You can keep cooked vegetables in a covered container for three to five days. Many cooked vegetables can also be frozen. Seal the cooked vegetables airtight in a plastic bag or a rigid container and freeze. Fully cooked vegetables can be kept ten to twelve months at 0 degrees Fahrenheit.

Freezing cheese is possible, but not without some sacrifice of quality. After freezing, cheese is mealy, brittle, and difficult to slice, but if it is not frozen for too long, it is perfectly good for cooking.

Eggs can be stored in the refrigerator four to five weeks after purchase, as long as they are clean and unbroken.

If it is stored in a tightly lidded container, it will last up to six months. Don't expose baking powder to steam, humid air, wet spoons or any other moisture. Even bone-dry baking powder eventually loses its potency. To test its strength, measure 1 teaspoon powder into 1/3 cup hot water. The mixture should fizz and bubble furiously. If it doesn't, throw the baking powder out.

Unopened bottles of ketchup can be stored up to one year on a cool, dry, dark shelf. You can store opened bottles, tightly lidded, on the shelf up to about one month. For longer storage, keep them in the refrigerator.