MARKET MILK
=Weight of Milk.= The weight of milk varies slightly with the
temperature and also because of the difference in the amount of solids
it contains. An average gallon of milk at 60 degrees weighs 8.6 pounds.
A ten-gallon can filled to the lid should weigh 86 pounds.
A can large enough to hold 100 pounds of water would hold 103.2 pounds
of average milk at 60 degrees, 103.6 pounds of skim milk, or 90 pounds
of pure butterfat. Cream weighs less than water. The butterfat in milk
is in the form of little particles or globules, which float around in
the milk. In Holstein milk they are small, in Jersey milk they are
larger. Cream is simply milk containing a large number of particles of
fat.
=Legal Requirements.= The law requires market milk to test not less
than 3% butterfat. Milk containing 3% butterfat but less than 11¹⁄₂%
total solids is usually considered watered milk. We determine fat
content by Babcock test and the solids-not-fat by an instrument called
the lactometer, which is simply an accurate means of determining the
weight of milk.
Milk from cows known to be diseased, or from cows fifteen days before
coming fresh can not legally be sold. After freshening, milk can be
sold as soon as it attains a normal condition. It is illegal to sell
milk to which water or any other substance has been added, or milk
which has been exposed to disease-producing bacteria, or milk that has
been stored, handled or transported in an unclean or unsanitary manner.
=Cleanliness.= The greatest handicap in the milk business is the
difficulty of getting milk that is as clean as other food which people
eat. It is not impossible to do, but it is rarely done. In most all
cities of the United States milk that meets the highest requirements
as to cleanliness and sanitation is being sold for from 20 to 35 cents
a quart. Such milk is guaranteed to be pure by a medical board and is
labeled certified milk. There are various requirements in producing
certified milk that need not all be explained here. But to the average
consumer the main difference is that the producer of certified milk is
as careful concerning cleanliness in milking and caring for the milk
as a clean, respectable housekeeper is in making bread. In regular
market milk we do not require cleanliness up to the standard for
certified milk, but all producers and dealers in milk should recognize
and admit the truth that common milk is not nearly as clean as it
should be.
The public is well aware of this fact, and the demand for dairy
products would be immeasurably increased if thousands of people did not
feel an aversion to drinking milk because as they say, “It’s so dirty.”
We can not go to the public and ask all we would like to have unless
we, in turn, give them just what they want. The public wants clean milk
and I believe that if milk improves in quality the public will use more
of it. No person with dirty hands should ever milk a cow and use the
milk for human food. A cow’s udder should be washed. The hair on the
udder and flanks should be clipped short, and to prevent dust and hair
from getting into the milk, her flanks and udder should be slightly
dampened before milking. A gunnysack cut up in pieces about 14 inches
square makes a very good towel on which to dry the udder and the
milker’s hands. A clean towel should be used for each milking.
The cleanliness of milk is usually judged by filtering a small amount
through a disc of cotton. This is called the sediment test. This
test, in a measure determines the amount of filth and foreign matter
which milk contains. Sufficient straining will make most any milk so
that it will show a clean record on the sediment test. But remember
that a strainer acts as a sort of pulverizer. Milk running through a
strainer gradually dissolves and washes away the particles until they
are so thoroughly in solution that we can not get them in a clarifying
machine. We would prefer milk strained through a metal strainer
only, but in many localities health departments require that it be
filtered through cloth or cotton. Where this is required we oppose no
objections. The greatest difficulty with cloth strainers is that they
do not get washed clean enough. A farmer usually rinses out his cloth
in cold water and hangs it up to dry. Sour strainers are about the
first thing we look for on a farm where the people have been having
trouble keeping milk sweet.
Absorbent cotton is all right, providing no cloth is used with it,
but that it be held between metal straining discs, or that the cloth
be thrown away each time with the cotton. Since to throw away cotton
strainers each time is expensive, I do not think the system is
practical for general use. It is easier and far better to keep dirt
from getting into the milk than to let everything go in and then try to
get it all out again.
=Sanitation.= Sanitation means “pertaining to health.” Clean milk might
be unsanitary for it might contain injurious bacteria. Bacteria are
plants. To avoid infecting milk with bacteria which cause souring and
decay we can not depend upon cleanliness alone. The first few streams
of milk from each teat of the cow will be found already infected to a
considerable extent. In certified dairies the first streams of milk
are never used. When cows are not milked dry at each milking there is
a considerable development of bacteria that takes place in the teats
and udder. Careless milkers have their trouble starting before the
milk leaves the udder. Various diseases infect the milk of the cow.
Milk from cows with garget or diseased udders causes sore throats in
children and should never be used as food. Dirt that gets into milk is
of itself objectionable, but it is also one of the greatest sources of
infection.
Milk utensils should be sterilized. This may be done by the use of
a chlorine solution called Bacilli-Kill, by boiling water, or by
the direct rays of the sun. Most sterilization is not perfect and
even the dust particles in the air contain enough bacteria to, in a
measure, re-seed any surface. Bacteria can not grow without moisture.
If utensils are not washed perfectly and food particles are left for
bacteria to grow on, there will immediately start a new development
from the re-seeding that will take place after the sterilization. Tin
cans can not be washed well enough to make them perfectly free from
foodstuffs on which bacteria may live. When milk dealers put cream in
cold storage, expecting to hold it sweet for as long as two months
they use cans that have never been used before. A metal surface is
rough and I know of no way to wash a milk can as perfectly as a milk
bottle. The milk utensils should be thoroughly cleaned with washing
powder, rinsed thoroughly with boiling water, then carefully dried.
In the operation of cleaning cans the most difficult thing to do in a
factory is to get the can properly dried. When it cools down there is
likely to be a certain amount of moisture deposited on the inside of
the can and there is always enough food left on which bacteria may grow
if the can is moist. In milk plants we sterilize all equipment just
before using. Cans washed and sterilized at the plant and used on the
farm twenty-four or thirty-six hours later become rancid because of
being shut with moist air in them. It is our ambition to sometime be
able to send cans to the farmers that will remain perfectly sweet, dry
and sterile, even if they are kept closed for a week. But now we must
confess to imperfection, and cans that get stale before being used are
perhaps the greatest menace to our milk supply. If a farmer can set
these cans in the sun with the lid off, it will help greatly. If he can
scald them with boiling water just before he uses them, it will help
even more.
Some farmers have great difficulty in delivering milk once a day and
having it sweet when it arrives at the plant. We have kept a bottle of
certified milk for more than three weeks in a refrigerator where the
temperature is above forty degrees and at the end of that time it had
not turned sour. Such results can be only obtained by experts, but it
is not difficult to become expert enough to always be able to sell milk
that is in a good marketable condition, delivered once a day.
=Cooling Milk.= The growth of bacteria in milk depends a great deal
upon its cooling. Milk has a great tendency to take up bad odors, and
its tendency to do this depends upon its temperature. Milk should be
cooled within thirty minutes after it is drawn from the cow. If cooled
below seventy degrees immediately and kept at that temperature or
below, there will be very little difficulty of milk souring, provided
due care has been taken regarding sanitation and cleanliness.
Well water temperature in this climate is usually fifty-four degrees.
By pumping fresh water through a tank, having it overflow so that
the warm water will flow off, it is easy in a short time to get milk
as low as sixty-five degrees. When running water is not available,
it is better to stir the milk until it is as cold as it will get in
such water as you have, then set the cans in a small tank of fresh
water that can be pumped by hand if necessary. Many farmers use the
stock tank to cool the milk in first, then use some half barrels cut
off at a height so that the water can not overflow into the milk but
that it will stand slightly higher than the milk in the cans. Use one
half-barrel for each can of night’s milk. In the morning cool the milk
in the tank only. However, the most satisfactory arrangement would be
to have a small engine with which fresh water may be pumped at milking
time, and let the milk tank overflow into the stock tank until the milk
is cooled and the tank is full of cold water. A tank should be divided
by partitions made of slats running up and down so that a can partly
filled may float without tipping over. It is not absolutely necessary
that milk be uncovered while it is being cooled, but the cover prevents
the milk from cooling as rapidly. Remember that warm water always
rises. The cold water will be at the bottom of the tank. Some farmers
divide their milk so that the cans will all float. The milk warms the
water and the warm water rises above the level of the milk in the cans.
Milk should always be covered when left sitting by the road waiting for
the hauler, and should always be covered in the wagon or truck. Wet the
blanket or canvas that covers the milk. This helps to keep it cool.