How do I keep tomato sauce from staining my plastic storage bowls?

Spray the inside of the bowls with “Pam”. The stuff you spray the skillet with before you fry. That will coat the bowl and prevent the sauce from staining. I has worked for me.

Foods with a lot of sugar or fat get hotter, faster, in the microwave than foods with less.

You can heat the foods more slowly, so that the plastic doesn’t get as hot (opening its pores and accepting stains). Use a lower power setting, and warm for longer — stirring the hot edges into the center more often.

Using the cooking spray helps, too.

Foods that can get super hot –
Tomato sauce
Gravy (fat)
Fruit (like pie filling and baby foods)
Infant formula (fat and sugar)