OXIDASES OR OXIDISING ENZYMES. 269 



moved by ether the disorder of the wine does not occur. 

 Whether this is due to the removal of the cenoxydase with 

 the tannin, or to the abstraction of the latter only, seems 

 uncertain. 



Cazeneuve further establishes a fact which indicates 

 clearly that the disorder is due to the enzyme. He has 

 submitted sound wine to the influence of a current of oxygen 

 for some time, and also to the action of ozone, and he finds 

 that neither process causes " la casse ". 



The enzyme can be preserved unchanged for some con- 

 siderable time if dissolved in weak alcohol or in wine which 

 does not contain more than 9 per cent, of spirit. It is, 

 however, rapidly altered by strong alcohol. 



It was mentioned above that Martinand had found this 

 oxidase in the juice of apples, pears and plums. Either the 

 same enzyme or a similar one has been described by Lindet 

 as causing oxidation of the tannin in the cider-apple (25). 

 If slices of apple, or a mass of the pulp, or sterilised sponges 

 soaked in the expressed juice are placed under a bell-jar 

 over mercury the material rapidly reddens, and there is 

 a simultaneous absorption of oxygen and an evolution of 

 carbonic dioxide. The phenomenon is the same if the 

 juice in which the sterilised sponges are soaked has been 

 filtered through porcelain, or if antiseptics are added, so that 

 it is evident the changes are not due to the presence of 

 micro-organisms. If boiled juice is used, it remains un- 

 coloured, and there is no exchange of the gases mentioned. 

 The juice may be precipitated by alcohol and the precipitate 

 collected and washed in the usual way, and it is then 

 found to be capable of setting up the changes in boiled 

 juice. 



It is of course a common experience that there is a 

 marked difference in the behaviour of the pulp of the apple 

 on exposure to air, according to whether it is raw or cooked. 

 The latter remains uncoloured while the surface of the raw 

 pulp soon turns a reddish-brown, particularly if it is unripe. 

 Lindet holds that the enzyme attaches itself to the tannin, 

 and explains the change of colour seen on wounding the 

 fruit by the suggestion that in the intact pulp the tannin 



