134
A Simple 'Ram-Ko' Method for Estimation of Fat in Milk
TABLE II
Effect of various alcohols on fat test
(Gerber test 4.3 per cent fat)
Without alcohol
Fat not separated at all . .
1 ml. amyl
alcohol
Fat not clear.
Amyl alcohol
separated out
1 ml. methyl
alcohol
Practically no
separation of
fat
1 ml. isopropyl
alcohol
Fat not clearly
separated
1 ml. butyl
alcohol
4.0 per cent
fat.
Took
longer time
for clearing
1 ml. isobutyl
alcohol
4.2 per cent
fat
experiment to add other substances besides
sodium hydroxide as protein solvents, to get
accurate results. With this object in view, solu-
tions of sodium phosphate, Rochelle salt and
sodium citrate were tried. These, however, did
not give any satisfactory results.
Nicol [1937] has recommended for the deter-
mination of fat in ice cream, a solution consisting
of sodium salicylate 645 gm., potassium carbonate
355 gm., sodium hydroxide 160 gm., distilled
water 2840 ml., and iso-propyl alcohol 945 ml.
For the experiment, 6.5 ml. of this solution were
mixed with 9.7 ml. of milk and kept at 52°C.,
but no separation of fat took place even after half
an hour. In further trials, therefore, 9.7 ml. of
milk were mixed with 5.5 ml. of salicylate reagent
and 1 ml. of iso-butyl alcohol. The results of
these trials are given in Table III.
TABLE III
Effect of using salicylate reagent on fat test
(Temperature 52°C.)
Pasteurized milk . . .
Sindhi composite . . .
Buffalo milk
.
.
.
.
Milk diluted with water . .
Buttermilk
.
.
.
.
Cream diluted with water . .
Percentage of fat by
Gerber
test
4.6
5.7
6.2
3.8
1.0
5.0
Salicylate
reagent
4.5
5.6
6.0
3.7
0.6
4.9
The figures show that there is a greater approxi-
mation of the results obtained by the salicylate
reagent to Gerber readings than what were
obtained by the use of sodium hydroxide alone,
though the results in most cases were still con-
siderably lower.
(4) Effect of using higher temperature. In the
last section where a temperature of 52°C. was
used for heating, the results were shown to be
lower than those obtained with Gerber method.
Trials were, therefore, carried out using a tem
perature of 60°C. The results obtained are shown
in Table IV.
TABLE IV
Effect of using higher temperature on fat test using
salicylate reagent
Fresh cream diluted 10
times with water.
Whey
.
.
.
.
Pasteurized milk . .
Sindhi cow's milk . .
Cow's fresh milk . .
Buffalo's fresh milk . .
Milk diluted with water .
Buffalo milk diluted 1:1 .
Buttermilk . . .
Percentage of fat by
Gerber
test
4.7
1.6
4.0
5.0
4.7
5.9
3.2
4.7
1.0
Salicylate reagent
52°C.
4.6
1.5
3.9
4.6
4.5
5.7
3.0
4.6
0.6
60°C.
4.7
1.6
3.9
5.0
4.7
5.8
3.2
4.7
0.9
These results show that keeping the tubes in
the water bath at 60°C. gave more concordant
results. The separation of fat also took place in
a shorter time at 60°C, (20 mts.) than at 52°C.
(30 mts.). So this temperature of heating was
adopted for all furher trials. The time of heating
was fixed at 20 minutes.
(5) Effect of varying the amount of iso-butyl
alcohol. Trials were carried out to find the opti-
mum quantity of iso-butyl alcohol required for
separating the fat. For this purpose, to a mix-
ture of 5.5 ml. of salicylate reagent and 9.7 ml.
of milk varying amounts of alcohol were added.
The results obtained are shown in Table V.