Drying seed for freezer storage. How dry?

[templeton]

Plant breeding generates mountains of seed. This seed attracts seed eaters. Freezing kills the bugs, particularly the nasty little beetles that are drilling holes in all my pea breeding lines.
Deppe recommends drying down until they shatter under a hammer blow - but I don't really want to smash up my breeding stock, particularly when I've only got 3 or 4 seeds of some lines. And I don't want to dry them to unviability. So how do I find the Goldilocks zone of dryness?

My pea chewing beetles seem to be eating their way out, rather than in. I suspect eggs have been planted inside, perhaps at the green stage, and they feed and develop inside the seedcoat, since there is no frass in the bottom of any of the seed envelopes, and no obvious entry hole into the seed.
I've currently got them in the fridge at a few degrees above freezing, but this only slows the bugs down to immobility, rather than killing them like 2-3 minutes in the freezer does. I tested them in some ziplock bags.
Any tricks or suggestions?

Would CO₂ work as a control method? I could use one of those soda stream canisters or a soda syphon.
T

[oxbowfarm]

Easiest way would be to use a dehydrator on a low setting 35 deg C. If you weigh the seed before and after you can get a good idea of percentage moisture.

Another idea would be to pack them in an airtight container like a canning jar with some oxygen absorbers if they are easily available, here you can buy then quite reasonably online. The seeds are fine without oxygen but the bugs die, I assume the bug eggs as well but I'm not 100% on that. But if you get a good sense of how long you need to dehydrate the seed to get it down to safe moisture levels then you can just freeze it.

[12540dumont]

Placing Dry Ice in the bottom of a dry food storage container (5 gallon bucket with lid) is a very economical way to fumigate and store dry goods for an extended amount of time. Make sure the Dry Ice is not frost covered, as that will add moisture. Put one quarter pound of Dry Ice per five-gallon storage container in the bottom and then pour in the dry food. As the Dry Ice sublimates it replaces the oxygen in the container with CO2. Leave the lid on but not tightly sealed until the Dry Ice completely sublimates. (About 5-6 hours) Then snap the lid tight. Without oxygen, neither bugs nor bacteria can grow. This process is good for seeds, grains, legumes, flower, powdered milk, etc. An excellent site for further information can be found at www.fcs.uga.edu/ext/pubs/html/FDNS-E-34-1.html

I was with a farmer in Northern California. He's using dry ice in blue barrels with lids. The barrels are full of corn. Yeah, Joseph, more corn than I have....

A lot more corn. (And beans too).

Of course you must take the seeds out of plastic, and put them in paper. After this process, you can return them to your seed fridge/freezer.

Peas and beans and weevils.....nasty little critters. I always give the beans and peas 2 cycles. 4 days in the freezer, 4 in the fridge, 4 back in the freezer before moving to the fridge or staying in the freezer.

One year I let kids help me, and they got the ones moving from the fridge to freezer confused, I had a nasty outbreak of weevils in my favas. Fortunately, they're in glass jars, so eventually the weevils died, I had to float all the beans and toss about half of everything. 2 file drawers full of beans lost. Well, no one helps me do this anymore.

And if it hadn't been for Lieven, who received a bad batch, I might have lost them all!

[oxbowfarm]

I've heard of using the dry ice, I don't actually store enough seed at once to justify the hassle, but is seems like a great method. One thing I really like about using the O2 absorbers is that they create a partial vacuum inside the jar as the O2 is removed that actually seals the jar extremely tightly.