Ours, when we make it, lasts for a few weeks until it is gone, it might last longer if we didn't finish it.

I've often wondered what supposedly goes off, because I've never noticed it go bad. Quick check on epicurious, the "recipes" are all pretty similar (sugar, water, heat, stir, dissolve...) yet storage times range from not specified to four days to three months.

I guess I'll stick with "if it looks funky it's time to toss," but I've yet to experience it turn funky.

I use mine unless there is mold on it (which takes a long, long time to develop). Really, you are not going to get food poisoning from sugar water! If I know I won't use it in a reasonable time, I just put it in a glass jar in the freezer (so it's easy to micro when needed). I do the same with hummingbird nectar 4:1. I make a batch and freeze it in feeder size packages.

edited to add link:
Here are some other ideas for keeping it longer

Here is a link that might be useful: Keeping simple syrup longer

This post was edited by olychick on Tue, Sep 16, 14 at 0:25

What exactly does the swirl look like? It sounds like one of two things. Either sugar recrystalizing, or mother. Mother should take a heck of a lot longer to develop than a few days! Or it could be mold starting, though mold usually occurs where it's exposed to air, i.e., on the top, usually along the edges. It sounded like the swirl was in the middle.

If it is fungus, whether mold or mother (yeast), you should be able to prevent it by giving all your tools a good hot wash right before you make it. For you and your SIL to both have it points to the spores being all over your kitchen.

But it could just be crystalizing. What happens when you zap it?

plllog, I think it is sugar recrystallizing or something similar.. Knowing how I handled it, and have continued to handle it and knowing that it is fresh, I seriously doubt that it is mold. I have not tried to re-zap it. It was made in the microwave, not in a pan. Would that make a difference? (1/3 c sugar to 1/3 cup water, zapped until it boiled, then cooled and stored in a clean lidded container in the fridge.)

The "swirl" is more or less clear, but appears slightly more viscous than the surrounding liquid. Just enough that if you don't shake it as you remove it from the fridge, and if you look closely down into the container, you can see it. It can only be seen when looking from the top down - not from the side across.

DSIL lives 2.5 hours from me, so our kitchens share nothing in common. He made his in his kitchen. I made mine in my kitchen.

This is more of a curiosity than a problem. I used it last night for an Old-Fashioned, and I lived to tell about it!

>It was made in the microwave, not in a pan. Would that make a difference?

Yes. It's probably just separating back out. Next time, use a pan and you almost certainly won't have this problem.

Agreed. It could be that a little of the sugar didn't melt in the MW, and perhaps it takes a few days to migrate together to be seen, or float, or whatever. If your SIL did the MW version, that's more evidence. Much more likely than mold after a few days.

BTW, just to be sure it came off right: I was not impugning your housekeeping. A properly active kitchen usually has lots of mold and yeast spores. If it's too sterile, the bread won't rise!

It might be as simple as microwaving for most of the time, giving it a good stir, and finish in the MW with a little time added to make up for the cooling. Even the very best microwaves heat the food unevenly.

If your container is glass, you could try either zapping it in the container, or putting the container in a pan of water on the stove, heat, stir, and see if it goes away, but you could also just keep using it. It's not like there's that much, and it's probably just sugar. :)

HA! It never crossed my mind that you might be calling me a lousy housekeeper. DD and I both bake bread and I know having all sorts of benign stuff in the air is just part of life. I keep a clean house, but I don't Clorox the counters every night after I wipe them off (DSIL does, bless his heart).

I think I'll just keep using this for Old-Fashioneds, until I run out of simple syrup or bourbon! It is more of a curiosity for me than a fear of something vile.

Yup, just crystallizing. It only takes a grain or so to start it. Any not melted thoroughly can start the recrystallizing. You can take it out when done and wash down the sides and let it boil again for a second.

I make a simple syrup for my hummingbird feeders, and then it goes into a container that is inverted. It takes the hummers at least a week to go through a batch - I use 1-1/3 cups of water with 1/3 cup of sugar and have two feeders. If I see anything strange in it, I replace the sugar water, but it seems to last okay at ambient temperatures.

Lars