264
Fluorescence in Ghee, and Detection of its Adulteration
originals in a Lovibond Tintometer. In every case
the original fluorescent colours were restored. The
results of bleaching are given below (Table VII).
TABLE VII
Bleaching of ghee
Sample
1. Sample
1 in
Table VI
2. Sample 3 in
Table VI
3. Ayrshire cow .
4. Porbunder.
February, 1942
5. Dacca, Janu-
ary, 1943
6. Dacc a, June,
1942
Colour by day light
Colourless liquid
Very pale yellow
liquid
Pale yellow .
Quite colourless .
Very pale yellow .
do. . .
Colour by ultra-
violet light
Fairly bright green
tint
Pale greenish yellow
Pa1e bluish green
Pale blue with
tint of purple
Pale blue with
green tint
do.
They indicate that the age of a sample is revealed
in a progressive blue colour, often masked by the
yellow colour of carotene. For example, the very
white Porbunder Sample 4 (Table VII) gave the same
colour even after bleaching; and the green tints
of samples 3, 5 and 6 may be explained as resulting
from the blue as a consequence of ageing together
with the slight residual yellow of carotene. The
following results (Table VIII) in every case confirm
the deductions stated above, and indicate that a
fresh fat should give a greenish-white shade on
bleaching.
TABLE VIII
Additional fluorescence colours
Sample
Cow ghee, fresh .
Cow ghee, bleached
Akola
(Sample
18) cow ghee,
2½ years
Akola
(Sample
18) cow ghee,
bleached
Akola
(Sample
125) cow ghee,
2½ years
Akola
(Sample
125) cow ghee,
bleached
Akola
(Sample
96) cow ghee,
2½ yours
Akola
(Sample
96) cow ghee,
bleached
Colour by day light
Bright yellow
Quite colourless
Fairly bright
Pale yellow
do.
Colourless
Pale yellow
Colourless
Colour by ultra-
violet light
Bright yellow
Pale greenish white
Pale yellow
Pale green with
blue tint
Pale
blue
with
faint green tint
Pale blue
Pale
blue with
green tint
Pale blue
TABLE VIII
Additional fluorescence colours
Sample
Buffalo ghee, fresh
Buffalo ghee., fresh
bleached
Lyallpur ghee,
May, 1942
Lyallpur ghee,
bleached
Lyallpur ghee,
April, 1942
Lyallpur ghee,
bleached
Kirkee ghee, Nov-
ember, 1941
Kirkee ghee, Dec-
ember, 1941
Gauhati, July, 1942
Gauhati, July, 1942
bleached
Cow ghee, cream
process
Cow ghee, curd
process
Colour by day right
Faint yellow
Colourless
Pale yellow
Very pale yellow
Pale yellow
Very pale yellow
Hardly perceptible
yellow
Slightly darker
yellow than
above
Pale yellow
Very faint yellow
Yellow
do.
Colour by ultra-
violet light
Greenish with tint
of yellow
Greenish without
tint of yellow
Pale blue with tint
of green
Pale blue
Pale blue with tint
of green
Pale blue
Blight bluish purple
do.
Pale yellow tinged
with green
Pale blue with
touch of green
Bright yellow
Bright
yellow,
faint green tint
The ageing of ghee results in various changes, and
these appear to be indicated in a blue shade. To
test this hypothesis, ghees were maintained at
90°C. in thin films exposed to the atmosphere
for 48 hours. While this does not involve
the same organic processes as normal rancidification
[Banks, 1944] the results are interesting in that
they show the marked blue colour produced in the
ghees, which were all quite colourless after the
teattment.
TABEL IX
Ageing of ghee
Sample
Fresh buffalo ghee
Ghee from soured
cream
Fresh cow ghee
Colour by day light
Colourless
do.
do.
Colour by ultra-
violet light
Beautiful bluish
violet
do.
do.
SUMMARY
1. The fluorescence of ghee and its adulterants
in ultra-violet light has been studied.
2. The pronounced effect of carotene on the colour
has been established. The sample should always,