Custards and cream pies soak into the crust. Meringue on meringue pies toughens and sticks to the wrapper. Milk sauces sometimes curdle and separate. Stirring while reheating helps keep them smooth. Using waxy rice flour or waxy corn flour as the thickener also helps.
Gravy tends to separate and curdle when thawed.
It is better to freeze broth and make gravy just before serving. Or use waxy rice flour or waxy corn flour as the thickener. Cooked, creamed vegetables tend to lose flavor rapidly and should only be stored for a few days. Lettuce, other greens and raw tomatoes lose crispness and become soggy. Ham and other cured meats may lose color when frozen and become rancid more quickly than other meats.