From what I can tell by reading websites such as this this, granulated white sugar lasts ‘indefinitely’. Given that sugar is a natural product without any added preservatives, it surprises me that there isn’t a common microorganism on earth that doesn’t actively consume processed sugar. Sucrose, or cane sugar, is made up of glucose and fructose, and is about as basic an energy source as you can get. So why doesn’t sugar go bad?
This came up when I found an old sugar bowl that I had completely forgotten about for 10 years. I opened it up and found the sugar was still there, looking as pristine as the day I had poured it into the bowl.
While plenty of things eat sugar, including molds and bacteria, they also need water. Sugar in its crystalline form is very dry.
Add some water to your sugar - enough to make it dissolve into a thin syrup - and it will grow stuff. Not as quickly as many other foods, but that’s because you’re starting with two products - sugar and water - that are already pretty clean. Other foods come with bacteria already riding along, and so they’ll go bad pretty quickly as the bacteria grow. Sugar water will usually need some airborne bacteria or mold to land on it before it grows.
Bingo, there’s not enough water in it to support microbial growth. Same is true for stuff like dried pasta, which you can keep in your cupboard for years without it rotting. Animals might munch on it, putting it in their stomachs where there’s enough water to digest it, but the stuff itself isn’t a viable growth medium.
So, what is required for something to be a growth medium?
Is it water + a fuel digestible by the organism? Is that it?
If so, aside from sugar, fiber, starch, fat and protein, what can be the fuel?
Do bacteria drink? Is the reason a bacterium needs water so that the nutrients can travel within it?
So far, people have talked about sugar going bad because of biological reasons. Are there not chemical reasons why it would go bad? As beowulff mentions, it has no oils to oxidize but aren’t there other things? Or is it like grain, another carbohydrate, where, if you keep it dry, it’ll last pretty much forever?
Basically, sugar is a rock. Although a somewhat soluble one, but commercially refined sugar is the rock extracted from the solution where it occurs in nature…
Same with honey. Since honey has a lower concentration of water than the cell contents of bacteria or molds, it will literally pull water out of them and kill them. (The property is known as being hygroscopic.)
Water is needed for basic cellular functions (that sounded good, right?) IIRC, that would be things like, um, osmosis and mitosis and meiosis. Without water the cells just dry up and if your entire body is just a few cells, you can’t really go long length of time with it (except for some of those bugs that seem to be able to cling to dry surfaces for a few days). Even so, sugar, I’d think, would actively draw moisture out of them.
This is the reason we’re always on the look out for water, or remnants of water, on the moon and Mars. No water, no life. It should be a lot easier to find some ice or evidence of a river and look there than to just start raking the whole planet to find something microscopic.
Sucrose (table sugar) is a pretty simple molecule. It’s composed only of carbon, hydrogen, and oxygen. It’s quite stable, and doesn’t spontaneously decompose to any great extent.
Alcohol, technically, but it’s also bactericidal; it will kill bacteria, not fuel them. You and I can get fuel from it, though. And of course carbohydrates, which are sugars stuck together with chemical bonds.
Most of them move in it. They’ve got cell membranes which need an aqueous (for a certain definition of “aqueous” - your skin has enough available water for some of them) environment to grow and move around to find those fuel sources. Some of them can live on hard surfaces without water for days, but they tend not to grow and divide and make baby bacteria there. Even those that don’t move much need water for their biological processes. Water is needed to break food down into usable compotents, for moving waste products out of the bacteria’s cell, for creating new cytoplasm so that the bacteria can grow and divide…I’m sure I’m forgetting a few functions.
Which isn’t entirely true. If you store sugar outside an airtight jar, it will become lumpy due to the growth of fungi. These fungi rely on moisture extracted from the air to survive. If you store your sugar in an air-tight jar, they will die of dehydration since you’ve deprived them of water.
But then if you store many foods in an airtight jar, they will keep indefinitely, so sugar isn’t unique there.
Processed sugar in airtight containers doesn’t exist in the natural world, so naturally nothing evolved to cope with it. Crystalline sugar exposed to humidity is occasionally found in the natural world, and organisms have evolved to cope with that.
Try it again with a sugar bowl that allows in fresh air. In 12 months time it will be lumpy or, in humid areas, a solid block.
That is completely and utterly wrong in ever possible respect. No part of that statement is in any way accurate.
Fibre and starch are essentially the same thing.
Organisms can grow on some pretty surprising media, including pure water and rocks. Fuel isn’t essential since plenty of organisms can get their energy from the sun, or from rocks, and their carbon from the air.
The only thing universally required for a growth medium is water, which is what your sugar lacks.
If grown in “dry” media they do the equivalent, in the sense that they scavenge whatever water they can from the from the air or from the medium
That’s part of it, but the main reason is simply that a bacterial cell is a little bag of oil with an ongoing water-based chemical reaction inside. Lose the water, the reactions can’t proceed no ,matter what nutrients are in there.
Given long enough, especially exposed to oxygen and/or UV light, and sugar will go bad. But it’s a slooooooow process.
Grain isn’t a carbohydrate, it’s an organism that contains a lot of carbohydrate. Outside an airtight container, grain will go bad in less than 2 years, when the organism dies and the fats start to go rancid.
Alcohol is a perfectly acceptable food for many (most?) bacteria. Of course dehydrated alcohol will kill bacteria, but so will dehydrated sugar, dehydrated fat or dehydrated protein. It’s the concentration that’s toxic, not the alcohol per se. Just as we can consume dehydrated sugar or protein with relative impunity because it gets diluted by our bloodstream, so we can consume dehydrated alcohol. But that doesn’t mean that alcohol is any more toxic or indigestible to bacteria than it is to us.
In addition to alcohol, carbohydrate (sugar, fiber, starch) fat and protein, you can also make growth media out of a variety of organic acids like lactic acid or acetic acid, synthetic polymers like nylon, short-chain hydrocarbons, detergents and surfactants, hormones, organic poisons like 1080, strychnine and curare, and a whole slew of other stuff. Basically any carbon source that’s reasonably common out there will be able to be used as an energy source by some microbe.
Right. We forgot about a pack of sugar for around a year, way at the back of the cupboard concealed by canned goods. When we finally discovered it the sugar was rock solid.
I stock up on sugar when it is on sale and store it in the pantry. Frequently it has lumps or the whole bag hardens by the time I use it. I just stomp on it while it’s still in the bag and it turns into perfect granules again.
Are you saying there is some fungus growing in it? Is this fungus dangerous to consume? Should I be worried? When you crush the lumps it looks just like fresh, new sugar.