K. S. RANGAPPA AND B. N. BANERJEE 67
Incubation
period in hours
45°C.
6
12
18
24
36
48
Curd
acidity
1.0
1.3
1.8
2.5
2.6
2.8
Butter
acidity
0.16
0.21
0.23
0.24
0.25
0.26
Ghee (Boiling process—B
Decantation procees—D
Acidity
B 0.07
D 0.03
B 0.12
D 0.04
B 0.12
D 0.06
B 0.12
D 0.06
B 0.13
D 0.07
B 0.14
D 0.06
Peroxide
value
0.14
0.21
0.15
0.20
0.15
0.22
0.15
0.20
0.15
0.24
0.17
0.23
Vitamin A
blue units
—
—
12.1
12.1
—
—
12.1
12.1
—
—
12.1
12.1
Caroteen
yellow units
—
—
2.75
2.2
—
—
3.9
3.3
—
—
3.9
3.3
Colour, flavour,
and texture
Good
Good
Good
Fair
Good
Fair
Good
Fair
Fair
Mild
Faintly mouldy
Fair
*Millimols of Peroxide per Kg, of fat,
DISCUSSION
Butter has been churned from curd of acidity 0.6 per cent to 2.8 per cent lactic acid, Curd
acidity was 5 to 6 times more than butter acidity. The butter acidity was about twice as high
as the ghee acidity made by the boiling process and about 5 to 6 times higher than that of the
ghee made by the decantation method. The ghee made by the decantation process had the
lowest acid value which was below 0.1 per cent lactic acid. Souring can be stopped when
the curd acidity is between 1 and 1.5 per cent lactic acid and a good quality butter and
ghee prepared. With a little care even at 45°0. and after two days of souring low acid
butter and ghee can be made. These results when they are compared with market samples
indicate utter carelessness in the manufacture and preservation of butter and ghee.
Souring can be performed in the hottest summer months of India and acidity kept down to a
very low level. While it is necessary to heat butter to 110°C. or near about that temperature
for flavour and other qualities of ghee, this should be done after the removal of butter-milk
and water soluble acids.
Acidity changes in ghee on storage. Variation in the chemical and physical constants of
ghee and butter fat with storage has been recorded by many workers, [Godbole and Sadgopal,
1936; Narsimhamurthy, 1941]. It has been observed that acidity increases with storage. It
is also the observations of ghee packers that well prepared winter ghee stored in sealed tin
containers filled up to the neck, with very little air gap left, keeps perfectly well for a year or
so, and suffers no deterioration for six months at least. In view of this, it was necessary to
find out the increase in acidity in well prepared ghee from reliable sources. In connection
with another scheme of research monthly samples of ghee were obtained for one whole year,
that is, 12 samples each from different parts of India. Among them, five lots that were one,
three, six and twelve months old were chosen. Their acidity, pH, colour, flavour, texture,
carotene, vitamin A and saponification value were determined. Each sample of ghee repre-
sents a separate batch or, in other words, all the samples do not belong to one and the same
batch. They were made without any special instructions to the manufacturers and there-
fore represent the usual local process. They were stored in tin or glass containers loosely
stoppered, open to air or air gap at room temperature, i.e., at 20°C. to 30°C. Samples were
taken from them as and when required. They represent, therefore, 20 different samples of
ghee carelessly stored for one month to a year and from five different parts of India. Factors
other than acidity mentioned before have an important bearing on the quality of ghee, and are
therefore included along with acidity.