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Vacuum brewed coffee. It’s all the rage on the greater coffee loving scene of late. Mark Prince has been into them for years, they’ve made numerous appearances in barista competitions, St Ali in Melbourne invited a Japanese syphon coffee champion to give a demonstration of the art, and snobs and geeks across the country seem to be getting in on the action in greater numbers.
My first dabbling with vacuum brewed coffee happened after I casually dropped by Fiori Coffee to pay Kam a visit and make a nuisance of myself (as I am prone to doing). Noticing a familiar looking device sitting in a box on the floor I soon found out it was a Cona Vacuum Brewer. Kam, being the gentleman he is, kindly offered to let me try it out, and I’ve been experimenting ever since.
The basic principle behind vacuum brewed coffee is that you have two chambers. Water in the bottom chamber is heated, gives off water vapour, and eventually the vapour expands so much that it pushes the rest of the water up the spout into the top chamber. The ground coffee in the top then brews until you take away the heat source, at which point the water vapour cools and the brewed coffee is drawn back down in the bottom chamber.
I am by no means any kind of expert when it comes to this kind of thing. I’ve been picking up as many tips from other people as I can. So this post is more of just a pictorial guide to one way you could do it, rather than any kind of how to.
The Cona is a very beautiful piece of equipment on it’s own. Shannon Bennett fell in love with it so much that he makes a table side bouillabaisse by infusing fish stock and shell fish using it. The process of brewing coffee in it to me seems more like a science experiment than making coffee, but that’s probably why I like it.
My process is as follows:
Filter some water and fill the bottom chamber up. This is a ‘D’ series Cona, which holds at most a litre or so in the bottom. I fill it with about 750 ml of water, and put it onto a gas burner to heat up. This isn’t strictly necessary, but the Cona’s standard heat source is a little spirit burner, which takes forever to heat this amount of water.
Once some vapours are coming out of the top of the pot, and before it starts to boil, take it off the gas, and lock the top chamber in place on top. Light the spirit burner underneath and add the coffee to the top.
I used a measurement of 8 grams of coffee per 150ml of water (I fudged that from the SCAA standard brew ratio recommendations). Which means 40 grams of ground coffee for the amount of water in this example. The coffee is ground at roughly the same level as French press coffee, though I have been varying it lately to see the effects. Obviously you should be using some nice fresh coffee for good results.
Now you basically let the Cona work it’s magic.
The water will gradually rise up into the top chamber and begin to infuse. When it’s all mostly up in the top, I give it a stir to make sure all the coffee is adequately soaked, which brings out the “bloom” some more. Then when all the water has risen to the top (there will always be some water that doesn’t come up) remove the heat source. The coffee will then slowly start to be sucked back down into the bottom chamber, and the spent grounds stay up the top.
Some people wait til the water had all risen to the top chamber before adding the coffee, namely because it infusion all happens at a similar temperature, but I can’t say I’ve tried enough to tell the difference.
Here is my pictoral view of the process:
- This is great way to brew coffee, it’s an interesting process and the results can be amazing
- The Cona has a glass filter rod. I’m not sure how it works exactly, but the cups I’ve had are generally very clean and without grounds. I like that it doesn’t need changing and is easy to clean, but not sure how it compares to cloth filters in brewers like the Hario.
- It works best with interesting single origins that are roasted much lighter than espresso to keep their inherent terroir characteristics.
- Measuring the coffee in the top chamber through the brew process showed I was getting temperatures around 90 – 95C, which is not boiling obviously, so should be ok. A more specific approach to temperature management would give more reproducible results.
- My experiments have yet to yield any outstanding experiences, but I think that’s due to roast level
of the coffee, and mastering the technique some more.
- There are lots of other ways to do it, here’s a list of other resources I’ve been using:
Also, enjoy the giant photos :)