OK, I admit - I don't take things at face value all the time - I mess with htings, experiment...etc.
The guy at mulberry told me once that I might try not cooking the chow, as cooking it may degrade its nutritional content... he did say it was a risk because of bacteria, etc.
However, I do not cook it any longer - add hot water to consistency, and that's it. Works fine.
I knew I had some spare chow lying around. It was an opened container -not even closed. Had been in my garage for over 2 years, open. I mixed it with hot water, and fed it off. No problems. I don't breed the things, so growign them to full size and feeding them all off is all I needed to do - worked fine.
Dry food might go bad, but it is unlikely to get spoiled by bacteria. Bacteria will not grow if it's dry. Bacterial spores can contaminate it - but they won't grow until it's moistened.
I don't order silkowrms enough to warrant new chow all the time. In fact, I still have a little bit of the stuff, still opened, and now over 4 years old. Next time I order some silkworms, I'll use this on some of them to see what happenes!