Posts Tagged ‘bunn’

TDS, Chemex and London’s terrible water

Thursday, January 3rd, 2008

So thanks to the lovely people at Bunn I have a couple of TDS meters and have begun to poke them into various coffee drinks.

The first thing that upset me was just how hard London’s water is. Out of the tap I get 410ppm, which is pretty hard. This means it is not ideal for brewing coffee as it is less “hungry” for new solubles than softer water. I didn’t realise until I started testing just how badly it was affecting the coffee.

Chemex and TDS

Testing some of Tim’s coffee brewed on the skinny Chemex

I was struggling to get into the Golden Cup zone of 18-22% extraction which, through years of filter brewing, is considered a suitable target. Different countries might like different strengths of coffee but they all generally like 18-22% of whatever dose that is.

I have know switched to bottled water for brewing (with a much more attractive TDS of 130ppm) and the coffee does indeed taste much better and my extraction percentages are up even though I haven’t changed the grind or dose. I had gotten used to a very coarse grind on the Chemex (after being advised by Kyle in Intelli.la) but have slowly been bringing it finer to get the percentage up. I will keep doing more but wonder how many other people out there have TDS meters and whether they have compared their brewers with different grinds and doses and compared the cups after.

To this end I’ve done a little spreadsheet that negates the need for a brewing chart as the maths is built in. It works on 2ml of water being absorbed by each gram of coffee but you can change that too. Input the amount of coffee you use, the amount of water you brew with and then TDS measurements. I’ve left columns in there for other useful data – such as brewer, coffee used and notes on grind settings. I probably should have found a way to include a cupping score/notes but haven’t. If anyone else fancies having a go then do download it and let me know how you get on. Once I have enough data I will post up about my Chemex experiments.

Thoughts and comments welcome….

XLSTDS Testing Spreadsheet


downloads

UPDATE
Mike Khan from Bunn sent me his spreadsheet which does percentages and graphs for each brew you do.
XLSMike’s TDS Calculator


downloads





Thank you Mike!

SCAE Brewmaster Certification

Thursday, November 8th, 2007

In the world of Speciality Coffee filter coffee isn’t very sexy. One criticism leveled at the SCAE is that it seems obsessed with espresso and yet espresso only makes up a small percentage of how all coffee is consumed in member countries so they have started a Brewmasters program.

Anette and I traveled up for a two day course held at Bunn’s UK office to take part. The first day is primarily lectures – Mick Wheeler gave a seed to cup, Christian Klatt from Mahlkoenig talked about grinding, and Shane Pender from Marco talked about grind size analysis. I’ve attended a fair few seed to cup lectures but there were a fair few interesting nuggets in there I hadn’t heard before and also another view point on the economics of farming. Equallly in a world with very little information on grinding coffee it is always nice to be able to ask difficult questions.

TDS Meter

Then it was onto the brewing lectures given jointly by Paul Stack of Marco and Mike Khan of Bunn. This was similar to the lecture given on filter brewing at the ETCC in Moscow, except in greater depth. Beyond better understand of the kit the focus was around the brewing control chart.

Brewing Control Chart

I am not going to explain it in great detail but essential filter brewing is a balance of extraction and strength – the amount of solubles taken from the ground coffee vs their concentration in the final brew. Extraction is hard to measure easily so with the chart you can test the strength and then, if you know your weight of coffee used, work back to the strength. The SCAE gold cup standard says that you should extract between 18-22% of the ground coffee, and that the final strength is between 1.2-1.45%. Interestingly there are other standards – SCAA, SCAJ or NCA and they all agree on the extraction but not on the strenth. Norwegians like a much stronger brew than the Americans – but everyone likes it properly brewed.

This all makes more sense on the course, I assure you. The first day ended with a written exam covering all the lectures.

TDS meter and control chart

The second day had a more practical focus. First Anette gave a cupping workshop, which is always a lot of fun and it was interesting to see how widely people’s taste preferences differ (I still can’t deal with the Malabar!). After this testing protocols were explained because the long view of this course is that we Brewmasters (I do love the title) are now able to certify a coffee shops filter coffee as achieving an SCAE Gold Cup standard. This is then verified by the SCAE by sending them a sample of brew water and brewed coffee along with details of the weight used to brew. (If you don’t send the water then they can’t subtract the solubles already in it, to give you an accurate reading of the coffee concentration.)

We all had to brew Gold Cup standard coffee, document it and measure the brew time and pH in order to pass the course. Which we all thankfully did – we were the only people not from a filter machine company, the rest were from Bunn, Marco, Animo and Bravilor.

Attendees at the Brew Master Course
I know the debate about what Speciality Coffee is will continue, but is nice to be able to at least measure good practise and standards and though good brewing doesn’t turn bad coffee into good coffee, it is at least tasting as good as it can. It is a great course, and I would recommend it to anyone – I guess it mostly has roasters in mind, or other coffee suppliers as they would be the ones verifying accounts. If you are curious then get in touch with the SCAE.  If you are in the UK I think they will be running this course at Hotelympia in February and if you are interested then drop Steve Penk and e-mail (sgp at laspaziale dot co dot uk)