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———
TREASURY DEPARTMENT
UNITED STATES PUBLIC HEALTH SERVICE
HUGH S. CUMMING, SuRGEON GENERAL

STUDIES OF RECONSTRUCTED
MILK

ALBERT F. STEVENSON
Sanitary Engineer

GEORGE C. PECK
Scientific Assistant
AND
C. P. RHYNUS

Assistant Sanitary Engineer
United States Public Health Service

REPRINT No. 608
FROM THE
PUBLIC HEALTH REPORTS
AUGUST 27, 1920
(Pages 2011-2045)

WASHINGTON
GOVERNMENT PRINTING OFFICE
1920

ADDITIONAL COPIES

OF THIS PUBLICATION MAY BE PROCURED FROM
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oreveer

®e,?

STUDIES OF RECONSTRUCTED MILK.!

By ALBERT F. STEVENSON, Sanitary E eer; GEORGE C. PEcK, Scientific Assistant; and C. P,
RHYNUS, Assistant aaa ngineer, United States Public Health Service.

FOREWORD.
By EARLE B. PHELPS, Consultant, United States Public Health Service.

Pure milk contains a variety of substances, which, for convenience
in analysis and reference, are conventionally divided into three groups:
Fats, solids not fat, and water. The proportions of these three groups
in the mixture vary with the breed of cattle, the feed, the season, and
other variable conditions, but it will be sufficiently accurate for the
present purposes and for illustration to say that normal milk contains

4 per cent fats, 9 per cent solids not fat, and 874 per cent water.

At a time when, in the interests of food conservation, the possibili-
ties of desiccated foodstuffs are being developed and their economic
advantages exploited, it is unnecessary to dwell at length upon the
purely economic benefits which would accrue were it possible to deal
with the milk supply of the country and, especially, with its problems
of storage and transportation, upon a water-free basis.

Desiccation in general has two principal advantages: It reduces the
weight of the commodity, thereby simplifying the problem of distri-
bution; and it improves the handling and keeping qualities of perish-
able foods by doing away with the watery environment necessary for
microbial activity. These advantages make it possible to distribute
foodstuffs over wide geographical areas and thus to provide markets
for those regions in which production is deficient or lacking. They
also make possible a seasonal distribution or leveling, whereby the
commodity may be carried over from a season of excessive production
into a season of nonproduction.

To these manifest advantages, which are common in the entire field
of desiccated food, there is added, in the case of milk supplies, a third
of equal if not greater importance. This has reference to the sani-
tary aspects of the milk problem, which have so occupied the atten-
tion of public-health workers in recent years. Milk provides so favor-
able a medium for the growth and multiplication not only of normal
and relatively harmless bacteria but also of the specific organisms of
disease that the entire development of this important food supply,

‘ Made under the supervision of Earle B. Phelps, Consultant, United States Public Health Service,
Reprint from the Public Health Reports, vol. 35, No. 35, Aug. 27, 1920, pp. 2011-2045.
3

4 STUDIES OF RECONSTRUCTED MILK,

especially as it relates to large cities, has been impeded and very
seriously complicated by the necessary public-health restrictions. The
storage and shipping of milk must be done at low temperature and
can not extend beyond a few days at most, and pasteurization has
come to be a recognized essential feature in the handling of a city
milk supply.

If, now, it were possible to desiccate the product in its fresh con-
dition by a process which would greatly reduce the existing bacterial
life and prevent the further multiplication of the surviving organisms,
the limitations referred to would in large measure disappear.

The actual realization of these conditions and the possibility of
supplying to a community a milk reconstructed from its previously
desiccated components and water, have been made possible by a
series of steps, the commercial development of which has been taking
place for many years. These are the mechanical separation of the
fats in the form of cream from the skimmed milk, and modern proc-
esses of butter making; the development of processes, first, of
skimmed milk evaporation, and, finally, of complete desiccation
to a powder containing, in readily soluble form, all the milk solids
except the fats; the development of mechanical means of emulsi-
fying butter fat in water or skimmed milk solution, thus reconstruct-
ing the cream; and, finally, the conception of reconstructing a whole
milk, by emulsifying butter fat into a solution of milk solids of proper
strength.

This paper is a report of what is believed to be the first experiment
upon a commercial scale with reconstructed milk. While the advan-
tages of the plan, under many conditions, are so obvious that the
idea had frequently been discussed, there were at the outset of this
investigation certain difficulties to be overcome. In order to prevent
fraud and protect health, it has been necessary for the States and
the Federal Government to enact food laws which prohibit, in large
measure, modification of natural food products. This raised the
question of the propriety of the proposed procedure, which admit-
tedly makes fraud, in the terms of the pure food law, easy and its
detection difficult.

The particular situation which has been created by the possibilities
of reconstructed milk is without precedent, and, as it deals with one
of the most fundamental of the human foods, a most conservative
attitude upon the part of the officials charged ai the enforcement
of the pure food laws has very properly been maintained. In view,
however, of the tremendous advantages which are foreseen in aie
development of this field, it is believed that the problem must be
handled entirely upon its own merits, and with the utmost frankness.
There can be no question of the impropriety of handling reconstructed

STUDIES OF RECONSTRUCTED MILK. 5

milk, except under its own label and with complete information as
to its source and method of preparation. If it can be shown, however,
that reconstructed milk can be marketed in a community uncer
cleaner and safer conditions and at less cost than can ordinary milk,
the consumer is entitled to these advantages just as he is also entitled
to know exactly what he is purchasing, and, if he prefers to use fresh
cows’ milk, to be assured that he receives that for which he asks and
pays.

A second possibility which has prevented more active development
of reconstructed milk has been the fear that the public might be
slow to appreciate its advantages and reluctant to give up a part
of the dietary so well established as milk in favor of what must
appear to be a sort of manufactured product. While this argument
will carry no weight whatever among physicians, dietitians, and
others competent to look into the subject with sufficient thorough-
ness, it is a matter to be reckoned with most thoughtfully by one
who would undertake the commercial development of a market for
reconstructed milk.

In the situation which arose at the new Government city of Nitro,
W. Va., both of these objections lost most of their force. A city
to house some 25,000 people was being built overnight, and was
without any visible milk supply, nor did it seem probable that a
sufficient supply of safe milk could be obtained. The health admin-
istration of this city was to be in charge of the United States Public
Health Service, so that there could be no question of conflict: with
traditional health regulations. The conditions made it unnecessary
to fear competition with normal milk, so that it was practically
assured in the beginning that, if the milk was satisfactory, a market
would be secured. Under these favorable conditions a plan which
had been gradually maturing was put into effect, and the present
paper is a report of the results obtamed. Unfortunately for this
particular purpose, the experiment had to be discontinued before
the complete data that were hoped for had been gathered. It is
believed, however, that the results obtained are of so great impor-
tance that the outcome of this first commercial demonstration of
the possibilities of reconstructed milk should be recorded.

Mr. Stevenson designed the plant and prepared the specifications
for the mechanical equipment and has been wholly responsible for
the planning and execution of the experimental work. He has been
ably assisted throughout by Mr. Peck who was in resident charge
during the construction period, and who, in the capacity of super-
intendent, was directly responsible for the operation of the station.

Mr. C. P. Rhynus made the bacteriological studies, and Mr. Leslie Z.
Peck served as assistant superintendent.

6 STUDIES OF RECONSTRUCTED MILK,

I. THE MANUFACTURE AND HANDLING OF RECONSTRUCTED MILK AT
NITRO, W. VA.

By ALBERT F. CHEV ENON, Sanitary Engineer, and GEorGE C. Prck, Scientific Assistant, United States
Public Health Service.

Introduction.

Nitro, W. Va., is located on the Kanawha River, about 13 miles
from Charleston. It.was built by the United States Government to
house the laborers and mechanics employed in building the United
States Explosives Plant C and later to house persons permanently
employed in the smokeless-powder plant. Accommodations were
made for about 25,000 inhabitants. The several institutions and
industries necessary to form a well-organized community, such as
schools, churches, hospitals, department stores, restaurants, water
supply, sewerage, abundant food supply, etc., were provided. In
short, a modern city was constructed on the land surrounding the
explosives plant.

The construction of this city and the organization of the various
necessary secondary industries was accompanied by many difficulties
which were increased by war-time conditions. The gathering together
of sufficient food of satisfactory quality proved to be one of the
serious difficulties, and radical departures from current practice
were made in order to overcome them. One of the most interesting
and instructive divergencies was made in securing a sufficient
quantity of fluid milk to satisfy the demand. The present article
deals with this part of the work.

Available Normal Source of Milk.

Very little milk is produced in West Virginia in the vicinity of
Nitro. The region is mountainous and little if any natural pasturage
is available. In fact, previous to the building of the various Govern-
ment industries located in this section, hardly enough local milk was
available to supply the normal Charleston market. Up to the time
Nitro was conceived, little attempt was made to increase the supply.
Some milk was shipped in from the dairy section of Ohio, but with
the advent of war, the scarcity of milk and the congestion of railroad
traffic made this source undependable. The United States Public
Health Service was called on to suggest some method of procuring a
milk supply for Nitro.

Reconstructed Milk Products.

For some time it has been known that a liquid closely resembling
milk and cream could be made by emulsifying butter fat obtained
from unsalted butter in a solution of skimmed milk powder or diluted
evaporated skimmed milk. This procedure has been very widely

STUDIES OF RECONSTRUCTED MILK, 7

used by the ice-cream industry and has been sanctioned for this pur-
pose by the pure-food officials. This liquid has also been made in
small quantities at some Army field hospitals, and on several of the
battleships to furnish a supply to the officers’ mess. It has been
made at various dairy and milk shows as a means of advertising
milk powders.

The manufacture of reconstructed products on a small scale led to
the assumption that a fairly large-séale plant could be successfully
operated and the milk supply of a city the size of Nitro manufac-
tured. After conferring with officials of the department of health
and sanitation and the commissary department at Nitro, it was
decided to recommend the building and equipping of a plant of suffi-
cient capacity to supply the entire city with reconstructed milk and
cream. It was certain that milk could be made which woeld be
satisfactory if consumed within a few hours of the time of manufac-
ture; but little, if anything, was known about the cost of manu-
facture, the method of handling, and the keeping qualities of the
products.

In order to make a thorough investigation of the subject and at
the same time supply Nitro with milk, the Public Health Service
undertook to design the plant and superintend its operation as long
as the process was in the experimental stage. An equipment was de-
signed which, it was estimated, would handle 2,000 gallons of bottled
milk in an eight-hour day, and which capacity could be increased to
3,000 gallons per day by the addition of another pasteurizing and
emulsifying unit. Milk and cream could be handled in either bulk
or bottled form, although equipment of sufficient size to bottle all
the output was provided. It was expected that all milk sold, except
that used for cooking, would be served in bottles.

Description of Building.

The ‘‘milk plant”? was located in the south end of the reserva-
tion in a one-story frame building 150 feet long and 51 feet wide.
This same building also housed a small cold-storage warehouse used
by the commissary department for the storage of perishable foods.
The space allotted to the manufacture of reconstructed milk was 123
feet long and 51 feet wide. This space was somewhat excessive, but
on account of the experimental character of the work, extra room
was provided. The general plan of the building is shown in Figures
1 and 2, and a sectional elevation in Figure 3. The building was
divided into eight rooms: A milk manufacturing room; a room for
the washing of containers; cold-storage space for milk and butter;
a dressing room; a storage room for milk powder; an office; and a
room for the refrigerating machinery.

STUDIES OF RECONSTRUCTED MILK,

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The milk room was 40 feet long and 50 feet wide. In the south-
west corner was located a balcony, elevated 8} feet from the main
floor. This balcony was 27 feet long and 17 feet wide. An emer-
gency exit from this room to the west platform was provided, but it
was kept locked while the plant was in operation.

The washing room was 35 feet long and 50 feet wide. In the south-
west corner of this room was located a platform 8 by 18 feet, raised
about 6 inches from the main floor. It could be entered from both
outside platforms.

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The refrigerator was 30 feet long by 23 feet wide. It could be
entered from the milk-manufacturing room through a single refrig-
erator door, or from the east platform through two doors and a
vestibule. The room was large enough to store one day’s output of
the plant, together with a carload of ice.

The butter-storage room was 30 feet long by 9 feet wide. It could
be entered only from the milk-storage room. This room was large
enough to store two carloads of butter. Both of the cold-storage
rooms were insulated with rock cork and were plastered inside with
cement plaster. They had an available head room of 6 feet 7 inches.

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Public Health Reports. Reprint 608.

Fig. 4.—Manufacturing and bottling room, Reconstructed Milk Plant, Nitro, W. Va.

Fig. 5.—Mixing vats and emulsors, Reconstructed Milk Plant, Nitro, W. Va.

STUDIES OF RECONSTRUCTED MILK. ES

The dressing room was approximately 15 feet square, and could
be entered from the washroom. It contained hand bowls and toilets
and lockers for clothing.

The room for the storage of milk powder, which was 20 feet by 16
feet, was of sufficient size to store 100 barrels.

The office was 16 feet square and contained a desk, chairs, a table,
and a telephone. The office could be entered from the outside and
also from the washing room. ‘This outside entrance was the only
entrance used by those not employed at the plant.

The room containing the refrigerating machinery was 30 feet long
by 154 feet wide. The floor of this room was at the ground elevation
and could be reached by a short stairway leading from the milk room.

The main floor of the building was made of heavily reinforced con-
crete, and was elevated about 5 feet above the ground level. It
extended 8 feet beyond the walls of the building on either side,
forming concrete receiving and shipping platforms. All rooms, with
the exception of the office and the milk-powder storage room, were
supplied with floor drains connected to the sewer.

The inside finish of the rooms consisted of a 5-foot wainscoting of
cement plaster over metal lathing extending around the base of the
walls. Above this wainscoting the walls were finished with matched
siding. Plaster board was nailed to the rafters to within 10 feet of
the peak of the roof. At this point the plaster boarding was carried
across to the opposite rafters, forming a horizontal ceiling with an
air chamber above. The wainscoting was tinted a dark blue-gray,
and the walls and ceiling were painted with white enamel over flat
white. The inside of the refrigerators was painted with white enamel
over flat white. This color scheme proved to be practical and very
pleasing in appearance.

The milk room and wash room were ventilated by means of five
ventilators operated by natural draft. These ventilators extended
through the roof into the air chamber, which, in turn, was provided
with openings located directly under the ventilators.

EQUIPMENT.

On account of the experimental nature of the plant, the equipment
was purchased with the idea of acquiring units which could be re-
arranged at will, until a satisfactory layout was obtained. The milk-
handling machinery, located in the milk room, consisted of a butter-
milk machine of 300 gallons capacity; a milk pump; two 300 gallon
ice-cream batch mixers; two centrifugal emulsors of 200 gallons ca-
pacity each, belt-driven from 2-horsepower motors; one tubular milk
cooler of 5,000 pounds per hour capacity, composed of two sections,
one for water and one for brine; an antifoam tank; a rotary bottle
filler and capper; scales and tank for weighing water, and scales for
weighing butter; a porcelain topped table for cutting butter; and a

12 STUDIES OF RECONSTRUCTED MILK.

Babcock tester. The locations of these machines are given in Figures
1 and 2. All of this machinery, except the mixing and pasteurizing
vats, emulsors, butter scales, and butter-cutting table, was located
on the main floor. These machines were on the balcony, as shown
in Figures 2, 3, and 4.

As it was necessary to start the construction of the building before
all of the machinery had been selected, it was not possible to deter-
mine the headroom necessary to insure a gravity system from the
mixing vats to the bottle filler. It was found necessary, therefore,
to elevate the mixing vats about 2 feet above the floor of the bal-
cony. They were supported on a stand made of 2-inch pipe. This
arrangement made speed in operation difficult and should be avoided.
Figure 3 gives the elevation necessary for a gravity system.

All machines were connected with 14-inch sanitary milk piping,
and the valves and fittings were of the easily cleanable sanitary type.
A no-foam can filler was installed between the antifoam tank and
the bottle filler. All machines were driven by individual motors,
thus doing away with the inconvenience of overhead shafting. The
plant as designed was not equipped to manufacture ice cream,
but when operations were started it was found necessary to manu-
facture a small amount of this product each day. A 60-quart con-
tinuous brine freezer was purchased but was never operated. In
order to tide over until this machine was available for use, two of
the old type can freezers were set up and operated. They were
motor driven and were located under the balcony against the wall
of the machinery room.

Bottles were washed with an automatic jet washer, having a ca-
pacity of approximately 4,000 bottles an hour. The pumps of this
machine were operated by a direct-connected 10-horsepower motor.
This washer was located in the center of the washing room and was
oriented so that the bottles coming from the machine could be
trucked directly into the milk room and stored. A small galvanized-
iron tank used for the washing of cans, which process was carried
out by hand, together with a rinser and steamer, was located against
the south wall of the washing room, as shown in Figure 1. A small
brush washer, on which extremely dirty bottles could be scrubbed,
was located on the north wall of the washing room. A two-effect
water still with a capacity of 350 gallons per hour was located on the
raised platform in the southwest corner of the washing room. The
effluent pipe from this still projected through the wall into the milk
room and discharged into a tin-lined distilled-water storage tank of
1,000 gallons capacity. This storage tank was connected by tinned-
covered piping to the suction end of the milk pump. At this pomt
a three-way valve was located, so that fluid could be drawn from
either the distilled water tank or the buttermilk machine as desired.

STUDIES OF RECONSTRUCTED MILK, 13

The discharge from this pump was also arranged so that the effluent
could be sent cither into a weighing can mounted on a small plat-
form near the skimmed-milk vat, or to the mixing vats on the
balcony.

A small field laboratory for determining the bacteriological content
of milk and milk products as well as the acidity and fat in milk, was
located in the dressing-room. This laboratory will be described in
the section on the analytical study of reconstructed milk products.
A Babcock centrifuge was located on a stand on the balcony in the
milk room, where frequent tests of the finished product could be
conveniently made.

The refrigeration used for both the reconstructed milk plant and
the cold-storage department of the commissary was furnished by a
15-ton refrigerating machine. The ammonia compressor was driven
by a 30-horsepower motor. All of the refrigerator rooms were cooled
directly by the expansion of the compressed ammonia. Brine,
cooled by the expansion of ammonia, was used for cooling the recon-
structed milk. The brine was circulated by a steam-driven brine
pump.

WATER SUPPLY.

The water used throughout the plant was obtained from the regular
Nitro supply, which had previously been filtered and chlorinated.
This water, brought into the building through a 3-inch main, was
used only for cleaning and cooling purposes.

STEAM SUPPLY

The steam used in the plant was generated in a central power
plant located about 600 feet from the milk plant. It was brought
to the plant by a 4-inch steam main.

Plant Operation.
RECONSTRUCTED MILK PRODUCTS DEFINED.

As has been stated, reconstructed milk products are products made
by the emulsification of butter fat in normal or reconstructed skimmed
milk. Reconstructed skimmed milk may be made either by diluting
unsweetened condensed or evaporated skimmed milk with distilled
water or by dissolving dried skimmed milk powder in distilled water.
The percentage of fat and solids not fat may be adjusted to suit the
use which is to be made of the product, provided these percentages
are plainly stated on the package. In the work described below
skimmed milk powder was used exclusively as a source of solids not
fat, and a high grade of unsalted butter as a source of butter fat.
Reconstructed milk, reconstructed cream, ice-cream, and fermented
milk products, such as cultured buttermilk and cottage cheese, were
all manufactured.

14 STUDIES OF RECONSTRUCTED MILK,

INGREDIENTS.

In the reconstruction of milk it should be borne in mind that no
matter foreign to normal cow’s milk should be added to the product.
It is necessary, therefore, to use only the purest water, and the
highest grade of dried skimmed milk and butter. The finished
product can grade no higher than the ingredients used. The extreme
importance of this point justifies a detailed discussion of each ingre-
dient.

Water.—Nothing but the very purest of water, from both a chem-
ical and bacteriological standpoint, should be used in the reconstruc-
tion of milk. Assuming that a normal water supply is available,
which is free from all harmful bacteria, this water may contain mineral
salts which might possibly be harmful to the weak digestion of an
infant. For example, the hard waters of the Middle West and those
containing a high percentage of sulphate could very easily cause
intestinal disturbances in the young. Also, from the manufacturing
standpoint, these salts would very probably have a deleterious effect
on the physical state of the emulsion. It is very probable that, in
some districts, a very pure water, free from mineral constituents and
free from all pollution might possibly be obtained, but this condition
is so rare that only distilled water should be considered as a general
source.

From a bacterial standpoint, water that is not absolutely free from
pollution would be much more dangerous when used in milk than
when used as water, for the growth of the harmful bacteria could
easily take place in the excellent food medium which is furnished, and
a very small number of pathogenic organisms gives rise to a number
sufficient to be harmful. As the best of our filtered supplies may
contain a small number of disease-producing organisms, practically
all waters except those which have been freshly distilled are elimi-
nated. It is, therefore, strongly recommended that no reconstructed
milk products be manufactured without using water which is free
from dissolved salts and pathogenic bacteria.

From a commercial standpoint it is highly important that the
water used in the manufacture of milk products should be free from
objectionable tastes, odors, sediment, and color. Even the char-
acteristic flavor of poorly made distilled water may be easily dis-
tincuished after the milk powder and butter have been added. This
flavor also increases with the age of the milk and is decidedly objec-
tionable in a product 24 to 48 hours old. In selecting a still for the
manufacture of distilled water great importance should be placed on
the ability of this still to produce a tasteless and odorless product.

Skimmed milk powder.—The skimmed milk powders available on
the market to-day may be divided into three classes: Those made by
drying on rolls at atmospheric pressure and a relatively high tempera-

STUDIES OF RECONSTRUCTED MILK, 15

ture; those made by drying under reduced pressure and a corre-
spondingly lower temperature; and those made by drying a finely
atomized milk in a current of hot, dry air. The manufacturers of
powder made by the various processes claim advantages over powders
made by other processes, and the purchaser must decide on the
product best suited to his needs.

In the manufacture of reconstructed milk, the following points
are of extreme importance in the selection of a skimmed-milk powder:

The powder should be wholly and easily soluble in water and when
reconstructed should give a solution with the characteristic flavor of
normal skimmed milk.

The various constituents, such as the sugar, proteins, and mineral
salts, should not have been altered during drying, and upon recon-
struction should appear in as near the original state as possible. A
solution of the powder should have the power to hold an emulsion
of butter fat similar to that found in normal milk.

As the reconstructed milk must meet all the legal requirements of
normal market milk, the original milk used for drying must be pro-
duced in a cleanly fashion, and must meet all requirements of the
local health department of the district where the reconstructed milk
is to be sold. The process of drying should also be conducted in a
cleanly manner, and rules prescribed for the handling of normal milk
should be enforced in the manufacture of the skimmed-milk powder.
It is needless to say that this powder should contain only and all the
ingredients occurring in normal skimmed milk, with the exception of
the water. Skimmed-milk powder is deliquescent and absorbs
moisture rapidly. If the moisture content is high, the powder will
lump in the containers and be unfit for use. It should therefore be
stored in moisture-proof containers and should be sold with a
guaranteed maximum moisture content.

Butter fat.—Sweet or unsalted butter is used as a source of butter
fat. A good quality of sweet butter is almost as difficult to obtain
as a good quality of skimmed milk powder or water. It should have
good flavor, be free from pathogenic organisms, and be manu-
factured in such a manner that objectionable flavors and odors will
not be produced in it during storage. It should never be artificially
colored, and manufacturers should guarantee the butter-fat content.
The butter should be shipped in proper containers, and every con-
tainer should be scored by the purchaser before it is accepted.
Butter should be stored at a temperature sufficiently low to prevent
the production of disagreeable flavors and odors and should be taken
out of storage only as needed.

Commercial Manufacture of Reconstructed Milk.
RECONSTRUCTION OF SKIMMED MILK.

If the skimmed milk powder to be used has been selected with
proper care the process of dissolving it is not a difficult one. At
Nitro a val buttermilk machine of ordinary design was used for this

16 STUDIES OF RECONSTRUCTED MILK.

_ purpose. This machine was of 300 gallons capacity and was equipped
with a revolving heating coil to which blades were attached, serving
simultaneously as agitator and heater. Jn selecting a vat, care should
be taken to obtain one with a cylindrical bottom, and sides which are
tangential to the surface of the cylinder. There should be no corners
in which the undissolved powder may be pocketed. The necessary
amount of distilled water should be placed in the vat and a weighed
amount of skimmed milk powder added. The powder may be dumped
in directly from the barrel, if care is taken to prevent foreign matter
from falling from the sides of the barrel during the process. It was
found that better results were obtained when the powder was removed
from the barrel with a large sugar scoop. ‘The coil agitator should be
in operation while the powder is being added. The temperature of
the water during the period of solution of the powder should be
between 70° and 80° F.

Adding butter, and pasteurization.—After the complete solution of
the powder had taken place, the skimmed milk was pumped to one of
the mixing vats on the balcony. Here the necessary amount of
butter, which had previously been cut into 4-inch cubes on the
porcelain topped table provided for the purpose, was added, and the
mixture brought to a temperature of 146° F., and held there for 30
minutes. It was found that by the time the temperature had reached
146° F. all the butter had melted. ‘The holding time for the pasteuri-
zation of the skimmed-milk-butter mixture may therefore begin
when the correct temperature is reached. It is necessary, however,
to cut the butter into 4-inch cubes or less if this procedure is to be
followed.

Emulsifying the butterfat.—After the mixture had been pasteurized,
and while it was at the pasteurizing temperature, it was passed
through the centrifugal emulsors.

Emulsification is brought about by the forcing of the mixture
of butter and skimmed milk through an extremely narrow opening,
using centrifugal force generated by revolving the bowl of the emulsor
at a speed of approximately 15,000 revolutions per minute.

Cooling.—From the emulsors the hot reconstructed milk was con-
ducted to the upper trough of the cooler through sections of 14-inch
sanitary milk pipe to which had been attached small conductor heads.
The milk from the emulsors contained a great deal of foam, and
difficulty was experienced in transmitting this foaming product to
the cooler. A large bank of foam collected where the milk entered the
conductor head and also in the upper trough of the cooler. This
necessitated the providing of ample capacity at both of these points
to prevent the foam from accumulating and running over the edge
of the conductor head and trough. For this reason it is felt that the
use of an external cooler should be avoided in this process. The use

STUDIES OF RECONSTRUCTED MILK, a PY

of an external tubular cooler would eliminate to a great extent this
waste and inconvenience. By inserting an antifoam tank, as
described below, between the emulsor and the cooler, much of this
trouble might be eliminated. This arrangement was not tried at
Nitro, however.

A proper regulation of the temperature of the milk as it leaves the
cooler is an important point in the process of manufacture. As with
ordinary milk, freezing throws the butterfat out of emulsion to a
greater or less degreee. The flow of brine should therefore be regu-
lated so that a minimum amount of milk freezes to the cooler. All
milk which does so freeze should be re-emulsified before bottling.
Satisfactory results can be ob-
tained if the milk leaves the
cooler at a temperature of from
40° to 50° F.

Foam removal.—As has been
stated, the reconstructed milk
as it leaves the emulsor con-
tains a great deal of suspended
air. This air is in such a finely
divided state that it is elim-
inated slowly. Bottles filled
with the milk directly from
the cooler show, on two hours
standing, an air space between
the cap and the surface of the
milk varying from 1 inch to 3
inches in height. In order to Fic. 6.—Seetion of antifoam tank used at the Recon-
eliminate thisfoam an antifoam Se peas eae tal ee
tank was inserted between the cooler and the can and bottle fillers.
This foam tank is simply a detention tank, from the bottom of
which the milk is drawn. A sketch of it is shown in Figure 6. With
the emulsors running at full capacity (approximately 400 gallons per
hour) this tank gave a detention time of approximately 3} minutes.
This arrangement eliminated practically all the foam from the
milk.

Filling containers.—From the foam tank the milk passed into a
rotary bottle filler. A ‘‘no foam” can filler was inserted between
the antifoam tank and the bottler. At this point all the cans were
filled. The bottle filler was driven by a direct-connected motor and
had a capacity sufficient to handle the effluent from the emulsors.
This type of filler and capper has a decided advantage over a case
filler in that all bottles have to be handled twice and therefore get
two inspections. When using the case filler there is a great tendency
to slight the bottle inspection, and many damaged “bottles which

12325°—20——3

18 STUDIES OF RECONSTRUCTED MILK,

should not be used are filled and put into circulation. The bottles
used were of the ordinary glass, common-sense type, capped with
paper caps. As is customary, the caps bore the package label.
Storage—Immediately after the containers were filled they were
trucked into the cold-storage room, where they remained until
delivered. The temperature of this room was approximately 33° F.
Labeling.—Regulations pertaining to all foodstuffs should be ap-
plied to reconstructed milk products. These products should be
sold only for what they are and only when the packages are properly
labeled. According to the present law, a milk made from skimmed
milk powder, water, and butter is not ‘‘milk,” and should not be
sold as such. The law distinctly states that milk is the normal
fluid secreted by the mammary glands of the cow, and a product
which has been reconstructed certainly can not be classed as ‘‘milk.”
In choosing a name for this product various titles have been con-
sidered. From the list has been chosen the term ‘‘reconstructed
milk.” It is felt that this is fully descriptive and leaves no reason

Fic. 7.—Bottle caps used at the Reconstructed Milk Plant, Nitro, W. Va.

for doubt as to the product. The word ‘‘reconstructed”’ may pos-
sibly arouse some sense of fear in the minds of the unenlightened con-
sumer, for it may signify to him a product which has been at some
time in an unsatisfactory condition and later renovated. Various
other names which have been suggested are ‘‘remade,”’ ‘‘emulsified,”’
‘reconstituted,’ ‘‘recombined,” and ‘‘rehydrated.”” Any of these
terms may be used, subject to the approval of the officials who are
intrusted with the enforcement of the pure-food laws.

In labeling any of these manufactured products the word “‘recon-
structed,” or any other similar word which may be used, should be
given as much prominence as the word “milk.” The label should
also set forth the percentage of butter fat and the percentage of milk
solids not fat which the product contains. Figure 7 shows samples of
the various caps used at Nitro. The reconstructed milk manufac-
tured there contained 9 per cent milk solids not fat and 3} per cent
butter fat. The cream contained 25 per cent butter fat. A form
of fermented milk similar to buttermilk was manufactured and styled

it a

STUDIES OF RECONSTRUCTED MILK, 19

“Nitrolac.” It was not considered proper to label this milk butter-
muk, for the term ‘‘buttermilk’’ has a distinct meaning. It is a
product of the churning of milk or cream and the name should be
used for no other product. The fermented milk used at Nitro was
simply a cultured milk of a low percentage butter fat.

Washing containers.—All containers were washed in the room pro-
vided for that purpose. The bottles were inverted and washed in
the cases. The washer used consisted of a series of tanks from which
water or alkali solutions were pumped with considerable pressure
through a series of jets. The cases were intermittently advanced by
a mechanical device and the jets so arranged that during the resting
period a powerful stream of water or chemical solution was injected
into each bottle while a number of streams were forced against the
outside and inside of the case. The temperature of the first rinse
water was approximately 110° F., a temperature sufficient to warm
the cold bottle without danger of breaking it. The temperatures
of the subsequent washing and rinsing solutions were so regulated
that the final temperature of the bottle was approximately that of
boiling water. Before leaving the machine each bottle was subjected
to a jet of live steam which acted as the final sterilizing agent.

All cans and metal containers were washed by hand in a galvanized
iron tub provided for the purpose. After a thorough brushing with
an alkali solution, the can and cover were inverted over a can rinser
and sterilizer where they received a hot-water rinse and a thorough
steaming.

Cleaning milk-handling machinery.—At the end of each day’s run
all milk-handling machinery and piping were completely disassembled,
rinsed with warm water, scrubbed with a brush and hot alkali solu-
tion, rinsed with hot water, and then sterilized by blowing live steam
into or through them for a considerable time. The machinery was
then partially assembled. In the morning before operations com-
menced, the machinery was completely assembled and connected at
various points to the steam line. Steam was blown through the
assembled machinery for approximately 20 minutes. This produced
a satisfactory sterilization.

The most difficult piece of machinery to sterilize was the tubular
cooler. This is the general experience where this type of cooler is
used. At the end of the run the tubes are full of water or brine, and
the ordinary methods of steaming are not sufficient to heat the whole
mass up to the sterilizing point. Satisfactory sterilization may be
accomplished by emptying the tubes and either blowing steam, under
pressure, through them, or by inserting a steam hose between the
covers and the cooler and allowing steam to blow in for some time.
If-either of these methods is used, a by-pass around the brine pump
must be supplied so as to drain the brine coil back to the tank without

20 STUDIES OF RECONSTRUCTED MILK.

wasting the brine. These methods of sterilization are very likely to
cause leaks in the cooler, owing to the uneven expansion of the coils.
It was found at Nitro that satisfactory sterilization could be accom-
plished by a thorough brushing with soda solution and then rinsing
with approximately 200 gallons of water which had been previously
heated to about 180° F. in one of the pasteurizing vats. From a
bacteriological standpoint this method is not as efficient as draining
the cous and applying steam.

a
QUANTITY OF THE RECONSTRUCTED PRODUCTS MANUFACTURED.

As has been stated, the plant had a capacity of at least 2,000 gallons
of reconstructed products in an eight-hour day. This amount of
milk was never sold in Nitro, owing to the impossibility of proper
delivery. Nitro was never completely finished, and the streets, up
to the cessation of operations, were in such poor condition that a
house-to-house delivery could not be made. It was intended to sub-
stitute for this retail delivery a wholesale delivery to a number of
small distributing stations centrally located, where the various milk
products could be purchased by the consumer and carried to the
homes. This system would have had the advantage of eliminating
bottle loss. Unfortunately, these milk stations were not finished in
time to take care of the rush. The fact that milk could be purchased
only at the general stores cut the consumption greatly.

Table I gives the daily quantities of the various products manu-
factured during the months of September, October, November, and
December, 1918, and part of January, 1919.

TasBLE I1.—Quantity of reconstructed milk products manufactured daily at Nitro, W. Va.,
during September, October, November, and December, 1918, and part of January, 1919.

Pounds | Pounds
Pounds | ofcream| of ice
of milk. | (25 per cream:

Gallons
Date. i

STUDIES OF RECONSTRUCTED MILK, a1

TaBLE I.—Quantity of reconstructed milk products manufactured daily at Nitro, W. Va.,
! during ee ae October, November, and December, 1918, and part of January, 1919—
Continued.

Pounds | Pounds

cent). | mix.

29 STUDIES OF RECONSTRUCTED MILK.

TaBLE I.—Quantity of reconstructed milk products manufactured daily at Nitro, W. Va.,
during Sas October, November, and December, 1918, and part of January, 1919—

LB eT E7 Ne i pi en DEN Reo Sn a Salem eS eR es ARON ras cacect losses 60
Dl. Aes SSO SER ERS Sake eg ok ee en eoteraretete 2 AOO Joc ccievce Seiclciowecoeele 45
DB Ta ohare wae We ees cy Med ee PME foe gan eS 2, 400 BODE Gees ease 80

IR 1 J TOME bE M ied RORM ES ce eay 22s Lie DS AON) eee te 1, 200 60
D6. Sd hee he aes accel iad ale Nae AS cou hh eRe US a pa RL DAGON Monee igs nee mio 45
QU SE SI ERP AT MI See ete re te 2,400 SOOM SSS scenes 50
ih A CEE ATS SIT Nee Rah de PRC SUE Seah EA ae cae D400! | ae eee eee eee 45
SO: ties Pte Me Zee CRORE ee ed Sees ee ite eee eee ZI4005|: cseeeeaes 1, 200 55
Bi RE ee Ae Pe re ee SNC ee a) ie ee a ee Be A004 |. ciaisie eoistanl Mone memicers 30:

1919.

AAT a fee SNA Me A Bh eee, 5 ayes ee a coe ee 2,400 1; 0000) <ccscnooe 60:
Bd Molen Ma a ctoees 8 us ap nee te WAM ip caer TO FAQ| Se ence 600 60
AISA 2. LSS AROS SS 5. eR? gl RN te 1a 2,400 BOO sede algae aoe
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6. UMS RSS Piso vn D8 SER RL | ee ei ae 2 MANN aS Se cee a 30
(ECE a, ERM Rng mens TENE ATTEN A 29400 a Saas | Sea 45
BE ROU, Pint Thy 0 hen ema Ns Oy Ge SPAIN OE ERED DEA0D! | eevee 1, 200 80
Ce erie ee he a) ee SS GSAS ene eae AEs Sel Sr Rel CSO NaS aIE Rea aaabor 50°

10), Joie SESS Wey vite Oh a VR ee thal pied BE (iy oe Ee 2, 400 BOO Reese 45
11 MOS oo Emcee aR eM, VMS Member meen a eee A800" | casa eee ee 40
1 AE Eee ee RR ee a es CN ey eens Re aie Sete ee Sp PAM oy as [Eo 8 ERS ac 65
Lae jess ee Boris SEEEAE Oe creed wee ae eee ere iio eee cell eee mciciinare 500 1, 200 80
ash Roe hae te rad Cn EE Bh oe at Ve Beaty A DEADON|Laer eee ak ye 60
DO clacicteatela hatches tee Pak totale e,¢ ot eis a SIS e ete rara bales eee eee 2 AOD eee sale inceicee 85
LG in fe He testes SESS SEES Sich cn es tec eo ree ete ie sla lore Soci wre | etcteaio ta eal letter cette cee iarereene 40:

The quantities of milk and cream produced are large enough to
serve as a basis for economic considerations.

OPERATING SCHEDULE,

It was expected that full data on the cost of operation of this
plant could be collected by keeping accurate labor charts and meter-
ing the electric power, the water, and the steam consumed by each
machine. Unfortunately the meters were lost in transit, due to
congested traffic conditions, and this part of the data is not available.
Time sheets of the various operations were kept, and the operating
schedule given below was computed from them.

The capacity of the plant depends on the time ey to mix
the ingredients and pasteurize them. It is therefore of first import-
ance to determine the time required for the various operations con-
nected with this part of the process. Accurate time sheets were
kept for two months, and it was found that the following time inter-
vals were required to perform the various operations included in the
mixing, pasteurizing, and emulsifying of one batch, 282 gallons, of

milk:
Minutes
Weighing and transferring water and skimmed milk powder to vat...................--------- 33.
Dissolving pow dera.cc<t os3 Sees ccs ces Smee ee OSS Sak Se ee ee ee oe eee ete le er ieerersic 10
Emptying skimmed milk Vat-2 =... 3-a-ceeenaes 5 sae cesinsae a eae mine a nla ae eres oie teeta l= isi 16
Preparing: and‘ adding butters... hacemos ae ten occ cence POC cee aR ORES E Beer ieeisinist-wistasite 13.
Heating mixtite-to 1467 Wh. See eee ee eb Le eee ee CAN RE ee Ree ee een oe ce emer 28
Molding forpasteurization same soc cceee nee oe ccecls Corl ere Se ee eee atc <i (ote cteelereieraes 30:
Bmulsifying:(2emiulsorsin 86) see t= sana ae eee eae eae een = eS eee eeeeeeee 45

Rn i oe eae |

STUDIES OF RECONSTRUCTED MILK, 23

Using these data, a daily schedule of operation of the three vats
and two emulsors was planned. This schedule is given in Table II.
Vats A and B represent ‘the mixing and pasteurizing vats on the
balcony, and vat 5 is the skimmed milk vat located on the main
floor.

It will be noted from Table II that vat 5 is in continuous opera-
tion, but that vats A and B are idle 20 minutes, and the emulsors 15
minutes, between every two batches. This loss of time could be
eliminated by changing the method of preparing the skimmed milk.
Too much time is consumed in measuring and handling the water and
powder. This time can be reduced by arranging the building so that
the powder storage room and the distilled water storage tank are on
the same level with the present balcony. A weighed charge of pow-
der could then be dumped directly into a hopper placed above the
skimmed milk vat while the powder in the previous batch is dissolv-
ing. If, at the same time, water from the elevated tank could be
run directly into the mixing vat through a 4-inch conductor, the time
of charging the vat could be reduced to approximately 10 minutes.
An ordinary gauge glass attached to the end of the vat, extending the
full height of the vat, could be calibrated accurately enough to pro-
vide means of measuring the distilled water. By using this arrange-
ment of measuring devices and by having the man responsible for
the mixing of the skimmed milk commence work an hour ahead of
the rest of the force, the output of the plant can be increased from
six to eight batches per day. Such an arrangement is outlined in
Table III.

It will be noted that between Batches II and III, IV and V, and
VI and VII there are 12-minute intervals during which no milk is
passing through the emulsors. These delays are unavoidable when
vats of this capacity are used.

STUDIES OF RECONSTRUCTED MILK,

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*10]8M PUB JOpAOd ZuTmMsvout ‘soyNUTUI ZI+"W “8 (ZG

WI ywg
“Aqduo 18a “ur “8
‘yea SutAyduroe ‘ ‘soqnuyay 9I+'U “8
‘1opMOd ZutAjosstp ‘soynuTut O{-+"Ur “B
*10]8M PUB JopMOd ZuLmMsevoul ‘seynuTU ZI+"U “se

TT ywg_

“Aydure 48a “ur “Bg

48a SutAyduio ‘ (SoNUTAL QT-+"UT *G 0)

“IapMOd VA[OSsIp 03 ‘soqnuTut OI+ UW “8 oO

*10]eM PUB IOPMOd ZuLIMsBoUt ‘soINUIUI ZI+"Ul “Bg

T Wwe

‘S A

a a i PE ee ee ee (eee eee ea Se Oe eee ee Ga meeen RT TE
“‘Buapyng fo quawabuviun mau buisn aynpayos pasodolg— ]{J LAV,

26 STUDIES OF RECONSTRUCTED MILK,

OPERATING FORCE.

A plant as described can be operated with a force of seven men.
This force should consist of a foreman, who would have general
charge of the plant and would personally operate the skimmed
milk vat; an assistant foreman, who would spend his entire time on
the balcony level, operating the pasteurizers and emulsors; three men
operating the bottling and capping machine—one man feeding the
machine with empties, one man removing the filled bottles, and one
man handling the cases of empty and filled bottles—one man trucking
the filled cans to the refrigerator, and one man operating the refriger-
ating machine and assisting as his time permits at any temporary
point of congestion. The foreman and assistant foreman should be
men skilled in the handling of milk and the operation of milk machin-
ery, and the engineer should, of course, understand the operation of
a refrigerating machine. The other employees may be of a good
grade of laborers.

COST OF PRODUCING BOTTLED RECONSTRUCTED MILK.

The cost of producing bottled reconstructed milk will vary with
the locality and with the market price of the various commodities
used in the manufacture and handling of the product; therefore, no
exact figures can be given. It can be stated, however, that the cost
of a plant to manufacture reconstructed milk, and the number of
men and the amount of power necessary to operate it, are no greater
than similar items in the operation of an ordinary modern pasteurizing
and bottling plant, and therefore, the cost of manufacturing and
bottling reconstructed milk is approximately the same as the plant
charge for pasteurizing and bottling fluid milk. The delivery charge
is, of course, identical in both cases. The economic advantage
gained by drying the skimmed milk and manufacturing butter at the
point of production and reconstructing the milk at the point of con-
sumption, rather than handling it in the normal fluid state, lies in
the difference in price between sweet fluid milk delivered in bulk at
the pasteurizing and bottling plant, and powder, butter, and water
delivered at the same location, plus the economic advantage gained
by always having the supply equal the demand.

Skimmed milk powder at the present time is manufactured in the
great dairy regions of New York, Pennsylvania, Ohio, Indiana, Ilh-
nois, Michigan, Wisconsin, Minnesota, and on the west coast. Sweet
butter is also manufactured in quantity in these States. Distilled
water can be produced locally. The prices of powder and butter are
necessarily the market prices at the point of manufacture, plus the
freight charges. During the past year (1919) the market price of
skimmed milk powder at the factories has varied in carload lots from
20 cents to 26 cents per pound. Sweet butter has varied on the New
York market from 46 cents to 71 cents per pound. Distilled water

STUDIES OF RECONSTRUCTED MILK, 27

can be made for less than one-quarter of a cent per gallon. Using
these figures, the cost of the ingredients entering into a quart of milk
containing 9 per cent solids not fat and 3.5 per cent fat will vary from
7.9 cents to 13.3 cents. To this must be added the freight on the
powder and butter, which is a minor item. The price paid the
producers in the South, during this period, for normal fluid milk has
varied from 10 cents to 20 cents per quart, depending on the locality.
It is certain, therefore, that in these sections reconstructed milk can
be sold for a lower price than normal milk.

Whether reconstructed milk is more economical for a given com-
munity than normal fluid milk can only be determined by a careful
comparison of the prices of the raw commodities delivered at the
point of consumption.

If all the milk produced in the country could be dehydrated and
subsequently reconstructed as needed to meet the demand, there is
little doubt that a great financial saving to the country at large
would result. Until such method is universally adopted a careful
study of the local conditions of each community must be made before
deciding on the correct method of milk handling.

From a bacterial standpoint reconstructed milk has decided advan-
tages over market milk of good quality, as will be shown in the sec-
tion on the bacteriology of this product.

THE QUALITY OF THE FINAL PRODUCT.

The manufacture of milk powder and reconstructed milk is in its
infancy. The processes have been studied to some extent, but
little is known regarding the effect of the various methods of drying
and reconstructing on the composition of the finished product.
Infant feeding experiments have been conducted in England, in
which dried milk powder was used. These experiments are reported
in Food Reports No. 24 to the local government board on Public
Health and Medical Subjects, New Series No. 116.2, These experi-
ments indicate that children can be raised on reconstructed milk
with no more difficulty than on normal cows’ milk.

To the casual adult drinker of milk, carefully produced recon-
structed milk made from the better grade of powders available in
quantity on the market to-day, has the appearance of normal milk,
except that it lacks a cream line. It has a flavor slightly more
“cooked” than the pasteurized market milk. This flavor to many
observers gives the impression of excessive ‘‘richness.”’ It is not
objectionable to those used to pasteurized milk, but is somewhat
distasteful to those accustomed to drinking raw milk. The freshly
made product very easily passes for first-class normal milk. One
serious physical defect exists, however: the fat emulsion as produced

2 See also “Dried Milk Powder in Infant Feeding: Safety, Usefulness, and Comparative Value—A
Preliminary Report,” by W. H. Price, Surgeon(R.), United States Public Health Service, Public Health
Reports, vol. 35, No. 14, Apr. 2, 1920, pp. 809-828.—E DITOR.

28 STUDIES OF RECONSTRUCTED MILK.

at Nitro is not wholly permanent. On standing for 48 hours at a
temperature approximately 35° F. or for 20 hours at room tempera-
ture, a thin crust of butter forms on the top of the fluid. If the milk
is kept in an ordinary refrigerator and consumed within 24 hours no
separationis noticed. This ‘ buttering” in all probability is caused by
some change in the complex ingredients of the skimmed milk brought
about by the drying process. The power to hold fat in emulsion
has been partially destroyed. As soon as this effect is overcome by
the manufacturers, a product will be available which will readily
compete with normal fluid milk. At present, reconstructed milk
forms an excellent emergency supply which may readily take the
place of normal milk during a shortage of the latter product.

Summary.

1. Reconstructed milk and cream made from skimmed milk powder,
unsalted butter, and water have been produced in large quantities
at Nitro, W. Va., and sold to the public.

2. The cost of manufacturing these products in the Southern
States is less than the cost of local normal milk. As the distance
between the points of efficient production and consumption is less-
ened, this difference in cost becomes less. In the dairy sections at
the present time fluid milk can be sold more cheaply than recon-
structed milk.

3. Reconstructed milk products serve as excellent emergency
supplies, and as soon as the process of manufacturing milk powder
is perfected they will no doubt compete in the open market with
normal milk products.

Acknowledgments.

The authors wish to express their appreciation of the valuable
assistance given them throughout this demonstration by Passed
Asst. Surg. J. A. Watkins, of the United States Public Health Service, »
resident officer in charge of the department of medical relief and
sanitation of Nitro; Mr. Hugh C. Leighton, executive officer of the
Nitro commissary department; Mr. C. S. Bassett; Mr. L. C. Johnson;
Mr. R. G. Soule; and all others who through suggestions or material
aid helped in making the demonstration a success.

Il. AN ANALYTICAL STUDY OF RECONSTRUCTED MILK.

By ALBERT F. STEVENSON, Sanitary Engineer, and C. P. Ruynus, Assistant Sanitary Engineer, United
States Public Health Service.

Before any process devised for the handling of milk can be pro-
nounced a success, aN analytical study of the product, both from a
bacteriological and chemical standpoint, must be made. If this
study shows the product to be materially altered or to be a potential
source of danger, from a health standpoint, the process is valueless.

It was therefore of the greatest importance to determine in this
plant, the initial one producing reconstructed milk on a commercial

Se a te i ee

STUDIES OF RECONSTRUCTED MILK. 29

scale, whether the product was of a high or low grade, from a
bacterial and chemical standpoint.

A plant laboratory was installed where bacteriological analyses
could be made. It was possible by this means to check the plant
operation and to determine, at all times, the quality of the product
which was being sold. As is always the case, the field laboratory
proved one of the most important assets of the plant. Samples of the
finished product as well as samples from the various stages of the
process of manufacture were analyzed daily. The finished product
was again sampled and analyzed, after delivery, by the division of
health and sanitation of the Nitro organization. These last analyses
correspond to those which would be made by the board of health of
an ordinary community.

The methods employed in making bacteriological analyses were
those recommended by the committee on standard methods of milk
analysis of the American Public Health Association. Samples were
collected from the various stages of the process of manufacture, in glass
test tubes plugged with nonabsorbent cotton. Filled pint bottles,
selected at different periods during the day, served as bottled milk
samples. These samples were refrigerated until the actual analysis
was made, which occurred, generally, within two hours of the time of
sampling. The culture media used for the bacteriological analysis
were made at the Hygienic Laboratory in Washington, D. C., and
shipped to Nitro in tin containers. The media were transferred from
the cans to 4-ounce glass bottles, after arriving at the plant, and were
then resterilized. A check titration was always made on each ship-
ment of media, after the final sterilization in the glass bottles. Sterili-
zation of media was accomplished by heating for one hour at 100° C.
in an Arnold sterilizer for three consecutive days, and then incubating
the media for 24 hours to throw out any contaminated bottles. The
dilution water was sterilized in the same manner. Dry sterilization
was accomplished in the oven of an ordinary gas stove. Forty-eight-
hour 37° C. total counts were made on the various samples. No
attempt was made to isolate any particular organism.

The results of the bacteriological determinations made on the
finished reconstructed milk in the final containers are given in
Table IV. Table V shows the results of arranging these counts in
the order of magnitude. Seventy-five per cent of them were 5,000
or less. The highest count obtained was 55,000, and only three
times was a count over 30,000 obtained.

Total counts made on the bottled milk by the department of
sanitation are given in Table VI. Rearrangement of these counts in
the order of magnitude, as shown in Table VII, emphasizes the fact
that 15 per cent of them are under 1,000 and 97 per cent are under
5,000. Only one count out of the total 33 was greater than 5,000.

30 STUDIES OF RECONSTRUCTED MILK.

A bacteriological study of the manufacturing process brought out
some useful information. Table VIII gives thenumber of bacteria pres-
ent in reconstructed skimmed milk. These figures, of course, include
both the number of bacteria in the water and in the milk powder.

Taste I1V.—Bacterial content of finished product in container.

Bac- | Bac-

Date. teria Date. teria
per c.c. per c.c.

1918. 1918.

Sept. 15] 7,000]} Nov 4] 1,200
16 | 8,000 5| 6,900
6, 000 7, 000
18 | 7,700 6, 200
19 10, 000 3, 500
20 1, 400 6} 13,500
5, 100 3, 700
2, 200 15,800
21 3, 400 7 5, 000
23} 1,200 2, 000
300 2, 500

100 3, 100
24! 41,000 11} 15,500
25 1, 200 12 1, 600
26 | 2,700 3, 200
30 | 11,000 8, 000
2, 400 1, 600

1, 100 1, 600

Oct. 1 3, 000 3, 000
10 | 13,000 13 1, 400
400 3, 000
11 13, 500 2, 800
12| 7,000 16] 4,700
14 | 30,100 6, 200
16 | 1,200 2,700
17| 3,100 2,100
1, 300 1,600
21 6, 000 17 | 20,000
4, 400 1,100
22 1, 200 18 4,500
5, 900 2, 200
2,100 19| 2,406
23 | 13,000 1, 100
22, 000 600
24) 1,400 2, 400
2,100 200
28 3, 300 20 2,700
2, 800 1,700
29 | 12,000 21 600
6, 800 600
30 | 3,000 2,300
500 2,800
31 | 2,000 22) 1,100
600 250
Nov. 2 2, 000 600
3] 1,000 6, 000
4 30,000 24/ 1,600
3, 500 12, 000
1, 000 25 1,900
1, 700 1,300

TaBLE V.—Results of arranging

ee
ofcounts
Range of counts. within
range.
Under i 000ns22 sarees sate 43
1 000=2)500 2 Fah. pac Si yates 91
2500-5; 00088 rn socse ee eae 54
§:000-1,500 na acst aeceasccmee 20
73000-10000 Pz acaceosaseee ees 7
10;000=15; 0002 2eee erase ees 13
15,000-20;000).. 5-7-5 =. = eS eee 8

Date.

1918.
Nov.

Dec.

aI oF

Bac-
terla
perc. c.

3, 700
3, 100
1,000
5, 000
2, 900
1, 800
2, 800

1, 200

Date.

1918.
Dec.

14
16

17
18

19
20
21
23

24
26

1919.

Jan.

Bac-
teria

peresc:

2, 900
2,100
800

7, 700
2,000
3, 600
28, 000
6, 000
3, 300

3, 500
600
700

2, 600

1, 600

2, 200

2,300

19, 000
15, 600

4, 100

4, 700

8, 600

2,800

10, 000

2, 200
700

4, 000

2, 000

. 500

26, 000

1, 800
900

4, 400

2,000

5, 500

4,700

1, 200
600
600

3, 600
1, 300
26, 000
1, 600
1, 900
2,000
3, 000
2,390
3, 200

500
2, 100

Bac-
Date. teria
pere.e.

31| 2/800

bacteriological counts of bottled milk according to

magnitude,
Per cent
ee Range of counts.
range.
17.4 || 20,000-25,000
36.6 || 25,000-30,000
1) 80||| SO! OOO 40 O00 sos sae ae aera
8.1 || 40,000-50,000
2.8 || Over 50,000
5.3
3.2 Total

Number | Per cent
ofcounts | ofcounts
within within
Tange. Tange.

RrOoONnwWo

248 at

STUDIES OF RECONSTRUCTED MILK, 31

TaBLE VI.—Bacteriological examinations of reconstructed milk made by the Sanitary
Division, Nitro, W. Va.

Bacteria Bacteria
Date. Source. per ¢. ¢. Date. Source. per ¢. ¢.
1918. 1918.

pep e2s |) Mess HallNo: 2)... .0s5...-- 2,000 || Dee. 16 200
VE SHOSpibal NESS sss. cas acse anes 1,650 17 580
25 d 2,350 19 1,550
2, 450 20 1,000
2,000 21 1, 900
1, 950 23 2,150
8, 600 24 1,600
Oct. 1, 950 26 2, 100
2, 600 27 2,450
2, 900 28 2,000
2,700 31 2,800

2, 850

Noy. 900 1919

2,000) || Jan. Lejos. .: GON ett cosa ta cee eee: 750
1,500 il eget 1G AUER aL ee SARE 1, 150
1, 400 Sou § x ON seen eS aa 1,550
700 Cig Sai C6 CS ys ee ee ae 1, 200

1, 800

Tape VII.—Resulis of rearranging the bacteriological analyses made on the bottled milk
by the Sanitary Division, Nitro, W. Va.

Number | Per cent
ofcounts | ofcounts

Range of counts. within | within

Tange. Tange.
PPB NO erciele cine ofos= c <jaiciaiclnroim o.cicia,ojoieiatniciniaie)= te ewe een tie Cae winien Soe ciesiseseceSerccecese 5 15
1 AUS Dnoacos Cop B eso b dang CoH OT DOO TEI Bec eB ne Ee ee 27 82
TET T TUSSI Ce 2 Re i RC ea Se een 1 3
ea eee ee tae Bee lak aaah se seiiaocme ee ea sa ae csiteedicebecccecabeccaccecis 33 100

TasLe VIII.—Bacterial content of reconstructed skimmed milk.

Bacteria Bacteria
Date. per ce. Date. per ce.

6,700 || Jan.

- Rearrangement of these figures, as in Table IX, shows that 23.4
per cent of the counts are below 10,000, and 76.4 per cent are below
50,000.

32 STUDIES OF RECONSTRUCTED MILK.

TABLE IX.—Result of arranging the bacterial counts of saniples of reconstructed skimmed
milk according to magnitude.

Number | Per cent

Range of values. of counts | of counts

within within

range. range.
Wider 0: 000k a isese ce ace cee ae cote casiaee a oe a eeeeeseene nee nee eee m ne emeiretst 8 23.4
TOS000=50!000 eee eee a Seeley re ale ares oe ara aaa ee ee ee en 18 53.0
GO MUU ee be del cones accescucodncacebaqn Abbecreepeesasqsgseosesamseass5s0n56F 4 11.8
OC eI ae onoe cuss sonnnecanccunsad osan tos coe oase oss cenassedzoassosssscosssa54 4 11.8
Total. 2-02 eso closeGhised acess sets Saws wa SSR n ie tesa sione ecebiaemeriscteseisec er 34 100.0

Table X gives the bacterial content of the butter used. A weighed
amount of butter was added to sterile dilution water and the mixture
warmed until the butter melted. This mixture was then shaken
vigorously and the water layer analyzed. The results obtained are
somewhat lower than might be expected.

TaBLE X.—Bacterial content of butter.

Bacteria
Date. per ¢.c.

1918.
Oct. 22 38, 000
Nov. 4 13, 000

22 | 2,000, 000
30 250, 000
Dec. 3 280, 000
1919.
Jan, 4 120, 000
17 650, 000
30 35, 000

Counts were also made from the milk as it passes from the mixing
and pasteurizing vats to the emulsors. These are shown in Table XI.

TABLE XI.—Skimmed milk and butter mixture after pasteurization.

Bacteria Date. Bacteria Date. Bacteria Date! Bacteria Date. Bacteria

Date. per ¢.c. per c.c. per c.c. per ¢.c. per c.c¢.
1918 1918 1918 1919 1919
Oct. 16 1,600 |} Nov. 30 400 || Dec. 13 520 || Jan 2 3,560 |} Jan. 22! 30,000
17 500 |} Dec. 2 760 14 660 2 720 22 300
22 1,000 3] 4,100 16 800 3 1,150 23 600
30 500 3] 1,100 16 440 4 910 23 890
31 700 3 1,400 18 1, 200 6 3, 000 26 600
Nov. 4] 3,100 4] 1,100 18 200 7| 3,200 26 780
12| 2,600 4 180 19 910 8 600 27 500
12| 4,400 7) 5,100 21 6, 500 10} 2,600 27 1,100
19 100 7 600 23 6, 000 11 | 12,600 28} 1,800
22 150 9 370 26 100 il 7, 100 28 910
22 70 10 | 24,600 26 580 14 7,900 30 1, 400
25 830 10 800 27 100 14 1, 400 30 740
25 340 11} 14,000 27 930 15 | 21,200 31 450
26 310 11 600 28 1, 750 15 1, 600
26 210 12} 3,500 28 305 17, | 11,000
28 170 12 950 30 820 17 9, 400
29 400 12 1, 900 31 200 18 | 40,000
30; 1,700 13 | 2,400 31 580 18 | 9,300

STUDIES OF RECONSTRUCTED MILK. 33

The killing of the bacteria in the butter and skimmed milk mix-
ture depends, of course, on the length of time this mixture is heated.
Samples taken at the first stages of a run or immediately after the
30-minute holding period, showed counts slightly higher than sam-
ples taken at the end of the emulsification period. This was due, of
course, to the fact that the last of the mixture to flow from the
mixing vats into the emulsors had approximately 45 minutes more
heating at 146° F. than did the first of the batch. Typical results
showing the variation in bacteria at the beginning and end of a
batch are given in Table XII.

TaBLE XII.—Dvference in bacterial count at beginning and end of batch from emulsors.

Bacteria per c.c.

Date
Begin-
ning. End.
1918
Dec. 1 1, 400 450
3 2,600 420
11 7,200 720
12 6, 000 710
16 1,300 450
26 1,200 780
1919,
Jan. 2 1,100 920
11 15,000 RITA

Analyses were also made of the discharge from the emulsors and
from the cooler. These figures show little if any variation from the
corresponding counts on the milk coming directly from the mixing
vats, and are not given.

Bacteriology of Cream.

Bacteriological counts were also made on the reconstructed cream
which was produced at Nitro. A summary of these results is given
in Table XIII. These figures, rearranged in the order of their
magnitude (Table XIV) show that 74.2 per cent of the counts were
below 10,000.

Tasie XIII.—Bacterial content of cream. 2

Bacteria Bacteria
Date pere.c. Date. perc. c.
1918 1918

Lote, “heer ea eee 2200's ee logl Sea ewe 8 ME ee see. 2 7,700
JD Lo lodb Sa ee ee 7,000 Lge See 2 oe at uss dota arenes sees 3,400
Lins SC RRO ee SO es ae 4,000 |W a Sy ae ee Sey a 3,100
OD ee ee 4,500 7 pyle ge ae Ee Rae eo 6, 600
Ji 55 See SS ee 1,500 Dy Re oe Ec, erage LIES 4,500
Ne were em see csi ele cee es 9,600 These nse ee pach esskesaepouca== ss 38, 000

Wilt SSE RCE IE Seno e See 400

OD: 34d ee Se ee 24,200 1919.

Ee olan acca tesenesece 255000) ro alae te tec ae eo en eso n natn ee h mam 5,300
Wie 0 eS eae a 4,300 Y (its Soe an sae es See es oe 6,000
ee a aiaiele ac woe waciedacese 2,000 1 | ne ee an Semen i 6,200
$26 ei LE ee eee 12, 000 1 BSE OSE AEE ce eos 5,100
Facing on ee 6, 000 7 ae ny gs > Rn ee Se Ba | 27,000
oe See 5,900 Bae oo cain deta doa ae ene amet 50, 000
Ree ae Ok calccciccsevaccvens 5,100 pe ee ee BRS erro ere 3,200
UG 2 ee 25, 000 71 ae ER UR DUS a alee el ote Se 2,100

i> 2 A 72,000

34 STUDIES OF RECONSTRUCTED MILK.

TaBLe XIV.—Results of arrangement of bacterial counts on reconstructed cream in
order of magnitude

Number | Per cent

ofcounts | of counts
Range of values. falling falling
within | within
Tange. Tange.

LOpIUG eG Leese eee tite ied iat A Rebar B on dna dodaoobee socecabessuancose 12 38.7
5}000=10; 0005: seize cece oe. 2 tee hehe dee cose see ene oe Saene 6 emers eeble ae sete tale iat il 35.5
10, CICA tt ea i Ge Pee en ena aaa a coatioe con saor neoue G SaeseRn Ear saoSdss 13 5 16.1
30:000=50, 000) jocSe8k «<5 co eteebeee he ays ee else eee ais art eet= = <tnree petal tnt ei= a= 2 6.5
(Ope ata Oneyaeiaee ea em etre ai Sep ieret s SO Re ona co waceueaonosemEocacSHotoe 1 she.

TO CATS Se eee os ete ee ne wae Rae Se Eee ee oe ae oe cee oie Seen cteis aane eae 31 100.0

Bacterial Content of Ice-Cream Mix and Ice Cream.

There has been a decided controversy recently concerning the
bacterial content of well-made ice cream, and many have taken the
stand that it is impossible to produce good ice cream with a low
bacterial count. At Nitro, ice cream was manufactured in a rather
crude manner, one which would tend to give the product a much
higher bacterial content than that produced with modern up-to-date
machinery. The bacterial content of the ice-cream produced at
Nitro was, therefore, determined with many misgivings, for it was
thought that the figures might be misleading. Samples were taken
of the mix shortly after it was manufactured and before any storage
period had elapsed. Between the manufacture of the mix and the
manufacture of the finished ice cream the mix was allowed to stand
at a temperature of approximately 33° F. for 24 hours. On manu-
facturing, the mix gave 95-100 per cent “‘swell,” showing that it
was sufficiently aged to be commercially useful. Table XV gives
the bacterial content of the ice-cream mix, and Table XVI that
of the finished ice cream:

TaBLE XV.—Bacterial content of ice-cream mix.

Bacteria Bacteria Bacteria
Date. | perc.c. || Date | pere.c. Date. | perc.c.

1938. 1918. 1918.

Oct. 12 1,700 || Dec. 3 2,200 || Dec. 30 4,600

Nov. 5 7, 200 3 11, 400

7 1919.

Jan. 3 5, 000

5, 100

13 6, 700

7} 31,000

20 5, 000

21 4, 000

24 6, 000

29 | 70,000

ee ee ee ee ae

STUDIES OF RECONSTRUCTED MILK, 35

TaBLE XVI.—Bacterial content of ice cream.

ietee Bacteria Tate! Bacteria Date. Bacteria

per c.c. per ¢.c. per c.¢.
1918. 1918. 1919.

Nov. 18 30,200 || Dec. 10 37,000 |} Jan. 20] 84,000
21 2,000 12 7,000 21} 9,000

26 105, 000 18 18, 800

30 | 23,000 21} 27,200

Dec. 2] 16,000 24 3, 000

% 4,500 28 1, 800

Rearrangement of these figures shows that 79.5 per cent of the
counts on the ice-cream mix were below 10,000, and 71.5 per cent
of the counts on the finished ice cream were below 30,000. These
figures indicate that, under average conditions, an ice cream can be
manufactured with a bacterial content which approximates that of
well-pasteurized creams.

Butter-Fat Content of Reconstructed Milk.

In the operation of a plant manufacturing reconstructed milk, one
of the important features is the proper mixing of the ingredients so
that the percentage composition of the various constituents are as
stated on the final package. The butter used in the making of the
products at Nitro was bought with the moisture content guaranteed
to be not over 15 per cent. Enough samples of this butter were
analyzed to show that the specifications were being complied with,
but no detailed analyses were made on the various tubs of butter
used from day to day. It was assumed always that the butter con-
tained at least 85 per cent fat. Butter-fat determinations made on
the finished product brought out the fact that the butter purchased
in many cases had a moisture content much less than 15 per cent,
making the fat content of the milk greater than was guaranteed.
This fact points out the great need for butter analysis, both by the
manufacturer and by the purchaser. The moisture content of a
sample from every churning, at least, should be determined, and if
possible this figure should be stamped on the tubs shipped. In all
cases a sufficient amount of butter was added to the milk mix to
give 34 per cent fat, assuming the butter contained 85 per cent
butter fat.

Analyses of bottled milk were taken at first which showed that
some variation existed in the fat content of the various containers
as put on the market. A study was made to determine whether the
fat content of the reconstructed milk at different points in the emul-
sification of a single batch varied. The results of these analyses are
compiled in Table XVII. Those values which are grouped around
definite points have been averaged, giving the values shown in

36 STUDIES OF RECONSTRUCTED MILK.

Table XVIII. These values have been plotted in Figure 8. It is
easily seen that the fat content at the start is generally less than
34 per cent, whereas at the end of the run it is much less than 34
per cent. After 70 per cent of the batch has been run through the
emulsor, there is a decided falling off in the percentage of butter fat

ys OF BATCH DISCHARGED PREVIOUS TO SAMPLING.

20 40 60 80
Lee eee eee TS

| hoo

Ba
EEEEESMGES Re Gee che sn
i iG a AB a ss
eT
oD” ewe ec.
Aa
dG
RRR PRE RERCGMMok cok)
Ta hate elle alk kale
PP eee et dona
6 Ka
ss ET
Oe
EUqSC CERRO
Pl Es
Popped [eal colle | ead foal eh laa
Os
UCR OUEROeON eee.
haan lela) tel || oie ee ee
(Reese ibe ata re
Bal al al SI CIR
ro Peake [ola shebals tu) (ial a] abc eae alee
IT OEE OR TOS Ie NOMEN aE Sa
tg feo ale flail alt etal ala ae eal ala

Fic. 8.—Variation in butter-fat content of reconstructed milk at various points in the manufacture of a
single batch, Nitro, W. Va.

in the product. As the vat agitator is in continual motion during
the whole process of the emulsion, the reason for the very consistent
variation in fat content is not obvious. However, as the condition
exists, a cold milk storage vat should be supplied with every installa-
tion to allow the equalization of the fat content before bottling.

STUDIES OF RECONSTRUCTED MILK, Bw

Tape XVII.—Results of butter determinations made at various points during the
emulsification of a batch of reconstructed milk.

Per cent of run discharged previous to sampling.

Date.
0 3 TZ) LS 1416), 25: || 27, 28" |) 28) 38° |) 40)" | 42: | 43-1) 50) 458
1
DEG leo ce. 5 subtests See! Ree a bee Sos6) b Secse es SA ee ee Beoee Hones Bessel Reece Bele Baer
Nee os os 6 oe ad Bese OHO Saks lease tecesi EN a ome breil eae Bic (| beeen bs eae eae BOS cscs
jt ee ath | Laogel Eeecel Banas Sey (ol | eae be Rien be ae SO ses (Ss Scc|sorwclccecs SB leno lees
1919
BED ne Siee sects = =< See nc. Ul Be ceca Saree Cia E41 Sees el ME ners 326 bees | secce dl epee (epee (pee
Eee eee Beg Bese tees IhonOn Panes eecmel SS a|ROS OS Asaale Sema cisaie|) Orfailecsselecesc|Gsewell ions
11 eee Soe S35c ll See ee SBA Sean |Secine saeee Se Sheen eae oe Somos By Ole se sclesers| has se 3.8
Per cent of run discharged previous to sampling.
Date.

TaBLE XVIII.—Average values of butter-fat determinations made at various points
during the emulsification of a batch of reconstructed milk.

Per cent of
run dis-
Per cent
charged
previous to butter fat.
sampling.
0 3.4
14 3.6
27 3.7
41 3.7
54 Sal
66 Bari
San |! 3.7
84 3.5
95 3.0
; 100 PA

Summary.

1. Studies of the bacterial content of this plant’s output of recon-
structed milk and cream show that it was satisfactory from a health
standpoint.

_ 2. It has been demonstrated that satisfactory ice cream can be

manufactured on a commercial scale, with a bacterial content com-

parable to that of well-pasteurized milk and cream.

3. Using the revolving coil type of ice-cream batch mixer for mix-
ing the ingredients entering into reconstructed milk, a product of homo-

geneous fat content can not be made, and the final product from an

_ entire batch should be mixed before bottling.

oyrac

PAT. JAN.

RARY OF C

DTD

OOOO89L1b54 _

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