BACTERIA IN OUR DAIRY PRODUCTS. 77 ^ 



first made, cheese is soft and tastes somewliat like milk curd. It 

 has none of the palatable taste which we find in the cheese of our 

 table. It is a long ripening which gives this taste to the cheese. 



Here, again, the ripening process is one of bacteria growth. 

 The millions of bacteria that were in the milk are stored away in 

 the cheese, and instead of being killed here, as they are in the but- 

 ter, they begin to multiply immediately. Here, too, there is a bat- 

 tle of bacteria, and now one species is in the ascendency and now 

 another. If the wrong species gets the upper hand, the cheese be- 

 comes bad, and cheese-makers have their greatest trouble from this 

 source. The bacteria do not grow so rapidly as they do in cream, 

 for the conditions are less favorable, but the ripening is kept up 

 for months, and during the whole time the bacteria are growing. 

 Under their action the character of the cheese slowly changes. 

 Here, again, the decomposition products are responsible for the 

 taste and odor. In some cases, such as Limburger cheese, the 

 action is allowed to continue to the verge of putrefaction. Ordi- 

 narily it is not continued so far, but in all cases the cheese-maker 

 favors the growth of certain forms of bacteria by regulating the 

 temperature at which the ripening is carried on. As the ripen- 

 ing continues, certain parts of the cheese are digested and decom- 

 posed by the bacteria growth, and, as the products of decomposi- 

 tion accumulate, the taste grows stronger. After a time it is 

 considered fit for the market, but the longer the ripening contin- 

 ues the stronger th* taste becomes. 



Little is known yet as to the bacteriology of different kinds of 

 cheeses. Whether the different tastes of Edam, Limburger, and 

 other characteristic cheeses is largely due to the character of the 

 bacteria ripening them can not yet be said. Cheese-makers do, 

 however, have much trouble with various irregular forms of ripen- 

 ing, and a great drawback in this business is the lack of uni- 

 formity in this respect. Beyond doubt this is due largely, per- 

 haps chiefly, to the variety and number of bacteria which succeed 

 in gaining a foothold in the cheese and contribute to its ripening. 



Along the line of cheese manufacture our bacteriologists are 

 promising us help from their researches. Of course, the cheese- 

 maker has never paid any attention to the sort of bacteria which 

 he plants in his cheeses, for he has never heard of them. Some- 

 times he has unwittingly planted species which produce violent 

 poisons, as is shown by the many instances of death from eating 

 poisonous cheese. Now, our bacteriologists are suggesting that 

 the ripening of cheese may be easily controlled. Artificial cult- 

 ures of the proper sort may be furnished the cheese-maker, and 

 if these are planted in the cheese not only will the danger from 

 poisonous cheese be prevented, but at the same time the desired 

 taste of the cheese be assured. More than this, when we recognize 



