An Improved Process of Sterilizing or Pasteurizing Milk . and Cream.
Year: 1896

page_text: Date of Application, 18th Aug., 1896-Accepted, 14th Nov., 1896
COMPLETE SPECIFICATION.
An Improved Process of Sterilizing or Pasteurizing Milk
.
and Cream.
We, LORENZO GUSTAF FAGERSTEN, Chemist, of 143 W. Garfield Boulevard
and CLAUS FERDINAND PETERSON KORSSELL, Physician, of 1012 E. Garfield
Boulevard both of Chicago, in the County of Cook and State of Illinois, United
States of America, do hereby declare the nature of our invention, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
The objects of our invention are to provide a simple and inexpensive process for
sterilizing or pasteurizing milk, modified milk or cream, whereby the same is
adapted to remain chemically unchanged, an indefinite length of time, and,
furthermore, to furnish means for proventing the agitation or churning of the
said sterilized product while being handled or shipped.
We accomplish the above as follows:-
The article to be subjected to our process is placed at ordinary temperature in a
receptacle of the desired size and a sufficient quantity of some suitable hydro-
carbon, melting ouly at moderately high temperatures, such as wax or paraffine,
is added thereto to form, when melted, a layer completely covering the top of the
liquid.
Care is taken in filling the receptacle to leave a space at the top thereof for a
volume of atmospheric air proportionate to the volume of liquid treated, which is
sufficient to supply a pressure in said receptacle at all times during the subsequent
steps of sterilization exceeding the vapour tension therein by one or more
atmospheres. That is, the volume of air permitted to remain in the receptacle
will cause a pressure greater than the vapour tension generated during the
heating process for effecting sterilization, whereby the liquid is prevented from
boiling.
Since in the sealed receptacle the pressure will increase approximately as the
volume of contained air is decreased, according to well known laws, the
proportion which the volume of liquid to be sterilized bears to the volume of
superimposed air must be such, that the expansion caused by heating will
produce the excess of pressure spoken of above, and the degree of filling
various receptacles must necessarily vary with the shape or formn thereof.
After the receptacle has been hermetically sealed, it is subjected to the action of
beat whereby the sterilization is effected, the heating of said receptacle and its
contents being so regulated that the conductivity of the substance subjected to
the process shall not be exceeded. In other words, by reason of gradual and
carefully regulated heating, the liquid is not subjected during the sterilizing
process, to sufficient heat to scorch or burn the same, and thereby seriously alter
the character of the sterilized product. The degree of heat required varies with
the length of time it is desired to preserve the liquid and ranges from 140 degrees
Fahrenheit to 230 degrees Fahrenheit.
The beating is gradually increased until the liquid reaches the requisite
temperature, all mechanical agitation being carefully avoided to prevent the
Beparation of butter or fats from the liquid. The receptacle and its contents
after being properely subjected to the requisite temperature are rapidly cooled,
the paraffine or wax almost immediately forming a solid covering or layer
upon the top of the sterilized liquid, which, under all ordinary circumstances,

page_text: will thereafter prevent the separation of butter or fats from the liquid which
the sterilizing process ordinarily renders more likely to occur.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. The process of sterilizing or pasteurizing milk, modified milk or cream by
heating it in hermetically sealed receptacles, the said receptacles being charged
with a superimposed volume of air sufficient to develop a pressure exceeding by
one atmosphere or more the vapor tension generated at any stage of the process
and at any temperature used, thus preventing any vaporizing of the article under
treatment, substantially as described.
2. The process of sterilizing and preserving milk, modified milk, or cream,
which consists in placing the article to be treated in receptacles together with a
hydrocarbon of high melting point, such as paraffine or wax, hermetically sealing
the said receptacles with a volume of air contained therein and subjecting the
receptacles to heat which is so regulated as not to exceed the conductivity of the
article under treatment in any portion of said receptacle or during any stage of
the process, substantially as described.
Dated this 29th day of July 1896.
LORENZO GUSTAF FAGERSTEN.
CLAUS FERDINAND PETERSON KORSSELL.
Haseltine, Lake & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.