Scarcely any of the various alimentary substances employed by man are consumed in the raw and crude state in which they are presented to us by nature. Almost all of them are previously subjected to some kind of preparation, or change, by which for the most part they are rendered more wholesome and more digestible, and sometimes more nutritive. Accordingly, the observations we have made on the properties of different vegetable aliments, are to be considered as applied to them in the state in which they are commonly used among us.
When in the preparation of bread a baking heat is applied to the flour dough, a complete change is produced in the constitution of the mass. The new substance of bread differs materially from flour, it no longer forms a tenacious mass with water, nor can starch and gluten be any more separated from it.
By the application of heat to vegetables the more volatile and watery parts are in some cases dissipated. The different principles, according to their peculiar properties, are extracted, softened, dissolved, or coagulated; but most commonly they are changed into new combinations, so as to be no longer distinguishable by the forms and chemical properties which they originally possessed.
In like manner the leguminous seeds, and farinaceous roots are greatly altered by the chemical action of heat. The raw potatoe is ill-flavoured, extremely indigestible, and even unwholesome. By roasting, or boiling, it becomes farinaceous, sweet, and agreeable to the taste, wholesome, digestible, and highly nutritious. Little is lost, and nothing is added to the potatoe by this process, yet its properties are greatly changed; its principles, in short, have suffered very remarkable chemical changes.
Even in the simple boiling of the various leguminous seeds, pot-herbs, and esculent roots, the effect does not seem confined to the mere softening of the fibres, the solution of some, and coagulation of other of their juices and principles; not only their texture, but their flavour, and other sensible qualities have undergone a change, by which their alimentary properties have been improved; the farinaceous matter by boiling is rendered soluble, the vegetable fibre softened. Saccharine matter is often formed, mucilage and jelly extracted and combined, and the product is rendered more palatable, wholesome, and nourishing. And, although every country has its own favourite articles of food, and modes of preparing them, and there is perhaps no subject in regard to which local prejudices are so strong, yet there can be no reason why the farinaceous matter of cereal seeds should always be consumed in the state of bread; many of them are not less agreeable, and not less wholesome in other forms of food.
In Scotland nine-tenths of those in the more humble walks of life live upon barleybroth, and there are not more healthy people to be found any where.—Cullen’s Materia Medica, v. I. p. 287.
It is chiefly to save the trouble of dressing any other kind of food, and that bread, from its portability and convenience of always being ready, has become the principal sustenance, but it is far from being the most economical method of using farinaceous grain. There can be no doubt that the same quantity of farinaceous matter made into bread might, in other forms, be used to a much greater advantage; for the great art of preparing good and wholesome food is to convert the alimentary matter into such a substance as to fill up the stomach and alimentary canal without overcharging it with more nutritive matter than is requisite for the support of the animal, and this may be done either by bread, or by converting the mealy substance of which it is composed into other forms, of which there is a great variety.
Persons who have travelled much on the continent are well aware that our neighbours have the art of throwing much more variety and gratification of the palate into the article of subsistence which has been emphatically called the staff of life, than we possess. The French and Germans convert the farinaceous flour of vegetables into a variety of excellent articles of food, and not serving, like our own, as a mere companion to pair off with so many mouthfuls of meat.
In speaking thus of the use of bread, I do not mean to deny that bread is highly alimentary, its nourishing powers are undoubtedly very great.
The finest bread, says an eminent physician (Dr. Buchan), is not always the best adapted for answering the purposes of nutrition. Household bread, which is made by grinding the whole grain, and only separating the coarse bran, is, without doubt, the most wholesome.