Subject: what is the rate of denturation of pectinase?

i've just carried out an experiment into the rate of denaturation of 
pectinase. i used a 3% solution, which i made from concentrate. unfortunately 
i dont know the source of the enzyme, but the bottle stated that the optimum 
pH was 7, and the optimum temperature was 20degrees - 75degrees.
i heated up the enzyme solution to 90degrees for different amounts of time 
(every 30 seconds up to 5mins, 10mins and 15mins) and seeing how this 
affected the juice yield from apples. i didnt get a graph which had perfect 
negative correlation and it seems to jump up in places. is this what i should 
have expected, and if so, why?
if it is not what kind of graph represents it accurately?
the apples i used were granny smith apples, and i pureed a bag at the 
beginning of the week and kept in an airtight container. however, is it 
possiblie that the later experiments could be distorted as the pectin was 
being partially broken down?
thanks

Re: what is the rate of denturation of pectinase?