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"(J) The rate of penetration of heat into the substance of the meat in tins during
"sterilisation is extremely variable. We have based our conclusions on the average
"of many experiments. To ensure complete sterilisation, the temperature of
"the medium surrounding the tins must always be above 112° C. (234° F.). The
"lowest temperature of the surrounding fluid which will completely sterilise
"the tins within a reasonable time is 120° C. (248° F.), and this temperature must
"act for not less than sixty minutes. From the two experiments recorded with a
"fluid boiling at 130° C. (266° F.), it would appear that even then at least an hour
"would be required to ensure the death of these very resistant spores. We are
"aware that the above results do not tally with the usually accepted idea of tin
" thermal death point of spore-bearing bacilli, but we would point out that experi"ments
have not before, to our knowledge, been made with this particular bacillus.
"The experiments were carried out with every available precaution against error
"and repeated often enough to ensure accuracy."
MARKING OF TINNED AND OTHER PRESERVED FOOD
PRODUCTS.
In June last I endeavoured to come to some arrangement with the New
Zealand Authorities with regard to the marking of tinned foods in such a way
as to indicate where and when they were packed. With this object in view
the Chief Veterinarian to the New Zealand Government conferred with the
Managers of some of the leading firms in New Zealand, who, while they
pointed out some commercial objections to the idea as originally propounded,
expressed themselves quite willing to do what was desired, provided it were
done in such a manner as not to raise any objections on the part of the
importers in this country.
The following arrangement was suggested:—
(1) That each tin bear a mark consisting of the initials of the packing
company or individual, with perhaps the registered number of their
premises (or the registered number alone, the New Zealand
Veterinary Office supplying your Medical Officer with a list showing
the premises to which each number applies).
(2) That a cypher mark indicating approximately the date of packing
be affixed to each tin. A schedule of cypher marks being sent to
your Medical Officer.
Each cypher mark to indicate a period of say two months—thus, one
mark indicating January and February, 1909, the next mark March
and April, 1909, and so on.
In reply to a request to be furnished with our views hereon, I expressed
my pleasure at hearing that the Managers of some of the leading firms in New
Zealand realised the importance of the question, and were prepared to deal
with it practically.