Fruits are composed largely of water, with starches, a vegetable jelly, pectin, cellulose and organic acids. The most important acids in fruit are citric, malic and tartaric. Citric acid is found in lemons, limes and oranges; tartaric acid in grapes; malic acid in apples, pears, peaches, apricots, gooseberries and currants. Among the least acid are peaches, sweet apples, bananas and prunes. Strawberries are moderately acid, while lemons and currants contain the most acid of all.
(1) To furnish nutriment; (2) to convey water to the system and relieve thirst; (3) to introduce various mineral matter (salts) and acids which improve the quality of the blood; (4) as anti-scorbutics; (5) as laxatives and cathartics; (6) to stimulate the appetite, improve digestion and provide variety in the diet. Apples, lemons and oranges are especially valuable for the potash salts, lime and magnesia they contain. Fruit as a common article of daily diet is highly beneficial, and should be used freely in season. Cooked fruit is more easily digested than raw, and when over-ripe should always be cooked in order to prevent fruit poisoning.