Recovery of carminic acid from carmine and carmine borax
Does anyone know if it is possible to recover the carminic acid from carmine and carmine borax? Carmine is a mixed calcium and aluminium lake of
carminic acid which is a trihydroxy methylanthraquinone carboxylic acid. Carmine borax is prepared from this carmine lake/complex by boil with a
dilute solution of borax. It is likely that the borax forms and ester type compound with two adjacent hydroxy groups and so is not a simple mixture,
but I have actually found a statement to this affect.
I can find no clear definition of the nature of carmine, only details on how to prepare it and its uses. Carminic acid is water soluble and usually
prepared directly from dried cochineal insects by warm water extraction. I suspect that carmine is actually the calcium salt of the aluminium chelate
of the anthraquinone. If this is so then removal of the calcium is probably easy using say oxalic acid. Old analyses show about 50-60% carminic acid,
some nitrogenous matter or protein plus small amounts of other organic impurities and inorganic salts.
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