Fruits.
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.