Monday, 17 October 2011

Dialing in the AeroPress

French Press... tick
Hario V60... tick
Time to get a better grip on the AeroPress.

The first thing I wondered was 'should AeroPress coffee be brewed according to the Brewing Control Chart?'
It's arguably a different beast... not immersion, not pourover, and definitely not (as it claims to be) espresso . People tend to talk in terms water volumes with the A/P (e.g. "fill it up to the number 4 marker") rather than weight... and the variety of approaches to brewing with it don't all seem to follow the typical 1:15, 1:16, 1:17 type of ratio.

But ultimately, after running a few preliminary cups and reminding myself how it tastes, I've decided that it's still brewed coffee and simply a hybrid of French Press and Filter, despite the pressurised element. (I'm thinking that perhaps the main benefit of the pressure plunge is to increase agitation to provide a faster extraction of solids.)  I therefore do need to work by the charts.  I'm also, at least initially, using scales rather than markers - although I expect that will change once it becomes clear whether the marker can consistently represent a certain weight of water.

First Brew
I brewed directly into the cup, which holds about 250g of water, so that's the amount I used to brew with... and therefore using approximately a 1:16 ratio I measured just over 15.5g of bean, grinding and then ensuring that was the weight I ended up with in grinds.
Setting 10 on the Gaggia MDF grinder.
Honduras, Finca Santa Marta Lot 232, Pacamara, roasted by Paul Travis at Hands-On Coffee in Wadebridge, Cornwall.
- Approx 40-50g pre-wet, with a little bit of blooming then seven or eight stir... all in about 30 seconds.
- Fill to 250g, which is around the number 4 marker
- Place the plunger on to create a vacuum, preventing dripping into the cup (I'm not inverting the A/P).
- Leave for 30 seconds... hence an element of full immersion

- Plunge, taking 30 seconds to reach the bottom... stopping at the first sign of a hiss of air.

It tasted good.  More acidic than the V60.  It was heading a little into the sour range though.
Taking a reading helped explain why. Although the temperature in the cup was fine at 67C, the TDS was a little low at 1.12% (bearing in mind I tend to aim for between 1.15% and 1.45%, as a combination of SCAA, SCAE and Nordic controls). Extraction Yield was 18.1%, which is fine.

Second Brew
OK, so I thought maybe this time I needed to stir more just before plunging, which I did.
However, the TDS this time was only 1.05%, and Extraction Yield 16.9%... and it was more sour.  Why? Well I did plunge slower ... around 35 seconds. Maybe there was less agitation because of that, and I need to plunge quicker to get the TDS higher and extract more solids. Alternatively I know I could simply grind finer, but where's the fun in that? :)

Third Brew
I had a change of heart and tightened the grind from 10 to 9. I also plunged faster... around 22 seconds.
Result: TDS of 1.17%, Temperature 66C.
Tasted great and left a fantastic buzz on my lips and the roof of my mouth.
Although the TDS is within target, it's still at the low end of the range. Let's try again and aim for around 1.35%.  Perhaps this will need a grind setting of 7...

Fouth Brew
Grinder on 7, a 20 second plunge. Doh! I forgot to stir a second time just before the plunge. That stir is critical, since the TDS ended up being only 1.10%. Taste... sour.

Onwards and upwards/downwards...

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