Starch Changes to Sugar. The carbohy¬ drates undergo important changes during rip¬ ening. Special enzymes change any starch present to the more flavorful sugars. The best example of this is the change in the banana during ripening. (See Table XII.) Bananas are fairly high in carbohydrate con¬ tent. In the green banana the carbohydrate is largely in the form of starch. As the banana ripens this starch changes to sugar. The quality of bananas seems best when the fruit is picked green and ripened under con¬ trolled conditions. Bananas should always be held at temperatures above 58° F. They are ripened for the market at a temperature between 70° and 7 5° F. When they must be held after ripening, the temperature is reduced to 60°-65° F. to prevent undue drying out. Similar carbohydrate changes take place in other starch-containing fruits. Other Changes. In most fruits the changes in texture are important. These also are brought about by the action of enzymes present in the fruit. These changes in texture Knell from U.S.D.A. Firm but Ripe • Peaches are among the fruits that are highest in quality when tree-ripened. To reach the market in best condition, they must be picked at just the right stage also may be retarded by cool storage and stimulated by placing the fruit in a warm place. There is an apparent decrease in acid during the ripening of fruits. In some cases, however, the acid content is actually in¬ creased, but this fact is hidden by the in¬ creased sugar content. In other fruits the acid becomes more dilute since the pulp takes up water from the peel as the fruit ripens. There are present in mostv fruits small amounts of complex carbohydrates to which the general term pectins has been applied. These are the substances responsible for the formation of jellies from acid fruit juices Table XII • Stage Per Cent Whole Water Solids Reducing Sugar Sucrose Total Sugar Starch Composition Fruit Invert of Banana Pulp Per cent Per cent Per cent Per cent Per cent Per cent Per cent at Different Stages of Ripening Green . 58.95 72.29 27.71 .53 .41 .94 22.26 Ripe . 62.12 72.16 27.84 11.54 5.39 16.93 6.34 Very ripe .... 68.14 75.50 24.50 12.59 5.98 18.57 .82 [47] cooked with sugar. Since the amount of pectin decreases as the fruit ripens, overripe fruit may not have sufficient pectin to make a satisfactory jelly. The proteins, fats, and ash in fruits un¬ dergo little change during the ripening process. The flavor of the fruit is contributed by certain essential oils, other volatile com¬ pounds, and salts of organic acids, as well as the sugars. During ripening the essential oils and the volatile flavoring substances are de¬ veloped. These are complicated chemical compounds that vary with the kind of fruit, and with the variety. They are unstable and break down if ripening continues too long. In general, the vitamin content of fruits seems to increase as the fruit ripens. Nat¬ urally ripened fruits are slightly superior in vitamin content to those ripened after picking.

AI-modernized reading of the original text

Starch Changes to Sugar. The carbohy¬ drates undergo important changes during rip¬ ening. Special enzymes change any starch present to the more flavorful sugars. The best example of this is the change in the banana during ripening. (See Table XII.) Bananas are fairly high in carbohydrate con¬ tent. In the green banana the carbohydrate is largely in the form of starch. As the banana ripens this starch changes to sugar. The quality of bananas seems best when the fruit is picked green and ripened under con¬ trolled conditions. Bananas should always be held at temperatures above 58° F. They are ripened for the market at a temperature between 70° and 7 5° F. When they must be held after ripening, the temperature is reduced to 60°-65° F. to prevent undue drying out. Similar carbohydrate changes take place in other starch-containing fruits. Other Changes. In most fruits the changes in texture are important. These also are brought about by the action of enzymes present in the fruit. These changes in texture Knell from U.S.D.A. Firm but Ripe • Peaches are among the fruits that are highest in quality when tree-ripened. To reach the market in best condition, they must be picked at just the right stage also may be retarded by cool storage and stimulated by placing the fruit in a warm place. There is an apparent decrease in acid during the ripening of fruits. In some cases, however, the acid content is actually in¬ creased, but this fact is hidden by the in¬ creased sugar content. In other fruits the acid becomes more dilute since the pulp takes up water from the peel as the fruit ripens. There are present in most fruits small amounts of complex carbohydrates to which the general term pectins has been applied. These are the substances responsible for the formation of jellies from acid fruit juices Table XII • Stage Per Cent Whole Water Solids Reducing Sugar Sucrose Total Sugar Starch Composition Fruit Invert of Banana Pulp Per cent Per cent Per cent Per cent Per cent Per cent Per cent at Different Stages of Ripening Green . 58.95 72.29 27.71 .53 .41 .94 22.26 Ripe . 62.12 72.16 27.84 11.54 5.39 16.93 6.34 Very ripe .... 68.14 75.50 24.50 12.59 5.98 18.57 .82 [47] cooked with sugar. Since the amount of pectin decreases as the fruit ripens, overripe fruit may not have sufficient pectin to make a satisfactory jelly. The proteins, fats, and ash in fruits un¬ dergo little change during the ripening process. The flavor of the fruit is contributed by certain essential oils, other volatile com¬ pounds, and salts of organic acids, as well as the sugars. During ripening the essential oils and the volatile flavoring substances are de¬ veloped. These are complicated chemical compounds that vary with the kind of fruit, and with the variety. They are unstable and break down if ripening continues too long. In general, the vitamin content of fruits seems to increase as the fruit ripens. Nat¬ urally ripened fruits are slightly superior in vitamin content to those ripened after picking.

Foods, their selection and preparation