When I store it in the refrigerator, my simple syrup always seems to crystallize. How can I prevent this? How long should I expect simple syrup to keep?

  • So we might be looking for data on the saturation concentration of sugar at various temperatures... something I was going to post a question about, since the syrup for my lemon sherbet crystallized slightly in the refrigerator today!
    – Cascabel
    Commented Mar 21, 2011 at 5:30
  • 1
    I think a more important question is, why is it crystallizing at all? I've had simple syrup in my fridge for months and it didn't crystallize. Perhaps my fridge is colder or warmer than Katie's? Is this a 1-to-1 water-sugar recipe? Commented Mar 22, 2011 at 2:45
  • @Neil - Yes, it's a one part water to one part sugar recipe.
    – KatieK
    Commented Mar 22, 2011 at 16:06
  • Agave syrup doesn't crystallize.
    – Chloe
    Commented Mar 27, 2012 at 17:45
  • @Chloe Agave syrup doesn't crystallize because it's mostly fructose and glucose, roughly the same as high fructose corn syrup.
    – SourDoh
    Commented Dec 24, 2013 at 17:53

8 Answers 8


There are a couple of things you can do to prevent sugar crystallising. You can add some glucose syrup, or you can 'invert' the sugar by adding some acid, namely cream of tartar. Both should be readily available, online if not at your supermarket. Cream of tartar is also useful when making meringue.

  • Doh! Shouldn't have followed Lebovitz's recipe so carefully - he had me add the lemon juice after chilling the syrup.
    – Cascabel
    Commented Mar 21, 2011 at 17:08

I always throw in some corn syrup when make a simple syrup. The extra glucose adds some "chaos" to the mix and keeps the crystals from forming their structure.

I also like to add some cream of tartar to help break up the sucrose in the table sugar into its component parts of fructose and glucose.


Simply adding a few drops of lemon juice in boiling sugar solution will prevent it from crystallizing.

  • 4
    If you can, I'd love a bit of explanation of how this works.
    – Jolenealaska
    Commented Aug 21, 2014 at 22:30

When my honey crystallizes, I put it in an electric oven set to 50 degrees C for a couple of hours. Perhaps this trick would work with syrup as well since their composition is similar. Also, make sure that there are no crystals when you put it in the refrigerator, they act as seeds on which more crystals grow.

  • You can cook simple syrup again to remove the crystals, but it's not really effective for preventing crystallization in the first place.
    – SourDoh
    Commented Dec 24, 2013 at 19:32

I make a lot of syrup because I love pancakes and waffles. There are a couple of things I do which I have found keep my syrup from crystallizing (this is based on personal experience and not any kind of scientific proof).

1) I only use about 3/4 the amount of sugar. My recipe calls for 2 cups but I only use 1 1/2 cups.

2) I don't boil the sugar. I boil the water, remove it from the heat, and immediately stir in the sugar. just make sure the sugar dissolves completely.

This does make the syrup thinner, but we prefer it that way.

  • 2
    This will surely prevent it from crystalization, because your solution is no longer supersaturated. But it will also be unusable for most recipes. It will only work as the end product (such as pouring over pancakes), but never as an ingredient in candymaking.
    – rumtscho
    Commented Dec 24, 2013 at 16:50

A scrupulously clean saucepan is important. It's possible that banging or scraping the spoon along the insides of the saucepan "seeds" the crystallization process. Also, "A seed crystal is a surface that sucrose molecules (that's the sugar) can begin to attach themselves to—it could be a few sucrose molecules stuck together, a piece of dust, or even a little air bubble." So, stirring well but not crazily is advised.


Add lemon juice, or citric acid.

You also need to clean the sides of the pot while you are boiling your syrup. The sides of the pot contained undiluted sugars, so when they touch the syrup your syrup will crystalize.


If you're adding sugar and water together, don't bring it up to a boil. Gently simmer it for a longer period of time until the sugar is completely dissolved. Also, the higher the sugar ratio, the higher the likelihood of crystals forming. From my experience, bringing it to a boil is what causes the crystallization, for whatever reason.

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