100
Methods of Preparation of Ghee
a comparison of the acidity of butter and ghee made by the boiling and decantation process
is very significant. It has been found that butter acidity is about twice as high as ghee
acidity made by the boiling process and at least four times higher than that of ghee by the
decantation process*. Even with curd acidity as high as 2.8 per cent lactic and butter
acidity, 0.28 per cent, the ghee acidity by the decantation process is only 0.06 per cent.
The acidity of village ghee of Mandya, Kodur, Guntur and Hogenical are all high; this
point is brought out from experiments carried out on storage of butter before being melted
into gheet. While in ghee melted from fresh butter the ratio of acidity is at least 4: 1 by the
decantation process, in the case of stored butter the ratio is reduced to 1 : 1 or 1 : 0.09. This
demonstrates that the high acidity is due to the breakdown of the fatty acid glycerides. It
is, therefore, necessary to study this increase of acidity in butter and ghee due to storage of
butter, before its clarification into ghee. This also raises the point as to when and how
butter should be clarified under village conditions.
Apart from the factors mentioned before lipase of milk (in the case of butter made
from unboiled milk) and that from microflora (milk and seed curd) are mostly responsible
for this increase of acidity. Acidity in butter due to souring also autocatalytically saponifies
the butter. Experiments were therefore designed to study the effect of these factors
separately. Infection can be killed by adding formalin to butter, which will not affect
adversely the catalytic activity of free acids or the activity of lipolytic enzymes. Again,
sterilization stops the enzyme action, but not the effect of acidity. In this way the effect of
each of the three factors can be deduced.
Experimental. A number of trials were performed to find out the amount of formalin
necessary to stop bacterial growth. Addition of 5 per cent by volume of formalin to curd
before churning did not incorporate it sufficiently in the resulting butter to stop bacterial
growth in it for more than three days at 37°C. Sterility was tested by seeding butter in
milk agar in sterile petri dishes and incubating them at 37°C. It was found that 0.5, 1.0 and
1.5 c. c. formalin in 100 gm. of butter kept down bacterial growth for 3 to 5, 6 to 8 and
over 15 days respectively. Butter with 2 to 3 c. c. formalin remained sterile for all pur-
poses. Formalin was added to butter in the molten condition (40°C). It was mixed thorough-
ly and then allowed to set.
Eight litres of unboiled buffalo milk were seeded with 50 c. c. of unboiled milk seed
curd of 1.2 per cent lactic acidity in an earthen pot of about 20 litres, as is the practice in
villages. The seed curd was specially propagated in unboiled milk from a sample of butter
from Mandya village that had been obtained from untreated milk. The flavour of the seed curd
was non-aromatic and it was slightly mouldy. After 24 hours of souring the acidity was
1.2 per cent when it was churned. The temperature varied during the experiment between
20° and 28°C. The resulting butter was used as a stock for the experiments.
Fifty-gram samples (two) from the stock butter were transferred to 250 c. c. conical
flasks and one was treated with formalin and the other sterilized. Sterilization was effected
in steam at 100°C. for one hour for three days. The flasks were all plugged with cotton
wool and maintained at 30°C. It was found that at 37°C. the acidities developed were irre-
gular as the fat and aqueous layers separated out.
The H-ion and acidity of the stock butter were determined when it was made. Then,
after 4, 7, 14 and 21 days samples were drawn from the stock and the experiment repeated
as described above. Acidity and H-ion determinations of the samples were made at every
interval. The acidity of the sterilized samples were determined only at the beginning and
end of the storage period of 21 days, A sample of unprocessed-milk butter bought from the
bazaar was similarly treated and experimented with. The results are given in Table II and
are represented graphically in Fig. 1.
Again, unwashed butter contains about 14 per cent milk serum or buttermilk. On
storage the protein content of butter may undergo decomposition and give rise to a putrid
smell, but the smell may not always be evident. During the process of decomposition the
insoluble protein is converted into the water-soluble non-protein nitrogen. The latter was,
therefore, determined in butter at the beginning and at intervals of storage. The determina-
tion was made with a slight modification of Ling's method [1940]. The protein content is
coagulated with trichloracetic acid at 70°C. and the soluble protein extracted with water
after cooling. The increase in the percentage nitrogen content of the extract, if any, in-
dicates the extent of decomposition of the protein in the butter.
*See Studies on the method of preparation of ghee, 1. Acidity in ghee—Table I.
†Studies on the method of preparation of ghee, III. Indigenous methods of manufacture.