SOME CHEESE DEFECTS 377 



In 1901 Harrison isolated a species of Torula 

 (p. 396) which he determined was the cause of serious 

 trouble in one of the leading cheese factories in Canada. 

 The organism, which he named Torula amara, produced 

 an unpleasant bitter flavour in milk and also in cheese 

 prepared from it. 



It was traced to the leaves of certain species of maple 

 which grew near where the milk- cans were stored. 

 Grown in beer wort, the cells are oval, from 7.5 to 9 /a, 

 long, and, like most yeasts, occur singly or in short 

 chains and small clumps. Inoculated into sterile milk 

 the bitter taste develops in five or six hours at 37 C., 

 with the formation of considerable quantities of gas and 

 very slight acidity. 



Cultures give the buiret-reaction of peptones. 



Cheese made from milk inoculated with the Torula 

 were bitter. 



Eckles in 1905 isolated a small bacterium which was 

 found to be the cause of bitterness in Cheddar cheese, 

 the objectionable taste often developing in a few days. 



The organism is a short rod, .8 to I /x long and .6 ^ 

 broad ; when grown in whey it assumes the form of an 

 oval coccus, .7 [L long, .6 ^ broad. 



It stains by Gram's method, and liquefies gelatine, the 

 colonies being small and white at first, afterwards 

 yellowish. Grown on agar at 37 C. for twenty-four 

 hours, the colonies are very small, resembling those of 

 Str. lacticus ; deep colonies are yellow, those on the 

 surface almost colourless. 



Milk is coagulated by it in twenty-four hours at 37 C., 

 the whey becoming straw-coloured and intensely bitter. 



