58
TITRATABLE ACIDITY OF COW AND BUFFALO MILK
[Vol. XXV, Part I,
In order to demonstrate the effect of dilution, the titratable acidity of a number
of fresh milk samples were determined and compared with the acidity found in the
same samples after dilution with one volume and nine volumes of distilled water.
The milk samples were taken from individual buffaloes in order to obtain rela-
tively wide differences in composition and in titratable acidity.
In the case of each sample, the following titrations were made with N/10 sodium
hydroxide : (1) 10 c.c. milk, (2) 10 c.c. milk plus 10 c.c. distilled water, and (3) 10 c.c.
milk plus 90 c.c. distilled water. The cubic centimetres of N/10 sodium hydroxide
used were converted into percentage of lactic acid, assuming for convenience that
the 10 c.c. pipette delivered 10 grams of milk.
The results obtained with 20 different samples of milk and colostrum are given
in Table VI. The three titrations in the order given above showed averages of 0.227,
0.209 and 0.143 per cent lactic acid in the case of milk, 0.316, 0.275 and 0.210, res-
pectively in the case of colostrum and total averages of 0.267, 0.239 and 0.113, res-
pectively. These results represent a decrease in titratable acidity of 0.018 and
0.042 per cent respectively, when buffalo milk and colostrum were diluted with an
equal volume of water and a decrease of 0.083 and 0.107 per cent respectively, when
diluted with nine volumes of water. Twenty other samples were titrated undiluted
and diluted with an equal volume of water with essentially the same results ; the
average acidity of the undiluted samples was 0.174 per cent, as compared with an
average of 0.151 per cent when the same samples were diluted with an equal volume
of water. As an average of the 31 samples, dilution with an equal volume of water
decreased the titratable acidity 0.0212 per cent. The results obtained are in good
agreement with those given in Table V. The acidity of buffalo milk seemed to be
slightly more affected by dilution than that of cow milk (Table VI).
SUMMARY
The titratable acidity of the freshly drawn milk from all cows and buffaloes in
the college dairy herd was determined at weekly intervals over a period of 14 months.
More frequent determinations were made with selected groups of cows and buffaloes
for shorter periods of time. A total of 2006 and 1006 samples from buffaloes and
cows respectively, were examined. Factors studied were : 1. species, 2. individuality
of the cow and the buffalo, 3. stage of lactation, 4. variations from month to month,
5. variations from day to day, 6. variations from milking to milking, 7. variations
from one quarter to another in the same udder, and 8. the effect of dilution on the
titratable acidity of buffalo milk. The following is a summary of the results:
1. Average acidity of buffalo milk and cow milk was 0.1767 per cent and
0.1920 per cent respectively at morning milking and 0.1656 per cent
and 0.2009 per cent respectively at evening milking.
2. The acidity of the milk from individual cows and buffaloes studied varied
from 0.098 to 0.26 per cent respectively. Approximately 85 per cent
of the samples of buffalo milk and cow milk could be grouped within
range of 0.07 per cent acid. The limits of the interval, however,
must be adjusted for these two species.