Improvements in the Process of and Apparatus for Manufacturing Powdered Milk.
Year: 1887

page_text: COMPLETE SPECIFICATION.
Improvements in the Process of and Apparatus for Manufacturing
Powdered Milk.
I, JOHN CARNRICK, of Mercantile Exchange Building, No. 6 Harrison Street, in the
City and State of New York, Manufacturing Chemist, 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 relates to the manufacture of powdered saccharated milk by evapora-
tion, agitation and granulation, at a low temperature, in a vacuum evaporating
apparatus.
Attempts heretofore made to produce powdered or granulated milk have not resulted
in commercial success and have not advanced beyond the experimental stage. Powdered
milk is therefore not known in the trade.
I have succeeded by my process in producing a cream white, dry, powdered or
granulated milk, free from stickiness or lumps, of a pleasant, sweet, milky flavor, and
possessing good keeping qualities. My powdered milk possesses all the constituents
and properties of fresh sweet milk and is therefore admirably adapted for all dietetic
and domestic purposes where fresh milk is now generally used. It is superior to fresh
milk in the fact that it keeps perfectly without deterioration and is as convenient and
agreeable to use as sugar.
In conducting my process, fresh cow's milk is first treated for the removal of one-
fourth, or other small fractional part (such as one-eighth or one-sixteenth) of its
cream; it is then placed in vacuum evaporating pan or cylinder, preferably provided
with a surrounding water jacket, and therein subjected to a low even temperature
of 140° F. to 160° F. during the early stage of the operation, and to agitation without
boiling. The milk is thus reduced to the condition of ordinary condensed milk or to
a thick syrupy consistency. At this stage of the operation, while the agitation is
continued, I add in a continuous stream, or periodically, granulated white sugar in
suitable proportion to make the mass friable and prevent balling or lumping. Toward
the last part of the operation, as the mass approaches the condition of powder, the
temperature is reduced to a degree between 120° and 130° F. to prevent coloration or
formation of caramel...

page_text: It is found in practice, that when liquids or semi-liquids are evaporated to the dry or
granular condition in ordinary pans, that they are liable to become discolored and given
a disagreeable flavor and be incrusted upon the steam coils and the hatch thus be spoiled
in consequence of the high temperature of the steam employed. The object of this part
of the invention relating to the apparatus, is to avoid these defects and for this purpose
I provide a cylindrical vacuum vessel, surrounded circumferentially by a water jacket,
for the circulation of hot water, so that a uniform and readily controlled heat of the
desired temperature, may be applied to all sides of the fluid or mass to be evaporated,
and connect with such jacket, supply pipes for hot and cold water and steam, and an
exhaust or overflow pipe. I also provide the evaporating cylinder with a central
longitudinal shaft having a connected spiral agitator and a longitudinal scraper blade
arranged to scrape the entire inner periphery of the cylinder, whereby milk and other
fluid and semi fluid substances may be so agitated as to prevent cohesion or
agglutination into an unmanageable mass, and be readily brought to a powdered or
granular condition.
Having stated the nature of my invention, I will now describe the vacuum
evaporating apparatus for carrying out my process, by reference to the accompanying
drawing in which the Figure 1, represents a vertical, longitudinal section of the
evaporating cylinder with the condenser and exhaust pump in elevation. Figure 2,
represents a detached perspective view of the scraper blade.
The cylindrical evaporating chamber A, may be made of copper or other snitable
metal, and has riveted to its ends, the heads a, which are of larger diameter and project
circumferentially a sufficient distance to connect with the larger outer cylinder or
jacket B, to which they are riveted by an outwardly turned flange. The jacket B, is
enough farger than cylinder A, to form between them a circumferential water space X,
of several inches-more or less-depending upon the size of the apparatus. The
dome C, is arranged centrally at the top of the evaporator and is riveted to the inner
and outer cylinders and connects with the exhaust pipe I, leading to the usual
condenser S. and pump T. Pipe 1, is provided with the usual overflow chamber F,
and depending stop-plate e and chamber E, has at the bottom a removable closing
plate or door . The head, is provided with an opening near the bottom of cylinder A,
closed by a door, having means for tightly securing it to its seat; this opening serves
for the removal of the dried contents of the evaporator. An opening and door may be
provided in each head of the cylinder. An opening and door, not shown, should be
provided for feeding in the granulated sugar at the proper stage of the operation,
hereinafter described. A hot water supply pipe I, having valve 7, connects with the
under side of jacket D, and a cold water supply pipe K, having valve k, connects, by a
bent portion inclined towards the jacket, with pipe I. A steam supply pipe P, having
valve p, also connects with the jacket. Overflow pipe G, connects with the
side of the jacket for the escape of water to keep up the circulation in the jacket.
A milk supply pipe F, having valve g, projects through the jacket and connects with
cylinder A.
upper
The shaft D, of the agitator, passes centrally through the heads a, in suitable stuffing
boxes and extends longitudinally through cylinder A. It is provided with radial arms
or spokes i, arranged spirally from end to end, and such spokes stop preferably, several
inches short of the inner surface of cylinder A, and have secured to their outer ends,
the spirally twisted blade H, which may be either wider or narrower than represented
in the figure of the drawing. One or more agitator blades may be secured to the
spokes i, inside of blade H, and nearer to shaft D, and one or more blades may be
spirally twisted around the shaft in the opposite direction to the blade D shown, so as
to form a double spiral agitator operating to carry changing portions of the liquid or
material under treatment, in opposite directions at the same time. It is apparent that
with a single spiral blade, changing portions of the liquid or condensed material, will
be positively forced toward one end of the cylinder, and then back by counter or return
currents. In addition to the spiral blade or blades, I provide one or more straight (or
if desirable slightly curved) scraper blades M, secured to the outer ends of spokes,
so as to almost touch the inner surface of cylinder A, from end to end, and operate to

page_text: keep its entire surface clear of adhering particles, which are liable to accumulate
without such scraper.
The blade M, is beveled at its outer edge m, so as to readily cut through any hard
or gummy portions which it might encounter. The shaft D, is to be provided, at
one or both ends, with a cog or belt wheel and connected with suitable operating
gear.
Important advantages are gained by entirely surrounding the evaporating and
drying cylinder with a water-heating jacket, as the liquid or other material is thus
subjected to a uniform low temperature on all sides, which will act efficiently and
rapidly but not injuriously.
In operation, hot water is admitted in regulated quantity to the annular space X, by
pipe I, and in order to heat or maintain the water at a higher temperature, steam may
be admitted to the jacket by pipe P. Should the temperature in the cylinder rise too
high, cold water is admitted to the jacket, in regulated quantity by pipe K. Hot and
cold water may be simultaneously admitted in graduated quantities or proportions to
the jacket by pipes I and K, and the excess be gradually conducted off at the top, by
overflow pipe G, which will be provided with a controlling valve. Since water is
admitted under pressure at the bottom, and is taken off at the top, the space X, between
the cylinders is kept full and imparts heat to the entire surface of cylinder A.
When it is desired to cool the contents of cylinder A, the steam and hot water
are shut off, and cold water alone is circulated through the jacket space.
A suitable quantity of milk to form a charge or batch adapted to the size of
evaporator in use, is first treated in a manner well-known for extracting one-fourth or
less (as one-cighth or one sixteenth) of its cream and is then admitted by pipe E to
the evaporating cylinder. The cylinder may have been warmed up by the admission
of hot water (below the boiling point) to the jacket, and the exhaust pump slowly
started before the admission of mulk to the cylinder. After the milk is well warmed,
the agitator is slowly started. The exhausting and condensing apparatus is kept in
operation till the batch under treatment is completely dried and granulated. The
temperature is maintained at a low degree-from 140° to 160° F.-and the agitation
continued until the charge is brought to a thick syrupy consistency, much like ordinary
condensed milk. An important part of my process is now commenced and is as
follows White cane sugar, preferably in a fine granular condition, is gradually fed
into and thoroughly mixed with the partially concentrated batch and soon causes it to
lose its vicid characteristics and become friable, and as the heat and agitation are
continued, to assume the granular condition. The sugar crystals or granules become
permeated and coated with the rich thick milk, and before the sugar can dissolve, the
whole batch quickly assumes the granular form, and is readily worked by the spiral
agitator. Except for the addition of the granular sugar or its equivalent granular
matter at the stage of the process named, the thickened milk would become sticky and
lumpy and adhere to agitating arms and blades, or roll around the evaporating chamber
in a large coherent mass which is impossible to successfully work and dry out so as to
give satisfactory results. As the batch thickens the temperature is gradually lowered
and as it approaches a granular condition the temperature is maintained at from 120°
to 180° F. This precaution is desirable, in order to prevent coloration or destruction
of the fine milk flavor which is a characteristic of the powdered milk made by my
process. Sugar is used in the proportion of thirty to fifty per cent. by weight, of the
batch of milk treated and is sufficient to secure the advantageous granulation above
described and to preserve the milk for an indefinite time. The evaporation is continued!
till the batch is brought to a dry granular condition, when it may be readily removed
from the cylinder or pan.
When taken from the pan it is of nearly uniform grain and
constitutes a marketable article of powdered milk. It can be used directly for many
purposes without further treatment, but in order to complete the process and give the
inilk a
more pleasant appearance the granular powder is ground very fine in a
revolving burr stone mill, or other suitable mill. The ground powder may be separated
into grades of different fineness by running it through fine mesh sieves or bolting

page_text: cloths similar to flour bolts. The finer grades of powdered milk made by my process
are in the form of a light, soft, smooth, powder resembling in touch and appearance
the finest confectioner's powdered sugar or wheat flour. It has a rich moderately
sweet taste, resembling the flavor of fresh sweet milk, though somewhat sweeter than
ordinary milk.
My powdered milk has been subjected to severe tests to ascertain its keeping qualities;
for instance, it has been exposed to moist air at a temperature of 115° to 120° F. and
has been exposed for months in the open air under varying degrees of temperature
without affecting its fine flavor and appearance. Instead of white granulated sugar
to cause the condensed milk to granulate, the dry granulated milk previously produced
may be used with good results. Malt sugar, grape sugar, and milk sugar, all in a dry
granulated condition, may be substituted for cane sugar. Mixtures of the above
mentioned sugars with each other and with cane sugar may also be used in the same
manner above described with. reference to cane sugar, for causing granulation of the
condensed milk. I do not limit myself to the removal of a portion of the cream from
the milk in carrying out my process of producing powdered milk, as good results may
be obtained without such removal. The powdered saccharated milk is well adapted for
use like sugar, and can be conveniently handled on the table for addition to tea, coffee,
chocolate and other beverages. In order to meet the popular demand and better adapt
it for army and navy use, the powdered milk is compressed or moulded into tablets,
cubes, or lozenges, so that it can be used like lump or cube sugar, for addition to
beverages.
Elegant preparations are manufactured for making instantaneous beverages, such as
coffee, chocolate and cocoa, by mixing powdered milk with extract of coffee, or
powdered chocolate, or powdered cocoa, and putting the powdered mixture up in cans
or bottles for the trade.
pung
Aren
Delicious beverages can be quickly and conveniently made by adding hot water to
the desired quantity of powder. Powdered milk is perfectly adapted for making
-cream, and for all culinary purposes where milk
vions confections
and sugar are used. It can also be advantageous
such as maccaroons, nougat, cream bon-bons, wafers, marsh mallow tablets, anu many
others, in which powdered sugar is now generally used.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is :-
1. The process of manufacturing granular or powdered milk which consists in
evaporating the fresh milk at a low temperature in vacuo, to a syrupy consistency and
then while subjected to continuous agitation, adding a granular substance, as one or
more of the different kinds of sugar, and continuing the evaporation and agitation till
the batch is brought to a condition of dry granular powder.
2. The process of manufacturing granular or powdered milk, which consists in first
removing a portion of the cream of sweet milk, then evaporating it at a temperature
at or above 140° F. but without boiling; subjecting the partially condensed charge to
agitation and adding sugar in granular form, and continuing the evaporation till the
charge is brought to a dry granular powder.
3. The process of producing dry powdered milk, which consists in evaporating sweet
milk, in vacuo, at a low temperature with agitation, adding to the partially condensed
charge a granular sugar and continuing the evaporation till the batch is brought to
a dry, granular condition, and then grinding it to a fine powder.
4. A vacuum evaporating vessel having a surrounding water jacket, and the connected
water discharge and supply pipes, arranged to maintain a circulation of water in the
jacket around the evaporating chamber, in combination with means for keeping the
circulating water hot and the exhaust or vacuum apparatus, as and for the purpose
described.
5. In combination with an evaporating vessel having a surround water jacket, the
water discharge and supply pipes suitably connected, as described, to maintain a

page_text: circulation of water in the jacket around the evaporating chamber and a steam
supply pipe connecting with the jacket for keeping the circulating water hot, as
described.
6. In combination with an evaporating vessel having a surrounding water jacket, a
hot and a cold water supply pipe, having valvos and connecting with such jackot below
its top, and overflow discharge pipe leading from the top of such jacket, for maintaining
a circulation of water therein.
7. A water-jacketed cylindrical vacuum evaporator having a shaft and spirally twisted
agitator blade, whereby all portions of the liquid or other material under treatment,
may be subjected to a gentle heat on all sides.
8. A cylindrical vacuum evaporator, having a shaft and spirally twisted agitator
blade, and a scraper secured adjacent to the inner surface of the cylinder, upon arms
projecting from the agitator shaft.
9. A horizontal cylindrical vacuum evaporator having an agitator and a scraper
blade connected to the shaft and placed adjacent to the inner surface of the cylinder for
keeping it clear of adhering particles, as described.
10. A cylindrical evaporator, having a surrounding water jacket, whereby the
evaporator and its contents may be heated on all sides, in combination with a revolving
scraper blade connected with a central shaft.
11. A cylindrical evaporator, having a surrounding water jacket and means for
maintaining a circulation of hot water in such jacket, in combination with a spiral
agitator and a connected vacuum apparatus, for the purpose described.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.