554 MICROBIOLOGY OF POODS 



become distasteful. It would, therefore, appear to be erroneous to 

 regard preserved foods as in every respect as valuable from the stand- 

 point of nutrition as the corresponding fresh foods. The difference is 

 not dependent upon a change in the food-principle content, but must be 

 sought rather in slightly altered composition of the food and the 

 specific effects of newly formed substances, and especially in the 

 possible effects of the continued ingestion of the contained chemical 

 preservatives upon the consumer. 



THE EFFECTS OF FOOD PRESERVATIVES ' 



The essential characters of a food preservative include antiseptic 

 action to prevent decomposition of the food, and absence of evident 

 poisonous or deleterious influence upon the consumer. It follows there- 

 fore that the effects of food preservatives upon the consumer, if they 

 exist at all, are at any rate not easily recognized, and on account of the 

 economic importance of the questions here involved, this field of 

 scientific research has been energetically cultivated by- investigators 

 with different viewpoints, and the results of investigation have been 

 discussed with some heat. The passage of the U. S. Food and Drugs 

 Act was followed by considerable discussion of these questions. Gradu- 

 ally the practical administration of the law has become more settled 

 and the use of many food preservatives is still permitted. 



SUBSTANCES WHICH PRESERVE BY THEIR PHYSICAL ACTION. The 

 preservative effects of sodium chloride seem to depend upon the high 

 osmotic tension of strong salt solution, and the same may be said 

 of cane sugar. When diluted so as to be eaten with relish, these 

 substances are themselves properly classed as foods, without deleterious 

 effects upon ordinary individuals. 



SUBSTANCES WHICH PRESERVE BY THEIR CHEMICAL ACTION. 

 These preservatives inhibit the activity of microorganisms in a dif- 

 ferent way, not by withdrawing water from the microbic cell, but by 

 entering into chemical combination with the living substance in such a 

 way as to hinder its activity, or by entering into chemical reactions 

 with the food to produce new substances capable of attacking the 

 microbic protoplasm in this way. The ideal chemical food preservative 

 would be one which, without altering the food substance, would ex- 

 hibit this poisonous property toward living protoplasm until the food 

 was ready for consumption, and then would suddenly and permanently 



