73 



{Ber. d. deui. chem. Gesell., 8, 679, 1875) has found that diastase in 

 the presence of COj can act upon unboiled starch. 



(d) Enzymes. 



The colloid problems of enzymes have been reviewed in Report II., 

 and but little can be added to this information so far as bread-making 

 is concerned. Those enzymes that have to be considered are principally 

 maltase, diastase, invertase, zymase, and certain proteolytic enzymes 

 that are not easy to identify. 



Of considerable interest to us is the future development of the 

 work of Panzer (Zeitsch. physiol. Chem., 93, 316, 339, 1914) on the 

 activation of carbohydrates. This worker found that dry lactose 

 treated with dry hydrogen chloride and subsequently with ammonia 

 acquires feeble amylolytic power. The same, he states, to be true of 

 starches, dextrins, gum arable, maltose, dextrose, Isevulose, and 

 galactose. (See also Jour. Soc. Chem. Ind., 1908, 389, Ford and 

 Guthrie.) 



II.— Yeast. 



The work of Professor Bayliss in Report II. (p. 117), surveying the 

 existing knowledge of protoplasm, its nature and properties, and of 

 enzymes that regulate the chemical reaction of the living organism, 

 fully covers the experience of the bakery chemist so far as yeast is 

 concerned. The problems are by no means simple, and involve the 

 biological history of Saccharomyces cerevisise {see Lafar, " Technical 

 Mycology ") in a variety of media {see Jago, " The Technology of 

 Bread -making," Chap. XI.), and the action of the enzymes contained 

 in and produced by the yeast, as well as certain bacteria, such as 

 the lactic, butyric, and acetic ferments. The auto-digestion of yeast 

 is particularlj' interesting and important to the baker, who to-day 

 uses, so largely, compressed yeast containing 70-75 per cent, of water 

 In the Army in France the deterioration of yeast during the hot 

 weather was studied, recourse to barms being frequent there in the 

 summer months. Barms were in constant use in Gallipoli and 

 Mesopotamia during the war. 



The growth of " rope " (B mesentericus) and moulds should also 

 be mentioned, since their presence must indicate that the bread had 

 become a suitable medium for their propagation from internal changes, 

 and by reason of suitable environmental conditions. 



III. and TV.— Water and Salt. 



As already indicated, the nature of the water is important in 

 considering the quality of bread produced, and the action of various 

 salts commonly found in water, and of sodium chloride in particular, 

 upon the strength or quality of wheat gluten has already been outlined. 



V. et seq. — Fat, Milk, dkc. 



The colloid nature of these ingredients has also been considtied 

 in previous reports. When used in conjunction with flour, water. 



