Our recent Sumatra Lintong ‘showdown’ showed how even a particularly distinctive coffee can produce quite a bit of variance in taste depending upon the brewing method used. Being coffee roasters we wanted to complicate things even more by checking-out how roasting can do the same. So, what are we trying to prove?
One day we’d like to come up with a formulae like E=MC² that takes into account all the variables (type of bean, processing method, roast profile, extraction etc.) and tells you what your coffee will taste like! But for the meantime we’re happy experimenting (because we’re no good at algebra and enjoy tasting a lot of coffee in the name of experimentation).
The rules for our roasting showdown were carefully drawn-up: Two roasts of Lusty Glaze espresso, each roasted to the same ‘end-point’, BUT using two very different roasting profiles to get there. That meant everything was the same (green beans, our Joper roaster ‘Pedro’ etc.), including the point at which each batch of Lusty Glaze was ‘dropped’ from Pedro. Both batches of Lusty Glaze looked the same, the difference was how we got to that end-point – a different time/temperature curve (controlled by heat input) and hot-air flow (Pedro has a damper). We could draw a graph but that would be getting a bit Open University, so hopefully you’ll get the picture.
The first Lusty Glaze roast profile was longer with a gradual increase in bean temperature, whereas the second by comparison was more like a 100m sprint to reach first crack…it took 3.75 minutes less to reach its end-point when it was dropped for cooling. Then came the hard part – waiting 48 hours to try both as an espresso.
We’ve tasted a lot of Lusty Glaze espresso, and know it better than pretty much any anything else (THIS is a close second!). So we felt pretty confident about being able to compare our two ‘showdown’ alternative roasts. Here’s our results sheet:
It came as a bit of a surprise to find that both batches were still clearly identifiable as Lusty Glaze. Both retained the full-body and smooth mouthfeel, even the 100m sprint version (AKA Speedy Glaze). But hidden beneath this were quite a few differences, most noticeably with Lusty Glaze’s chocolatey taste. This was all down to how the differing roast profiles effected sweetness. Lusty Glaze normally has a dark chocolate taste that carries through milk. Our slow-roasted batch of Lusty had much more of a milk chocolate sweetness, whereas the “Speedy Glaze” version had a well-developed dark chocolate taste, similar to Bakers Chocolate. The acidity was also a notch lower.
The darker that coffee is roasted, then the greater the caramelisation of sugar that takes place (so it tastes less ‘sweet’). So these results would be expected if our coffee had been roasted to a different ‘end-point’, but not necessarily by simply using different profiles. But what we think had an even greater impact was moisture loss – Speedy Glaze was roasted using a lower airflow setting, meaning the beans got hotter more quickly but with less overall moisture loss. Loosing less moisture seemed to help retain more ‘brightness’ in the espresso.
So just like brewing techniques, two different roast profiles also created two subtly different espressos. What next? 2 roasts, 4 extractions, 1 cup. Plus, one confused and caffeinated roaster.