556 MICROBIOLOGY OF FOODS 



removing odors of decomposition. It thus not only delays decomposi- 

 tion, but also to a certain extent masks the decomposition which has 

 already occurred. The ingestion of moderate quantities of sulphites 

 in food has at times been followed by acute gastric derangement in 

 man, and prolonged feeding of meat containing sulphites has been 

 followed by inflammatory changes in the kidneys of experimental 



animals. 



Fluorides have been used to a slight extent in beverages, but acute 

 gastric derangement and depression of the heart are caused by rather 

 small quantities, and probably on this account the salts of, hydrofluoric 

 acid have not come into very general use as food preservatives. 



ORGANIC FOOD PRESERVATIVES. Formic acid (H-COOH) and 

 acetic acid (CH 3 COOH) are produced by microbic activity and their 

 preservative action appears to depend more upon the degree of acidity 

 than upon the character of the acid radical. Both these acids appear 

 to be utilized as food in the body of 'the consumer. 



Benzoic acid and benzoates are rather extensively employed in 

 prepared vegetable food products, such as jams and catsups. The 

 antiseptic effect seems to be due wholly to free benzoic acid, even where 

 it is added in the form of the salt, but the action is not due merely to 

 the acidity (i.e., the hydrogen ion). Benzoic acid is not utilized as a 

 food in the body, but is excreted by the kidneys in the form of hippuric 

 acid. It has been said to produce irritant effects upon the stomach 

 and the kidneys, and to arrest the action of digestive enzymes in dilute 

 solutions, but the Referee Board* of the United States Department of 

 Agriculture, after extensive investigations, concluded that small doses 

 of sodium benzoate mixed with food are not injurious to health, and 

 do not impair the quality or nutritive value of the food. 



Salicylic acid and the salicylates have been used for much the same 

 purposes as benzoic acid, and there does not appear to be much dif- 

 ference between the two acids, either in their efficiency as preservatives 

 or in their possible deleterious effects upon the consumer. Salicylic 

 acid is more expensive. After extensive investigation Wiley | has 

 concluded that the addition of salicylic acid and salicylates to foods is 

 reprehensible in every respect, this conclusion corresponding to the 

 results of similar work by the same investigator^ upon benzoic acid. 



* U. S. Dept. Agr. Report No. 88, May, 1909. 



t U. S. Dept. Agr., Bureau of Chemistry. Bull. No. 84, Part II, 1906. 



J U, S. Dept. Agr., Bureau of Chemistry, Bull. No. 84, Part IV, 1908. 



