COOKING TESTS. 



39 



These results show that in this instance all gas-producing organ- 

 isms were destroyed by from 5 to 10 minutes' exposure to live steam. 

 In Table 15 a similar experiment on hard clams in the shell shows 

 that gas-producing organisms survived and were recovered in 5 cc 

 quantities of liquor from clams exposed 20 minutes to live steam. 

 After 5 minutes' exposure, however, 91.11 per cent of the total organ- 

 isms were killed. The dense shells of hard clams may account for 

 this delayed destruction of bacteria. 



TABLE 15. Bacteriological results showing the effect of steaming qaahaags (hard clams) 

 in the shell for varying periods. 



a Thirty clams were exposed to live steam in a sterilizer and five were removed for each sample at inter- 

 vals of five minutes. 



These results indicate that 2 minutes' exposure to live steam 

 destroys 50 per cent of the bacteria, but B. coli types remained after 

 10 minutes' exposure, although these germs failed to grow in the sam- 

 ple consisting of five clams removed after 8 minutes' exposure. It 

 appears from these experiments that at least 10 or 15 minutes are 

 required to destroy B. coli in small quantities of ordinary market 

 oysters and clams; therefore, the usual methods of cooking shellfish 

 will not remove the danger of infection from disease-producing 

 organisms should they be present. When larger quantities of 

 shellfish are cooked* at one time in the same container a sufficient 

 temperature may not be reached within the interior of the mass to 

 destroy the germs thus protected from the action of the heat. In 

 such cases it would be advisable to maintain a high temperature 

 for a longer time. Herdman and Boyce 41 say: 



Shellfish must not be taken as a food from grounds where there is any possibility 

 of sewage contamination; after removal from the sea, while in transit, in store, or in 

 market, they should be carefully 'protected from any possibility of insanitary environ, 

 ment; they should not be kept longer than is absolutely necessary in shops, cellars, 

 etc., in towns, where even if not running the risk of fresh contamination they are under 

 conditions favorable to the reduction of their vitality and growth of their bacterial 

 contents; the fresher they are from the sea the more healthy they are likely to be; 

 finally, only absolutely fresh shellfish should be eaten uncooked, and those that are 

 cooked must be sufficiently cooked, raised to boiling point and kept there for at least 

 10 minutes. 



