204 ECONOMIC BACTERIA IN MILK AND MILK PRODUCTS 



The Use of Artificial Cultures in Cheese-making" 



The practicability of employing pure cultures as " starters " in 

 cheese-making in a similar manner to that employed in butter- 

 making has been tested. Upon the belief that lactic acid bacteria 

 are the main agents in the curing of cheese, this species has been 

 suggested as a " starter " under the following conditions, viz. : {a) 

 that the organism should be a pure lactic acid producing germ in- 

 capable of producing gaseous products ; ijj) that it should be free 

 from any undesirable aroma ; and {c) that it should be specially 

 adapted for vigorous development in milk. Such a " starter " 

 might be propagated in pasteurised or sterilised milk although it 

 has been found in practice that such milk does not make good 

 cheese. The advantages accruing from the use of such a " starter " 

 are that with sweet milk it saves time in the process of manufacture, 

 that with tainted milk in which acid develops imperfectly, it is an 

 aid to the development of a proper amount of acid for a typical 

 Cheddar cheese, and that the flavour and quality of such cheese is 

 preferable to that of cheese which has not been thus produced. 

 Professor Russell is of opinion that the lactic acid organisms are 

 to be credited with greater ripening powers than the casein digest- 

 ing organisms, and Lloyd holds that " the greater the number of 

 lactic acid bacilli in the milk the greater the chance of a good 

 curd." Still, in his opinion, " this organism alone will not produce 

 that nutty flavour which is so much sought after as being the essen- 

 tial characteristic of an excellent Cheddar cheese."^ Lloyd con- 

 cludes, however, that by the growth of this species and the resulting 

 production of lactic acid, most of the organisms which are present 

 in the milk due to air contamination are gradually destroyed, while 

 even those which are not destroyed are frequently checked in their 

 growth, and thus taints in the milk are diminished ; that up to the 

 time of vatting the curd all the operations in the manufacture of 

 the cheese are dependent upon and subservient to the growth of 

 the lactic acid bacillus in the curd ; and that subsequent ripening 

 of the cheese is also dependent upon this organism. 



Three difficulties have, up to the present, prevented any wide 

 application of the method of artificial starters. The first is that 

 of not being able to use pasteurised milk, which is uncoagulable 

 by rennet (Lloyd). The use of ordinary milk means some degree 

 of contamination, but it contains the enzymes which may be 



1 Board of Agriculture, Report on Cheddar Cheese-makhig (F. J. Lloyd), 

 1899, p. 164. 



