EFFECTS OF HEAT ON TRICHINA 



By B. H. Ransom, Chief of the Zoological Division, and Benjamin Schwartz, Junior 

 Zoologist, Bureau of Animal Industry, United States Department of Agriculture 



INTRODUCTION 



It is a well-known fact that the larvae of Trichinella spiralis, which 

 are of rather common occurrence in pork, may be killed by thorough 

 cooking and the meat thereby rendered safe for food so far as concerns 

 the danger of trichinosis. As to the actual temperature required to kill 

 the parasites, however, various writers give very different figures, so 

 that the question of the thermal death point has been rather uncertain. 



The thermal death point of trichinae is a matter of great practical 

 importance in connection with the control of cooking processes employed 

 by meat-packing establishments in the preparation of cooked products 

 containing pork. The simple rule of cooking pork until it is well done, 

 which can be applied satisfactorily by a careful cook in the household 

 kitchen, is not suited to conditions in meat-packing establishments. 

 Instead of such a rule a more exact statement of requirements is desir- 

 able. In fact, the Bureau of Animal Industry, which is charged with 

 the enforcement of the federal meat-inspection law, requires that pork 

 or products containing pork cooked in establishments operating under 

 Federal inspection shall be heated sufficiently to insure a temperature 

 throughout all portions of the meat that will destroy the vitality of any 

 trichinae which may be present, specifically a temperature of 137° F. 

 (58° -^ C). This temperature is several degrees higher than the tempera- 

 ture that has been accepted by the bureau as representing the thermal 

 death point of encysted trichinae, but the difference between the two 

 represents no more than a reasonable allowance as a margin of safety. 



Before a decision could be reached as to the degree of heat required 

 to destroy the vitality of encysted trichina, it was found necessary to 

 supplement the investigations on this question which are recorded in the 

 literature with further experimental work; and it is the purpose of this 

 paper to set forth the results obtained. This work was begun by the 

 senior writer in 191 3, continued in 191 4 and 191 5, and in the latter part 

 of 1 91 5 taken up by the junior writer. 



REVIEW OF LITERATURE 



Haubner, Kiichenmeister, and Leisering (5) * state that trichinae are 

 killed by prolonged salting, followed by 24 hours of smoking, but do not 

 give data as to the temperature of smoking. 



1 Reference is made by number (italic) to "Literature cited," pp. 220-221 . 



Journal of Agricultural Research. Vol. XVII. No. 5 



WASmNGTON, D. C. Aug. 15. 1919 



sc Key No. A-48 



(201) 



