Nature's spring supply of fresh food begins with early green vegetables, as lettuce and radishes. These are followed by young starchy vegetables, as beans, and later by such as mature late, both starchy and green, as potatoes and tomatoes. The season for fruits opens with early berries and ends with late apples. Using fresh foods as they become abundant secures the best food-supply, also the most economical.

Some such foods are necessary at other seasons. This need is met by storing or preserving them for out-of-season use or by transporting them from other climates where they grow at other seasons. Foods that contain starch keep well because starch is stable, that is, not easily changed. It is because starch does not readily change that it is indigestible raw. Foods to be eaten raw must contain little or no starch; lacking this stable substance, they keep less well.

Green fruits contain much starch. The plant as fruit matures has the power to change starch to sugar. As fruit decays or fruit-juice ferments, sugar is changed further and alcohol is formed. This is the process of wine-production from grapes that are themselves 1/3 to 1/2 sugar. Cider is thus derived from apples that are 1/20 to 1/7 sugar.

To have fruits fresh for out-of-season use they must be transported or stored. Bacteria usually are the foes of food. Low temperature delays or destroys bacterial growth. Temperature lowered sufficiently to da this, but not so low as to freeze the fruit, preserves fruit palatably during transportation or for six months of storage for reserved use. It is thus fresh fruit is made available throughout the year, but at high cost out-of-season.

Fruits are dried and preserved by cooking for deferred use. Drying deprives fruit of moisture until desired for use. Returning water to it revives it and its flavor somewhat.