does sugar go bad faster once mixed with liquid?

If I mix just water with a lot of sugar, like the amount in soda or fruit juice, can I leave it in room temperature (air-tight), or is there any reason to refrigerate it?
I also just mix sugar and milk; will that mix go bad faster than just milk?
thanks gang!!

Sugar doesn’t go bad because it’s way too dry for bacteria to live. Add it to water and it’ll go bad real quick. Refrigerate it.

Milk already has lots of sugar in it, so it won’t go bad significantly faster by adding more. It’s a different sugar than table sugar, but makes no difference.

It doesn’t ‘go bad’ when you mix it with liquids. In fact its still quite good that’s why the bacteria will thrive feeding on it. Your issue is you don’t want to share with the bacteria. Sugar by itself isn’t a good breeding ground, add water you have the basic building blocks for bacteria to thrive.

Very popular with yeasts, too. Fermentation can make some yummy stuff!

What is the perishability of sugar+water compared to milk? Can I leave it out 6 hours? 12?

It’s in the multiple-days range, but generally depends on whether there are other compounds (natural lemonade will last longer than water with sugar) and on the actual temperature (wine caves were caves precisely in order to keep temperature stable and at a range the desirable ferments like).

Are dtilque and Nava disagreeing here?
By “perishability” I meant leaving it OUT of the fridge… how long would it last IN the fridge?

Depends, are you freezing it? And “real quick” and “days” can actually agree - depending, among other things, on how hot it is and what exactly have you done, and what someone’s concept of “real quick” happens to be.

Right now, temperatures outside my window are in the 30Cs (90 Fs). If it was winter, they could be actually colder than the fridge. What the actual temperature is and what exactly have you done with the water matters. If you’ve mixed the water and sugar, sterilized the mixture and kept it in a sterile, closed pot, it can last forever (that’s what Pasteur proved, that “bugs don’t just appear”). If you’ve left it out in an open jar, it will not last as long. If you’ve taken a sip of your beer, licked a spoon and used the spoon to mix the water and sugar, even less.

Right. When I posted “real quick”, I was thinking of current conditions. I.e. summer with high temperatures over 30C. Sugar water will go bad in half a day or so at that temperature range.

“Going bad” is all a matter of bacteria growth. And that is a function of temperature and initial amount of bacteria. For temperature, different bacteria have differing optimal temperature, but there’s a very large percentage of them that grow best at 30-37C. Most of the bacteria that we can culture (and thus will grow real well in sugar water) fall into this group.

Unless you’ve sterilized something, you can be sure it has bacteria in and on it. Even the sugar will have some in it, even though it doesn’t grow in that dry environment. In hostile environments (such as the dry sugar), some kinds of bacteria form spores which are a dormant phase. When the environment gets less hostile (add the sugar to water), spores reactivate and start gobbling up the sugar. But there’s also bacteria in the container, the water, and floating around in the air (usually on dust particles). And of course, there’s lots and lots of bacteria on living beings such as yourself. All these are sources of bacteria that will cause the sugar water to go bad.

Dumb question, but… if everything you’re saying is true, why doesn’t honey go bad?

Same reason for dry sugar: too little water.

ETA: there’s a few other reasons like acidity and peroxide, but mostly it’s too dry.

It’s worth noting that bread behaves similarly. If you keep moist bread in an airtight bag at room temperature, it’s going to develop mold within a matter of days. OTOH, if you leave a slice of bread out in open air in a dry environment, it’ll dry out in fairly short order, and then it’ll take much longer (if ever) to develop mold.

I think that must be why honey not going bad surprises people, but granulated sugar not going bad doesn’t surprise. Honey looks wet. I guess it just isn’t as wet as people think it is.

Yeah, it’s not solid, but it’s *extremely *hygroscopic. What this means in terms of bacteria is that any that end up in/on the honey actually get dehydrated by it. Same thing works for most highly sugary syrups like that- brewing malt extract has the same property. Mold will grow on it though if you’re not careful.

Exactly. Honey has some water, but it’s more than 80% sugar.

Bacteria need water to grow and they absorb that water from the environment. Honey is so concentrated that bacteria can’t pump water from the honey into their cells. Or they can, but the water just osmotically diffuses back out faster than they can pump it in, and they dehydrate and become inactive.

You have to mix the honey with a lot of water before you create an environment that bacteria or yeast can grow. So to make mead you wash the honeycomb with water and then ferment the honey and water mixture.