(a) The Cereals, from Ceres goddess of corn, comprise all grains or corn-bearing plants. They are really grasses cultivated so as to develop the maximum of food material with a minimum of husk - the growth of millet, lentils, and barley being prehistoric in origin. In geographical distribution they extend over the whole globe - sorghum and millet growing at the tropics, while barley, oats, and rye are grown in the extreme north of Europe. The seeds dry easily, and can be stored and shipped without loss. They contain from 5 to 14 per cent, nitrogenous matters, chiefly in the form of gluten, while the bulk of the grain consists of starch, the whole enclosed in a covering of cellulose. The proportion of fat varies in different members of the group. It is interesting to note that it tends to be most abundant in those cereals which grow in the temperate or cold zones, e.g., oats, whereas in cereals of tropical growth, e.g. rice, there is hardly any present Wheat and rye, owing to peculiarities in their gluten, are the only ones suitable for breadmaking, but all of them can be made into cakes, porridge, puddings, or soup.
The process of grinding first removes the outer coats of cellulose, and an unbroken meal or flour is obtained. The gluten lies next the outer surface. The salts in grains amount to about 2 per cent. This amount depends largely on the kind of soil and manure employed - they consist chiefly of phosphates of soda and potash, with lime and magnesia, and a little silica and iron. The organic salts are almost absent.
The average composition of cereals is as follows: -
10 to 12 per cent.
10 to 12 „
65 to 75 „
1/2 to 8 „
The average composition of the more important individual cereals may be taken as follows: -
Oats, hulled .
Rice in the husk, paddy
Parkes gives the following order of merit of the common grains, in respect of proximate principles: -
The cereals contain a great excess of carbohydrate, and mankind has instinctively added fat and protein; so that we eat butter with bread, milk with porridge, and make cereal puddings up with eggs and milk.
The first place among the cereals must be assigned to wheat - it is estimated that 6 bushels per head each year are consumed. There are two varieties, summer and winter wheat. The following is the average composition: -
Higher in Italian and Russian wheat.
Varying from 60 to go per cent.
Chiefly phosphates of potash, magnesia, with lime, soda, and silica in small quantity.
Russian wheat is richer in nitrogenous matters, ranging up to 2\\ per cent. The hard Italian and Hungarian wheats are also rich in nitrogenous matters, containing soluble albumin as gluten. In order to transform wheat grains into a useful domestic substance, the grains have to undergo the process of grinding or milling. It is necessary, in order to follow the processes of grinding, to have some knowledge of the different parts of the wheat grain. These are: -
1. The husk, or cuticle.
2. Kernel, or food supply.
3. Germ, or young plant.
The husk consists of three layers, consisting mainly of cellulose with some pigment. When the wheat is decorticated the product is known as bran. Wheat-bran contains about 15 per cent, nitrogen, 35 per cent, of fatty matter, and 6 to 7 per cent, mineral matter, mainly phosphates; all of which materials should be nutritious, but very little bran can be absorbed, and it is irritating except to patients with a robust digestion. The kernel or endosperm: this consists of the nutritive material for the young embryo, and makes up 85 per cent, of the grain. Microscopically it is found to consist of a honeycomb of cellulose, into which is packed starch cells and gluten granules. Gluten is a mixture of proteins, viz., gliadin and glutenin, which have the peculiar property of becoming viscid when mixed with water. This important feature will be mentioned again under Bread-making. The relative proportions of starch and gluten differ in different kinds of wheat It may be said that the hard, translucent, horny grains are rich in gluten, while those that are soft, opaque, and floury on section are rich in starch.
The germ or young plant represents 1 1/2 per cent, of the whole grain. This is very rich in nitrogen and fat. The germ in removed as well as the bran in the preparation of flour, for the following reasons: - The abundant supply of fat in the germ may become rancid, and so spoil the flour, and the soluble proteins present are apt to act on the starch of the flour, converting part of it into soluble forms (dextrose and sugar), which darken in colour in the oven and detract from the appearance of the cooked flour.
Thus, in the process of milling to which the wheat is subjected, its different parts are broken up and various mill products are produced. The outer coats yields bran, fine pollards, sharps, and middlings; the germ is removed as offal, while the flour is derived solely from the kernel.
Flour, according to the amount of grinding, is yellowish white, from the presence of gluten; or pure white, in which case it is likely to contain little except starch. Good flour should have a pleasant smell, and should have no acid or rancid taste. It should not contain more than 15.2 per cent, water. The flour itself is classified and divided into two parts: the larger part, known as "bakers" or "household," and a smaller portion, very white in colour, and therefore poor in proteins, known as "patents"; from the latter, genuine Vienna bread is made, and also the best class of fancy breads and pastry.
The "bakers" or "household" flours are still further divided, but as they are again blended before being sold, it is not necessary to follow the commercial terms.
By removing the germ and the bran, the most useful constituents of the wheat are lost, viz., germ protein and fat, and the bran minerals and protein matter. Whole wheaten meal baked is more nutritious, much better flavoured, but is apt to be irritating on account of the indigestible outer coat, consisting of cellulose and silica, etc., and while it is useful as a laxative its use has not become general.
Other flours are obtainable where only the two outer layers of the husk are removed. Bread made from these is not nearly so indigestible as bread made from whole wheaten meal.
Two patent processes have also been devised to prevent the waste. Smith's patent takes the separated germ and partially cooks it by means of superheated steam. This kills the ferment, which otherwise acts on the starch and at the same time sterilises the fat, and so prevents it becoming rancid. The germ so heated is ground to a fine meal, and of this one part is added to three of ordinary flour, and the mixture is known as Hovis flour. It is much richer in protein and fat than ordinary' flour. There are now several germ breads in the market, in all of which the germ is treated much along these lines. The Frame food process treats the bran. The bran is boiled under high pressure, the mineral matters and part of the nitrogen are recovered. The watery extract is filtered and evaporated to dryness. This is Frame food extract. This extract forms the basis of preparations prepared by the Frame Food Manufacturing Company.
This brings us now to the cooking of flour, or bread-making; but before taking up this point, I would direct special attention to the present-day methods, largely in vogue, of artificially bleaching flour. This is really a form of adulteration.