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128
The bacterial examination of ices has received a
large amount of attention during the year, two or three
of the Metropolitan Authorities having had careful
estimations made of the microbes present in samples
from various sources. It will be interesting to review
the information obtained.
Ice creams are of two kinds, in one, the cheaper
form, the basis is custard flavoured with essences or
jam, and in another, the dearer, cream and fruit are
the chief ingredients. In making the first variety the
ingredients, after being mixed, are boiled for so long as
may be necessary to obtain the proper consistency.
After cooling, for which several hours are allowed, the
mixture is frozen. In the cream variety the mass is
frozen as soon as the ingredients are thoroughly mixed.
In the custard variety all the microbes present in the
ingredients would be destroyed by boiling, and any
present in the finished article would be due to contamination
after such boiling. The danger of bacterial
pollution would here arise from dirty vessels used for
cooling or storage, and from the settlement of dust
from the places where it is cooled or stored. This
variety is the kind sold in the streets and is usually
made in the living rooms of the vendors. Supervision
of the homes of the makers and regulations as to cleanliness
of the vessels would reduce the chances of
dangerous pollution to a minimum. In the cream kind,
the dangers are rather greater, as the bacteria present
in milk tend to multiply whilst the cream is rising and