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If I freeze a sauce, particularly something with mince in it, when defrosted it produces excess water.

The sauce before frozen is nicely thickened.

I think it might be because the proteins in the meat are damaged in some way by the ice crystals so that they are unable to retain as much water.

EDIT The sauce I'm referring to is bolonaise and the only thickening agent I used is a bit of tomatoe puree.

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rgvcorley
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  • What kind of sauce? Something with meat in it, I guess? – Cascabel Apr 08 '12 at 17:28
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    I think it's not just the meat that gets damaged like that--any un-burst tomato or other veg cells will likely be burst in the crystallization process, and will release any trapped liquid after thawing. At least that's what I've heard. – bikeboy389 Apr 08 '12 at 21:03
  • @Jefromi I'm mainly referring to bolonaise sauce. – rgvcorley Apr 10 '12 at 09:15

3 Answers3

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Sauces separate when frozen for several reasons.

  • If it contains vegetables, the plant cells rupture when the water in them freezes. This means the sauce gets watery and the taste changes as the contents of the cells escape.
  • With emulsions, the oil/fat microdroplets clump together when they freeze. When you thaw the sauce, the emulsion is wrecked, giving a runny consistency. You can defeat this by re-emulsifying as you thaw the sauce. See How can I prevent bacon mayonnaise from splitting when above fridge temperature?
  • Due to colligative properties, areas of less concentrated solution will freeze first, and more concentrated solution freeze last. As the solution gradually freezes, this has the effect of concentrating dissolved thickening agents in the last regions to freeze. When the solution thaws, the thickener isn't as evenly mixed.
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BobMcGee
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Some thickeners loose their ability to thicken if frozen. Wheat flour and cornstarch both have problems with freezing after used as thickenters.

Tapioca, arrowroot, rice flour and xanthan gum don't suffer from this problem.

Joe
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  • thanks for the response - I don't actually use any thickening agent in the sauce apart from a bit of tomatoe puree, however thanks for the link that may well come in handy! – rgvcorley Apr 10 '12 at 09:16
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The water and fat separate out when it freezes. This should just stir back in when it's reheated fine without affecting the thickness of the fully heated sauce.

Water could be getting into your food in the freezer though. If you have a large quantity of ice on the top when you remove things from the freezer then you should remove that before defrosting and look at using better sealed containers. You might also need to defrost your freezer.

vwiggins
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