The morning news. [volume] (Savannah, Ga.) 1887-1900, 1890-07-27
BACTERIA IN MILK.
Interesting Report From an Experi-
mental SIation-The Points.

mental Station-The Points.
From. the Baltimore american.
WASHINGTON, July 21.-A number Of the
agricultural experiment stations have, IN
der the direction of the Secretary Of Agri-
culture, devoted much time and labor to the
investigation of the subject If milk. Prof.
Il. W. Conn, at the Storr's station in Con-
necticut, has devoted himself especially to
the study of bacteria in milk. His state
ments are interesting. After defining bac-
terra microbes, he says; Bacteria collect in
milk and cream that have been exposed to
the air, grow readily and multiply rapidly.
While growing IN the milk, they
cause it to sour and curdle, and induce
other changes in it. Milk, as drawn from
the healtny COW, is free from bacteria.
Under ordinary conditions. however. it
cannot he kept free from them, for they
will get into it from the hands of tie
mixer, or the teats of the cow, or from the
air with which the milk comes in contact.
The vessels in which the milk is kept are
the most common source Of contamination.
The bacteria collects upon the sides and III
the Joints of these, and here develop in the
minute portions of milk, grease or other
matters from which it is difficult to free the
walls of the vessel.
Within certain limits heat increases and
cold retards their growth. Different species
differ in regard to the temperature at which
they grow best Most species find the lest
conditions for growth at temperatures be-
tween TO- and 1909 Fahrenheit. A few will
grow readily at a temperature below SOY
Fahrenheit A temperature below freezing
stops their growth. The heat of boiling
water will kill the active forms, but several
successive boilings are required to kill their
spores corresponding to seeds). 1t is not
a fO haOtaria thnV have
once succeeded in getting into the milk.
This may be easily done by heating the
milk to the boiling temperature for ten
minutes upon three successive days. Milk
thus deprived of bacteria is said to be ster-
iliZed and if we prevent the further en-
trance of bacteria by closing the vessel
tightly with plug Of cotton, it will remain
sweet Indefinitely.
The number of bacteria present in milk
depends chiefly upon the length of time that
the milk has been standing and upon the
temperature. Estimates made upon the
milk under diffe ent conditions have show
from 800, 600, COO TO SOC, 600, 600 per quart
The effect of temperature is shown by an
experiment; a specimen of milk which had
been standing for four days in cold place
was found to have about 100000 bacteria
per quart. The milk was then allowed to
stand in warm room for seven hours, an /
during this time the bacteria increased a
hundred fold. From this it appears that
| the most effective method of prevent
ing milk from Souring is to keep
it cool. Milkmen sometimes find that tn =
mornings milk in summer sours before the
milk of the previous night It is easy to Sc
why this happens. Milk, when drawn
from the COW, is at a temperature best
adap, ed for bacteria growth. The nights
| milking is cooled over night. The morn
irg's milk, however, is poured directly into
| the cans and the bacteria which have en-
tered it are we'll started upon their growth
before the nights milk is warmed by the
air. The bacteria in the mornings milk
actually get several hours start, therefore,
of those in the cooled milk of the night be-
fore. The immediate cooling of milk is
thus of great advantage in preventing
souring.
Between forty and fifty species of bacte-
ria have been found in normal milk and
cream. This large number is due to the
fact that the milk may collect almost any
kind of bacteria that may be floating i'll the
air. The individuals of most of the species
are few in number, and ordinarily are of
little significance. A few species are almost
universal and extremely abundant.
Many of the species cause curdling of the
milk. Some of them do this by the pro-
duction of an acid, and the milk sours.
Others curdle the milk apparently by pro-
which case the curdled milk may not be
sour. When a curd is formed it differs in
character with the different species. Ac-
companying the curding various odors are
| found, among which may be recognized
| odors of the COW, the barnyard and even
| the pigsty. The souring Of milk is thus
| more complex than has been supposed, and,
while it depends upon the action of the
| bacteria, any of number of species, or
several combined, may be the cause.
| Though the presence of bacteria is
| nuisance to the milkman, it is of positive
advantage to the butter-maker. The ripen-
ing of cream undoubtedly depends upon the
| presence of bacteria, though it is doubtful
| whether any one species can produce what
is known as rpened cream. Rpened cream
| contains immense numbers Of bacteria. Over
| 100,0 900 have been found in a single small
drop. Dairymen let their cream ripen be-
| fore churning, because their experience
| tells them that the butter separates
| C'comes'1 more readily, has a better flavor,
and perhaps keeps better. A plausible ex-
PLANTATION of the first fact is that the bacte-
ria break up the albuminous matter con-
nected with the fat globules so that these
| globules are more easily separated from it
and more easily shaken together into large
Jumps. The products of decomposition
| usually possess prominent odor and taste,
| and their presence in the cream probably
| gives the special flavor to butter made from
ripened cream. Pure butter fat is taste
| less.
Few people understand what the thorough
cleaning of milk vessels meaus. A great
deal of milk is unnecessarily spoiled by lack
of sufficient care to remove all material in
| which bacteria can grow. Vessels in which
milk is kept cannot be properly cleaned by
pouring boiling water into one, allowing it
to remain for a few minutes, and then
pouring it into another, thus making one
heating do for several vessels. The last ones
thus treated will not be much cleaner, SO
far as bacteria are concerned, than if they
were washed with cold water. The use of
sal-soda IN washing is advantageous, be-
cause it acts chemically upon fatty mat
ter and thus helps to remove these and
other materials which adhere to the vessels.
In like manner the use of live steam" to
dry vessels after washing them has the ad-
vantage of steriilzng them, !. e., killing
the bacteria As ordinarily used. however,
the live steam does not completely sterilze
the vessels, since its effects are not allowed
to continue long enough Two minutes
action of live steam is not sufficient to kill
the spores of the bacteria that may lie
hidden in the cracks of the milk vessels.
In brief, vessels in which milk is to he
| kept should be most carefully cleaned be-
fore milk is put into them. AS cold retards