604 REPORT— 1903. 



The very great differences between the constants yielded by the starch mashes 

 and the starch paste conversions are apparent. It is also to be noted that the 

 starches from ditierent barleys give different constants, and the author hopes to 

 continue his work in this direction. He brings forward evidence showing that in 

 the process of mashing, as conducted in breweries, the starch granules are dissolved 

 directly by the diastase and are not gelatinised prior to hydrolysis, as it is usually 

 stated they are. It is probable that the products formed in these starch mashes are 

 different from those resulting from the hydrolysis of starch paste ; and it is hoped 

 that a study of the former may yield results of both theoretical and practical 

 importance. 



4. Action of Malt Diastase on Potato-starch Paste. 

 By Arthur R. Ling, F.I.C. 



Brown and Millar have shown that the so-called stable dextrin— one of the 

 products of the hydrolysis of potato-starch paste by diastase — is converted by the 

 further action of diastase into a mixture of about equal parts of (i-glucose and 

 maltose. The observation of Davis and Ling (next abstract), that no rf-glucose 

 is formed when unrestricted diastase acts on starch paste, stands in apparent 

 antithesis to this. However, the author has confirmed the result of Brown and 

 Millar, and has found further that other isolated products of diastatic action 

 yield a proportion of rf-glucose when submitted to the further action of un- 

 restricted diastase ; thus the maltodextrin, a of Ling and Baker, when treated in 

 3 per cent, solution with an active preparation of diastase at 55° for 140 hours, 

 gave the constants [a]D 3-93 127 6°, R 3-93 lOoG, corresponding approximately 

 with maltose 90 per cent., ti-glucose 10 per cent. The presence of 10-5 per cent, 

 of d-glucose in the product was proved by weighing the phenylglucosazone formed 

 under standard conditions. Taking into account the fact that potato-starch 

 paste is never completely converted into maltose, although the final product has 

 the constants of that sugar, and that a substance is always present which is 

 identical with the isomaltose of C. J. Lintner, the simple dextrin of Ling and 

 Baker, and the dextrinose of Syniewski, which when isolated and submitted 

 to the action of diastase yields rf-glucose, the author suggests that the reason 

 no c?-glucose can be detected among the products of the action of un- 

 restricted diastase on starch paste is that that sugar is immediately condensed by 

 the action of the enzyme forming dextrinose. \N'hen, however, diastase is pre- 

 heated, its condensing action is weakened, and the (^-glucose formed can be 

 isolated. Attempts to condense rf-glucose or mixtures of it with maltose have 

 not been successful. 



5. Action of Malt Diastase on Potato- star cJt Paste. 

 By Bernard F. Davis, B.Sc., and Arthur R. Ling, F.I.C. 



In a previous paper* it was shown that when malt diastase is heated in 

 aqueous solution above the temperature at which the activity of the enzyme is at 

 its optimum, namely 55°, the reaction with potato-starch paste at about 55° is not 

 only slower, but difl'erent products are formed; thus rf-glucose can be readily 

 isolated from them after the reaction has been allowed to proceed for several 

 hours. Special experiments, employing the same quantities of diastase which has 

 not been heated in solution above 55°, show that d-g\ncose is not formed either 

 from starch paste or from maltose. It therefore appears that the produc- 

 tion of this sugar is connected with the preheating of the hydrolytic agent in 

 solution above 5.5°. As a result of a very large number of new experiments, 

 which will be published shortly, the authors have arrived at the following 

 conclusions. 



' Journ. Fed. Inst. Bretv. 1902, 8, 475. 



