I bought "Professional Tomato Soup Mix" and it comes out slimy when prepared according to package instructions. Specifically, after 10 minutes cooling, a film forms on the surface. When stirred, the film does not dissolve, and instead separates into slimy clumps, a bit like snot.

I don't know what causes it but I think it's the modified starch.

Ingredients: Potato starch, sugar, tomato puree powder, salt, yeast extract, maltodextrin, palm fat, sunflower oil, glucose syrup, onion powder, citric acid, flavourings, modified starch, pepper, beetroot juice concentrate.


  1. Ensure the product is well mixed before weighing out.
  2. Stir the required amount of soup mix into cold water.
  3. Bring to the boil, while stirring.
  4. Simmer for approximately 4 minutes, whisking occasionally.
  5. For best results, whisk thoroughly before serving.

Is there some sciencey way to prevent this?

1 Answer 1


That's the kind of stuff I call "instant goop".

The only way to deal with it is not let it sit still long enough to skin over - keep whisking every minute, or make it closer to serving time.

Once it skins, you could see if a paper towel will pick it off in almost one piece. Otherwise you'll just have to punch a hole in it, ladle through the hole & try not to get any in the bowl. You're basically fighting a losing battle with it, as the skin will thicken over time.

[btw, in the UK, you wouldn't be allowed to sell that as 'tomato soup'. Even instant 'cup a goop' is more than 50% tomato.]

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