Farinaceous foods are composed of flour of different kinds, and constitute a subdivision of starchy foods. The different starchy and farinaceous foods are derived from a variety of plant structures, including roots, tubers, bulbs, stems, pith, flowers, seeds, fleshy fruits, etc. Some, like the banana and certain vegetables, are eaten raw, but the majority require cooking, and the starches derived from grain-bearing plants of the grass tribe or cerealia usually must be prepared by grinding and milling before cooking. About one sixth of the protein of the various grain flours passes through the alimentary canal undigested.

The following table by Professor Atwater will be found useful in giving at a glance the average percentage of starch contained in the commonest vegetable foods:

Atwaters Table Of The Percentage Of Starch In Vegetable Foods

Wheat bread.....................55.5

Wheat flour...................... 75.6

Graham flour..................... 71.8

Rye flour........................ 78.7

Buckwheat flour.................. 77.6

Beans........................... 57.4

Oatmeal.........................68.1

Cornmeal........................ 71.0

Rice............................ 79.4

Potatoes......................... 21.3

Sweet potatoes................... 21.1

Turnips......................... 6.9

Carrots.......................... 10.1

Cabbage......................... 6.2

Melons.......................... 2.5

Apples.......................... 14.3

Pears........................... 16.3

Bananas......................... 23.3

In round numbers it may be stated that starch composes one fifth of potatoes, one half of peas, beans, wheat, rye, and oats (their flours contain more), and three fourths of rice and Indian corn.

In addition to the cooking which the cerealia require, they are often predigested by diastase for invalid use. Strong heat converts starch to dextrin; but diastase, like the natural digestive ferments, can convert it into maltose, and as such it is fitted for absorption.

Fortified gruels, as they are called by Roberts, are made of cereal flours or dried legumes, with addition of milk, beef tea, or eggs. The flours if used alone, in strength of 5 per cent, become pasty and taste insipid, but if one eighth of their weight of ground malt be added they remain fluid with 20 per cent of flour, and, as this starch is largely dextrinised, they are highly nutritious. Thus made, Roberts says they contain 2 per cent of proteid and 14 per cent of carbohydrates.