Matt Holden

Joseph Liu and his Aeropress.
Joseph Liu and his Aeropress. Photo: Eddie Jim

Stop me if you've heard this one already.

A high school chemistry teacher bins the chalk and turns his attention from the synthesis of fruity esters and aldehydes to the preparation of one of the world's most traded mood enhancers.

He gets so good (or is it bad?) that he takes on some of the local heavy-hitters in the game, and soon he's the regional champ …

But we're not in Albuquerque with badass Walter White. We're in Melbourne, Australia, the stimulant is coffee, and the chemistry teacher is called Joseph Liu.

The mode of preparation is AeroPress, that gadget created by the same guy who brought us the Aerobie flying ring.

(Flying rings and coffee? Smells like Palo Alto … and, in fact, inventor Alan Adler lectures in engineering at Stanford University.)

Liu, who teaches at a northern suburbs boys' school, is the current Victorian AeroPress champion, and although he isn't a professional barista, he beat various local cafe guns in last year's final.

There's this thing about how to use the AeroPress - the way it says on the box it comes in, or the inverted method favoured by many AeroPress geeks. Liu uses the standard, non-inverted method, and ''lots of coffee - 18 grams rather than 14 or 15.''

What's his secret? ''The key is to keep the water temperature low - about 80 to 85C,'' he says. ''I reckon that's why I won. If you go over 90C, you over-extract and make the coffee bitter.''

Liu drilled a hole in a perfectly good pouring kettle so he could insert a thermometer, but don't try that at home - just pour boiling water from a kettle into another vessel, and it will cool to around 85C in 15 or 20 seconds. Also important is giving the filter paper a good rinse - about 20 seconds under the tap, Liu advises.

Liu favours Kenyan coffees for their clean fruit flavours, and a grind almost as coarse as for French press - coarser than recommended in the instructions. He also presses very slowly - about 45 seconds - and stops pressing at the ''1'' mark on the AeroPress to minimise extraction of bitter flavours from the grounds.

Liu produces an AeroPress brew that many of us would hardly recognise as coffee, with a pale, soupy colour and very bright, delicate fruit flavours. Absent are the chocolate, nutty and bitter notes that espresso drinkers are used to.

Liu once worked at Melbourne's Bio 21 Institute researching a cure for anthrax, but ''I found sitting in a lab boring'', he says.

''I still enjoy experiments. But I want to experiment with the stuff I like - coffee.''