480 BREAD 



known, a frothy, thickish material, of a brownish or drab colour, which, when recent, 

 is in a state of slight effervescence, exhales a sour characteristic odour, and has an 

 acid reaction. 



When viewed through the microscope, it is seen to consist of small globules of vari- 

 ous size, generally egg-shaped. They were first described by M. Desmayieros. 



The best, and in fact the only, brewers' yeast used in broad-making is that from the 

 ale breweries ; porter yeast is unavailable for the purpose, because it imparts to the 

 bread a disagreeable bitter taste. 



German yeast is very extensively used by bakers. It is a pasty but easily crumbled 

 mass, of an agreeable fruity odour, and of a dingy white colour. German yeast will 

 remain good for a few weeks, if kept in a cool place. When in good condition, it is an 

 excellent article ; but samples of it are occasionally seized on bakers' premises, of a 

 darker colour, viscid, and emitting an offensive cheesy odour : such Gorman yeast, 

 being in a putrefied state, is, of course, objectionable. 



The so-called 'patent yeast' is tho cheapest and at the same time the weakest of 

 these ferments ; very good bread, however, is made with it, and it is most extensively 

 used by bakers. It is made either with or without hops: when with hops, it is 

 called hop yeast, and is nothing more than a decoction of hops to which malt is added 

 while _ in a scalding hot state ; when tho liquor has fallen to a blood heat, a certain 

 quantity of brewers' or German yeast is thoroughly mixed with it, and the whole !; 

 left at rest. Tho use of the hops is intended to diminish the tendency of this solution 

 to become acid. 



Potato yeast is a kind of 'patent yeast ' in general use. See YEAST. 



Tho theory of panification is not difficult of comprehension. ' Tho flour,' says 

 Dr. Ure, 'owes this valuable quality to the gluten, which it contains in greater 

 abundance than any of the other cerealia (kinds of corn). This substance does not 

 constitute, as has been heretofore imagined, the membranes of the tissue of the 

 perisperm of the wheat ; but is enclosed in cells of that tissue under tho epidermic 

 coats, even to the centre of the grain. In this respect tho gluten lies in a situation 

 analogous to that of the starch, and of most of the immediate principles of the vege- 

 tables. The other immediate principles which play a part in panification are par- 

 ticularly the starch and the sugar ; and they all operate as follows: 



' The diffusion of the flour through the water hydrates the starch, and dissolves the 

 sugar, the albumen, and some other soluble matters. The kneading of tho dough, by 

 completing these reactions through a more intimate union, favours also tho fer- 

 mentation of the sugar, by bringing its particles into close contact with those of the 

 leaven or yeast ; and the drawing out and laminating the dough softens and stratifies it, 

 introducing at the same time oxygen to aid the fermentation. Tho dough, when 

 distributed and formed into loaves, is kept some time in a gentle warmth, in the folds 

 of the cloth, pans, &c., a circumstance propitious to the development of their volume 

 by fermentation. The dimensions of all the lumps of dough now gradually enlarge, 

 from the disengagement of carbonic acid in the decomposition of tho sugar, which gas 

 is imprisoned by the glutinous paste. Wero these phenomena to continue too long, 

 the dough would become too vesicular; they must, therefore, be stopped at the 

 proper point of sponginess, by placing tho loaf lumps in the oven. Though this 

 causes a sudden expansion of the enclosed gaseous globules, it puts an end to the fer- 

 mentation, and to their growth ; as also evaporates a portion of tho water. 



' The fermentation of a small dose of sugar is, therefore, essential to true bread making ; 

 but the quantity actually fermented is so small as to be almost inappreciable. It seems 

 probable that in well-made dough the whole carbonic acid that is generated remains in 

 it, amounting to one-half the volume of the loaf itself at its baking temperature, or 

 212 F. It thence results that less than one-hundredth part of the weight of tho flour 

 is all the sugar requisite to produce well-raised bread. 



' Although the rising of the dough is determined by tho carbonic acid resulting from 

 the decomposition of the sugar, produced by tho reaction of the gluten on bydrated 

 or moist flour, considering that the quantity of sugar necessary to produce fer- 

 mentation does not amount, probably, to more than one-hundredth part of the weight 

 of the flour employed, and perhaps to even considerably less than that,, tho saving 

 and economy which are said to accrue to the consumer from tho use of unfermentod 

 bread (which is bread in which the action of yeast is replaced by an artificial evo- 

 lution of carbonic acid, by decomposing bicarbonate of soda with muriatic acid, as wo 

 said before) is therefore much below what it has been estimated (25 per cent. !) by some 

 writers ; and is certainly very far from compensating for tho various and serious 

 drawbacks which are peculiar to that kind of broad, one of which and it is not tho 

 ceast is its indigestibility, notwithstanding all that may have been said to tho 

 contrary. 



' In a pamphlet, entitled, " Instructions for making Unfermonted Broad, by a Phy- 



