Preservation of Foods. 227 



Salting. If certain substances like salt are added to 

 organic matter, they tend to preserve it. Most kinds of 

 bacteria are unable to grow in a saturated solution of 

 common salt. This fact is made use of in the preserva- 

 tion of pork and corned beef, where the meat is placed in 

 a strong brine. If the brine is too weak, certain of the 

 bacteria will grow and the meat will spoil. Such a con- 

 dition is more apt to obtain during warm, than during 

 cold weather. The effect of low temperature, which has 

 a restraining influence on bacterial action, together with 

 the inhibitory action of the salt, exert a more pronounced 

 preservative effect than either of the preservative agents 

 alone. Salt may be applied in a dry form as in the pres- 

 ervation of hides and meats. 



Smoking. In the preservation of meats such as hams 

 and bacon by smoking, another factor is operative. In 

 the slow combustion of wood, antiseptic compounds be- 

 longing to the cresote group are formed. These are de- 

 posited on the surface of the meat and are absorbed, and 

 together with the salt protect the meat from the action of 

 the bacteria on its surface^. 



Preservative action of sugar. Sugar, although fur- 

 nishing an ideal food medium for bacteria and molds, 

 may exert a preservative action such as is shown in syr- 

 ups. All solutions containing sugar, as molasses, cane 

 and maple syrups, or fruits conserved in sugar, will not 

 keep unless they are sufficiently concentrated. "Where 

 they undergo a fermentative change they are said to have 

 "worked." The preservative action of sugar in concen- 

 trated solutions depends upon the extraction of water 

 from the bacterial cells causing them to become flaccid or 

 wilted. Under such conditions growth can no longer 

 go on and fermentative action can not follow. 



