Based on a the coffee questions I've seen, it seems that hot beverage questions are in scope, so here goes mine:

We like keeping iced coffee in the fridge, particularly in the summer. It's easiest to add sugar to the entire batch, but we both like differing amounts of sugar to coffee. Sugar doesn't dissolve in cold liquid very well.

If I make a sugar suspension and put it in the fridge to sweeten the coffee as we drink it, will the mixture stay liquid or will the sugar crystals re-form? If this is impractical, can anyone offer another solution?

Edit: Here's a picture of sugar solution that we've been keeping in the fridge and using. I made it 8 days ago and it's staying in solution quite well. alt text

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    To follow this up, the syrup started growing... things in it around late December. A 3-month life in the fridge is pretty good. (I also made far more of this than I needed, since we don't drink a lot of iced coffee in the winter.) Jan 22, 2011 at 21:34

3 Answers 3


I do exactly that.

I use a clear plastic squeeze bottles. I fill a mug 2/3 full with sugar, and top up with boiling water, stir, cool, funnel into the squeeze bottle, and keep in the fridge door. The squeeze bottle makes it easier to get the right amount of sugar into your beverage.

squeeze bottle

I don't even worry about keeping it sealed. There's nothing much to oxidize. And the osmotic pressure of sugar solutions makes it very difficult for pathogens to live. This is why jams and jellies keep forever in your fridge. Like jams and jellies, the first thing you're probably going to see in the way of spoilage is mold. In the case of simple syrup, we're talking dark thready stuff at the bottom of the bottle. This happens about a month out. I chuck it, wash the bottle, and carry on.

On a related note, I have a blog post about iced coffee. And it's kind of a little wrong. Cold-brew coffee is pretty good for making iced coffee, but it's not better than leftover percolated coffee. Seriously. We make hot coffee at my workplace using this cheapo percolator urn. We learned from the reviews on Amazon that we could just pour off the leftover coffee in the afternoon and have excellent iced coffee. And that's exactly what we do. (To be fair, we use Gorilla coffee, so that might have something to do with it, but I think it'd be good with average coffee.)

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    Wow, great answer! @Neil Fein and I do in fact make our iced coffee out of the leftover hot coffee. We'll make a little extra each day, and pour it into a pitcher we keep in the fridge. After a few days, we've got a full pitcher.
    – Martha F.
    Aug 20, 2010 at 12:39

Make a simple syrup. Simply dissolve one to two parts sugar into one part boiling water, cool, and pour into an empty 20oz soda bottle. As long as the sugar is fully dissolved it will remain syrupy, and not recrystallize.


We do this all the time. As long as you don't dissolve so much sugar in it that you've made a super saturated solution, no crystals will form.

For coffee, we make the following simple sugar recipe:

  • 140g sugar
  • 200ml water

Bring water to a boil, dissolve sugar. Drop into a glass container (we use an olive oil bottle with pourer), allow to cool at room temperature until reasonably cool, and put in the fridge.

You can make vanilla syrup by adding 5ml (1 tsp) to the solution right after the sugar has dissolved after bringing to a boil. You want to make sure that you have it well above 140F to boil out the alcohol that is present in vanilla extract or it will taste a little "off".

Adding room temperature sugar to boiling water drops the temp to around 180F, which is the perfect time to drop in the vanilla extract.

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