290 M. IT. Chittenden — Ferments of Pineapple Juice. 



proteids contained in 10 grams of j^repared muscle* tissue, 2-7258 

 grams. 



]4 hour at 40° C. 

 1 iiour at 40° C. 



The acidity of pineapple juice is due to organic acids and acid 

 salts, far weaker in their action on ferments than mineral acids. 

 Addition of dilute mineral acid in small quantity to pineapple juice 

 of natural acidity checks, hut does not prevent the digestive action 

 of the ferment. Thus, the addition of an equal volume of 0-2 per 

 cent, hydrochloric acid to pineapple juice diminishes very greatly its 

 digestive power, but does not prevent it altogether. From this we 

 may conclude that pineapple juice can exert its proteolytic power, 

 to a certain extent, Avhen taken into the stomach and mixed with the 

 acid of the gastric juice. Obviously, the addition of an equal vol- 

 ume of 0-2 per cent, hydrochloric acid to neutralized pineapple juice 

 does not necessarily mean the presence of 0*1 per cent. HCl, since 

 the acid may be in great part used up in decomposing the various 

 salts present, and in combining with the various forms of organic 

 matter contained in the juice. 



Experiment VI. — The acidity of the pineapple juice employed 

 was equal to 0-268 per cent. HCl. The 10 grams of moist albumin 

 coaguluni used in the digestions contained 1*7972 grams of dry 

 albumin. The mixtures were warmed at 40° C for 17 liours. 



Pineapple juice of natural Undissolved Percent, 



acidity. albumin. digested. 



A 100 c. c. + 100 c. c. H,0 1-2238 grams 32-0 



B 100 +100 0-2^ HCl 1-4673 19-0 



Were it not for the large quantities of salts, etc., in pineapple 

 juice the above inhibitory action of the hydrochloric acid on the 

 ferment Avould be far more pronounced. This is shown by the two 

 following experiments : 



By adding about five volumes of 95 per cent, alcohol to pineapple 

 juice, a flocculent precipitate results composed of the proteids of the 

 juice, together with the proteolytic ferment and some salts. On 

 dissolving this precipitate in water a solution is obtained with 

 marked proteolytic power. 



* Prepared by soaking chopped muscle tissue, freed from lat and tendons, in water 

 until all blood and soluble extractives were removed. 



