a. H. Chittenden — Ferments of Pineapple Juice. 29 V 



While neutralized pineapple juice is capable of digesting more 

 proteid matter at 60° C. than under like conditions at 40° C, warm- 

 ing the ferment solution alone at 60° for fifteen minutes, prior to the 

 introduction of the albumin, diminishes the proteolytic power of the 

 ferment full 50 per cent. This result suggests that the products 

 of digestion protect the ferment, to a certain extent, from the 

 destructive action of the high temperature. The ferment acts quickly 

 on proteid matter, so that even after a few minutes exposure of a 

 mixture of albumin and pineapple juice to 40°-70° C, some proteoses 

 and peptone are doubtless formed, which can in some manner exert 

 their protective action. When, however, the i^eutralized juice alone 

 is heated to 60° C, in the absence of proteoses and peptone, the 

 ferment is rapidly destroyed. Doubtless, the ferment as contained 

 in pineapple juice is more resistant to heat, than a solution of the 

 isolated ferment would be, from the possible protective action of 

 salts present, although of this point we cannot speak definitely. 

 These results accord with Biernacki's* observations on the ferments 

 pepsin, trypsin and ptyalin. This investigator found that albumose, 

 amphopeptone and antipeptone raised the temperature at which 

 trypsin was destroyed five degrees or more ; that peptone raised 

 the temperature at which pepsin was destroyed in acid solution, 

 from 50°-55° C. up to 7u° C. These results may perhaps be ex- 

 plained on the ground of a combination of the ferments with the 

 albuminous bodies, the hypothetical compounds having greater 

 resistance towards heat than the ferment alone. In any event, 

 the general statement may be made that the purer the ferment the 

 less resistant will it probably be to the destructive action of high 

 temperatures. 



While the preceding results show that the pineapple ferment, as 

 contained in filtered pineapple juice, is liable to be killed on long- 

 continued exposure to temperatures favorable for its proteolytic 

 action, the fluid may be heated at temperatures under 40° C. for long- 

 periods of time, or even evaporated to dryness, without destruction 

 of the ferment, provided the temperature is carefully regulated and 



* Zeitschrift fiir Biologie, Band xxviii, p. 49. 



