Method development and HPLC analysis of retail foods and beverages for copper chlorophyll (E141[i]) and chlorophyllin (E141[ii]) food colouring materials

Abstract

An analytical method using high performance liquid chromatography with photodiode array and fluorescence detection has been developed and applied to the determination of the food colour additives copper chlorophylls and copper chlorophyllins (E141[i] and [ii]) in foods and beverages. The analytical procedures from previously reported methods have been refined to cover a range of food colour formulations and retail foods. The method was single-laboratory validated. Recoveries of the polar copper chlorophyllins from spiked samples (at 14.5 mg/kg in all but one case) were in the range 79–109%, except for jelly sweets (49%). Recoveries of relatively non-polar copper chlorophylls were in the range 77–107% (except for ‘made’ jelly at 50%). The %RSD for recoveries was generally below 12%. Quantitative estimates of the total copper chlorophyll/chlorophyllin content of a small range of food commodities are reported, based on the use of trisodium copper chlorophyllin as a surrogate standard. The majority of E141-containing foods and colour formulations analysed exhibited a multiplicity of components due to the various extraction and purification processes that are used to obtain these colour additives. This was confounded by the presence of overwhelming amounts of native chlorophylls in certain samples (e.g. mint sauce). Food commodities containing significant amounts of emulsifiers (i.e. ice cream), gelatine or fats were problematic during extraction hence further development of extraction regimes is desirable for such products. All of the samples analysed with added E141, had estimated total copper chlorophyllin contents of below 15 mg/kg (range 0.7–13.0).

Keywords:

• Food
• additives
• colours
• analysis
• chlorophyll
• chlorophyllin
• copper
• E141

Acknowledgements

The authors would like to acknowledge the help of Dr Benoit Schoefs of the Laboratoire de Dynamique des Membranes Vegetales, Paris, France, for providing helpful information on chlorophyllin analysis (2003, personal communication). Financial support for this work was provided by the UK Food Standards Agency (FSA). Any views or opinions expressed in this paper are the authors alone, and should not be taken to represent the opinion of the FSA.