Maize, or Indian Corn, is deficient in gluten, and so not suitable for making vesiculated bread. Like oatmeal, it is made into cakes, called in America “Johnny cake.” It contains much fatty matter, and is largely used for fattening poultry and other animals. Oswego flour and corn flour are maize flour deprived by a weak solution of soda, of its proteids and fat; hominy contains all its constituents. Maize is a cheap and nutritious food. When wheat flour is dear, it is occasionally adulterated with maize. The adulteration can be detected by the forms of the starch granules, examined under a low power of the microscope.
Rice contains less proteids and fat than any other cereal. Its chief value as a food depends on the large amount of starch it contains (table, page [16]).
Leguminous Foods.—The chief seeds belonging to this group are peas, beans, and lentils. They contain a smaller proportion of starch, and a larger proportion of nitrogenous materials than cereals. Thus while flour contains 9.5 and bread 8 per cent. of proteid, lean meat 15.18 per cent., and cheese about 30 per cent., peas and beans contain 21 to 26 per cent. (green peas only 4 per cent., dried peas 21 per cent.) of proteid. The nitrogenous material exists chiefly as legumin, which has been called vegetable casein. Although leguminous seeds contain more nutritive material in a given weight than cereals, dietetically they are inferior, owing to the fact that they are less digestible, often causing flatulence and other dyspeptic symptoms. Cereals, again, are more palatable than leguminous seeds, and are more prolific, and consequently cheaper. In the absence of animal food, legumens form a useful substitute. They are advantageously diluted with oily substances, or with rice. The farm-labourer’s dish of broad beans and fat bacon is founded on strict physiological principles. A mixture of lentil and barley flour is sold under the name of Revalenta Arabica. Lentil flour costs 2½d., Revalenta 3s. 6d. per lb. Green peas, French beans, and scarlet runners are much more easily digested than are dried peas or beans. Lentils contain the largest proportion of proteid of any of the pulses. They also contain very little sulphur, and so do not give rise to the same liberation of sulphuretted hydrogen in the intestine, as other pulses. The ash of the Egyptian lentil is particularly rich in iron.
Amylaceous Foods. Amylaceous or starchy substances are contained in many of the preceding foods; but some other foods consist almost entirely of starch. The chief of these are sago, tapioca, and arrowroot.
Sago is obtained from the pith of the stems of various species of palm; a single tree may yield several hundred pounds. Alone it is easy of digestion. Boiled with milk it forms a light, nutritious, and non-irritating food. Fictitious sagos are frequently sold, made from potato starch.
Tapioca and Cassava are derived from the tubers of more than one species of the poisonous family, Euphorbiaceæ. The juices are removed, and the prussic acid removed by heat. Tapioca only differs from cassava in being a purer form of starch; the latter is more nutritious, and among the Indians takes the place of bread.
Arrowroot is obtained from the tubers of Maranta Arundinacea.
Tous-les-mois is a form of starch obtained from the tubers of a West Indian plant, the Canna edulis.
Fig. 1.—Different Forms of Starch Granules.
Potato. Wheat. Rice.
Oats. Barley. Pea.