So, I was reading the first couple Boot "Ruling the Roast" articles the other night, and started thinking about how to measure moisture content in greens, without buying a many thousand dollar meter.

I came up with this hairbrained idea of taking a handfull of beans, weighing them, trying to bake the moisture out of them, and then weighing them again.

I tried it today.
Started with 10.09 grams of El Savadorian greens.

I stuck them in a convection oven, and baked at 300 deg f for 40 minutes, in convection mode.
Weighed 8.78 grams after this, 13% weight loss. They were yellow after this.

I decided to bake some more, to see if there was any more moisture in them.

Baked at 375f for 15 minutes. They came out brown, and I heard cracks while they were baking this second time. There was oil on the beans, and oil on the alumimum foil, so I am sure I lost some weight in oil.

They weighed 7.89 grams now, a 21.8% loss.

So, does this sound at all reasonable?
I know the second number is off, but I figure that one was off because I actually roasted the beans, and lost weight to oil and other things.
But, the first number, of 13% seems reasonable. I realize part of the 13% is probably other compounds that also baked out of the bean, but I would guess that a pretty large part of the 13% is water.

I may try it again, with the same beans, at 300F for a little longer, and see what I get.

Comments?

Randy

I did a similar test, see this thread, part way down first page and some on page 2. click here Be careful not to over heat the sample. You want to get the moisture out without causing any other reactions that will effect the weight.

The technique in Sivetz for calibrating moisture meters is weight loss after baking at 175F/80C for 24 hours (I think, I'll have to confirm when I get back). The temperature you were using is going to remove some chemically bonded water too.

Thanks for the replies.

I searched, and did not find that thread.

I did not think about grinding the beans up, but that makes sense, it will make the bake time much quicker.

I can't do 175 for 24 hours, but I will lower the temp, to 200 or so, and see how long I need to bake them until the weight stays the same.

Randy

A whirley blade grinder works best. Just dice them a bit. This really cuts down on the time needed. The espresso baskets work well. I made a fork out of coat hanger size wire to handle the baskets.

randytsuch wrote:... and see how long I need to bake them until the weight stays the same.

Randy

Yes, do a sample and keep weighing it and you can definitely tell when it levels out. My tests take 2 to 2 1/2hrs