BH Unlimited Update, Feb. 27th, 2021.

The two microscope slides above, taken at 10 times magnification, compare raghweh made in a cezve to crema from espresso. The images have been taken of foam samples that have been pressed between two glass slides to produce a more stable 2D foam. This method allows us to photograph the foams at very high magnification, and to compare the relative differences in foam size. So whilst cezve foam, or raghweh as it’s called in arabic, is very silky and delicious, the bubble size is far larger in diameter than a typical espresso crema. 

We’ve spent a lot of the last two weeks brewing cezve , trying to get an in-depth understanding of how this fascinating brew method works. We owe our gratitude to Saudi barista trainer Sara Alali, whose own approach to the cezve formed the basis of our standard recipe in these tests. We have adopted her standard brew ratio 1:8 (Sara’s usual range for brewing cezve falls between 1:8 to 1:8.5, though most of us at BH prefer the stronger end of the range) for all our tests, and we gave each cezve 20 stirs at the beginning of the process as she recommends in this great interview from last update. The experiments we conducted were as follows:

  • Is it necessary, or desirable to grind as fine as possible for cezve?
  • Why do traditional Turkish coffee companies grind as fine as possible?
  • Should I preheat the water before adding it to my cezve?
  • At what temperature should I remove my cezve from the flame?

BH Unlimited subscribers can head in there and read our synopsis of all these experiments. But we wanted to let all of you know about the one particular finding. There is one variable, much more than the others, that impacts the eventual extraction yield in cezve brewing. That’s the grind setting. There was a clear linear increase in extraction yield when we adjusted the setting from around the 01 pour-over level to just below an espresso grind, then to ‘as fine as possible’.

This table shows the evaporation and TDS averages over three repetitions for cezveler brewed on different grind settings.

For all the simplicity of this grind/extraction yield relationship, what wasn’t so simple was the taste preferences. Diana and Gwilym, who again were doing all the brewing for this experiment, found that they way preferred the ‘slightly finer than espresso’ brews, over the ‘as fine as possible’ ones, and found the V60 ones very bland indeed. This is possibly a good outcome, because obtaining a grinder with granite burrs rather than steel ones is not always that easy these days.

The Coffee Buyer’s Guide to Guatemala

This week we begin our investigation of what characteristics coffee roasters and baristas can expect from Guatemalan coffees. Guatemalan coffee has a reputation for being versatile and easy to roast. The combination of its accessible flavour profile, high elevation, and the attention paid to growing and processing make Guatemalan coffees a common feature of budget espresso blends and top-tier brew bar menus alike. Last year’s Cup of Excellence winner set a new record for Guatemalan coffee at auction, fetching US$180.20 per pound.

There’s very little published research on how coffee from different origins behaves in the roaster — but one innovative and complex piece of research shines a light on the different ways Guatemalan, Colombian, and Ethiopian coffees behave in the roaster. The researchers rigged up a Probatino and analysed the chemicals in the exhaust gases that were created by chemical reactions inside the beans during the roast. They found that their Guatemalan beans behaved quite differently to the others, releasing certain volatile compounds much faster than other coffees.

The coffees also behaved differently through the first crack. In the Ethiopian and Colombian coffees, the first crack had a noticeable effect on the chemical reactions taking place in the beans — but the Guatemalan coffee seemed to be unaffected. What this difference means for the flavour of the coffee remains to be seen, but the method the researchers developed paves the way for more detailed investigations to understand what really happens during a roast.

We also feature some information about export regulations in Guatemala. Coffee is subject to a 1% tax on export — Guatemala’s only export tax — which is the main source of funds for Anacafé. Anacafé recently announced the decision to leave the International Coffee Agreement, which makes Guatemala the only major producing country not to be a member.

Quick Links

James Harper, creator of Filter Stories has teamed up with Professor of History and author of Coffee: A Global History to create a 6-part podcast called A History of Coffee .
“If we’re going to make coffee more equitable, and more environmentally friendly, then the place we have to start is actually understanding how we got here.” Prof. J. Morris.

CBG Guatemala - New Lessons!

Notes for Green Buyers:
CBG 4.02 • Export Regulations in Guatemala
CBG 4.03 • Notes for Roasters

Immersion - New Lessons!

IM 6.03 • Brass, Copper, Silver, Aluminium, Glass, or Steel?
IM 6.04 • Interview with Emir Ali Enç from Soy Türkiye
IM 6.05 • Raghweh and Serving Temperature
IM 6.06 • Experiments with Cezve Coffee

As always, we're just an email away if you have any queries! Have great weekends and we look forward to seeing you next time.

To the Boundaries of Coffee,
Team BH