December 1948]
M. P. SRIVASTAVA,
et
al
205
In view of the fact that milk used at Bangalore was mixed from cow and buffalo, and at Jahallar
from buffalo only, ghee was also prepared from the same aliquots of milk by the standard cream-
butter method to facilitate comparison of yield, market quality and storage property of ghee obtained
by the methods under investigation.
RESULTS AND DISCUSSION
The effect of the method of heat treatment and subsequent preservation on the quality milk, curd, lassi
and butter : The role of the hay-box is essentially to offer insulation to heat processed milk so that at
an elevated temperature it can remain sweet till the evening's collection is ready to be added. The
efficiency of the method is to be judged, therefore, from (i) the degree of heat conservation it affords
against continuous heat transmission entailed in the simmering of milk and (ii) the extent of prolifera-
tion of the surviving micro-organisms.
The temperature of hay-box preserved and simmered milk just before evening quota is added
has been found to be 120-130°F and 145-155°F respectively. The lower and upper limits of the range
are obviously influenced by the seasonal atmospheric temperature.
In Table I are given the average figures of acidity, total count and presumptive coliform in the
morning milk at different stages of its handling.
TABLE I
Quality of morning milk at different stages
Particulars
1. Raw
2. Processed (just boiled)
......
3. Processed (boiled for 10 min.)
....
4. Preserved hay-box (just boiled)
....
5. Preserved simmering (just boiled)
....
6. Preserved hay box (boiled for 10 min.) .
7. Preserved simmering (boiled for 10 min.)
Per cent
acidity
(lactic)
0.15
016
0.10
0.22
0.18
0.22
0.18
Total count
1,000,000—4,000,000
600—1,200
300—1,000
10,000—12,000
8,000—10,000
8,000—10,000
5,000—8,000
Presumptive coliform
+ ve (1 : 1000)
—ve (1 : 10)
—ve (1 : 10)
—ve (1 : 10)
—ve (1 : 10)
—ve (1 : 10)
—ve (1 : 10)
A perusal of the data shows that the initial processing by maintaining the boiling temperature
for 10 minutes is relatively more efficient than just bringing it to boil as is evident from the lower
bacterial count at different stages, both in hay-box and simmering method of preservation.
Although the total bacterial count at the end of the preservation is about the same for the two
methods, the increase in acidity by 46.7 per cent in hay-box as compared to 20.0 per cent in simmering
suggests that in the former method of preservation, there is relatively much greater proliferation in the
acid-forming thermoduric organism which cannot be counted by plating at 37°C.
The use of hay-box as a means to preserve milk has been doubted by the Agricultural Bacterio-
logist, Punjab Agricultural College, Lyallpur. In a private communication, he reports that milk
samples preserved in hay-box in hot weather show very poor keeping quality and are often found
curdled before the evening milk can be added. The deterioration is due to the growth of micro-
organism active at high temperatures. In winter, although the temperature of milk stored in hay-box
is fairly high, the curdling seldom takes place before the evening milk is ready to be added. This is
owing to the low initial bacterial contamination of milk usually observed during this season and
B 2