Update: I managed to properly incorporate the gum without any clumping. I used an immersion blendsr (blade attachment) and mixed it with sugar this time, and it helped.

To thicken a home made tomato sauce, I tried added xanthan gum. While the sauce did thicken (too much in fact, it was mucus like), it resulted in little white 'seeds' floating in the sauce, which was visually unappealing.

  1. First, I placed the sauce in a tall metal cup. I placed my immersion blender (with whisk attachment) inside and turned it on.

  2. With the high speed immersion blender whirring inside, I sprinkled xanthan gum inside, bit by bit.

  3. The xanthan gum powder did not mix well and white 'seeds' could be seen floating in the sauce.

Are the 'seeds' a result of the xanthan gum clumping together? What should I do differently to mix it well to avoid this from happening

I should note that the sauce was quite hot (between 160F- 180F) when I added the gum. The sauce also consisted of mainly vinegar, and some sugar.

  • 2
    I seem to recall that either xanthan gum and/or gum arabic need shear to properly emulsify. Try using the blades of your blender instead of the whisk?
    – millimoose
    Aug 29, 2017 at 17:26

2 Answers 2


Kevin's answer is close: a slurry is best, but the mechanism and technique are different than starch based thickeners. With starches, the cells explode when heated, but xanthan gum simply needs to be hydrated, and it can be hydrated at any temperature.

Mix a smaller amount of xanthan gum in water in your metal cup, add water, and blend it with your immersion blender. For your slurry, you're looking for a consistency which is much thicker than your sauce, but still thin enough to be able to stir in fairly easily. Like you said, add too much and you'll end up with a pan of tomato snot. A one percent mixture (1 gram of xanthan gum per 100 grams of liquid, by weight) will be pretty thick, even if the starting liquid is water. A little dab will do ya!

Good luck!

  • Thank you, I will try the slurry. Do I need to let the sauce 'sit' in the fridge for a few hours after mixing, or will the result right after mixing the xanthan gum be it's final texture?
    – user60513
    Aug 29, 2017 at 23:59
  • The immediate result will be the final texture at whatever temperature you serve it.
    – ChefAndy
    Aug 30, 2017 at 1:43

Flour or cornstarch are added to broth to make gravy. The recommended practice here is to mix the thickener with the cold broth and allow the entire mixture to heat together. Adding cornstarch to hot broth will cause clumping because the outside of a clump will gel, trapping any unhydrated starch inside, where it will slowly gel as well into a ball. One way to avoid this when making gravy is to remove some of the thin gravy and allow it to cool. Add the thickener, mix well and incorporate the hydrated starch into the hot mixture.

Your xanthan gum likely behaves in the same manner. If you feel you need to use this procedure in the future, add the thickener to cold liquid and incorporate the slurry into the hot liquid.

  • 1
    I find it dangerous to give advice based on the assumption that "xanthan gum likely behaves in the same manner", because it doesn't. Starch doesn't thicken at all until it has reached its critical temperature, and it also has much less thickening power, so it doesn't clump as easily. I still don't know if it clumps even worse when added to a hot liquid, so it could be that your practical suggestion still has merits, but the assumption behind it is factually wrong.
    – rumtscho
    Aug 29, 2017 at 15:18
  • Indeed. The great thing about xanthan gum is that it doesn't need to be heated to thicken, all it requires is shear force.
    – Stefano
    Aug 29, 2017 at 21:34

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