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 quahaugs (hard clams) 
in the shell for varying periods. 
Organisms | Per cent gas in dextrose five days 
per cubic at 37¢7.C, 
Mime’ of centimeter Per 
No. eaatan (plain agar cent Remarks. 
8+ | “at 25° C. |~ killed. 
for five 5cee | lee |0.5 cc)0.1 cc| 0.01 ec 
days) | 
Series A:a} Minutes. 
cee 0 4,500 60 1 0 0 0 0.00 | Variety of colonies. 
De reve 5 400 25 0 0 0 0} 91.11 Do. 
Sear: 10 200 50 0 0 0 0 | 95.60 | Less variety of colonies. 
. eee 15 60 60 0 0 0 0| 98.67 | Largely spore bearing. 
Dees 5 20 40 20 0 0 0 0| 99.12 | Spore-bearing colonies. 
GPss: 25 30 0 0 0 0 0| 99.34 Do. 
Vice 30 20 0 0 0 0 0| 99.56 Do. 
Series B: ; 
deer 0 106, 000 65 50 36 35 0 00 
Ree Da s.c 2 BSR 000 Ie 20) eye 205120 0 0 | 50.00 
Bee 4 2, 400 30 0 0 0 0} 97.73 
Ae aac 6 2, 000 80 0 0 0 0} 98.20 
Ossie 8 1,500 0 0 0 0 0) 98.70 
Gere 10 1,000 58 0 0 0 0} 99.06 
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. cola 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. colt 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“! 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. 
