Reporter and farmer. [volume] (Webster, Day County, Dakota [S.D.]) 188?-1946, 1898-02-24


Rrssell publish in Hoard's Dairyman O
valuable accouns Of their experiments
in the chemistry and biology Of cheese
.ripening. Ii is the most obscure Of the
operations involved il the making Ct
dairy products, and the professors pa
per throws light on it. Following are
extracts:
Cheese is a highly heterogeneous sab
ssanse and is therefore susceptible OF
many fermentation changes that do not
occur in butter. Euttar fat is nos suited
as a food medium fer bacterial growth,
but IN cheeses, even these rica b fat
bacteria multiply very rapidly aus con
tinue to do so for q long period oE tme
When the curds are put 20 press they
are firm, elastic and insoiuble. "Ercau
cheese as all article OF diet Il not very
tempting, but If the same cnrd is al
lowed 60 stiand under proper conditions
for . considerable period Of ti.ae i ipses
Its original qualities and becomes spft,
friabIe and rendily soluble. Chemically
the change which occurs is aconyersiCn
of the insoirble casein into soluble pep
tones. and with this bTeakug down Of
the casein there is developed the pecul-
lar havor that marks q we'll ripened
cheese.
Ia our American Cheddar cheese
within a few days a marked develop
ment OF bacteria occurs. particularly
those forms that are able to soul milk.
This class has been supposed by Frau-
denreich and Lloyd &c be the cause Of
the ripening Of cheese, but when pure.
cultures Of various germs OF this class
are inoculated into milk sterilized by
heat no change other than the usual
souring is to be noted. This has been
the insuperable objection to the theory
that this class was tho cause of the
breaking down changes.
This summer in the course of some
experiments with milk to which ether
had been added we noticed that the
milk curdled and underwent digestive
changes without apparently increasing
In acidity. This fact could only be ex-
planned by assuming that bacteria could
live iii this etherized milk or that GER
tain ferments Of an ~unorganized nature
were present in the milk and that the
digestion-the conversion of the casein
into soluble peptones-was due TO these
agents. By further experiments we
were. able to exclude bacterial action
and show that there were naturally pres
emit in milk fern.ents comparable TO
those that ara found in the alimentary
tract and that these ferments, technical
ly known IS engines. were the canse Of
the spontaneous digestion OF milk.
This discovery IN itself was a contri-
button of some Importance to the science
OF physiological chemistry. FOR no
has previously claimed that milk con-
tains these digestiug ferments, although
similar ferments are found in the body
juices and many OF its tissues.
Although VI yalHa from this stand
point OF, physiological chemistry. this
discovery is invested with far greater
significance when VIC study tho rela-
tiols which it bears to the ripening
changes in cheese.
sItwas found that MilA invariably un-
derwent this decomposition il the bsc-
terial'ferrentations we're held in cheek
by. the addition OF chamiclis thai lid
not siestroy the action or these unargAn-
lied or chemical fermessts. Among tie
Substances useG were ether, chiorcf1rln
and benzol. Furthermore, this change
was Of . progressive character Ii was
also Immediately suspended II the milk
was boiled. or treated with u stralg
chemical disinfectant.
~ comparative study al the p~rodhsets
Canned ia these milks 40 treated corl-
pared with those that occur in a ncrraal
cheese showed thac they were strikingIy
similar.
ATTEMPTS were then made to isolass
the ss1pposes engyznes, and ty means Of
the nsuai physiological methods it was
possible to separate from ,censrifuge
slime certain extracts that were rela-
lively tpnre. Slime vas taxa for the
reason that, these enzvmes are likely 70
attach themseEes to solid matter held
In Suspension, and this being true we
expected to, find that the slima thrown
out OF che milk during its separation
would be krlatively richer in these sub
stances than the whole roilk. Achem-
ical analysis Of slime xsnd skizimilk
showed thU the, change Was much snors
rapid IN the slime, thus iEdicatingzth that
larger quantities, OF the Eerments were
present.
While every lanakog showed tkat
cheese changes were identical in charac-
Ger with those that occur in nornxl
cheese. still we did not consider or
paint concluxiyaly proved until cheese
made from milk that lad been
kepk under chIcxoforn. The same
cheese was also kept in a saturated at
mosphere Of this anGsthetic for q long
period of time. Usder these conditions
bacterial growth was impossible. and
sast az . normal cheese kept under fa-
yorabie eopditions.
1t WAS therefore possible 20 break
down the easein entirely without tn
aid OF bacteria. Thus tho proper texture
~ the curds 10 produced not by the &C.
taon OF ths jaottc acid organisms on ANY
nfHsz known form OF living germ, tut
w digestion ~ tbs eAsein CAUSED by fkA
}NAerSnt enyymey ykaf ne naturally