Well, based on what I have read and common sense it's balancing act. Lower temps decrease it's effectiveness. On the other hand leaving your juices out at 'room temps' risks spoilage to bacteria not just yeast fermenting the juices. 36 hours seems like a LONG time to leave juice unprotected without the addition of K-meta/Campden tablet(s)
And of course it is recommended to add pectic enzyme or pectinase well before you add k-meta as it also inhibits pectinase/pectic enzyme function.
Personally I would go no longer than 24 hours without introducing K-meta to the juice. Even if it inhibits the function of Pectinase, there is no indication that it totally prevents the function. So I would go with a 24 hour time limit and then add K-meta and then 24 hours later check SG and pH and once adjusted pitch the yeast.
Pretty sure Luc Volder did an experiment a few years back showing it didn't matter if you add pectic and KMS at the same time.
Luc also did lots of pectic enzyme experiments. It's been a while since I looked at them but I bet the answer to your question is there if you don't find it elsewhere. Search Luc Volder winemaking. Scroll down for English translations.
I've had pectinase sitting with fruit pulp and juice for upwards of four to six days. But I also add a lot of potassium metabisulfite. All during the height of summer. But take care of your skin. I know we all want to get in there with our hands and do a bit of squeezing etc... but wear some type of protection and/or at least give your hands a good wash afterwards. The pectinase has a nack of drying out your skin.
"Pretty sure Luc Volder did an experiment a few years back showing it didn't matter if you add pectic and KMS at the same time.
Luc also did lots of pectic enzyme experiments. It's been a while since I looked at them but I bet the answer to your question is there if you don't find it elsewhere. Search Luc Volder winemaking. Scroll down for English translations."
Very much interested but my search did not locate the gold... I found his pages and the English translation but saw nothing about pectin and KMS... I wll try again but could you point me to subject matter?
How do I get from the English translations to the stuff about pectinase / KMS ?
"I took two jars of apple sauce. In one jar I added a teaspoon of sulphite and a teaspoon of pectic enzymes and mixed them with the sauce. In another jar I put a teaspoon pectic enzyme and a teeny bit of sulphite (0,1 gram as much as you would at to your must).
After a few hours the jar which had the minimal amount of sulphite added was fluid again. 24 Hours later the jar with the large amount of sulphite added to the enzymes was still mashy.
So a small amount of sulphite will not harm the abilities of the pectic enzyme."