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can is a hydrogen swell we are not justified in concluding that every other blown can
in the consignment is blown for that reason and that reason alone. Again, the contents
are more or less deteriorated, the conditions varying from softness and loss of colour
of the solids and opalescence of the syrup to complete disintegration of the food, and
therefore the consumer is not getting the product in the really sound condition he is
entitled to expect. Further, everybody who opens a can of food, whether in the home
or an hotel or restaurant or elsewhere, should know that a blown can is a potentially
dangerous can. This is the only safe rule; if we qualify it and say that hydrogen swells
are harmless and allow them to go into consumption, we cannot expect the housewife
or the cook to appreciate the difference between blowing from this cause and blowing
from a bacterial cause and she may well get the idea that, after all, she need not
worry if the can she is about to open is bulging at the ends, though of course she would
be annoyed to receive a shower bath of syrup when she punctured the cap.
It has been suggested that we should allow hydrogen swells to be vented and
resealed. This in my opinion would be a most discreditable proceeding for apart
from the uncertainty as to the cause of blowing, the can will certainly blow again
unless it goes into consumption very quickly, but worst of all, once we admit the
legality of venting blown tins, where is it going to stop and how are we to know when,
where and under what circumstances it has been done. If we permit this why should
not the retailer, going through his stock of canned goods and finding some blown,
just vent them and reseal them. The merchant would not knowingly accept hydrogen
swells from the canner neither would the retailer accept them from the merchant.
Why then should they expect us or the consumer to accept them ? No, the canner
must solve his own problem either by discovering how to prevent hydrogen swells or
arranging for such conditions and time of storage as will ensure his product being
retailed before symptoms of blowing are apparent, or discontinuing the canning of
foods which are particularly prone to develop this trouble, for, after all, they are mainly
luxury, rather than essential, foods.
For our part, we must stick rigidly to the principle that a blown can is a bad can,
and in support of this I may quote from the report on "The Corrosion of the Tin Plate
Container by Food Products" to which I have already referred. On the very first
page of the introduction the following sentence occurs in relation to hydrogen swells—
"The contents of such cans are not necessarily harmful, but since bulging may also
be due to bacteria or yeasts, they present a risk which no buyer is justified in taking."
Another point in the inspection of canned food to which very close attention
should be given is the "repaired" or "resoldered" can. It is true that a leak may
be detected at the time of packing and be dealt with on the spot, but how are we to
know whether the repair was effected then or at some latter stage in the history of the
can ? Again in regard to soldered vents, the majority of food stuffs are now put up in
sanitary-cap cans in which the lid is crimped on the exhausted can by a double-seamer
machine, no solder being used and no vent being required. A soldered vent in such
a can or more than one vent in the hole and cap type of can should excite suspicion
that there has been blowing, venting and resealing. We are justified in refusing
to pass any can in regard to which we have reason to suspect that the original sealing
has been broken, even if the contents have been reprocessed subsequently. On page
175 of the Annual Report of the Chief Medical Officer of the Ministry of Health for
the year 1933 the following paragraph occurs:—
"Canned Foods.
"Resoldered Cans.—From time to time canned foods, such as canned
tomatoes and canned pineapples, are received at ports showing evidence
of having been resoldered, and on further examination the cans may be found
to be blown and their contents not sterile. It may be contended by the
importers that the additional soldering has been carried out at the time of
sterilisation or has been done to correct soldering deficiencies at the time of
canning and has not been carried out at a later period in an endeavour to
remedy subsequent defects which have arisen as a result of imperfect canning
methods. In proper modern canning, however, adventitious soldering should