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What is the foam on my tomato sauce

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I have a big pot of fresh tomato sauce simmering on the stove right now - trying to reduce it down to make a thick pasta sauce. There is a pale pink foamy like substance coming out of the sauce and floating on the top. It doesn't look like fat or oil, just pink foam. What is it, and should I skim it off?

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  1. I hope it's not soap left from last washing. I never saw this in my sauce ever. How did it taste (if you tried it) ?

    1. It's air...fresh tomatoes have a lot of air in them. When you cook it down, it lets the air off. YOu can skim it off, and also a little bit of oil wil disperse it too. No worries. It won't hurt you - it's just asthetics. If you cook it long enough it will go away.

      1. Tomatoes do have a little protein in them, about 2g per cup of raw tomato. Proteins often produce a "scum" when heated in liquid. It is possible that you are seeing this protein foam as you reduce from the bubbles capturing these protein compounds and carry them to the surface. Like the foam at the sea shore.