Freeze dried mealworms aren't frozen and then dried.it's a special process whereby the freezing actually dries the material. http://en.wikipedia.org/wiki/Freeze-drying. Probably not practical at home. You could try just drying them (without freezing) that might work. Freezing them first may cause water crystals to form that break down cells and cause the brown/black you're seeing as they thaw. Anybody tried to dry mealworms at home?
Some wonderfully scientific minded person on the mealworm farming thread found that just freezing them and thawing them at a later time, but feeding them quickly after that resulted in appearance/texture of live ones, just no wiggling. Leave them too long after thawing and they did turn black, but I believe the chickens don't care as most on that thread feed the dead black ones that show up in the mealworm farms! Hope that helps, and farming them is really as simple as you want it to be. I've just started myself
--Carrie in Des Moines
