Thermal degradation of commercial grade sodium copper chlorophyllin.

Sodium copper chlorophyllin (SCC), a water-soluble commercial derivative of chlorophyll, has gained importance as a food colorant and dietary supplement with apparent chemopreventive activities. The thermal stability of SCC was studied to assess the potential application of this chlorophyll derivative for use in thermally processed foods and supplements. Thermal degradation of an aqueous 500 ppm SCC solution was monitored between 25 and 100 degrees C by a loss of absorbance at 627 nm. Decomposition was also followed by reversed phase C18 HPLC with photodiode array detection to monitor the loss of Cu(II)Chlorin e4, the major component of commercial grade SCC. The rate of thermal degradation of SCC was found to follow first-order reaction kinetics. HPLC analysis confirmed the ultraviolet and visible absorbance data and also demonstrated loss of the major SCC component, Cu(II)Chlorin e4, at a rate faster than that of overall SCC. The activation energy was estimated using the Arrhenius equation and found to be 13.3 +/- 0.8 and 16.0 +/- 2.1 kcal/mol for the thermal degradation of SCC and Cu(II)Chlorin e4, respectively. The observed temperature sensitivity of SCC was determined to be similar to that of natural chlorophyll and raises the possibility of color deterioration when used in food products where mild to severe thermal treatment is applied. Furthermore, the implication of rapid loss of Cu(II)Chlorin e4, a reported bioactive component of SCC, upon heating may result in alteration of potential dietary benefits such as antimutagenic and antioxidant activity.