114 RESEARCH INTO INDIAN CITY MILK [VOL. XX, P
METHODS
Collection of milk samples
Milk is marketed in the Bombay city by (1) the Government subsidised milk
shops where milk produced in the buffalo stables of the city and suburbs is sold to
regular customers at the rate of 14 annas per seer, (2) the owners of stables themselves
who arrange to distribute a high quality milk to regular customers at a high price,
(3) milk shops owned by Bhaiyas, halwais and others who generally buy milk from
buffalo owners of the city and suburbs and sell it to a few regular and a large number
of other customers and (4) milk hawkers who collect milk from any producer or whole-
sale dealer and sell it at the chawls of poor classes of people. In the latter two cases
no standard quality or price is maintained except for a few regular customers. The
samples tested by us were obtained from all these four categories but the samples
from the first two sources are referred to as coming from buffalo stables and from
other two as coming from milk vendors in this paper.
The milk samples were collected at the supply end in the mornings between
5-45 a.m. and 8-30 a.m. in the bottles sterilized on the previous day. The milk
bottles were then transferred to wide mouth thermos flasks containing ice imme-
diately after collection and transported to the laboratory where they were main-
tained in a refrigerator pending examination. Two samples of milk were collected
alternate days. Forty samples of milk were thus collected and subjected to various
tests within about four hours after collection. The tests included a determination
of specific gravity, fat, total solids, total viable bacterial numbers, coli test,
methylene blue reduction test, alcohol test, phenolphthalein test and cultural
examination, for the identification of the milk flora.
ANALYTIC PROCEDURE
Chemical tests
1. Specific gravity. The Quevenne lactometer was used. Every milk sample
was thoroughly shaken and brought to a temperature of 15°C. when the specific
gravity of milk was calculated from its lactometer reading by dividing the lactometer
reading by 1000 and adding one according to the method stated by Simmons and
Gentzkow [1944].
2. Determination of fat. This was done by adopting the Gerber's method. Strong
sulphuric acid 10 c.c. was introduced into the Gerber's acid butyrometer tube and
then 11 c.c. of well shaken milk was allowed to trickle slowly down so that it formed
a layer upon the acid. 1 c.c. of amyl alcohol was added and the neck of the tube closed
with a tightly fitting rubber stopper. The contents were then centrifuged in
Gerber's centrifuge at a speed varying from 1000 to 2000 revolutions per minute for
five minutes. The tubes were then transferred with the stopper downwards in a
water bath maintained at 60°C. and the percentage of fat read.
3. Total solids. Direct Gravimetric method was used. Five grammes of milk
were placed in previously weighed fiat bottomed dish 7 cm. in diameter, and
thoroughly dried by evaporation. The dish and contents were then weighed and
the total solids content calculated according to the official laboratory method of the
United States Army described by Simmons and Gentzkow [1944].