Foods can be classified as perishable, semi-perishable, and non-perishable. Perishable foods are those that spoil easily unless there is some means of preserving them. Milk, meat, fish, and juicy foods like mangoes and tomatoes are perishable. Semi-perishable foods keep for a limited time. They do not spoil readily and can be kept for several months by common storage methods. Foods of this class are mature potatoes, beets, carrots, and garlic. The non-perishable foods are foods which can be stored for an indefinite length of time. These include rice, oatmeal, dried beans, such as mongo, and bulgur wheat.
Perishable foods keep best at low temperature usually just above the freezing point. However, if refrigeration is not available, then these foods should be bought only as needed. The semi-perishable foods are best kept in a dark, dry, cool place. A dry atmosphere keeps bacteria and other microorganisms from growing, while the low temperature and exclusion of light prevents growth among such foods as potatoes and onions. Non-perishable foods should be stored in dry, airtight containers so that bugs and insects cannot get in.