K. S. RANGAPPA AND B. N.
BANERJEE
99
Experience of many a century has shown that in cold countries butter could be made,
stored, and consumed as such ; but in hot countries butter must be clarified into ghee or
sanne (the Egyptian equivalent of ghee) for storage and consumption. Nowadays even in
cold countries, for export and storage, there is a tendency to dehydrate butter to prevent
rancidity and then to homogenize it into butter again before consumption. It is a pity
that, due to ignorance and other causes, milk fat should be stored or consumed in India
in a form other than ghee. The following causes are responsible for the development of
rancidity in butter on storage and the resultant ghee.
It is well known that oils and fats are prone to develop rancidity ; and in the case of
butter the following five causes play their part :—heat (high temperature), air (oxidation),
moisture (14 to 16 per cent water), acidity (acids from souring or otherwise) and infection
(harmful microflora). In countries where the temperature is very low, microflora do not
thrive well, or thrive only at a very slow rate, and chemical changes (autoxidation) take
place at a very much slower rate than in the tropics. Cream is pasteurized and thus in-
fection is destroyed. Salt is added to butter, and this acts as a preservative and elimi-
nates the effect of moisture. Only low acid butter is used for storage purposes ; and in
this way the effect of acidity is reduced. When butter is melted into ghee, the factors of
moisture and infection are removed. Acidity due to souring is removed in the aqueous
phase and is reduced to a very low level in the ghee, in fact almost to a harmless stage. The
effect of air can be reduced to insignificance if ghee is stored without any air gap. The
only cause .unrectified then is the tropical temperature; and this has been found to be not
very serious, autocatalytic factor in the development of rancidity in ghee. Well-made
winter ghee can be stored in India for one to two years ; and this length of storage is enough
for all practical and trade purposes.
An examination of Mandya and Hogenical village experiments on ghee manufacture
on the storage of butter before melting it into ghee showed that a high rise of acidity
took place in butter and ghee*. In the case of Mandya butter, the rise in acidity in butter
is from 0.2 to 0.6 per cent in a week, and to 6.0 per cent in a fortnight. The corresponding
rise in ghee acidity is from 0.1 to 0.5 per cent in a week, and to 6.0 per cent in a fortnight.
The acidity in stored butter at Hogenical rose from 0.2 to 0.5 per cent in a week and to 1.0
per cent in a fortnight. The corresponding acidity in ghee was from 0.05 to 0.3 per cent
in a week and 1.5 per cent in a fortnight. With control samples, the rise in acidity was
only 50 per cent of the initial acidity in a week, and three times in a fortnight with both
butter and ghee. Another notable degradation was the fall in the induction period of ghee,
that is storage property. The reduction in the induction period at 95°C. was from 14
hours to 8 hours in ghee from butter stored for a week, and to 1¼ hours when butter was
stored for a fortnight. With the control sample the reduction was nil in a week and to 12
hours in a fortnight.
For the sake of comparison, the rate of rise in the acidity of tinned creamery butter
was obtained from one of the largest tinned butter manufacturers in India. Table I re-
presents the average results obtained from experiments carried on for years.
TABLE I
The rise of acidity in tinned creamery butter
Age of batter
Fresh
1 month
2 months
3 „
4 „
5 „
12 „
Butter made from pasteurized, beet
quality cream available, on a com-
mercial acale. Acidity in percentage of
oleic acid.
0.09
0.2
0.26
0.3
0.42
0.42
3.0
Butter made from pasteurized
average quality, commercial
cream in general. Acidity in
percentage of oleic acid.
0.19
0.28
0.44
0.51
0.59
0.61
—
This confirms the statement made before, that butter should not be stored in India under
village conditions, for even the best attempts, that is say, pasteurization, salting and canning
of butter under controlled conditions, do not keep it well for more than six months. Again
*See studies on the methods of preparation of ghee, III, Indigenous methods of manufacture—Table 14