DAIRY FARMING DAIRYING. 587 



'■The general results of this analytical study of the bacterial changes that take 

 place in the curing of cheese may be briefly summarized as follows: 



"(1) There is at iirst a marked falling off in the number of bacteria in green 

 curds for a day or so. (Period of initial decliue.) 



"(!') This is followed by a very rapid iucrease in numbers, in which the bacteria 

 reach scores of millions of organisms per gram. (Period of increase. | 



•■:!) This period is followed by a diminution in numbers, at lirst rapid but later 

 more gradual, until the genu content sinks to insiguificant proportions. (Period of 

 final decline, ) 



"(4) The time necessary to reach the maximum development (I'd period) is has- 

 tened or retarded by such external conditions as temperature, etc. 



''(5) The second period also marks the beginning of the physical change that 

 occurs in the cheese in the earlier part of the breaking down of the casein. 



"(6) The bacterial ilora of cheese differs markedly from that of milk. In milk 

 the lactic acid bacteria predominate, but accompanying them are always liquefying 

 or peptonizing organisms, and as a rule bacteria capable of developing gaseous by- 

 products. 



"In the ripening cheese the peptonizing or casein digesting bacteria are quickly 

 eliminated; the gas producing bacteria disappear more slowly, sometimes persisting 

 in very small numbers for a long time. 



'•The lactic acid bacteria, on the other hand, develop enormously for a time, until 

 the cheese is partially ripened, when they, too, begin to diminish in numbers. 



"(7) The generally accepted theory that the peptonizing or digesting bacteria are 

 able to break down the casein in thecheeseas they do in milk is improbable, because 

 this type of bacteria fails to increase in the cheese and usually disappears before 

 there is any evidence of physical changes in the condition of the casein. The same 

 is true where cheese is made from pasteurized milk to which copious starters of these 

 peptonizing organisms have been added. 



"(8) The coincidence existing in point of time between the gradual ripening of 

 the cheese and the marked development of the lactic acid bacteria seems to indicate 

 that these phenomena are causally related. This view is further strengthened by 

 the fact that cheese made from pasteurized milk in which the lactic bacteria have 

 been destroyed fail to ripen in the normal manner, while the addition of a pure lactic 

 acid ferment to the, pasteurized milk permits the usual changes to occur in a per- 

 fectly normal way." 



Pure lactic cultures of bacteria in cheese making, H. L. Bus- 

 sell ( Wisconsin Sta. Rpt. 1896, pp. 112-126). — Four preliminary experi- 

 ments were made with a pure culture of the lactic acid germ, control 

 cheeses being made at the same time. 



"The results attained so far showed that the use of the culture starter had one 

 very great advantage in lessening the time of manufacture. Instead of waiting 

 for the acid to develop naturally, a process sometimes requiring several hours, the 

 addition of the pure lactic ferment brought the acid rapidly forward, so that the 

 milk could be expeditiously handled." 



These results led to a trial on a large scale at the university creamery. 

 During the winter of 1895-'96 a large number of cheeses were made in 

 which a x>ure lactic acid culture prepared from ripening cheese was 

 used. In many cases control cheeses were made without the use of a 

 starter. The cheeses were scored by a disinterested party, and the 

 results are, tabulated. 



"On the whole the use of the lactic ferment improved not only the flavor of the 

 cheese but the texture as well, where it was compared with cheese made with milk 

 ripened without the addition of any starter. By making several cheeses from each 



