292 B. H. Chittenden — Ferments of Pineapple Juice. 



Experiment IX. — The acidity of the pineapple juice employed 

 was equal to 0-462 per cent. HCl. Necessary to neutralize 100*== of 

 juice, l-S^^'^of 5-0 per cent, solution of IS^CO^. The 10 grams of 

 moist albumin coagulum used in the digestions contained 1-3516 

 grams of dry albumin. The mixtures were warmed at 40° C. for 1^ 

 hours. 



Experiment X. — The acidity of the pineapple juice employed was 

 equal to 0-656 per cent. HCl. Necessary to neutralize 100="=, 19-1°'' 

 of 5*0 per cent, solution of Na^COj. The amount of dry albumin 

 equivalent to the 10 grams of moist coagulum used in the digestions 

 was 1-3468 grams. The mixtures were warmed at 40° C. for 2 hours. 



Hence, as is evident from the above experiments, the addition of 

 sodium carbonate to neutralized pineapple juice to the extent of U-5 

 per cent., almost completely stops the action of the ferment, while 

 the presence of 1-0 per cent, of the alkali carbonate checks it 

 altogether. Doubtless, the isolated ferment would show a still 

 greater susceptibility to the action of dilute alkaline fluids. 



From the foregoing, it is evident that digestion with bromelin, 

 the ferment of pineapple juice, goes on most vigorously in neu- 

 tral solutions, but that the presence of small amounts of acid, espe- 

 cially such as are contained in pineapple juice, and of sodium 

 carbonate interfere with the proteolytic action only slightly; larger 

 amounts, however, check the action of the ferment altogether. 



It is further evident from the foregoing results that the pro- 

 teolytic ferment of pineapple juice is an exceedingly vigorous fer- 

 ment. We cannot say definitely how much pure ferment by weight 

 is contained in 100*^° of filtered pineapple juice. There is no doubt 

 that the amount varies greatly in different specimens of fruit; in 

 fact, our results show plainly differences in proteolytic power hard 

 to be accounted for in any other way. Experiments to be described 



