I was pondering the idea of the effects of flash-cooling of beans right out of the roaster. Like instantaneous, not just rapid cooling. The only way I could think of (short of liquid nitrogen) was to douse the beans right out of the roaster with ice water, and then drying them off and throwing them back into the roaster for a drying cycle.

So here goes...

Beans used: Ethiopia Arbigon / Sidamo / Heirloom Varietal
1500m / Washed processed
Roaster: Lysander sample roaster


The beans were dumped at about 1 minute into first crack, yielding a FC roast. Unfortunately I was shooting for City or City +. oh well. Still haven't gotten the hang of my sample drum roaster.



Dumping in the beans resulted an a sizzling crackle sound not unlike Rice Crispies!





I let the beans dry out with air and the remaining heat from the still-hot drum, for about 30 minutes. The beans steamed in the roaster for about 10 minutes before it subsided, and then the rest of the time the remaining chaff was pushed out the vents at the back of the drum.



Anyways, I started with 180g, and ended with 155g after the drying process a 13.8% moisture loss. After a day the beans dropped in weight by 1.5 grams.



Tasting:
Aroma was very nice and smelled of stone fruit, very similar to Blue Bottle's Three Africans blend. At FC I was expecting some ashy notes but didn't encounter it. Maybe some of it washed off in the process? Anyway, I'm not sure I would do this all the time, but the result was actually very, very good. Much better than my typical FC roasts. I was not able to identify specific fruit notes in my earlier roasts using the same beans. Cupped this side by side with a C+ roast I did around the same time and found it actually tasted better. I am definitely going have to try this again with a city roast of these beans.

Im not sure your testing how flash cooled bean taste, but rather how washed and dried beans taste. Right? Maybe it would of been a good idea to separate out a portion of that very same batch to cool normally too?


*also dry ice is cheap and pretty cold, and wont wet the seeds

No the process needs to be specifically a wet process to extinguish the heat instantaneously, which was the effect I was curious about. The one thing that came out of this experiment was that the beans being rinsed and dried actually pulled out the smokiness without having a negative effect on the brewed flavors that make up what's good about coffee.

This experiment was triggered by the other thread "roast experiments" which I found double roasting the beans actually resulted in more of that smoke burnt ash smell.

Quenching has been around for a while, research suggests that an increase in water content will increase degradation... but a confusing study found that water quenching in the roasting area rather than cooling area (no further information given) didn't lead to either.
https://home.zhaw.ch/~yere/pdf/Teil70%2 ... linary.pdf

If you manage to keep them from absorbing more water, might work out. As far as I know it's not used often in specialty coffee due to concerns about decrease in quality.

I believe the other poster has a good point regarding testing water vs no water quenching, as a useful comparison.

I don't typically get ashy or smokey flavors with a full city roast. Hard to say if quenching made a difference or if it was just a good roast without a control.

I believe the other poster has a good point regarding testing water vs no water quenching, as a useful comparison.

I agree as well and intend to do a more thorough comaprison. I did say though that I noticed an immediate difference in the post roast aroma from what I would normally expect.

Yakster, by the very nature of the roasting, all roasts have a smokiness to them (some more than others). If you can't smell it you are one of the lucky ones. I, for one, can smell and taste smoke in *all* roasts, purchased or otherwise. . If there is a method that can reliably reduce excessive smoke associated with darker (FC and beyond) roasts then I would consider adopting it as part of my process. I can see why commercial application for such a process wouldn't be viable due to the added costs, even if proven to produce a superior product. But would not be surprise, assuming this would be an acceptable method, that something like this might show up in barista competitions (if it hadn't already). There is great complexity in the darker roast but unfortunately much of what's good is greatly masked, or overwhelmed by the burnt notes associated with them.

I might misunderstand you, but I think we usually talk about this as coffee vs roaster flavors. Most of us figure out how to manipulate our roasters to either minimize roaster flavor or to roast for it without sacrificing sweetness and complexity. This isn't always possible with every bean, but it's nearly always worth a try.

As for instantaneous cooling, I'd think cooling coarse ground coffee with dry ice might be worth a try.

millcityroasters wrote:As for instantaneous cooling, I'd think cooling coarse ground coffee with dry ice might be worth a try.

Did you see my first post?

You are suggesting something entirely different from this topic. I am talking about rapidly cooling beans straight out of a roaster.

Uh, yeah, and I'm talking about grinding hot and cooling with dry ice.

This might actually make sense for pod packaging.

EspressoForge and OldNuc are going to have a field day with this post, I don't know where, but read something where they found that cooling too quickly damages the bean structure or something and is actually not good. Maybe someone else can better speak to it, right or wrong.