STUDIES IN SANITIZING DAIRY UTENSILS UNDER
INDIAN CONDITIONS
By Zal R. KOTHAVALLA, M. S. PHERWANI and E. V. SESHAGHARYULU, Imperial Dairy
Research Institute, Bangalore.
(Received for publication on 31 July 1943)
INTRODUCTION
MILK, which is a valuable human food,
provides a favourable medium for the
growth of micro-organisms. The Bacte-
ria on entering the milk multiply at a
rapid rate if the temperature is favour-
able to them, and bring about undesirable
chemical changes, as a result of which the
keeping quality of the milk is consider-
ably impaired. It, therefore, becomes
imperative to take proper precautions
against its contamination from all pos-
sible sources during handling. One of
the most common sources of contamination
of milk is the utensil used in its produc-
tion and handling, if it is not properly
cleaned and sterilized. Rowlands [1934]
has shown that ropiness in milk can be
spread by churns (large milk cans) which
are not properly sterilized. Barkworth
[1941] has given the following figures
indicating the extent of contamination
of good quality milk through dirty churns:
Milk in the bucket
.. 12,000 bacteria per ml.
Same milk in churn (dirty) . . 9,900,000
„
„ „
It is, therefore, evident from the above
that the sanitizing of milk utensils is im-
portant not only from the point of view
of enhancing the life of milk, but also to
supply milk of a low bacterial count
to the consumer. Investigations by Kelly
[1914], Prucha and Harding [1924], Pas-
son [1926], Theophilus and Atkeson
[1931], Yale [1935] and Burgwald [1939]
have indicated the importance of clean and
sterile utensils in the production and
handling of high quality milk.
Extensive research has been carried
out in the past to find out suitable deter-
gents for cleansing dairy utensils and
equipments to render them sterile enough
for the safe handing of milk for all
practical purposes. Some of the common
detergents that are highly alkaline include
caustic soda, soda ash, washing soda,
sodium metasilicate, trisodium phosphate
and sodium hexametaphosphate. Mixtures
of these are sold under a variety of
trade names such as 'Dairy detergents, or
Washing powders.' Washing or cleaning
of milk utensils with these detergents, fol-
lowed by sterilization with steam or scald-
ing with boiling water, is a common
practice in most of the up-to-date dairies.
Farral [1929], Barker [1929], Rogers and
Evans [1936] and Provan and Treble
[1941] have shown that the cleaning of
dairy utensils and equipments with alka-
line washing compounds and the applica-
tion of steam render them practically
sterile.
Although much work has been carried
out in Western countries on the cleaning
and sterilizing of dairy equipment, no pub-
lished data are available in India except-
ing the investigation carried out by
Verma, Paul and Kothavalla [1941] who
have shown that the comparative deter-
gent efficiency of soda ash, wood ash
and mud on milk utensils is in the descend-
ing order. Due to war the prices of
washing soda and other dairy detergents
have greatly increased and it, therefore,
became necessary to investigate the pos-
sibilities of finding a suitable substitute
for them and to evolve a cheap and effici-
ent method of cleaning dairy utensils. In
India the villagers use mud, wood ash,
tamarind and mud or ash and mixture of
mud and cow-dung cake ash for cleaning
their milk utensils. The last mentioned
method (mixture of mud and cow-dung
cake ash) is generally employed, followed
by an exposure to the sunlight. The bac-
tericidal potency of this method, however,
has not so far been studied systematically.
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