do enzymes expire?

could the enzymes be expired? I always used prozyme and just bought a gallon of it and opened it up and the styrofoam seal was like digesting and there was a few milky white blotches floating in there I figured it was just the styrofoam falling apart into the enzyme. So I used it in my dwc with a few other different products than usual and got root rot. Not sure If it was the organic calmag or subculture from gh or the prozyme but I never have had slime like this b4. Could the prozyme be expired? I read organic nutes are only guaranteed for a year but what about enzymes? And they never put expiration dates on anything so how the heck you suppose to know. I had gh flora nectar go bad on me before...started growing moldy but no expiration date.