Hi Daniel
I found this when I googled your question .. on the US Winepress website
'It will do no good to add more than the recommended dose of pectic enzyme. It is an enzyme, which is like an organic catalyst. The definition of a catalyst is a substance which does not react but aids in a reaction without being consumed. Like the catlytic converter on your car which removes unburned hydrocarbons and CO gas from the exhaust and keeps on doing it till the car falls apart or until it gets poisoned by something that should not be in the gas like lead. Just so, an enzyme assists in speeding up an organic chemical reaction without being consumed. In this case it reduces the pectin in fruits which would cause it to jell in other endevors or in the case of wine to not clear. It does not hurt, but why waste it?"
Cheers Allie