USE OF COLOUR FRINGES IN BUTYROREFRACTOMETER FOR
DETECTING ADULTERATION IN GHEE
By NOSHIR N. DASTUR, D. R. KASHYAP and ZAL R. KOTHAVALLA, Imperial Dairy Research Institute,
Bangalore
(Received for publication on 2 July 1943)
GODBOLE [1936] and Godbole and Sadgopal
[1939] have advocated the desirability of noting
the colour of the fringes visible when fat
samples are examined, along with the refracto-
meter reading. According to these authors,
ghee of good quality gives invariably colourless
fringes and is at times violet tinged. Hawley
[1936] in reviewing some of the methods pro-
posed for the detection of adulteration in ghee
states that it is doubtful whether the colour of
the fringes can be
used as a reliable
method, especially when it is possible to
prepare artificial mixtures of fats having the
same refraction.
Athavale and Jatkar [1938] extended these
studies and recommended that measurement of
both refractive index and dispersion on a Pul-
frich Refractometer using the green and violet
lines of mercury are, provide a much more
sensitive test. These authors, however, do not
give any data as to the amount of various
adultrants detectable by this method, the effect
of feed on the fat secreted, etc. One of the
main reasons why the problem of detection of
adulteration in ghee still remains unsolved is
the great variability in the composition of ghee,
due both to the large number of breeds both of
the buffalo and cow distributed all over India and
the great variations in the foods fed in different
places. Any method to be fool-proof must
stand these tests. Neither the studies of God-
bole and Sadgopal nor those of Athavale and
Jatkar throw any light on these points.
The
present study was therefore undertaken to test
great details the utility of the Refractometer
colour fringes in detecting adulteration of ghee.
EXPERIMENTAL
The apparatus used in the present studies was
the Butyrorefractometer made by Carl Ziess.
The source of light was diffused sunlight. All
the readings were taken at 40°C. in dupli-
cate, observing the usual precautions.
In all about 150 samples of ghee, known to
be genuine, were examined. They represented
samples collected from almost all the im-
portant parts of India, thus giving a very re-
presentative data. For the sake of convenience,
figures of cow, buffalo, mixed and yellow* ghee
are given separately in Tables I to IV. Almost
all cow, buffalo and *yellow ghee samples were
collected in co-operation with the Marketing
Agricultural
and
Veterinary
officers
of
different provinces and states. Hence their
purity is guaranteed. Most of the mixed ghee
samples were obtained from ghee packers.
Their origin, either, as pure cow or buffalo, is
not known. So they have been classified as
mixed.
TABLE I
Refractive indices and colour fringes of cow
ghee samples
Sample
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
Place of origin
Cuttack . .
Dohad . . .
Asigabad . .
Gulburga . .
Indore . . .
Anand . . .
Dargai . . .
Warangal . .
Parachinar . .
Gwalior . .
Trichur . .
Nalgonda . .
Salem . . .
Srinagar . .
Kumbakonam .
Madura . .
Calicut . .
Ahmedabad . .
Tanjore . .
Coimbatore . .
Chittor . .
Mohmedabad .
Tanjore . .
Cuddapet . .
Cuddapet . .
Calicut . .
Vizagapatam .
Madura . .
Coimbatore . .
Bikkanolu . .
Tenali . . .
Bezwada . .
Shiyali . .
Refractive
index at
40° C.
44.0
43.4
43.6
43.5
44.3
43.7
43.7
43.9
42.0
43.8
44.0
41.8
42.8
43.5
43.0
42.7
41.8
41.8
44.0
41.0
44.3
43.4
45.2
41.5
41.8
432
44.1
43.2
43.8
43.2
43.9
43.6
44.6
Colour of the fringe
Violet
Pink
Pink
Pink
Violet
Pink
Pink
Pink
Orange
Pink
Pink
Pink
Diffused yellow/pink
Pink
Pink
Pink
Pink
Pink
Pinkish violet
Diffused yellow /pink
Pinkish violet
Pink
Violet
Red
Red
Violet
Pinkish violet
Pinkish violet
Pink
Pink
Pink
Pinkish violet
Pinkish violet
* Yellow ghee is so called because of its yellow colour.
Usually it is a mixture of cow, goat and sheep's ghee.
49