few moments of sieving the ground Yirgacheffe, decant it into a dry bowl. Next, rinse the paper filter with about 500g of hot water to get rid of any papery flavours and warm up the Chemex for brewing.

Now for the real action.

Andrew Leitch is originally from Brisbane, and started his coffee career working in a typical Italian-style café. When he came to the UK to study for an MA in publishing, he knew he wanted to work at Prufrock. “Prufrock inspired some sort of reverence in me and certainly in a lot of others,” he recalls. “Gwilym’s personal reputation as well as the reputation of the shop have spread to Australia. Prufrock’s never had any sort of arrogance or any claim to knowing everything – it’s a collective, and it’s also really subjective most of the time. No matter what you know, there’s always something else to learn.”

things easy to replicate, so they recommend keeping your pouring technique simple – just smooth concentric circles – and to avoid pouring down the edge of the vessel.

When the timer hits sixty seconds, keep adding 100g of water every 30 seconds, all the way up to 750g. All the

water should be poured in by 31⁄2 minutes, and it takes about 2 minutes for the draw-down, where the rest of the water drips into the vessel below. “At the moment we’re having lots of

fun brewing large volumes of lter coffee with the Chemex, but if you’re just brewing a cup for yourself, stick to a 60g/L ratio and just use less water,” Andrew says.

When the water level is 2 or 3 centimetres above the coffee bed during the draw-down, give it one nal swirl to bring down any coffee particles stuck to the side of the lter and to ensure
the coffee bed is at. Now savour a clean and complex Yirgacheffe. Chemex is fabex!