If you listen to the Coffeegeek Podcasts then you may have heard what my sig drink this year involves.
Having picked up a new centrifuge today I have to admit I gave in to curiousity and brewed a load of espresso and put it in. With the rotor in there at the moment I could only achieve 4,500 rpm (which exerts around 3,300 G on the liquid). I let the espresso run for about 15 minutes and then had a look at what had happened.
In truth I hoped for a little more, though I think with a different centrifuge that could maybe get up to around 20,000rpm+ then you may get a bit more seperation.
However it did cause most of the oil to come out of emulsion and congregate at the top. Now we (speaking for an industry as one does!) often extol the virtues of the lipids in coffee. They are responsible for some much of coffee’s wonderfulness, aren’t they?
Well I had a little spoonful of pure oil today. It was horrid. Really nasty. Completely mouth coating, some stunning bitters and a planty/woody taste. Very odd. Perhaps this only further reinforces how the need for balance in this particular drink. A little oil in a mouthful is good and brings body and mouthfeel but too much and it is all nasty.
This of course doesn’t take into consideration things like the coffee cooling (though the centrifuge did allow me to maintain a temp during the spin of about 40C. It also doesn’t take into account the 15 minutes or more between brewing and drinking which generally does nothing good for espresso anyway.
Still – it was very interesting. At the bottom of each tube was a silty goo of the fines that had made their way through. The larger pieces of coffee had come to the top, perhaps as they had retained a more porous structure. I didn’t know what to do with the fines – I knew I didn’t want to taste them, so I daubed them onto a sheet of white paper for inspection. Alas – not overly interesting.
Today was a very amateurish and uncontrolled little experiment and it accomplished little (apart from giving me a bad taste in my mouth for about half an hour!). However it does encourage me to try something again in the future. I have a much smaller, but faster, centrifuge at home but the model is so old I am having trouble sourcing the tubes. However the people at DJB labcare – who helped me out with this piece of kit at very short notice and (unlike everyone else I rang) were very helpful start to finish – think they may have a place for me to try so perhaps another experiment is in the pipe line!