I just had some of my mom’s leftover spaghetti, and I realized that it always has a slightly more bitter taste in the morning after being reheated. What causes this kind of reaction?

Question

It happens both when stored in pyrex or tupperware.
Ingredients aren’t anything unusual; onions, garlic, hamburger, tomato paste, etc.
Tastes sweeter when fresh off of the stove, but has a more bitter taste when reheated as leftovers.

In: 159

Answer 1

More onion, cooked slowly to bring the sugars out, will help lessen acidity in tomato sauces.