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87
Canned Sardines: Lead.—Fourteen samples of sardines of Portuguese
origin comprising 5 different brands were analysed and found to contain lead, in
quantities varying from 4 to 25 parts per million; the three samples which
contained 15 or more parts per million were all of the same brand and were
obtained from a stall in the market. The entire stock in question was surrendered
and destroyed, and other Authorities were notified. The quantities of lead
found in the samples of other brands were also undesirably high and as I have
pointed out in the Report for 1935, this contamination can and should be
prevented.
Canned Salmon.—A sample of canned salmon was examined, following a
complaint that the salmon contained broken glass. Several small crystals
varying in size from l½ to 3 mm. long and about ½ mm. thick were found
embedded in the flesh, chiefly near to the bone. These crystals were quite hard
and sharp and might have been mistaken for broken glass, until magnified, when
their uniform orthorhombic form could be seen. Analysis showed them to
consist of magnesium ammonium phosphate, identical in form and composition
with the mineral struvite.
Crystals of this substance have been found before in canned fish, and
excepting possibly through causing discomfort in the mouth would be unlikely
to be injurious to health, since they would at once dissolve in the acid contents of
the stomach. They are formed presumably by the combination of ammonia,
which appears soon after the fish is killed, with the magnesium salts and phosphates
naturally present, and being insoluble in neutral or alkaline solution,
gradually crystallize out in the flesh ; their presence suggests that the salmon
may have been kept, possibly in cold storage, for a time before being canned.
Lobster Paste.—In view of a complaint that a pot of Lobster Paste was sour and
fermenting, a bacteriological examination was carried out on the sample in
addition to the chemical analysis; no grow th of any kind could be obtained,
however, the sample being apparently sterile; furthermore, the taste, although
highly seasoned, was in my opinion quite normal, and the small air bubbles in the
sample, to which attention was called, appeared to have been incorporated in the
mixing; such air spaces are frequently to be seen in pastes of this type. The
sample was accordingly regarded as genuine.
Sweets. Clear Mints.—A question arose as to the amount of sulphur dioxide
permitted by the Preservative Regulations in boiled sweets. Not being specifically
mentioned in the Schedule, these sweets may only contain that proportion
of a preservative which has been necessarily introduced by the use of legitimately
preserved ingredients in their manufacture; during the process of boiling
however, the greater part of the preservative used, sulphur dioxide, is evolved,
and opinions differ as to how much may be allowed in the finished sweets.
A sample of "Clear Mints" was found to contain 130 parts per million of
sulphur dioxide and an analysis of the composition of the sweets indicated that