Amazing Discovery - Butter Tempers Tomato Sauce

I was watching America's Test Kitchen this weekend, and they put butter into a slightly acid sauce to bind it and to reduce the acidity. I wish they'd said why butter can do that.

It's something I've been wondering about for years. Way back in college I discovered that putting a pat of butter, on top of the tomato sauce, on top of my pasta made it much less acid. I have no recollection, now, why I would have done such a thing, but I did. For most people this would not necessarily be a good thing, but I get a rash if I eat too much acid food. I'm not giving up my pickles and hot sauce, so the tomato sauce gets buttered. I've done that for years every time I eat tomato sauce at home. :G: And I'm still wondering why it works that way.

Anyone have a clue?