Webster City freeman. [volume] (Webster City, Hamilton County, Iowa) 1884-1946, 1916-02-22

(. b q.
cent Of all the bacteria in milk, al
though when the bacterial count oil
the raw milk is low the reduction
may be somewhat smaller. The effic-|
iency of the process, it is pointed
out, can not be based on the per
cent, but rather, on the character of
the bacteria destroyed. .a5
The kinds of bacteria that remain
(alive after pasteurization depend on
the temperature to which the milk is
heated and the species OF bacteria
which are in the raw milk. Three
processes of pasteurization, known
respectively as the flash process, the
holder process, and pasteurization
in the bottle, are now practiced in
this country. In the flash process
| the milk is raised quickly to tenn
perature of about 16O degrees 2. or
more, held there for from 80 Sec
onds to a minute, and then cooled
quickly. In the holder process the
milk is heated to temperature OF
from 40 degrees to $50 degrees F.
and held there for half an hour.
When pasteurization in bottles is
practiced, the raw milk is put into
bottles with water-tight seal caps,
which are immersed in hot water
and held for from 20 to 80 minutes
at a temperature Of 145 degrees F.
In this way the pasteurized milk is
not subjected to any danger OF rein
lection. On the other hand, the seal
caps must be absolutely tight and
this involves increased cost. In gen
eral, it may be said that the holder
process is coming into greater favor
than either of the others,/ This pro-
cess permits of the use of lower
Temperatures which, for various rea-
sons, is highly desirable. Another
method of pasteurization, or rather
la modification of the present holder
process, suggested by the Depart
ment investigators, is that of bot
Ting hot pasteurized milk. The pro-
cess consists in pasteurizing milk by
the holder process at 145 degrees F.
for so minutes, then bottling it
while hot in hot bottles steamed for
IL minutes Immediately before fill
ling. After filling, the bottles are
capped and may be cooled by any OF
the systems in which the caps are
protected. The bottles are sprayed
with water or cooled by forced-air
|circulation.
| When milk is held at las degrees
If. for 30 minutes, all the disease
producing bacteria, so far as can,be
ascertained, are completely Destroy
led. At the same time a larger per-
centage OF the bacteria that cause
milk to sour and smaller percent
age of those that cause it to rot are
left than when higher temperature
lis employed. Pasteurized at low
Temperature, milk undergoes no
change which affects its nutritive
value or its digestibility. subjec-
ltion to a temperature of $50 degrees
F. or more, however, does result in
certain chemical changes, Finally,
Ipasteurization at low temperatures
lis more economical because the ex-
pense of heating and cooling is less.
/ This, of-course, does not mean
THAT insufficient pasteurizatlon
should ever be tolerated. AS mat
ter of fact, the process of pasteuriza-
ton is frequently performed improp-
erly. For the holder process, l4o
degrees F. is the point at which In
vestigations have shown that dis
4 ease-producing bacteria are killed,
lbut in practice it is advisable to use
Ia temperature several degrees above
this minimum for safety. When the
flash process is used, investigation
has shown that very many dealers
fail to heat the milk to sufficiently
thigh temperature. This appears to
he another argument for the use Of
the holder process, although condi-
ttions in this respect are said to have
been improved greatly in recent