BREAD is a light porous spongy sub stance, prepared by fermentation and baking from the flour of certain farina ceous seeds, especially wheat, and is the principal sustenance of man in the tem perate regions of the northern hemi sphere.
When flour is kneaded with water, it forms a tough paste, called dough, if kept in a warm place, swells, becomes spongy, and filled with a number of air bubbles : in this state it is called leaven : and this leaven, if incorporated with fresh dough, will bring the whole into a fer menting state much more speedily and uniformly, than if the mass was exposed to spontaneous decomposition. But though leavened bread is perfect in every other respect, it always retains a slightly acidu lous flavour from the leaven by which it is fermented ; for it is impossible to carry the fermentation of the gluten to a suffi cient extent to change it into leaven, without at the same time exciting the acid fermentation in the sugar of the flour. It was therefore a very important improve ment in the art, and one which is attribut able to the English bakers, to substitute yeast, or the froth of malt liquor in a state of fermentation, to leaven ; for the former not only communicates no unplea sant flavour to bread, but is also a more speedy ferment, and by acting first on the gluten of the flour produces the desired effect, before any acid has time to be evolved from The other ingredients. The process of making common bread is ex tremely simple, though its perfect success depends considerably on a kind of knack in manipulation which cannot be describ ed by words. It is of essential conse quence, that the flour and yeast should be mixed together with perfect accuracy, in order that the whole mass may be equally fermented, and that this action may com mence in every part at the same time.
Now, though in the making of a single loafthis may easily be effected at one con tinued process, yet, where a considerable quantity of bread is to be made at once, this is impracticable. See BAKING.
The changes produced upon dough by baking are very remarkable, nor can they in any degree be attributed to evapora tion, since the loss of weight never ought to exceed and is very often not great. er than A. In the first place, the pro gress of fermentation is entirely stopped: the bread may be kept for several days without experiencing any alteration, and the first sign of spontaneous change is its becoming mouldy. Secondly, the tena cious ductility of the dough and its com pact texture are exchanged for a mode rately firm and slightly elastic consist ence, and a very spongy texture, in con sequence of the alterations produced in the gluten by heat and moisture. Third ly, th e fecula, or starch, Nvhich was merely diffused through the dough, without be ing in any degree affected by the panary fermentation, is combined during the bak ing with a portion of water into a stiff jelly, like common starch when boiled with water, and thus renders the bread considerablymore transparent than dough, as well as more digestible. Rye and bar ley are the only substances, besides wheat, that are capable of being made into bread, because they alone contain gluten enough to admit of being formed into a moderate ly tenacious paste with water. Even in these, hOwever, the proportion of gluten is too small to afford light bread without the use of an acid ferment, to disengage the proper quantity of carbonic acid ; so that they can never, for the purpose of the baker, be at all comparable to wheat en flour.