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Methods of Preparation of Ghee
culture the rise in acidity on storage is less than one tenth in a week. This high acidity
makes it unfit for consumption as butter and also ruins the ghee if clarified from stored
butter. Under tropical conditions, lipolytic microflora thrive at an alarming rate in
unwashed butter prepared from uncontrolled seed culture, unboiled milk or unpasteurized
cream, making it unfit for consumption on storage. In cold climates, the growth is not
altogether stopped, but the rate of growth is slow enough to permit storage and consumption
as butter for a certain length of time.
Once lipolysis has taken place in butter, the free fatty acids pass into the ghee on
clarification, and it is very difficult to get rid of it. Fortunately for the ghee trade, lipolysis
in the milk and curd stages is very small and negligible. But once butter is churned
out from curd and the lactic acid solution removed, undesirable microflora have their
full play. The total acidity of curd and lactose consumed give a picture of the action of
microflora in curd and, to a certain extent, determine the quality of butter, especially its
storage property. If butter be at once melted into ghee, then further development of acidity
is stopped and a low acid ghee results with good storage property. On neglect, that is,
delay in melting butter into ghee, acidity goes on increasing at an increasing rate and it
cannot be removed on clarification, and it proportionately shortens the storage property of
ghee. High acidity in ghee on storage also destroys vitamin A and carotene B
quickly.
Acidity in butter, that is not derived from the fat phase, is not markedly harmful to
the vitamin A or carotene of butter. Its effect as a catalyst on the development of
rancidity in fat, or rise in acidity of butter fat is very little. The slight rise of acidity
in ghee on clarification is a measure of this cause. But the free fatty acid in butter or
ghee, that is derived from lipolysis, is autocatalytic and is proportional to its strength.
However, broadly speaking, the small quantity of free fatty acid that finds its way into
butter and ghee, (up to 0.2 per cent in butter and 0.1 per cent in ghee) is not very harmful,
and its effect is negligible. This can be achieved if the milk is not soured beyond an
acidity of 1.2 per cent and the butter is then churned out and at once melted into ghee by the
decantation process, but the same is not true of high acidity in butter or ghee resulting from
lipolysis.
CAUSATIVE ORGANISM OF HIGH ACIDITY IN MANDYA (UNPROCESSED MILK) BUT
The investigations on acidity in Mandya butter, described before, showed that lipolytic
enzymes elaborated by the uncontrolled microflora of the untreated milk and of the seed curd
are almost entirely responsible for the enormously high acidity developed in butter on
storage. No attempt had, however, been made to trace the cause to any particular flora, but
the fact had been noted that the same butter, when raised to 40°C. — 45°C. just for a minute,
developed much lower acidities at a slower rate. This butter also failed to develop the
characteristic estery flavour of the unmelted, stored Mandya butter. This flavour has been
known to arise from the lipolytic action of moulds, either by ester hydrolysis (Oidium), or by
the oxidation of the lower fatty acids to the methyl ketone stage (Penicillium, Aspergillus,
etc.). Davies [1941] has shown that the mould, Oidium, produces the highest acidity in stored
butter, and is able to metabolise glycerol after splitting up the fatty glycerides, while
Penicillium causes the discolouration of butter also. These observations having led the
authors to suspect the activity of moulds in Mandya butter, experiments were conducted to
isolate and identify the organisms responsibe for the estery flavour and high acidities in
stored butter.
Experiment. Two separate samples of Mandya bazaar butter were chosen for experi-
ment. One of these was seeded into unprocessed milk and the resulting curd was used for
the preparation of untreated milk butter in the laboratory. This butter and the remaining
bazaar sample were both used independently for experiment.
Each of these samples was plated, after suitable dilution with sterile water, in milk agar
containing liver extract and incubated for three days at 22°C. Three types of colonies grew on
the surface of each plate. One was a mould forming green spores, the second, a white mould
with a mat surface, and the third, a colony with a glossy surface. Microscopic examination
showed that the green mould was a type of Penicillium; the white mould, of the class
Phycomycetales, and the last one, a type of yeast that did not ferment lactose. Each organism
was then planted in three agar slants and stored at three different temperatures along with
the samples of butter.
The laboratory and the bazaar butters were separately distributed in three conical flasks