How long will strawberry jam last if left out?

As long as the cookies would stay not stale.

Basically – if the sugar level in the finished product does not go below that of 65% of the total volume, the micro-organisms have a hard time thriving. In store-bought jam, it is not always just sugar that keeps the jam fresh; Sodium Benzoate (E211) is common in those cases. This conservative, causes the intracellular pH to change to 5 or lower, and the anaerobic fermentation of glucose through phosphofructokinase is decreased, effectively.

To answer your question in short, the cookies will last pretty much on how much suger you put into them, and depending on the quality of the jam. Give or take from the sugar percentage of the jam, and you will get an approximate expiring date.

It is far more likely for mold to grow on top of it, rather than the jam will spoil. I wouldn’t worry if left out over night, but don’t leave it out indefinitely, if it’s supposed to be refrigerated.

I used to refrigerate my peanut butter, but my Grandson made me stop.

Before refrigeration, it was customary to allow mold to grow across the top of opened jars of jellies and jams. The mold secretes antibiotics which prevent the growth of other, more dangerous organisms, acting as a seal. The mold and the layer of jam just beneath would be scraped away to reveal the uncontaminated jam for eating. That doesn’t do you much good for cookies, of course, since mold is the last thing you want growing on them.

Honestly, I have a pretty laissez-faire attitude to food contamination, which is probably what keeps my healthy. So-called “clean house syndrome” is caused by a lack of exposure to foreign organisms, which cripples your immune system. If you’re not overly picky about your food hygeine, you soon develop a robust immune system capable of dealing with the odd bit of salmonella from an undercooked egg.

I don’t keep jams in the fridge. They are called “preserves” for a reason…! As @marinelife said, I’d agree that it’s likely that the cookies will go stale before you have any problems with the jam. If they are good cookies, I am sure they will have been eaten before that time comes. :)

I’ve had one experience with a jar of jam going off, and as @SebastianUllmark said, it was probably because the sugar content wasn’t high enough, or the jar hadn’t been sterilised properly. I just picked out the mouldy bit and ate the rest.

As @SmashTheState said, I think people could be quite a lot more relaxed about food contamination and storage before it became a problem. I am of the belief that people rely far too heavily on external instruction (e.g., guidelines, sell-by-dates, etc), rather than their own instincts and common sense about these sorts of issues. The human race thrived for thousands of years before anyone invented fridges, and whilst undoubtedly, people are living longer than they used to (for a huge variety of reasons), people can be unduly paranoid about food safety as a result of the messages that people selling food, or food-related products (hmm..vested interests?!) give them. I’m not advocating people being cavalier about things that can adversely affect health, but I think it helps if people learn to trust their own judgments a little more.

Thanks for the responses! :) I just wanted to be sure just in case I wanted to ship them to someone!