628 



ground meat were heated above 100^ O. the digestibility of the albumi- 

 noids decreased in proportion to the height to which the temjjerature 

 was raised. 



The following experiments were made at temperatures between 90 

 and 100° C. 



1. Wheat bran. — When 2 grams of wheat bran were treated with one 

 fourth of a liter of acid pepsin solution for 30 hours, HCl being gradu- 

 ally added till the solution contained 1 per ceut HCl, the albuminoids 

 remaiuiug undigested were found to be equal to 0.308 per ceut nitrogen. 



When, previous to the digestion experiment, the bran was heated in 

 100 c. c. of boiling water for one fourth of an hour, or heated in a dry 

 state at OS*^ O. for C hours, or when mixed with water, dried, and then 

 heated at 98° 0, for 48 hours, the percentage of nitrogen in the undi- 

 gested residue remained the same as where the bran received no pre- 

 vious treatment (0.308 per cent nitrogen). Likewise when 2 grams of 

 bran were treated with 400 c. c. acid pepsin solution containing 0.2 per 

 cent HCl during 36 hours, without increasing the amount of HCl, the 

 undigested albuminoids contained, as before, 0.308 percent nitrogen. 



Two series of experiments were made with bran in which determina- 

 tions were made of the amounts of albuminoid nitrogen dissolved by 

 water, by dilute hydrochloric acid, and by acid pepsin solution, after 

 the bran had been subjected to diiferent preparatory treatment; 6.25 

 grams of bran, containing 100 mg. of pepsin-soluble nitrogen, were used 

 for each test. In the first series of experiments the bran was heated 

 in 100 c. c. of boiling water for some minutes, allowed to cool to 40° C, 

 the solvent added at the same temperature, and allowed to act 1 hour. 

 In the second series the dry bran was heated for 8 hours at 97-99° C, 

 100 c. c. water at 40° C. (saturated with chloroform to prevent decom- 

 position of the bran) added, and on the following day treated with the 

 solvent for 30 minutes. The results indicated that the amount of albu- 

 minoid nitrogen soluble in water was not decreased by heating the 

 bran in boiling water. HCl without pepsin dissolved very little more 

 albuminoid nitrogen from the cooked bran than water alone, but acted 

 somewhat more strongly on the heated bran. The author states that 

 these observations seem to corroborate views previously expressed by 

 him,* that wheat bran contains a ferment which in the presence of HCl 

 acts similarly to pepsin, but which is destroyed by the action of heat. 

 The amount of albuminoid nitrogen dissolved by pepsin solution was 

 considerably decreased by the heating ; and the author believes, from 

 other experiments, that the action of boiling water in this direction is 

 much more rapid than that of dry heat. 



2. Bread and flour of cereals. — Experiments similar to those described 

 above were made with wheat flour and with bread made from a mixture 

 of rye and wheat meals. The conclusions were as follows: 



* Laudw. Versucbs-Statioueu, 37, j). 117. 



