Synthesis and chemical characterisation of curcuminoid colouring principles for their potential use as HPLC standards for the determination of curcumin colour in foods

The three major colour principles of curcumin have been synthesized, purified and chemically characterized using nuclear magnetic resonance spectroscopy, absorption spectroscopy, high- performance liquid chromatography and liquid chromatography–mass spectrometry. System suitability criteria for the simultaneous determination of the curcuminoids and annatto colorant (bixin and norbixin) by HPLC are presented and the importance of the water content of sample extracts discussed. The results show that synthetic curcuminoids may be synthesized with sufficient purity for use as standards for HPLC analysis provided that both the spectrophotometric and chromatographic purities are known. The potential for their use in the determination of turmeric and/or added curcumin colour (with annatto) in foods and especially fish is discussed.