142
Colouring of Vanaspati Ghee
CONCLUSION
A careful examination of the results has brought forth the interesting results that there is not
a single dye (harmless or otherwise) that cannot be removed from ghee by simple treatments which
require no elaborate knowledge of chemistry. Activated charcoal for instance can bleach all the
dyes, simpler still, light can remove practically the entire quantity of natural dye.
It is, therefore, clear that we are up against practically an unsurmountable difficulty in the
problem of clouring artificial ghee. There is no doubt that every organic chemist will endorse the
view that it would be impossible to find a dye that would be absolutely stable in fat solution.
The bleaching of even fast c lours in sunlight is well known and every one must have noticed
the fading away of beautiful colours on garments which owed their attractiveness to the pleasing
combination of colours. The Government must, therefore, drop this legislation as
will never
be the faintest hope of finding any dye that would be fast enough to last any length of time under
normal conditions of exposure even if it is not subjected to simple treatments that would remove
them entirely. In view of these results research on the physiological effect of any one of these dyes
would be utterly useless for the purpose in hand. In fact any new dye not listed in here, and which
might be suggested as possible colouring for artificial ghee, should be tested first for stability before
its claims for harmlessness are gone into. By the very nature of things all possible dyes must be
of organic origin and without knowledge of the general properties of such dyes it would be futile
to consider any new dye unless the advocates are prepared to bring forth proof of their stability on
lines detailed in the present investigation.
It is not merely a question of the stability of a dye, we have also to consider the possibility of
the decomposition of an organic dye on heating and the production of harmful bye-products. Arti-
ficial ghee has come to be regarded as a valuable article of food. In any case there is not enough
natural ghee in the country to supply the demand of even 10 per cent of the population. The pre-
vention of adulteration of natural ghee with vanaspati is a laudable object, but it cannot be achieved
by colouring the artificial ghee. The only satisfactory solution to this problem is to refine our ana-
lytical methods so that it might be possible to detect such adulteration by physico-chemical tests
in the laboratory.
APPENDIX I
Experimental details of the preparation of various natural dyes
1. Ratanjot, Onosma echioides Linn.
This substance has been used as a substitute for alkanet as it imparts a rich red colour to oils
and fats, and for this reason it is most suited as also due to its harmless nature.
Preparation of the dye
Method I. One hundred grams of root bark is well extracted in amyl alcohol. The amyl alcohol
solution is concentrated under vacuum (Maximum temperature 110°C.). The thick mass is dissolved
in alcohol and filtered, concentrated under vacuum and last traces of amyl alcohol removed by boiling
with water.
Crude dye recovered=6 gm.
Method II. One hundred grams of root bark is extracted with acetone by refluxing for three
hours. The acetone is distilled and the dye extracted by alcohol. The alcohol is distilled.
Crude dye recovered=9 gm.
Purification of the dye
The dye is precipitated as copper salt by adding copper sulphate in boiling condition. The
copper salt of the dye is slightly soluble in alcohol, so dilution of the alcoholic solution of the dye after
adding copper sulphate, but before heating, facilitates the precipitation of the dye salt. The pre-
cipitated copper salt is filtered and washed with water.