On this thread, this method for estimating green moisture content was proposed. I'm curious if anyone has any experiences with this method?

I tried it by dropping a plastic, analog, RH meter into one of my bean vacuum bags then vacuumed and sealed them up. After a day, the meter was still reading %40 inside the bag. According the linked thread, that's too low.

So, any one tried this out?

Hi coffee.me

your posts are always very interesting. Don't know about the bag trick but doing a google came out with this:

$395 http://www.coffeelabequipment.com/QCCOFFEEPRO.html

Cheers

I've yet to hear of a cheap meter that will work accurately enough to make it much help. On the first page of the thread you linked I did a drying/weighing process that has continued to work well when needed.

Moved the cheap meter to another bag, vacuum sealed it, and after a couple hours it stabilized on 51%. The exact reading of the 1st bean bag was 39% vs 51% for the 2nd bag. So this method, even with my pathetic meter, seems to give some indication of bean moister content.

The meter I use has some spiral of metal attached to the back of the dial pointing at the RH level. I don't think there's a cheaper, older, or worse meter you can buy. It looks something like this, but not exactly, I also couldn't locate pictures of the backside where you can see the metal spiral used to measure & indicate RH.


Guys, this is an extremely easy method to try and if you only have zip bags, just throw the meter there and draw out as much air as you can and see what numbers you get. . . . . and report back!!!

farmroast wrote:On the first page of the thread you linked I did a drying/weighing process that has continued to work well when needed.

I saw that process earlier, but it's too much work and sacrifices too many beans. If the one we're talking about here gives a relative indicator, it should be enough for us home roasters.

coffee.me wrote:Guys, this is an extremely easy method to try and if you only have zip bags, just throw the meter there and draw out as much air as you can and see what numbers you get. . . . . and report back!!!

I proposed this method originally, yes it is quick and easy. Thanks Chris, for the tip on saturated salt solution cal - my $10 (inc freight) LCD panel meter measures 78% over NaCl, not bad when the manufacturer's spec was +-5%. So far my mean ERH measurement at 16C is 65% (so that's probably 62%), with an SD of 3.3%(abs) over 24 different greens samples. One outlier was way down and I could not get a good roast from it, even with a short drying phase. Solution was to leave the beans in an open tray (depth 50mm) in the wine cellar where humidity is not controlled, but is modified to compensate for dehumidification of the aircon. A week brought them up to ERH 60% (est response time 3 days) and they roast well now.

Eric

Coffeengineer wrote:One outlier was way down and I could not get a good roast from it, even with a short drying phase. Solution was to leave the beans in an open tray (depth 50mm) in the wine cellar where humidity is not controlled, but is modified to compensate for dehumidification of the aircon. A week brought them up to ERH 60% (est response time 3 days) and they roast well now.

Eric, thanks for proposing the whole thing on the other thread and for this additional info too. Any info you can share on the approximate temp/humidity of the wine cellar?

I think something like this is better for a true read, unfortunately the probe spacing is probably too far, but I bet it could be modified somewhat easily with a terminal block type adapter. http://www.amazon.com/gp/product/B0006OC3FK Test a couple beans from the bag, to see actual moisture content is the idea.

An environment RH meter doesn't really tell me much to be honest. Since RH changes with temperature, and it is only the RH of the surrounding air, it only corresponds to the actual bean moisture. Although if you are trying to correct a bean moisture, it is useful to know the RH of the air you are subjecting the beans to, either to dry them out a bit more, or to give them a bit more moisture.

Just my ideas.