204
Hay-Box and Simmering Processes of Preserving Milk
[Vol. XVIII, Part IV
EXPERIMENTAL
The studies on the preservation of milk and subsequent preparation of ghee by simmering and
hay-box methods were carried out by using two sets of processing conditions. In the first set, process-
ing of raw milk consisted in bringing it just to boil. In the second set, boiling Was continued for
10 minutes.
In the hay-box method two sets of duplicate lots of 7½ lb. morning's raw milk filled in well seasoned
mud pots of 8 lb. capacity were given initial treatmnets as mentioned above. Immediately after the
treatment the pots were transferred into uniformly packed hay-boxes and left undisturbed till evening.
In the evening, warm milk in the pot kept in hay-box was transferred into a second pob of 50 lb.
capacity containing 7½ lb. raw evening milk. Morning's warm preserved milk and evening's cold
raw milk together with 2 per cent (Bangalore) or 1½ per cent (Jhallar) of lactic starter from stock
supply were thoroughly mixed and allowed to ripen.
In the simmering method, the two sets of duplicate lots of 7½ lb. morning's raw milk filled in
seasoned mud pots of 50 lb. capacity were given the prescribed heat treatment. The pots with their
contents were then transferred to separate choolas with smouldering fire of cowdung cakes. The
milk in the pot was thus kept simmering until evening when 7½ lb. of evening's raw milk was added.
The mixed milk was then treated in the same way as in the hay-box method.
The treated milk samples by different methods were allowed to ripen for a period of 15-16 hours
under atmospheric conditions. The curd at the end of the ripening period was thoroughly mixed and
samples were taken for determining the acidity before churning. Churning was done in the same
vessel with the aid of indigenous churning device. No special precaution was taken in controlling
the temperature of churning except that cold water was added from time to time. The total quantity
of cold water added was equivalent to that of the curd. The churning was discontinued when the
butter granules were formed. After allowing 15 minutes for settling, the butter granules were collect-
ed and worked up to a lump as practised in the villages. As soon as a sample of butter was prepared,
it was tested for acidity, curd content and moisture. The quality of butter-milk was also examined
for its taste and flavour.
Soon after butter from each treatment was prepared, it was clarified into ghee in aluminium
degchies held over kerosene stove. During clarification the melt was continuously stirred and the
flame of the stove was so adjusted as to finish the removal of moisture between 110-120°C. After
allowing to cool, the ghee samples were strained through fine muslin cloth and their weight recorded.
The fresh ghee samples under each treatment made in different seasons were judged for their market
quality according to the following basis :
Points for judging
I. Aroma . . . . . . . . . . . . . .
II. Flavour . . . . . . . . . . . . . .
III. Texture . . . . . . . . . . . . . .
IV. Colour
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Total .
Score allotted
30
30
30
10
100
The fresh ghee samples were also chemically examined for Saponification Value (S. V.), Reicher
Meissl Value (R.M.), Polenske Value (P. V.), Iodine Value (I. V.), Peroxide Value (Per. V) and Aci-
dity (per cent oleic). The methods followed in the determination of these constants were the same as
given in the Miscellaneous Bulletin No. 64 of the Indian Council of Agricultural Research. The
keeping quality of the samples was followed by determining the peroxide value at regular intervals
of representative preparations which were filled in 1 lb. tins of uniform size and stored at a constant
temperature of 104°F. The market quality and the physico-chemical constants of the stored samples
were also judged at the end of the storage period of three months.