I want to store my 60kg juta bags content inside airtight bags like GrainPro
SuperGrainbags (http://www.grainpro.com/grainpro-supergrainbag.php) but with
a one-way valve in order to take out the air inside the bag so to create a
zero-air atmosphere inside the bags.

Just imagine the bags in this picture
http://coffeetime.wikidot.com/vacuum-pa...onclusions big enough
to contain 60kg of green coffee.

I need the airtight because I'm going to open and close the bag many times,
to take just the amount of green coffee I need to roast.
I need the one-way valve to create a zero-air atmosphere inside the bags.

Is there anything like that out there ready to be bought?

Thank your for your help.

Won't the vacuum dehydrate the beans

Freeze 30 x 2kg

How long are you expecting to store the green for?

cafeIKE wrote:Won't the vacuum dehydrate the beans?

I think that the vacuum simply take the air out, leaving the bean with its humidity.

Does dehydration occur in a protected zero-air atmosphere?

I assume that by "dehydration" you mean bean giving off its water content (lower humidity) to the surrounding environment.
Since the surrounding environment is "protected" by the grainpro bag layer, I assume that the bean simply cannot lose its water content.

Is this consideration of mine correct?

rubensgardelli wrote:I want to store my 60kg juta bags content inside airtight bags like GrainPro
SuperGrainbags (http://www.grainpro.com/grainpro-supergrainbag.php) but with
a one-way valve in order to take out the air inside the bag so to create a
zero-air atmosphere inside the bags....
I need the one-way valve to create a zero-air atmosphere inside the bags.

What kind of pump do you intend to use to create a "zero-air" atmosphere? The typical home or shop vacuum cleaner that most people use for this purpose removes only about 20% of the air. In other words, you don't have a "zero-air" atmosphere, you have an "80% air" atmosphere. This leaves an atmosphere that is still ~16% oxygen. In professional circles, this is considered utterly useless in retarding oxidation.

If you are serious about removing oxygen, you need a vacuum pump like this, which can easily cost thousands of dollars. In addition, the 10 cent plastic "one-way valve" that you're looking for is woefully inadequate to maintain your bags in such a high vacuum condition.

AndyS wrote:In addition, the 10 cent plastic "one-way valve" that you're looking for is woefully inadequate to maintain your bags in such a high vacuum condition.

Why? Do you think they are going to let the air get back inside the bags?

rubensgardelli wrote:Why? Do you think they are going to let the air get back inside the bags?

Yes

This topic is based on a misunderstanding.

High end green coffee is hard vacuum packed in mylar. No valve is needed, since it doesn't outgas. For roasted coffee, one way valves and a perfunctory air exhaustion or nitrogen flush are used since the outgassing CO2, which dilutes all remaining oxygen to negligible proportions, needs to be exhausted.

These valves work best when they to maintain a slight positive pressure inside the bag. They are not intended or designed to maintain a vacuum.