Hacker News Reader

Comment by chongli | Hacker News Reader

As a daily coffee drinker I wouldn't mind less caffeine in coffee. I drink coffee for its flavour (and have tried dozens of different coffees from many different roasters). I have tried some decafs but they just taste different and generally much flatter. They also behave very strangely in my espresso machine, requiring a much finer grind to sustain brewing pressure. From my limited understanding of decaf processes, they all remove more than just caffeine, so the effect on flavour is unavoidable.

View on HN

The biggest reason decaf brews, tastes, and grinds so different is the processing essentially causes the beans to expands (so you can extract the caffeine out of the center of the very dense, green coffee) and then you need to dehydrate them back to the proper moisture content for roasting. You take a green coffee that is previously extremely dense and non-porous, and make it much much more porous. This leads to roasting difficulities and brittleness when grinding which seems to lead to fines.

I'd agree, less caffeine in the bean without decaffinating would lead to a better tasting coffee (if you want the lesser caffeine).

Huh. As an avid home coffee roaster, this is interesting to learn. I find that decaf also really struggles to “crack” when roasting, and emits way less smoke. I guess that’s because there’s perhaps nothing left to really crack anymore?

This makes sense! The coffee has expanded a lot from the decaf process so it's not going to expand as much during roasting, hence no "crack" (which is really the same kind of process as popcorn popping)! The reduced smoke may be due to the removal of the skins and residual dried fruit which would have been washed away along with the caffeine, whereas I would expect a natural process coffee to produce a lot more smoke (compared to the most common washed process coffee).

Less-so that it has expanded from the decaf process, and more-so that the additional porosity leads to the 'crack' you get from reaching that critical temperature is much less violent, since there's essentially already many micro-fractures in the bean. Think of it like attempting to burst a pipe with a leak in it, vs. a pipe that is sealed. The leak will bleed off pressure, so you need much more flow (in coffee roasting, this would be power from heat) to get the same build up and explosion.

Reply on news.ycombinator.com