GDM528 wrote:You got me to check: green beans sink, and dark roasted beans float. What about light roasted beans, do they sink, or float?

my two lightest roasts at home (10,6% weight lost from roasting, one being a fairly but not extremely dense Ethiopian grown at 1900masl) are very buoyant indeed. Even in spirits they'll float at first, but they'll sink after soaking overnight in water as well.

I did an experiment that involved soaking greens in carbonated soft drink. Everything floated at first, due to high carbonation (the 4% denser solution wasn't enough in the unpressurized control). Took a few days for the beans to swell and sink. The experiment was a success (sugar infused beans!) although it turned out to be too much of a good thing since the beans started smoking way before first crack

GDM528 wrote:You've hit on the two things I was trying to accomplish:

1) I hate carbolic acid, so that CO2 has gotta go. ...

I assume you meant carbonic acid...carbolic acid would be disastrous for other things besides the taste of the coffee...

Just thinking out loud: what about putting the hot beans right out of the roaster into the sous vide? Of course they'll have to go into a ziploc bag first and thus probably must'nt be at 200°C, but the general idea is to not let them cool down to room temperature and then bring them back up to 60°C.

you want the beans to cool down ASAP after reaching the desired roast level, slow cooldown to 60'C will make you lose flavor.

Yes, quick cool down after dropping the roast is extremely important, mainly to prevent the beans from "coasting" further along in the roast. I suppose you could allow beans to cool down more slowing without adversely affecting them, but doing so would entail adjusting for more roast variables to make things come out as you want them to.

In short, you'd be making both the art and science of coffee roasting to get great tasting coffee much more complex and difficult than it already is. IMHO.

Okay, thanks for clearing that up.

GDM528 wrote:A few words about my arguably cavalier use of the term "vacuum": I'm using a Foodsaver system to draw the air out the bag before sealing. The pump in the Foodsaver just needs to pull out enough air to make the thin plastic film deform around the contents and create the customer perception of a 'vacuum'. However, the Foodsaver only pulls to a bit lower than one-half atmospheric pressure.

I have a low end Foodsaver that I bought for about $70. One time I inserted a small (1" square) absolute pressure sensor with display along with some coffee beans into a bag and vac sealed it. The sensor registered 0.28 atm (I'm close to sea level). It was actually lower when the vacuum turned off but it seems that there is a little leakage that occurs in between the pump shutting down and the seal forming. I've wondered if the same thing happens with jars in high end chamber vacuum sealers.

GDM528 wrote:I did try to remove as much air as practical from the ziploc bag, but it still floats pretty aggressively.

Could you weigh it down with something heavy, either in the bag or connected to the outside of it?

a trick I'm using when doing sous vide cooking in ziplock bags is to immerse them in water as far as possible without water entering whilste keeping them upright and zip them.

Marcelnl wrote:you want the beans to cool down ASAP after reaching the desired roast level, slow cooldown to 60'C will make you lose flavor.

Although it's a bit off topic, you still make an interesting point. Air roasters (FreshRoast, IKAWA, etc.) generally hold onto the roast during the cool-down process, which is into the ballpark of 60C. Takes 60-90 seconds of cooldown before my IKAWA will let me eject the roast. Could this be one of the many reasons drum roasters and fluid-bed roasters don't produce the exact same result?

Pressino wrote:I assume you meant carbonic acid...carbolic acid would be disastrous for other things besides the taste of the coffee...

Whoops, thanks for catching that!