BREAD 187 



better than those produced from the same mixture baked soon 

 after the mixing is done. Such loaves weighing 2 lb. measure 

 say 1,200 c.c, have a peculiarly sour, but not unpleasant, taste, 

 and smell like cake. A man travelling in the bush would find 

 this form of fermentation very much better than none at all. 



There have been many attempts to obtain a satisfactory 

 aeration of loaves without the use of yeast. Yeast itself is not 

 inexpensive, and there is this further point about its use which 

 adds to the expense. When " sown " in a favourable " soil " the 

 plant grows amazingly, and yields as a result of its growth 

 the gas carbon dioxide, the best of known bread aerators, and 

 alcohol. But " out of nothing nothing comes," and the yeast 

 lives on the "soil" or, to be precise, on those elements of the 

 " soil " which it can assimilate. This means that the yeast 

 absorbs and converts into those products, the greater part 

 of which is lost to the baker, a substantial proportion of the 

 ' flour, say 2 per cent. — a large amount in the course of a year. 

 But none of the substitutes for yeast are satisfactory, though 

 they do not use up for bread-making purposes any of the flour 

 itself. One gas-producing combination used was hydrochloric 

 acid and bicarbonate of soda, yielding carbon dioxide, the good 

 aerator, and salt, the necessary condiment. But the process 

 is bad for two principal reasons : one, that commercial hydro- 

 chloric acid often contains arsenic ; the other, that the gas 

 generated is evolved very rapidly — so rapidly that the difficulty 

 of retaining it in the dough, always a great one, is very much 

 intensified. The second of these two objections can be raised 

 against any form of baking-powder aeration. To minimise it, 

 small quantities of flour and water can be used; but that provides 

 its own condemnation in the estimation of the baker, and in any 

 case a far larger proportion of the gas generated can be retained 

 by the dough if evolved in the slow and comparatively regular 

 way of yeast fermentation. 



The most successful of all the alternative methods of aeration 

 is the Dauglish process, used for the production of aerated 

 bread. Everybody is acquainted with aerated water as a 

 beverage, and the gas which bubbles out of it when an outlet 

 is provided. The essential idea of the Dauglish process, which 

 has been modified in details since its introduction, is the 

 mechanical kneading of the proper proportions of flour, salt, 

 and water under a pressure of from 7 to 14 atmospheres of 



