334 
Name of ferment. 
Temperature at which destroyed (°C.). 
Laccase 
1 60-63. 
Lipase 
Maltase 
My rosin 
Oenoxydase. 
Papain 
Pepsin 
Rennin 
Trehalase . . . 
Trypsin 
Thrombase. . 
Tyrosinase. . 
Urease 
72 (Hanriot), 65-70 (Kastle & Loevenhart ). 
55. 
81-85. 
72. 
82.5. 
55-57. 
70, neutral; 63, faintly acid. 
64. 
75-80. 
70 (Schmidt). 
55. 
i o— 80. 
P. T. Muller (58) gives the following data bearing on the subject of 
the resistance of the several ferments to heat: Hemodiastase (Hahn) 
is not destroyed at 55° C. It is weakened by heating to 66° C. for half 
an hour and at 65°-70° C. is destroyed. Parachymosin (Bang) with 
stands a temperature of 75° C. for some time. Papain is weakened 
at 75° C. and destroyed at 82.5° C. The oxidizing ferments (Abelous 
and Biarnes) increase in activity from 0° C. to 60° C. At 80° C. they 
are still active and are first destroyed at 100° C. Lactoserum (P.T. 
Muller) is rendered inactive by heating for half an hour, at 70°-75° C. 
So far then as the question of temperature is concerned it is evident 
that the milk enzymes are much like enzymes from other sources. 
Indeed they are all very much alike and all of this great group of 
substances stand in such intimate and close relation to the vital 
activities of the cell that all of those conditions and influences which 
tend to destroy the one tend also to destroy the other. (See also 
Kastle (60) “On the Vital Activity of the Enzymes.”) All of the 
bacteria of milk can not be destroyed -therefore without at least 
diminishing the activity of the milk enzymes or perhaps destroying 
them altogether and the enzymes can not be destroyed without 
rendering the milk sterile. 
Similar conclusions have been reached by Marfan (60a) . According 
to this author the enzymes in general can not withstand a tempera- 
ture higher than 70° C., so that by heating milk to deprive it of its 
bacteria, we also deprive it of those ferments which probably exer- 
cise a favorable influence on nutrition. He is of the opinion, how- 
ever, that this is not sufficient ground for doing away with the prac- 
tice of sterilizing milk by heat. In this connection Rosenau has 
recently made the important observation that the pathogenic 
bacteria are either killed or rendered inert by exposure to 60° C. for 
twenty minutes, see Hyg. Lab. Bull. no. 42. 
