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MKIOCOPV RiSOlUTION TIST CHART
(ANSI anH ISO TEST CHART No. 2)
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^ rJ PPLIED IMjG E_
^BT; 1653 EosI Mam street
^^ (716) 482 - 0300 - Phone
^^ (716) 288 - 5989 - Fox
BULLETIN 117
Ontario Agricultural College and Experimental
Jam
'fax
CO B9S
th;
HP CONTINUOUS PASTEURIZATION OF Mlf k' \T
DIFFERENT TEMPERATURES i'OR BUTTER MAKING;
By Pkof. H. H. Dean. B.S.A., and Pr„k. F. C. Hahrison. B.S.A.
The constant striving of ajrricultural countries to produce tlio Lest
articles at the lowest possible cost for the En^Hish n.arliets has res„ ted
in very keen competition, and new competitors are constantly entering
the held \\e have lately heard that Siberia is sendin.r considenTle
quantities of butter to England, and that special refrigerator trs
and steamers have been built in order to handle this product At
presen this butter, althoush good in texture and make, licks uniform
ity and flavor; but these defects will probably be spJe iily remeS
he Russians have lately sent expJrts to Denmirk, to stu v he
metho.ls toliowed in that country, and have even in.ported 'kil ed
dairymen tor the purpose of instructing the Siberian peasants. H -nee
it behot,ves the Janadian maker to take a.lvantage „f every new
method which IS shown to be of value in producing a tirst-class article
AS It has been the strenuous endeavor to cheapen pro<luction in
those countries which make a specialty of dairying, tfiere niust be good
grounds for their adoption of pasteurization, a,roperation whi^l^ i^-
creases the cost to a, considerable extent in the outlay, both for appara-
tus and for the production of the heat required in the operation^^
Ihat buttermakers should incur this additional expense is verv
good evidence that pasteurization is an important operat on, and that
without It there is difficulty in obtaining the best results
Ihe comparison that has often been made between the farmer and
the dairy.nan explains the chief reason for pasteurization. The farmer
cultivates his land and prepares his soil for tho special crops he intends
to grow ; he eradicates as far as possible all weeds, and he selects with
sown. The dairyman also prepares his soil, the raw milk, bv heatine
It to such a temperature as will kill all or the greater number of bac-
teria which may be present, these being his weeds ; then I.e seeds his
milk with a selected varied, of mic.o-organism found to produce a
good flavor in butter ; and h also expects to reap even as he Ls s ,wn
These two points-Hrst, the preparation of the milk by pasteurizing.'
and, secondly, the seeding with selected races of bacteria-have enabled
al niakers to secure the great desideratum, unifom.iU, of product
which IS of such importance to both producers and consumera
[11
W
l^
In addition to this uniformity. th« l.utter-iniiker w mcKlontally
able to drive ott'crtain unpleas^vnt .)<l.)urH that nuiy be nre^ent in the
milic snpplitd to hiu. ; and the keeping .piality o his product m hereby
creasHi lH.cause he ban killed the hiryer nunda-r -d the harndul bac-
teria, wJuch, if they had ren.aiued living, nuKht have unpaired the
(lualitv of iii» butter. , ,, c ; . „«
Further, if the ri«ht temperature ih used, a\\ <hs,UHe.j>ro<h', >np
orgonlsn,. are destroyed, inch.din- the bacillus tuberculo«.H. wh.ch ,s
very fre.,uently found in l.utter. This fact alone wdl u-ld eonsi.lerably
to the coud'ort and security of the consuni.r.
The whole problem of pasteurization is a question as to the p'oper
temperature; and unfortui.ately this is a n.atter of so.ne complexity^
The effect of temperature on bacteria depends ..n the.le^i.o ot
heat and the length of exposure.-a low de-rce ot heat and a Urn ex-
posure bein« e.,mvalent t.. a hi;,'her temperature ami .ho, ter exposure ;
Li the former takc.s too much tii.ie au.l is not pract.cahle, while the
latter is apt t.. yive a cooked taste to the milk. Hence we have tw
Im-thodsof pasreuri^in« f.>r two diri'erent objects, which have been
termed the Discontinuous and Continuous systems,
n. l);HC,>nflnunUHS>,.(nn,or a system of pasteurizinjj froiii the
milk-dealer-H Htandpoint, re.,uire.s that all di8ease-pro.luclI.^' 'acte'-ia
be destroyed, that the milk possess «ood keepin- .piabty and that the
taste b- not injured. In order to obtain these re-iuisites, the milk must
be hellln 1^0 decrees F.. be stirred durin, tl. process to preven
the formation of a pellicle, or scum, on the -urtace ; and be 'leld at
this temperature for 15 to 20 minutes. This t'jnipenvture /or th,>
length of time, has been found sufficient to kill the baeillus tubercul-
osis the most resistant disease-producinjr ^eim found in milk.
n,.Contni>um^ii>lxte.m, or a system ot pasteurization from the
butterinaker's standpoint, was Hrst introdu..-e.l by the Danes. By
this method, the milk H .ws in at the bottom of a vessel hef . . ,
steam, is whirled against the .side, and (having reached the
temperature) Hows continuously from an outlet in the top. li u ■
is to kill most of the Lacteria present in the milk. I .y a v,
actinent in Denmark, this temperature has been hxed at «\«2;-- -.
(185 .le.'rees F.,) as Dr. Bang has shown that the tubercle bacillus ,i
bacillus'^tuberculosis, is killed in milk heated to this temperature. By
this means the buttermaker gets ri.l cf bacteria that might subs-
quenth prove harinful, and pi^epares the milk for his selected bacteria,
Dr culture, as it is usually called. . • x
In Canada and the Tnite.l States, the usual pasteurizing tempe, -
Rtnre is 158 detrrees F., (70 .legrees C.) to 160 Degrees \ ., a temperatur.'
selected becaust bythe.liscontinuous system a cooked taste was impart-
ed to the milk at higher temperatures ; but, as pointed out b> .i
recent New York ExpJ^iment Station bulletin, the American expen-
menters went astray in their reasoning, " for the cooked taste is tl.^
St of an exposure of hot milk to oxygen, and the cooked Havor do.-s
1
»isi.i:il
not Httiich itsflf tenaci..usly t.. the f.it. ..n.| l.i.tt.r iiui.le fn.m liiirhly
heateij milk that may havi- n ' ' ^ *" ^
churning' Iohcm this .flijoctional.lf fl
)r
«tx)ki'il tusti', iiiiiiu'<liat<ly after
avour ill u short tiiiie."
r<.i; HIS years Mm. Dairy Kepannu.nt of ih.- CoILm* has Jnieii
condnctii.j. experiments to .letenuii.e the effects of pasteui i/ati')n .,n
milk ami eream tor huttermukiny.
i«or'^" i'ri',?-^''* *'"■ '''''■'"'<^'-"'""t»'""ftl'<'<l«"f pftsfeuri/alion since
1«9«. amny.»<,we.,uote Iron, the aan.i;.! ivport ..f the Coll for
those two years : o ' "
"< )\viii!,' to the lick of s.iita'.le appliune.'"^, ni..st of o„r i-astenriz-
mj^expenments were con.inete.! l.y simply h.-atin;; tl..- cream eontuin.'.l
;?,r.MroT''''^'^i "'.''' ^""^ '" " •'"•^ ^^"terl«lth)to ,i tempna-
ture ol l(,() .io^rees. In ahont 20 minutes afterwanls. tl ream was
coole.l to ripenin- temperature an.j the starter" was a.l-le.l " -
'• It has heen s.i;r<r,.ste(i that i.ast.-Mi-i/in;; tl,.. whole milk /w;„v-
separa M.i,' was pn.|eral.le to h.-afin- the cream an.i skim-milk ,.//.r
Hepaiatin- A vat of milk was heate.l to a temp..rat..re ran.'in.r IV„„,
!».. .K^rees to )H ,le«rees. ami half of it was s.-parat..!. The Mh^r hal
was then h..ate.l trom 1.50 cle;,.rees to UiO ' 1..,^,.,..., ..n.) s..parate!i
Al the I";*!!!.- was .lone in a vat l.avin^r a capacitv of al'.ut .SOO
pouiuls The chief rhthculty was in piever.tin- th. milk from eo.,l<-
mL' on the sides of the vat. Hy earefully nuuTatin,^ th.. ^tean. and
by keeping' ih.- milk in motion, this trouMe was lai^'ely pr..v,.nt.d "
The experimenis instituted at the l nlU;r., Dairv^in l!»01 were to
determine the (juality and keeping prop.-rty of hutter ma.le Iron, milk
pasteunzed at dirierent temperatures. I,, the hacteriolococal I.thora
tory, our attention was .lirected to the numlM.r and kin.l of t.icteria in
em lo' ed""'' "" " I*'**''""'''**'''" "< ^he dilK.ivi.t ten.p..ratures
Tests at the Wi.scon.sin Station, with the R..id pasteii.iz..r at tem-
pera ures between 1.50-105 deir.eesF. showed eon.si.lerahle variation
Ihe lowest number in the pasteniized san.ple was ,S7,400 bacteria i.er
c.e., and the h.^^hest 17,-)00,0<)0 per c.c.,-a verv wi I,. diHeience The
avera-e number left (14 tests) after pasteurizinsr, was about 1 NOOOOO
or nearly !t2 per cent, of the bacteria were destroye.1. But this hardly
represents the variation in the effect of the h.,.atin;r; for in some cas/s
40 per cent of the fwcteria surviv..!.
The Pennsylvania Station, whilst -rivinj,' no numerical .lata, states
that lieatin^r to this temperature (l.5.-,-1.58 de-rees) dostroved few if
any, ot the bacteria present in the milk."
The New York Experiment Station have fuller data on this poir.t
At l.o«,legre.ss >., they foun.l that the pasteuii/iiig action was v,.rv
nncertain, and that this temperature lies near the lower limit of the
killing effect of heat applied in thi.s way ; and. when operatinir a pas-
teurizer in ordinary practice, temporary reductions of temperature are
II i!
•Imcwt sure to occur. Hence the kJlHnK effect below tVw teiii|)er»turo
in yAPV Bllfirh^* 1 Kt
ObaervationK by the same station were made at 170 .l.'>rre.'4 ¥.,
and the renultH of panteiirization at this temperature ' ^howeil a hui -
prisinir rwhiction inth^. gerin life, and thin re<luctu>n woHaccou.pl.Hhe.l
with very nliRht variation on each of the 25 dayn on which the tenlN
were made. Thene t.^tn gave an average ot nly 117. with a maxi
mum of 2!)7 and a minimum of 20. living germs per c.c. in thepa^teur
Seven tents at the tempei-rttuie UMed in Denmark. 1M5 degreeHF.
gave an average of 1 1 ^ living germs per c.c; an.l. as the writers remark
•were it not for the fact that in the present state of our knowledge, it
in believed that a heating of milk to \Hn degreoH F in a continuous
pasteurizer, is necessarv to lemov all dang.!- of tuberculosis, the us.
of hOdegivcHi;. (I7C d.grees F»iu pasteurization tor J.utter-makiiiK
would leave little to be tlesired." , . ., • . .
Tin' Pant, arizern.— The pasteurizers used m the experiments
here were the " Rei<l " in March an 1 the first seven days in April, an.l
the " Li- er '• for the remainder of the season.
The Reid machine is driven with a Wit and. in addition t.. heatiii;.'
the milk, elevates it several feet Th. ...ilk is heated by m.ss.ng over
a Hteam heate.l surface, and it is kept in a circular i.K,tu.nby means ..
paddles which revolve in the milk. The w..Hknes.seH of the Re.^l
pasteurizer are . The difficulty of maintainuii? a uniform tempenitu...
and the fact that it requires a firm foundation .or the large machine.
Its strong point is that it not only pasteurizes the milk, but act*- as a
milk puinp tor lifting the milk from the receiving vat to the ■•'eP'V^ato'--
the Lister maclune is driven with steam directly from the boiler
and is what is commonly calle.l a turbin.- pasteurizer. It does no
elevate the milk above the outlet near the top of . machine, and must
be placed above the separator in order to have the .ailk flow into th.'
separator. The milk for this machine was pumped from the receiving
vat directly Into the feeding funnel of the pasteurizer; and the
temperature of the milk, which was received at a temperature .)t
aboJt 60 degrees, was raised from 125 to 130 degrees wh.l
passing through the machine, when fed at the rate ot about
2 600 pounds of milk per hour. M.Ik which was heate.l ah...'
185 degrees, rec.uired a preliminary heating before entering tlu-
pasteurizer. The three weak points of the Lister machine a.o.
That it does not elevate the milk, that the centre bearing of the
paddles fills with milk if the machine is allowed to get to.^ tull, an.l
that the turbine has not at all times sufficient force to keep the ...ilk
in constant motion. The strong points of the Lister iire that i
occupies a small space, nu belt is required to run it. and no sp.ml
foundation is needed. c i i. u
The Danish Pasteurizer, invented by Fjord, has of late bee con-
siderably altered, because the Danes are now compelled to heat tr..-
milk t<> 85 .lejjrt...M (•..«„ | the oM fnrin of npp«ratiiH in not c*i>able of
econoinically h. atm« the milk to this t.iniK.ratur... Thf impr(.vt.m,.nU
Are iiH followH : "^
A Mcri.-H of rin«H nre Mohk-r.'.! on the hentimj Hurfuce of the wm-
teunzer. llu-se tiiikh hIo .e .lownwiii-.Is, ^Mvinij the »i>p«5*rance of
cftvcH arranjCHl concentrically aroun.l the he/iter. Thes. • inim gather
ami «he.l the water formed hy cn.lensation of th.^ steam on the heat-
inK Hurface; ,r thia water .l.|,osite.i ,i. « thick layer upon theHiirface
of the heater, is a U.| conductor, opposes the r-sistance. and enfeebleH
the penetration ot the heat to the milk, which is tiirown by the asrita-
tor apiinHt the inner surface of the heater.
The agitator httH al.s*) lH.,.n improved i.y the addition of horiz.mtal
piatcH on the paddle, t.) prevent the milk from takinK t«K) vertical a
movement m the pivsteurizer ; and this improvement helps to irive the
same temperature to all parts of the milk, and prevents frothing.
A thud unprovement \h an air cock fixed on the water-trap which
allows the air carried alon« into the steam jacket to escape
No (h.ubt the efficiency of the Lister and Reid msteurizers could
be increased considerably by attachinif the improven.ents suL'Lrested
by Prot Storch. of the Experimental LalK)ratorv of the Koyal Airri-
cultural and Veterinary Collejre of (.'.)penha<,'en. '
Daiuv Data.— In our Dairy, the experinients con.Hi8ted of several
series .
Serie>> I. In the first, abcjut M.OdO lbs. of milk wa« mixed in a
receiving yat ( )ne-half of .several lots was separated at a temperat.ire
of about 90 degrees V .. and the oth-r half was pasteurized at tem-
peratures ol 140, ItiO. and l«o degrees K.
^l>''»'» II- In this series, ,S,000 lbs of milk was well mixed. One-
half of .several lots was heated to 140 degrees F. before separating-
an.. >e other half was heated to IGO, IH.5. and l!)-> degrees ¥.
^nex III In this series, (me-half of several lots wa.s heate<l to
IbO degrees, and the remainder to IH.t degrees
S^'t'is IV. In this sf.rifs, samples "of butt.'r made from milk
heated to 185 and 11)5 degrees were compared.
Sn-h'H V. In this lot. one vat of ab.nt .S.OOO lbs of milk wa.s
•lividefl into four parts During April and May, each of these parts
was heated to 140, KiO. 185, and 19.-, degrees respectively ; but durintr
March. July, and August, the temperature.s used were 90 140 IGO
and ]85 degree,s. ' '
Setiex VI. In the last series, experiments conducted during
March un June, vats of milk were divid.'d into two lots. One part
was left nnpa.steurized, and the oth. r w.is pasteurised at about ifiO
degrees.
Boihr PrfA-«?v'— The boiler used for generating steam at the
i>airy is a 50 horse-power boiler situated about 50 feet from the pas-
teurizer. An average pre.ssure of 75 to S(» pounds was maintained as
tar as possible. When the steam pnssure was reduced below 70
If,
iS. , li
poun.lii, it wrt-i .lirtJcHlt t.. iimin»*ln tli.- milk at IH.1 t.» lin .l.tfn>0H
without iclucintf t»i« ftwl. It in ..vi.l.nt tlmt. if i>»Mteiiri/,in4 »»i IHO
ilfKii'«'H i" prACtiMt^l, a liir;(»< l<.>iliT hikI »Um\y rttoaui i.r«M«ir.' will Jhj
nxiiiirtMl. , , ,
Durinij the >.nr nwirly 100,004) 1»>h. of milk wer« um'.! in the ex-
periiuoiitH. Kor April rikI M.iy milk whs r.ctMv...l four tinu'H n wf.;k.
Thf aveniK" pt-m-ntjip- of fnt in th^' milk «>f the HrHt four M.-rii-M
riingwl from 'AM* to «.<.!». Th« t.'miHjrature of tho milk whmi ro-
cciviMl wiiM 40 to HO (U-Kn'.H in Marrh iiixl April. In May it wan
about :>!» .le«ivt.M. Jiuu' 6i» ih'«r«i>H, July .ui.l Au^'UhI «:> <|.';(re.'«. The
avera;:.' .ici.lity in th.' tir>tt four hitIoh, whi-n the milk whs .h.liv..rt'«l.
»ii.H.l7 to.lH percent. Th.avi'rft}?enci.lity of the cream at th.-tiim- the
cultniv for ripcninjr was achl.il, vaiitM! from OHH per cent for the l"tH
heated to ItiO .i -r.es to .IIH for the ht> heated to 140 .l.'«ree.s
Those heated to IH') <l. triers had an avoraKe acidity ol .114; and
thiwe lotH o» cream from milk heated to 105 dejree-. lH.f..re He|>arivtin«
had an averap- of .104 per cent, of acidity at the titne the culture was
wlded. At tlu' time ot ehurnin),', there was very little <liHerence in
the acidity of the ditlerent lots— heinjj from .'» to .0 jxr cent.
The perceiitaue of fat in the cream in th.- Hrnt four HerieM varied
from an averay«« oi 'Ml in the lotM separated at 14i> duu'n-.s to -'Hi] in
the lots separated at 195 dejrrees. There was practically no diHerence
in the fat lost in the skim-milk and huttrmilk, whether the milk wiw
separated nt 140, KiO iNri. or 195 deyiveH The skim milk avera-jed
one-tenth of one per cent, fat, and the hiittermilk avenijjod aUnit .15
per cent. fat. The temperature of the cream at the time the culture
wa,s adde.1 varied from 6('. to (IH dejrrees. The avera.-e tempeiature
for ripeiiinj,' the cream was ahout 05 de;,'rees for all the lots. Ihe
average churninj,' temperature was 49 dejjrees f..r all lots. Th.- aver-
age time required to churn the cream wa.s 41 iiiinuteH for th. lots
separated at 140 decrees, :{9 minut.s for the lots .separated at l«iO
dejjrees, HH minutes for the lots separated at 185 •lejjrees, aii.l 8t)
minutes for the lots separated at 1!>.') dejrrees.
The i)eicenta<:e of moisture and salt in the hutter were : L ii-
pasteurize«l, i;i.690 per cent, moisture and 2.1.') per cent. salt. Pasteui-
ized at 140 de- rees, the moisture ami salt were, re.spectively. 18 12>S
and 2 57 ; ••♦ " -"> de;;r.'es. 18.224 and 2.85 ; at l«.^ <le;riees. 18.994 and
2.55: a/l9i3 uegrees, 18 501 and 2.62. All the hut er was salted at
the rate of erne ounce of suit per pound of I. utter.
After workinjj, the hutter in the first four series was put into
pound prints and wrapi)eil in parchment hutter paper. < )ne print ol'
each lot was numbered by the buttermaker, when it was placed iii
cold storajje at an average temperature of 40 decrees. The prints
were scored by numbers, so that the scorer did not know what kind
of butter he was scorintj. Nearly all of the butter was .scored twice
— once when made about two weeks, and again when one month to
six weeks old.
<V>ii.pari-«.ii of hutfr „«.!« frm,, iu,p„Mt..uri/...| ii,i|k with l.iit'^r
"'*''" '»•""■ ""'k »'"*t.'.l to I4(t. im, ari.l In:, .l.-^nTs.
No. of
Kind of BtiUvi
i
Is
<3I
i
i
fa
rnpa* rnriiad
I'Mtriirixml at IWiirgtt—.
t'n|jMti*uri«Mi
pMi«u*it«d k( 100 (li-KrcM ,
' ' rwnteiirixM) .
i'»';^iiri/*l At 18ft d^Kriwit. .
S9 H
41 3
87 I
24 ft
10 n
4\ .*.
2ft
20
1
U.l
14 ft
U »
04. S
•••ft.r
Ul L'
»4 N
Uft.B
Coinparison ofhuttn- ma.l.. fr,.,„ milk past.-urlz.".! ,»i UO .li-nwa
with butter niu.i*- fn.iii iiiill< heute.! to IfiO. \Hb, aii.i IJ»5 iU^'^rwH F.
!5
l*Mteuriz«<t at 140 d»((rw*
Paatfuriz-Hl at lAO dc^refii
PmUuH/.»<1 at 140 flecnwa
Paitearizaii at IR'. (I^^'re*-*
Pa«tanrl7«d at 140 <\ntnn
Paatfiiriz'd at 196 defrrnf*
24 U
14
11
Hi 7
'J3.»
3!» ti 1
«0 4 j
2.-.
as
14
14 1
iM.ft
I !
4
14 8
24 H
14 »
14.3
1»4
Scnriiiu '.(' Si rifs J If,
Coinparison or b;tt, r nia.h i,< m ,„ilk pnsturized at 170 (i.-iire..s
th butter tiuKif froi.. ., ilk pastcuriz..! at 185 .|»Mrret;.s F.
10
10
Pa«teariz«d at 160 devrfei.
Pattear z>d at 180 deffreei.
40 7
41 U
3S
26
I 14 2
14 1
94 N
95.1
Scorinff uf Srrii'n IV.
LT made from milk pa.«s
milk pasteurize.1 at 19.'> <le;,'rees F
•^u^^'llP*"""'! "^ ''"^^''* ""'••''' *"•■"'» '"'"« lia.'steurized at 1S6 de-'ree
with butteriuude from •-"- ^ • ' ■'-- • I"- «->o ue^rtt
Pa«teurized at 1H5 degre«i . . .
Paatenrized at 196 degrep*. . . .
41
40.8
26
25
14
14
96
94.8
p-
i
i-
f. 1
In the fifth fleries, where vats of 3,000 lbs. milk were divided into
four different lots during April, May, July, and August the average
percentage of fat in the milk ranged from 3.7 to 3.H. The per cent,
of acidity in the lailk delivered was .17. and that of cream at the time
of adding culture was .09 ; and at the time of churning it was .55 for
the lots heated from 140 degrees to 195 degrees and .59 for the lots
separated at ninety degrees. The percentage of fat m the lots ot cream
rancred from 27.6 to 32. The percentage of fat in the skim-milk was
less^than one-tenth of one per cent, for all. The fat in the buttermilk
was about .15 per cent, for the pasteurized lots, and .25 for the un-
pasteurized samples. All the lots had the cultures added at an aver-
age temperature of 68 degrees, were ripened at 65 degrees, and were
churned at 46 degrees to 47 degrees. The average time required to
churn the unpasteurized lots was 47 minutes ; the 140 degrees lots, 40
minutes; the 160 degrees lots, 39 minutes; the 185 degrees lots, 3/
minutes; and the 195 degrees lots, 42 minutes.
Scoring of Si-ries V.
Comparison of butter made from unpa-steurized milk and butter
made irom milk pasteurized at 140 degrees, 160 degrees, 185 degrees,
and 195 degrees.
No. of
Kind of Butter.
k
<
<
o
Is
I'm
u
Is
u
<
2
4
4
4
1
Unputeurized
Faateurizei at 140 dejfreea
Pasteurized at 160 degrees
Pafteurizp . at 186 deRrees
Pasteurized at 196 degrees
39.2
39 2
39.6
41.1
40.8
26
25
25
25
24.5
1
14.2
14.1
14.1
14.4
13,6
93.4
9» 3
93.7
95.6
93.8
i^i
In the sixth series, during March and June, 2(1,000 lbs. milk, test-
ing an average of :"..84 per cent, fat, was equally divided : and one-
half was .separated at al.out»0 dejirees and the other half was pasteur-
ized at KiO degrees. The per cent, of acidity m the milk when re-
ceived was .15.i. The acidity of the unpasteurized cream at the time
of adding the culture was .154, and that of the pasteurized cream was
131 Both lots had about the same acidity at the time ot churning,
viz 5 per cent. The pertenta<ies of fat in the cream were 30 per cent
in both cases. Tlie fat in the skim-milk in both cases was less than
one-tenth of a per cent., and the buttermilk averaged .15 per cent. tat.
Both lots were ripened at the same temperature (04 degrees) and wer.'
9
churned at the same temperature (47 degrees). The average time of
chuTMUg was 41 minutes for the unpasteurized cream andl? minutes
loi the pasteurized cream.
Scoring of Series VI. '
Comparison of butter made from unpasteurized milk, with butter made
from milk pasteurized at 160°.
No. cif
Samplei.
Kind of Butter.
no
110
/3
13
{
(JnpMtrurizer)
Pasteurized at 160 degreei ....'.'.'.
UnpaHtxiirized, March .
Pasteurized at 160 degrees March
Unpasteurized, June
Pasteurized at 160 degrees, June!
i
6
1^
1.
h
Average
Max.
<
>
<
>
<
38
24,8
14 4
92. VO
3».4
25
14.3
9.S 65
:«.;<
24.3
M.3
87
;«.H
35
14.2
'.to
40
25
14 4
94.4
41
35
14.2
96.2
The keeping quality of boxed butter from milk pa-steuiized at different
temperatures.
T>ateof
Making.
Temperature.
July 5
Aug. 5 . . . .
Apr 24....
May 27....
July 5
Aug. 5 . . . .
Apr 24....
May 27....
July 5
Aug. 6
Anr. 24....
M«y27. ..
July fi
Aug. 6
May 27
Unpastnurized
14
Pasteurized, 140 decrees
140
140
140
160
160
160
160
185
185 "
185
185
195
Scor«H for flavor at end of
14 days. I 60 d
42
43
42
43
41
43
42
4S
41
42
43
42
42
43
43
36
39
32
42
34
38
37
41
37
39
88
41
41
40
41
1 125 days.
j 164 days.
.36
42
36
40
r"v •
' 36
"'39'"
41
40
41
h ' i|
U
39
41
10
Keeping Quality of the 2/tt«cr.— Butter for cold storage and for
export must possess teep 1*1.9 quality, a point which is usually over-
looked in judging butter. If we are to compete in the British markets,
Canadian butter must overcome the prejudice which exists in England,
that it will not " keep. ' „ . j- i ^u *
Our experiments during the past six years all indicate that pas-
teurization improves the flavor and keeping quality of butter made
from winter milk In summer, when conditions are more favorable
for the making of fine-flavored butter, there is not so much difference
in the flavor of the butter when first made, whether pasteurized or
not However, when samples are kept for some time— 60 to 160 days-
there is quite a marked difference in favor of the butter made trom
pasteurized milk. Our experiments for the past two years also show
that the higher temperature of 185° is more favorable m the produc-
tion of " keeping quality " than the lower temperatures of 140 to 100 .
Bacteriological Data.— The culture media used were ordinary lac-
tose agar and whey gelatine. Usually 4 plates from each sample were
poured, two of lactose agar and two with whey gelatine. Ihe whey
gelatine gave very satisfactory results. It was made from whey, boiled
and filtered, to which was added h per cent, of peptone. ^ per cent, ot
Heyden's Nutriment (Niihrstcff Heyden), and 10 to 12 per cent of
^^ * tS acrar plat-s were kept at 20 to 30° C. (83 to 86' F.), and the
gelatine pktes at 20 to 21" 0. (6S to 70'> F.). Of the two kinds of
media whey gelatin.- was preferable, as the colonies of the lactic acid
bacteria were larger: and the spreading surface colonies on the agar
plates made counting rather difficult. But little numerical difference
between the plates made from the different media, was noticed.
The samples of unpasteurized milk were taken directly trom the
receiving vats, after the milk from all the different patrons was
thoroughly mixed. ^ . i xv.
The temperature of the pasteurized milk was taken by a ther-
mometer inserted close to the outlet oi the milk from the pasteurizer ;
and the^e samples were taken from the outflowing milk in large steri-
lized test-tubes, and brought to the laboratory, where the analyses were
made at once.
f)il„fion.— The sample was thoroughly shaken, and i c. c. was
added to 10 c. c. of sterilized water, and i c. c. of this mixture again
added to 10 c. c. water, and a small fraction of this was added to the
culture medium, and plates poured. By means of this dilution, the
colonies were not too crowded on the plates ; so they could be easily
counted. With the pasteurized .sample no dilution with sterihzed
water was made, about 1-20 to 1-30 of a c. c. of the pasteurized milk
being directly added to the culture medium.
;A
11
Jiesults of Continuum Pu^horizaflo,, of At ilk at UO-IAO F
Thirteen tests, percentage of bacteria killed, itr).42.
Date.
April 10
<<
12
11
15 ■■
May
1
4
11
18
It
21 ■■■
27
»i
29 ■
June
3
»«
6 . ...
(t
Aug.
8
6
UnpaRteurizad. i PMtrurJMd.
Average No. of
Kerms per c. c.
8,090.000
■■<.7.S6,000
3,7a5 00O
8,73fi.00O
13,400 000
14,510,000
S«,8S0,000
16,260,000
17,()00,tlOO
15 670.000
I'>,".'3.000
22 340 000
61,(t0t>,000
Average No. of
gerniB per c.c.
243.600
2.(6.000
218,600
567.000
367,000
887.000
800.000
667,000
a'JO.OOO
7L>0,000
672,000
812,000
1,400,000
R''.svlt>^ ofGontiniiom Pa.^trariz',t;,„i of Milk <>t WO-Pjr/ F
Twenty? tests, percentajre of hucteria killerl. 99.9,5.
Date.
PaateurizingI '''«•«'!*'•»•
tempera- l'"!* "' """' Aciditv
tore I ''^fo'e PM- |'*«""'y-
I teuri/.ing.
UDpa§teurized. Paateurize.l.
Mar
2J»
April 1
• «
3
<l
6
u
8
t
10
II
17
11
19
(«
29
May
1
15
(1
16
t.
18
(1
23
II
27
11
28
June
8
11
5
II
7
Aug.
5
Average germa Average germi
P^f C.C. J per c.c.
160
53
.15
160
46
.16
164
52
.15
160
54
.16
160
ra
.15
160
54
.15
160
66
.19
160
46
.17
165
60
.21
160
58
.15
165
60
.19
IfiO
60
.18
160
61
.19
160
61
.17
IKO
.58
.17
160
62
.16
160
5S
.16
160
60
162
68
.16
165
507,600
1,402,100
288,000
2,784,000
7,040,000
8,090,000
9,090,000
1. 820.000
25,100.000
8,7.W,0()0
4.060,000
1,511,000
14.510,000
13,276,000
16,2.50.000
23,400 000
15,670,000
16,274,000
31.113,000
51,900,000
510
8,9.50
610
410
9,026
650
2,800
9.<,800
ll,4l'.J
-'.■t,2f0
10,700
16,800
13,000
7,400
12,000
6,300
4,700
11,700
8,370
10,200
It 1
ft \
!•?
12
Resvlts of ContinuouB Pa.teurimtinn of Milk at ISo' F. (85' C.)
Fourteen tests, percentage of bacteria killed. 99.99953.
iHte.
PMteariziog
teiuper«-
ture.
Tempera-
tars of milk
bvfore P»«-
teurizing.
April
M»y
Jane
Aug.
19 .
17 .
33 .
29 .
4 .
IB
23
2S
37
98
29
30
4
5
185'F.
186
186
186
1H6
186
186
185
185
186
18o
186
186
186
Acidity.
UnpMtaarized. I PMtearized
63
.16
6A
.19
60
.19
60
.21
58
.17
60
.19
62
.17
61
.17
68
.17
62
.16
60
.17
61
.16
60
.16
Average No. of
germ* per e, o.
3.736,000
9.090,000
2,964,000
26,100,000
18,400,000
4.060,000
18,500,000
18,276,000
16,350,000
23,400,000
17,000,000
14,600,000
23,110,000
61,900,000
I
Average No. of
germs per c. c.
80
144
44
30
33
80
113
60
66
300
34
90
117
113
Eight tesb, percentage o( bacterii. killed, 90.99968.
Date.
Paateurizing
tempera'
tare.
April
If
It
May
15 .
19 ,
22
16
21
22
27
80
200
195
196-200
195
190
195
195
19b
Tempera-
tare of milk
\cidity
before Pas-
teurizing.
54
.18
46
.17
an
.12
60
.18
til
.17
62
.17
58
.17
61
.16
Unpaiteurized.
Average No. of
germii per c. c.
Pasteurized.
Average No. of
germs per c. c.
3,705,000
1,820,000
2,964,000
1,571,000
38,.*<80,000
18,500,000
16,250,000
14,500,000
16
77
It;
87
96
Mi
13
The Bacteriological Results.— The milk used in the variouH paa-
teurizing experunents may bo sjvid to have been of goal quality fn
only one or two instances did the acidity exceed 0.2 per cent of lactic
acid, an arbitrary standard proposed bv Russell, as it was shown bv
that experimenter that milk having a low percenta^'e of acidity was
as a rule freest from spore protluciug bacteria; ami the stamlard
mentioned (0.2 per cent.) was found to give good results in practice
A comparison of the acidity with the number of bacteria per c c'
m any ot the tables will show, however, thut nodeHnite relation exists
between the two ; as, for instance, the bacterial content in one sample
was over as millions, and in another two millions, and yet the acidity
in both these owes was the same, viz., 0. 17 per cent. . he explanation
ot this tact IS that large numbers of Iwcteria were present which either
produced no acid or else but a slight amount. Bacteria belon-ring to
the colon group were often present in large numbers : and the.se
whilst producing acid, do so to a far less extent tlian the true lactic
acid bacteria.
The effect of continuous pasteurization at UO degrees is undoubt-
edly etficient.as 96.42 percent, of the bacteria an- killed ; but we must
remember that the effect of this temperature is just on the border
between efficiency and non-effieiency. In practice there is apt to be a
lowering of the temi)erat\ire from time to time, periiaps due to les.sen-
ed steam pressure, too great an inflow of milk, or other causes • and
when this happens, there is a great loss of efficiency, and the number
of bacteria which escape destruntion is greatly increased
Unfortunately, too, the desirable lactic acid bacteria necessary for
buttermaking are the Hrst to succumb ; and the undesirable bacteria
hardier and more resistant to adverse influences, are either not affected
or only to a flight degree by tliis temperature ; and if left, even in
moderate numbers, they rapidly increase when the cream is placed in
the ripening vat, and may give rise to " of! flavors." A glance at the
accompanying diagram (I. t will show the large number of bacteria
which remain living after continuous pasteurization at 140 degrees—
too many which are as a rule undesirable for the best results.
At 185 degrees, however, the results are ranch better (diagram
III.), probably all bacteria except those forming spores being killed.
We must also remember that this temperature has been shown by
Trof. Bang of Copenhagen to be sufficient to kill the ti cle bacillus
(hacdlus tuberculofiu) thus removing a source of dang o man and
animals.
L PMtoarued fl.t 14 0* F.
IV76 Batteria per cUJi
o ceni.m'trc life drop*)
n. pMteuriied M IfcO'
321 BACteria^ per civcent
7. Bacteria, per tu. cen-
E pAStearised ftt 195* P
I B&cfftriam per cu. cent.
[14]
15
Slmmahy.
paHteuri/ed. Tho in.lk use.l in thoHo experiments was lar.relv furnished
by patronn who had but oniinarv facilities for takin.' care of it ,,
n..lk^eoa«nIat.nK when heated, if it clntains ,„ore thai 2 pe"; cent, of
;<• It was noticed that the lots heated fro.., 18.-, .Je-M-e.-s to l'>o
decrees produced ...ore foa... than those heated to the Im er te mer
atmes of 140 .le^reeH to l.iO ,le«.ee.s. This was ..1 , ot^^ ^.ble i7u J
saiuples heated to 19.5 dejjrees. At 18.5 .le«rees. the foam Zns . t
suthc.ent to cause much trouble in I.andlinL'
4. Hy co<ilin;; the Hki.n-..nlk with water to a te...pe,-ature of aln.ut
6o dejrrees .......ed.ately afte.- it co.,.es fro.., the sepamt r e wm
•>. The use of 10 to l.'. pe.- cent, of culture in tho i.a-teu.i^e.J
cream enabled us to ripen the crca... without any diffieulty ' The c-i
ture used was a lactic acid bacillus. ^ ^ *-"'
6. Pasteuri/atio.i of milk at IS.j d.'<rrees and the im,. nf « ,..,..„
culture s the best .nethod of securing unif/Sy kl in." , .^ i^y' " J
the mild flavor requisite for export butter. i., |uani>,aml
milk'»;oJ-'lVr^'"\S-''7' '^'"'''' '''"" I""^'*^"^ >» t''« ''"tter ...ale f.-o,,,
milk heated from 18.-, decrees to 19.5 de^-rees. usually disappeared at
the end ot about two weeks. In one or tv.-o lots, heate.! to U^h^L^
the cooked flavor remained for some ti,..e. There is appare, % no
dannrerot cooked flavors on butte,' made fro,.. ...ilk pasteurized at iSs
were kept m the stable, were very i.n.le.sirable. Many putrefactive
and fe^al bactcia were present, hence the necessity of keepino-t he
stable walls and rafters well cleaned. A jjootl coit of whitewash
increases the amount of li.ht, and ,dves a General clean etfect t Se
9. The avera^re number of bacteria per c.c (KJ drops) found in
To 8ir T;-''.^ ''' 140 decrees F. wa.s 631,040, at l.iO .ij.ree.s T wis
l.-,S48, at 18.> dej/rees F. was 81, and at 195 de-rees F. was 4() (See
diagrams). " ^
ill
1
The tlleet of Iht etmtinMuui patttitriMtion of milk
at !!/>' <« ^■^''' ''•
The white wiuare rt^prfteoti the b«cterj»>c»n-
tent of r»w n.ilk-»ver«t{e of thirteen dayn in
April. M«y. .Iuo« »nd Augnrt. The bl»ok
•mce repreient. the b»ot«ri.l content of the
■•me wmple* after oontlnuont pMt«uriz»tlon at
140" to 14<i« F.
TKt tfttet of the eimtinuovt pa$teuriiation of mtik
at It'" (.. 105" F.(71''-74'' O ).
The white wniare repreMnU the bacterial con-
tont of raw uiiik -average of twenty day* in
March. April. May. June and AuKuit. Th«
black »pace re|>re«enU the bacterial content ol
the iame •ainile* after continuou* pMteurwa-
tiun at IWlt.i" F.
The etfeet of the con/''""""* rmtt^irization of milk
utlSSOFASS^C).
The white Kiuarr reprcaenti the bacterial con-
tent of raw milk-av«r.Ke of fourteen day* in
April, M«y. Ju..*- »nd Augnrt. The black Mt
lepresentu the b.ct>Tial content of the lame
■ample after pasteurization at 185" F.
The f fleet ot the continuout parteuri:ation of b»W|
at 195-> to mf (F. dV^ff O.)
The white jquare rep reents the bacUrial cop-l
tent of raw milk-average of ewht dayi i»l
April and May. The black spot representJ tbei
bacterial content of the lame MmPjea »"«' '=<'"f
tinuouB paateurization at 190" to 200" F.
[16 I
jaiaKi * ii