Improved Method of or Process for the Preparation of Condensed Milk.
Year: 1891

page_text: Date of Application, 24th Mar., 1891-Accepted, 15th Aug.. 1891
COMPLETE SPECIFICATION.
Improved Method of or Process for the Preparation of Condensed
Milk.
I, Dr. CASIMIR BARON LESSER, of 26 Sienna Warsaw, Russia, 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 for object, a process for condensing milk characterized by
never allowing the pure milk skim milk, cream and sweet milk to reach during the
condensation process an acidity of 55, in which process, I use red or yellow light
in the vacuum apparatus. The milk in the preliminary process is decomposed or
separated into cream, caseine, and milk scrum, the cream being mixed or joined
again with the milk serum, with the addition of milk sugar.
For the proper working of the dairy as well as to increase the use of milk
throughout the commercial world, it is necessary to convert the same from the
liquid form, in which it is not readily transportable and is moreover liable to dete-
riorate, into the solid form. All the experiments hitherto made to attain this
object have been fruitless owing to the condensed article not dissolving freely in
water, having lost its taste or become physiologically inferior.
As soon as the caseine in the milk is separated therefrom either by means of
precipitants, or by spontaneous coagulation, the milk loses its solubility in water
and if this solubility is restored by the aid of chemicals, changes occur which have
an injurious influence upon the taste of the solution or impair the digestion of
those who consume such milk.
The following well known facts may here be mentioned.
1. That cow's milk always reacts both ways, that is to say, acid and alkaline at
the same time.
2. That the acid in the milk is fixed by filtering the milk through ordinary
solutions of potash or soda.
3. That the quantity of acid in the milk can be accurately ascertained according
to the method of Soxhlet and Henkel of Munich, by means of of normal soda
lyes, 50 cub. centimeters of milk being decomposed by 2 cubic centimeters of a
2% solution of phenolphtalein and normal soda lyes being added thereto until the
liquid acquires a pink hue and thus loses its pure white colour.
4. That fresh ordinary cow's milk treated by the process mentioned under
heading 3, requires about 35 cub. centimeters of normal lye per 50 cub. centi-
meters of milk, for the final reaction to be exhibited and hence has, according to.
Soxhlet and Henkel, an acidity of 3.5.
These facts are known and contain nothing new.
It is further well known that by "acidity" the acid contents, or better the acid
action of the milk is meant which according to Soxhlet and Henkel amounts to 3.5
for fresh cow's milk.
I have discovered that the cause of insolubility of the condensed milk hitherto
prepared lay in the natural acidity of the milk which increases as the water is being
extracted in the course of the condensing process and has for its unavoidable result
an automatic precipitation of the caseine in vacuo, while as, has been demonstrated
by scientific researches, milk which has an acidity of from 5.5 to 6.5 (Söxhlet-
Henkel) does not bear boiling, while when it acquires an acidity of from 15 to 16
an automatic coagulation takes place without the application of heat.
Accordingly, I take care that when the milk is condensed in vacuo, the same
should never reach the limit of 55 of acidity, whereby the solubility of the con-
densed product in water is maintained, even when the milk is thoroughly dried up.
D
47

page_text: I have further discovered that in the condensation of milk as well as in many
albuminous substances, the photographically acting colours of the spectrum or of
the daylight upon the restoration of solubility in the final product, have an injurious
influence, and hence, I take care that the condensation shall be effected in a red or
yellow light, and I make the sight glass of the vacuum apparatus which is
indispensable in order to watch the progress of the process of red or yellow glass.
Finally I do not raise the heat in the vacuum apparatus beyond 75° C. as
otherwise the condensed product takes the taste of having been boiled.
In this manner pure milk as well as skim or whey milk and cream may be
condensed. In order however to obtain a condensed product the composition of
which is similar to pure milk I subject before condensation cows fresh milk to the
following treatment.
The milk is freed by a centrifugal machine from the impurities which it may
contain and separated into cream and skimmed or whey milk. From the whey
milk obtained I carefully precipitate the cascine by means of rennet or other
precipitant or by means of a centrifugal machine (while using suitable filtering
material) while the excess of rennet ferment is rendered inactive in the milky
serum (sweet milk) obtained by heating the same to a temperature of from 60° to
75° C. The cream is now mixed again with the milk serum and milk sugar is
added thereto.
The milk prepared in this manner is of analogous composition with the new fresh
milk and is condensed to a suitable consistence in a vacuum apparatus while
observing the conditions hereinbefore set forth or it may be dried in order to be used
in the form of a powder.
The essential feature of my invention is that by condensing the milk, the
condensed product never attains during condensation a bigher acidity than 55. As
in the process of condensing, the water is as a matter of course removed from the
milk, the acidity increases as the process continues. To prevent however the
acidity of 55 (according to Soxhlet and Henkel) to be exceeded, I add to the milk
such substances as are capable of saturating any excess of acidity, that is to say, of
neutralizing the same. For this purpose I select substances which already exist
in the natural milk, namely, caustic or carbonated alkalies, alkaline earths, lime and
magnesia, or their combinations with carbonic acid.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The process for condensing milk characterized by never allowing the pure
milk, skim milk, cream and sweet milk to reach during the condensation process an
acidity of 5-5.
2. In the process above claimed the use of red or yellow light in the vacuum
apparatus.
3. In the process above claimed the preliminary treatment of the milk in such a
manner that the same is decomposed or separated into cream, caseine and milk
serum, the cream being mixed or joined again with the milk serum with the addition
of milk sugar.
Dated this 3rd day of March 1901
H. GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said Dr. Casimir Baron Lesser.
H. GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said Dr. Casimir Baron Lesser.