214 THE LOSS OF COLOUR IN RED WINES, , 



deposit greater. Both film and deposit were coloured with the 

 colouring matter of the wine. 



A determination of the loss of colour was made b}?- diluting 

 5 c.c. of the wine with 45 c.c. of water and comparing the depth 

 of colour of this with similarly diluted wine from a control 

 flask. The colour of the diluted 5 c.c. of infected wine was 

 matched by 50 c.c. of diluted wine, containing 4-2 c.c. of the 

 control wine. The infected wine had, therefore, suffered a loss 

 of 16% of its original colour. 



The infected wine had also become more acid. Normally the 

 wine contained 7 milligrams of volatile acid in 10 c.c, while the 

 infected wine at the end of ten days contained 298 milligrams of 

 volatile acid in the same quantity. The acid is expressed as 

 acetic, for it was shown to be such by the appearance and analysis 

 of the silver salt. 



The experimentally infected wine had, while losing its colour, 

 deposited a coloured sediment, which consisted of dark-coloured 

 zoogloea masses of bacteria. The phenomenon differed materially 

 from what had been observed in the case of the wine from which 

 the sample had been taken. Upon removal from the cask and 

 exposure to the air, it had become dull and had thrown down a 

 powdery deposit. The two phenomena are, therefore, quite 

 different, but it must be remembered that the wines were under 

 widely different conditions. The experimental wines were small 

 in quantity (20 c.c.) and had been under aerobic conditions for a 

 short time. The natural wine had been contained in casks, where 

 the bulk had been for a long time under practically anaerobic 

 conditions. Probably under the adverse conditions the aerobic 

 bacteria had practically ceased to multiply, but had continued to 

 secrete their oxidases, giving them off to the wine, so that upon 

 exposure to the air the colouring matter was quickly oxidised to 

 an insoluble darker-coloured product which slowly settled as a 

 deposit. 



What is generally known as the loss of colour of red wine is 

 recognised as a complex process,"* inasmuch as there are certain 



* Lafar, Technical Mycology, London (1898), "i., 311. 



