CHAPTER XLIII 



OTHER MEANS OF PRESERVING FOOD 

 PRODUCTS.— PICKLING 



Food preservation in the canning industries is made 

 practicable and efficient by the destruction of the micro- 

 organisms by heat and their subsequent exclusion from 

 the sealed can. On a smaller scale, the housewife makes 

 use of the same principle in preserving fruits, berries, 

 and vegetables. She may also eliminate bacterial growth 

 by the addition of larger quantities of sugar. There are, 

 however, still other important methods for the preserva- 

 tion of perishable foods from destruction by bacteria. 



Low temperatures. — Reference should be made to 

 the extensive employment of low temperatures, particu- 

 larly for the preservation of meat and dairy products. 

 At times, such materials are kept and transported in a 

 frozen state. This is true of meats exported from Aus- 

 tralia and of fish exported from Scandinavia. The effi- 

 ciency of the method is determined, in this case, not by 

 the destruction of the bacteria, but by the more or less 

 complete checking of their activities. 



Drying. — Another method, more or less efficient, 

 for the preservation of food products, is that of drying. 

 When the moisture content of food products is reduced 

 below 25 to 30 per cent, the bacteria no longer find coii- 



(439) 



