Sugar contains a lot of easily accessible chemical energy. Why seemingly nothing likes to grow on it?
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4$\begingroup$ 1. lack of water. even if water is present then 2. high osmotic pressure will cause plasmolysis. Since I don't have a source I am not writing this as an answer. $\endgroup$– JM97Commented Apr 9, 2017 at 16:32
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1$\begingroup$ Ever make bread? Typically you'll mix a bit of sugar into warm water, add yeast, and wait an hour or to for the yeast to grow. So the yeast is eating the sugar, but as JM97 says, it needs to be in a dilute solution. $\endgroup$– jamesqfCommented Apr 9, 2017 at 17:43
1 Answer
Our food mostly gets spoiled by bacteria and / or fungi. There are 2 main reasons for sugar crystals not getting spoiled.
1- Lack of sufficient amount of water to sustain metabolic processes by microbes.
2- Even if sufficient amount of water is present , then due to high osmolality of the fluid formed, will cause plasmolysis or cell shrinkage.
Some technical data:
Microorganisms differ widely in their ability to resist salt- or sugar-induced reductions of aw. Most disease-causing bacteria do not grow below 0.94 aw (roughly 10 percent sodium chloride concentration), whereas most molds that spoil foods grow at an aw as low as 0.80, corresponding to highly concentrated salt or sugar solutions.
Source: https://www.scientificamerican.com/article/how-do-salt-and-sugar-pre/
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$\begingroup$ Pop-sci reference: "How do salt and sugar prevent microbial spoilage? (from Scientific American) $\endgroup$ Commented Apr 10, 2017 at 14:00
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$\begingroup$ @fileunderwater thanks a lot for providing source. $\endgroup$– JM97Commented Apr 10, 2017 at 14:08