254 DOMESTIC ANIMALS, DAIRYING, ETC. 



butter produces usually a very small amount. Genuine butter boils 

 usually with less noise, and produces an abundance of foam. The 

 difference in regard to foam is very marked, as a rule. Rarely, a 

 butter is found which yields an uncertain result ; such a butter should 

 receive the benefit of the doubt. (Dep. Agr. P. B. 131.) 



FOOD PRESERVATIVES AND BUTTER INCREASERS. 



The subject of the preservation of articles of food against decay 

 is one of no little importance. Decay or fermentations is known to 

 be due to the action of living germs or ferments. If in any way 

 these germs can be destroyed or their development prevented, without 

 any change in the food product itself, it seems possible that food 

 might be preserved almost indefinitely. Two conditions that are 

 absolutely necessary for the growth and multiplication of these germs 

 are a moderate temperature and moisture. The methods most gen- 

 erally used for the preservation of food aim to destroy these germs by 

 depriving them either temporarily or permanently of one or the 

 other of these conditions. These methods may be grouped as follows ; 



1st. Those depending upon the use of heat for the destruction 

 of the germs and subsequent sealing to exclude other germs. This 

 principle is illustrated in the process of canning fruits and vegetables. 



2d. Those depending upon the use of cold to prevent the mul- 

 tiplication of the germs for lack of sufficient heat. An example of 

 this is found in our extensive systems of cold storage. 



3d. Those in which the food product is dried in order that 

 the germs present may not multiply for lack of sufficient moisture. 

 The production of evaporated fruits illustrates this principle. 



Where it is impossible to employ any of the above methods, or 

 where their use might injure or destroy some desirable quality of the 

 food, resource is often had to the direct addition to the food of some 

 substance that is detrimental to germ life. The familiar process of 

 preserving meats, especially pork, by salting, illustrates the class. 

 There seems to be little or no objection to the use of foods preserved 

 by any of the first three general methods, nor to this last provided 

 that the substance added has itself no bad physiological effect. Be- 

 sides common salt the following substances are often used: Borax, 

 boric acid, salicylic acid, benzoic acid, sulphate of soda, saltpeter and 

 formalin. There is no doubt that they possess the power of arresting 

 the action of germs, but there is some question about the advisability 

 of the continued use of foods containing them. Inasmuch as there 

 is some prejudice on the part of dealers and consumers against their 

 use, frequent attempts are made to introduce preparations of these 

 substances under new forms and names. 



Some butter increasers contain acids which curdle the casein. 

 This is shown in the souring of milk itself when lactic acid is formed 

 from the milk sugar; or by adding vinegar or other acids to milk. 

 Hence it is plain what the effects of an acid Increaser would be. 

 The acetic acid would curdle the casein which would become mixed 

 with the fat, and yield a product that would be neither good butter 

 nor poor cheese. This incorporated casein furnishes a medium for 

 the growth and multiplication of millions of organisms. It is to re- 



