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STUDIES ON DAHI—II GENERAL SURVEY
[Vol. XXII, Part I
Among the constituents of dahi, ash content appeared to show the least variation
due to the type of milk used. In Table IV, the individual values for acidity, fat,
protein and ash in respect of a few typical samples of dahi, which might be considered
to be fairly normal on the basis of their ash contents, have been shown. The results
bring out the variations which may be expected in the composition of market dahi
samples and agree closely with the values recorded by Davies [1940] for different
types of dahi. The samples of dahi with low fat content may be presumed to have
been prepared from skimmed milk or a mixture of whole and skimmed milks and
those having high fat content as having been made from buffalo milk. The varia-
tions in the methods of preparation, particularly the extent of concentration of
milk, have considerable influence on the values. Accordingly, the present data
are useful only in providing information on the quality of dahi available in the
market and cannot serve as a basis for fixing any chemical standards for this product.
It would be desirable to collect further information on the normal variations in the
composition of dahi with reference to the type of milk used, age of samples and other
conditions of production.
SUMMARY
A qualitative survey of the types of dahi produced and marketed in different
parts of India has been made. A total number of nearly 1,000 samples of dahi
(including lassi) were collected from dairies, halwais, street vendors and private
houses in different localities. They were examined for texture and flavour, titra-
table acidity, nature of microflora (as revealed by microscopic appearance), total
bacterial count and percentages of fat, protein and ash.
Samples of dahi collected from North India were generally characterised by
firm curd formation and sweet to mildly sour taste with an agreeable flavour, although
during summer and monsoon an appreciable number of them were sour and also
showed gassiness and peptonization. Some of the best samples were obtained
from Tirhut Valley (Bihar), Allahabad, Karnal, Brindavan (Mathura) and Calcutta.
Samples from south India were usually poor or watery in texture and sour to
taste, irrespective of the season, while a large percentage of samples secured from
sea coast areas, particularly during monsoon, showed gas formation, alcoholic and
estery flavour as well as mould growth.
There was either a preponderance of streptococci or a balanced proportion
of streptococci and lactobacilli (short rods in pairs or chains) in the samples of dahi
produced in north India. Yeasts were present in many cases and during monsoon
both yeasts and lactobacilli were more numerous. Almost all south Indian samples
of dahi contained a preponderance of lactobacilli (large rods with prominent granules)
as well as yeasts, while streptococci were present in samples collected in Gujarat,
Nagpur and Bombay.
The above differences between the samples from different areas have been
attributed to the initial quality of milk, type of starter used, technique of manu-
facture and influence of atmospheric temperature.
There were very wide variations in the values for acidity, fat, protein and ash
irrespective of the source or season of collection. The significance of the initial