6 
BULLETIN 1344, U. S. DEPARTMENT OF AGRICULTURE 
the time required to heat the milk. All samples included in this 
table were cooled without agitation to a temperature • of approxi- 
matelv 42° F. as soon as collected. 
Table 3. — Effect of heating and holding milk for SO minutes at various tem- 
peratures at pasteurization plants 
Percentage 
increase or 
Character of agitation 
Tempera- 
decrease 
ture at 
which milk 
was held 
for 30 
minutes 
Temperature 
of heating 
medium 
Time 
Cream 
volume 
Butter- 
fat in 
under 
Heating 
Holding 
required 
to heat 
milk 
layer 
o F 
o p 
Minutes 
149 
-32.3 
Agitator, 200 r. p. m... 
Agitator, 200 r. p. m 
Steam at 5 lbs. 
pressure 
25 
147 
-41.7 
—40 
+34.4 
+20 
Coil, 38 r. p. m 
None.. _ 
None. 
180 
53 
147 
Slowly moving paddle. 
None 
Not over 160 
o to 3 
148-146 
-18.5 
+45.4 
Coil, 38r. p.m. 
Not over 155— 
65 
146.5-146 
-26.1 
+26.9 
Coil,60r. p. m 
do 
Over 180 
20 
146 
—28. 5 
+50 
None.. 
Slowly moving paddle- 
None _ . . 
2 to 3 
146-145.5 
-25.9 
Coil, 38 r. p. m 
Not over 180. - 
48 
146-145 
-25.0 
-14.8 
+15.6 
+36.3 
.....do...... 
do 
do 
do 
180 
50 
146-145 
Not over 155... 
58 
146-145 
-13.4 
do.— 
Coil, 38 r. p. m 
do 
24 
146-145 
-16.7 
do 
do 
do 
20 
146-145 
+22.2 
-29.4 
Slowly moving paddle. 
Slowly moving paddle. 
Not over 160. - 
45 
145.75-145... 
-7.1 
do 
do 
Not over 200. . . 
40 
145.75-145... 
-12.5 
Coil, 38 r. p. m 
Coil, 38 r. p. m 
Not over 170-.- 
40 
145.75-145... 
-12.5 
do 
None ... 
do 
40 
145.75-145... 
-6.3 
do 
Coil, 38 r. p. m 
do 
40 
145.75-145... 
-14.3 
do 
do 
Not over 155--. 
20 
145.75-145... 
-13.3 
do 
do 
do 
30 
146-145 

Agitator, 200 r. p. m... 
None ... 
Steam at 5 lbs. 
pressure 
29 
145.4-145..- 
-8.7 
Coil, 46 r. p. m 
Coil, 46 r. p. m 
Not over 160— 
90 
145.5-145 
-4.5 
Coil, 60r. p. m 
None 
Over 180 „ 
20 
145.5-145 

-46.6 
Coil, 32r. p. m 
do 
Not over 155— 
25 
145.5-145... . 
+9.1 
-43.7 
Slowly moving paddle . 
Slowly moving paddle. 
Not over 160— 
45 
145 
-14.2 
— 10 
-18.2 
do.-. 
148-150 /— 
Under 200 
2 to 3 
145 
Slowly moving paddle- 
None . 
43 
145 
-13.4 
-12 
~~+7.7~ 
Coil, 32r. p. m 
Coil, 38 r. p. m 
do 
Coil, 38r. p. m 
Not over 155--. 
do 
24 
145-144.75. . . 
62 
145-144.75. ._ 
-4.0 

do 
None . . _ 
do 
62 
145-144.5 
-3.7 
-6.1 
do 
Coil, 38 r. p. m 
Not over 180- . - 
48 
144.5-144 
-57.7 
-10 
-6.3 
-11.1 
"-9.T 
Coil, 46 r. p. m 
Coil, 38 r. p. m 
do 
do 
None..- 
Not over 160- 
Not over 155..- 
do 
Not over 180. .. 
105 
143. . 
do 
do 
do 
22 
143.... 
22 
143 
47 
143 

+3.3 
-43.7 
-25.0 
do 
do 
180 
47 
143 
Slowly moving paddle. 
None— . ... ..- . _ 
Not over 160. - 
2 to 3 
143-142.75... 

-10 
-36.7 
Coil, 38 r. p. m 
do 
Not over 155... 
do 
52 
143-142 
Slight 
20 
143-142 
+7.7 
Agitator, 200 r. p. m... 
None. ... 
26 
142 

+8.7 
-3.9 
Coil, 38 r. p. m. 
do--. 
59 
143.5-141 
Coil, 46 r. p. m 
do 
Not over 160— 
100 
142-141 

+12.5 
Coil, 38 r. p. m 
do 
Over 180 
26 
142-141 
-7.3 
+18.2 
.....do 
Coil, 38 r. p. m 
do 
26 
142.5-140 
+13 
Coil, 46 r. p. m. 
Not over 160— 
90 
The control samples upon which the percentages of difference 
are computed were taken from the raw milk entering the heater ; and, 
in the case of vat-type pasteurizers, just before the heating medium 
was turned on. Examination of the data contained in this table 
shows the following facts : 
In six tests at temperatures ranging from a maximum of 148° F. 
at the beginning to a minimum of 145.5° at the end of the holding 
period, there was in every instance a decrease in the cream volume, 
ranging from 18.5 to 41.7 per cent, with an average of 31.1. In five 
tests of the butterfat percentage in the under layer at these tempera- 
tures, there were increases ranging from 20 to 50 per cent. 
