Study on preparation and stabilities of sodium copper chlorophyllin, sodium zinc chlorophyllin and sodium iron chlorophyllin from pine needles

Chlorophyll was extracted from pine needles by ethanol-H2O, and then sodium copper chlorophyllin (SCC) , sodium zinc chlorophyllin (SZC) and sodium iron chlorophyllin (SIC) were prepared by the processes of saponification, acidification, reaction with CuSO4, ZnSO4, FeSO4and basification. Colors of SCC, SZC and SIC solutions in the same concentration were dark green, emerald and dark brown respectively. Moreover, their stabilities to light irradiation, thermal processing, pH and oxidants were determined. Results showed that SCC had the best stability to light irradiation and SZC was stable to high temperature. Different concentrations of hydrogen ion resulted in isomerization of structure. SCC, SZC and SIC were all stable under low concentration, but unstable under high concentration of oxidant.