An Improved Method of Producing Sterilized Condensed Milk and other Substances.
Year: 1893

page_text: GUMI LEIM SPECIFICATION.
An Improved Method of Producing Sterilized Condensed Milk and
other Substances.
I, AUGUST FJELSTRUP, of Nybrogade 24, Copenhagen, Zoologist, do hereby
declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement :-
This invention has especial reference to a method of producing sterilized condensed
milk, but it is also applicable to the preservation of other articles of food or similar
substances.
Owing to the power possessed by certain germs of bacteria to withstand the
temperatures usually employed for sterilizing purposes, milk cannot be sterilized in
a perfectly satisfactory manner by heat alone without sacrificing the quality of the
milk, as the required temperature is so high, that the fresh taste of the milk is
destroyed.
Now this invention has for object to obviate this disadvantage and enable
condensed milk and other substances to be produced in such a manner that they
shall be effectually sterilized and rendered capable of being kept for a long time
without deterioration. For this purpose the milk or other substance to be preserved,
is sterilized condensed and bottled in an atmosphere of perfectly sterilized nitrogen.
The sterilized nitrogen may be produced, for instance, by passing atmospheric air
over incandescent copper shavings, whereby the air will be deoxidized and the
microscopic organisms contained therein will be destroyed.
In order that the nature of my invention may be readily understood I will proceed
to explain the method of producing sterilized condensed milk.
Fresh, carefully strained milk, is warmed, while exposed to a stream of sterilized
nitrogen, for a suitable time say for instance for about thirty minutes at a tem-
perature of from about 68° to 70° C., in order to destroy the developed bacteria
and a portion of the germs therein. The milk is then conveyed to a vacuum-pan
provided with a stirring apparatus, where it is condensed to a fourth or a third of
its original volume at a moderate temperature in a sterilized atmosphere of nitrogen.
A suitable temperature is from about 40° to 50° C. and 650-700 millimetres is a
suitable vacuum. The condensed milk thus obtained is then introduced into bottles
or other receptacles by means of apparatus such as that shewn in the accompanying
drawing. The air is exhausted from the receptacles by means of an air pump
through the tube A, which is provided with branches to all the receptacles which
are charged with sterilized nitrogen through a branch pipe C and the branch-
tubes b. The receptacles are then charged through the pipe B and branch pipes b
with condensed milk from the vacuum-pan, the sterilized nitrogen previously
introduced into the receptacles being simultaneously expelled. When the receptacles
are full they are closed by suitable stoppers.
Other substances can be sterilized and conserved in a similar manner.
By conducting these operations in sterilized nitrogen instead of in atmospheric
air, the germs of bacteria are prevented from developing even though they might
be able to survive the moderate temperature to which it is possible to expose the
substance without altering its properties or spoiling its appearance and taste.
Milk and other substances when treated according to this invention can be kept
for a long time without deterioration.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The herein described improved method
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page_text: and other similar substances which consists in sterilizing and condensing the milk
or other substance and charging it into receptacles in an atmosphere of sterilized
nitrogen in order to prevent the development of germs of bacteria that may not
have been destroyed by the process of heating, substantially as described.
Dated this 12th day of July 1893.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.