CIRCULAR 5. 



United States Department of Agriculture, 



DIVISION OF CHEMISTRY. 



CHEMICAL EXAMINATION OF CANNED MEATS. 



In obedience to the request of the Secretary of Agriculture, I have 

 secured samples of canned meats in the open market, and also certain 

 samples furnished us by the officials of the War Department, and 

 subjected them to a preliminary examination for the purpose of 

 determining whether any deleterious substances have been added to 

 them in the course of preparation to more perfectly preserve them. 



In order to present the matter as fully as possible, I may say that 

 the object of preserving meat in air-tight packages is to secure its 

 consumption in localities where the shipment of fresh meat is not 

 practicable. This is particularly true of meats to be used on ship- 

 board during long voyages ; in logging, lumber, and hunting camps ; in 

 armies marching at long distances from the source of supply, or into 

 countries where fresh, unprotected meat easily and speedily decays. 



The principle underlying the preservation of meat in air-tight com- 

 partments is one well known, namely, the fact that the decay of 

 organic matters is not due simply to oxidation, as was supposed to 

 be the case a few years ago, but. to the action of organisms, ferments, 

 oxydases or enzymes, which attack the organic substances, decom- 

 pose them and resolve them into their original elements or into sim- 

 pler compounds. If these organisms can be destroyed, or their 

 activity paralyzed, the organic substances remain indefinitely un- 

 changed. The destruction or paralysis of the activity of these 

 .organisms is secured in two ways, namely : First, by the process of 

 sterilization by heat, and, second, by the addition of certain chemical 

 substances called antiseptics, which have the property of suspending 

 or paralyzing organic activity. In the preservation of vegetable or 

 animal substances in air-tight packages it is presumed that steriliza- 

 tion by heat is the process which has been followed, as in the majority 

 of cases such sterilization does not impair to any notable extent either 

 the palatability or the digestibility of the preserved food. On the 

 other hand, it is well known that the processes of digestion take 

 place also under the action of certain ferments, and the ingestion of 

 food which has been preserved by chemical means tends to retard or 

 impair the digestive processes. The chemical substances which pre- 

 serve food from decay without the body interfere to a greater or less 

 extent with the processes of digestion within the body. For this rea- 

 son hygienic and medical authorities unanimously condemn the use 

 of any so-called preservatives in foods. 



