Oats contain considerable fat, protein, salts, and indigestible cellulose, in addition to a large percentage of starch. They have been eaten in Germany for over a thousand years, and constituted the original grain food for all Europe.

Oatmeal is much less used than other cereals for bread because it lacks gluten, although it is still so employed to a limited extent among the poorer classes in France. It makes a dark, bitter bread, but forms a better porridge than can be obtained from rice or barley. The use of oatmeal porridge by all classes is very extensive throughout the United States. This is largely attributable to the improved methods of its preparation by high milling, rolling, etc. Scotch groats are prepared by removing the outer husk, leaving the grain almost whole. The grain is then reground between closer set millstones. It forms two grades of meal, the coarser of which is used for porridge and the finer to make bannocks or oatmeal cakes. A good deal of the oatmeal sold in America is identical with Scotch groats. True Scotch groats are heated by the miller over perforated iron plates and slightly parched for three or four hours before being ground. For those who can digest oatmeal well, it ranks among the cheapest and most satisfying of foods.

The nutritious value of oatmeal is great, but it depends very largely upon the skill with which it is cooked. It is not infrequently cooked in such a manner that the individual grains are left whole, but in this form the flavour is less well developed than it is by prolonged cooking; the oatmeal granules are much more difficult of digestion, and are capable of exciting gastro-intestinal irritation in feeble persons. But for many people oatmeal thus cooked possesses a decided advantage from the fact that it is less completely absorbed, leaving a considerable residue which adds to the bulk of fecal matter, excites peristaltic action, and reduces the liability to constipation. For most persons, however, and especially for all those with limited digestive power, oatmeal should be so thoroughly cooked as to acquire the consistence which enables it to be easily poured, and on cooling it should form a tender, gelatinous mass.

Oatmeal is a very hearty food, and those who eat much of it should live a vigorous outdoor life. If ill-cooked and if given to very young children, it occasions colic, flatulence, and rashes.

It is best when of recent crop and freshly ground. If it is kept long it absorbs moisture, and, losing its delicate flavour, becomes mouldy and sour.

The following analysis of oatmeal is given by Letheby:

Nitrogenous matter................................. 12.6 per cent.

Carbohydrates, starch, etc........................... 63.8 "

Fattymatter....................................... 5.6 "

Mineral matter..................................... 3.0 "

Water............................................ 15.0 "

Total......................................... 100.0 "

Oatmeal, like cornmeal, has more protein and fat than the flours and meals derived from other cerealia, and hence, like bread, it may be eaten daily without impairing the appetite.

Revalenta, or revalenta Arabica, is a farinaceous food much eaten in some parts of Europe, which is a mixture of several meals, principally ground peas, beans, corn, and lentils, but barley and oatmeal may be included.