8 



(3.) These requirements are easily satisfied in food factory, market, shop, dairy, 

 kitchen, larder, and store-room, unless constant and intelligent care and suitable 

 precautions be exercised. 



It is therefore evident that in 



THE PREVENTION OF DECAY 



is found the means for the preservation of food. Housekeeper and food-purveyor alike 

 are confronted by the problem how to prevent the access to foodstuffs of these germs, 

 yeasts, and moulds, of which decay is the product. 



THE PRESERVATION OF FOOD. 



Attempts to solve this problem have been made along the following lines : 



(a. ) By so treating food that it becomes unfavourable to their growth and unsuitable 



to their nutrition : 

 (b.) By submitting food to conditions which will destroy these micro-organisms, if 



there is reason to believe they are present : 

 (c.) By protecting and sheltering food from their attacks. 



(a.) MEANS BY WHICH FOOD is RENDERED UNSUITABLE FOR AND UNPALATABLE TO 



THE SOURCES OF DECAY. 



(1.) Food can be smoked (i.e., exposed for a longer or a shorter time to the vapour 

 of burning wood or peat). The results of this treatment are threefold : 



(i. ) The meat or fish becomes saturated with certain acid antiseptics, such as creosote, 

 which are produced by the combustion of wood, peat, and coal. It is thereby 

 rendered unpalatable to the germs of decay : 

 (ii.) The foodstuffs become too dry to supply the amount of moisture necessary to 



germ -growth : 



(iii.) The smoke also destroys the micro-organisms, if present, though here 

 Two Cautions are necessary. 



Exposure to smoke will not affect the poisonous products of these putrefactive 

 germs if decay has already set in ; neither does it destroy parasites. Consequently, 

 smoked but uncooked " measly :> pork or meat otherwise unsound cannot be made fit for 

 food by this treatment ; neither should the consumption of smoked but uncooked 

 sausages ever be permitted. In Germany it is illegal. 



(FIG. 4.) 



How flics infect food with seeds of decay and also with the germs of 

 disease ; consumption, for instance, or typhoid fever. 



(2.) Food can be dried by Ej-poxure to Sun, Air, or Artificial Heat. This is prob- 

 ably the oldest of all methods of food-preservation, and is still in general use all over 

 the world. Uncivilized man still dries his strips of meat or fish in the sun and wind ; 

 civilized man more often relies upon this raeaiis of removing moisture to preserve 



