Abstract: In this paper, the determining means and stabilities of carminic acid extracted from Dactylopius cossus Costa were studied in different conditions. The results showed that the carminic acid can be determined by means of standard curve (SCM) consistent with the means of the FCC (Food Chemicals Codex) standard (the means of formula, FM). Carminic acid is stable under conditions of darkness and indoor scattered rays, temperature range 20～90 ℃, oxidizer different concentrations of H2O2, different HCl concentrations, and low consistency reducer Na2SO3. Adding Cu2+, Mg2+ and K+, it is relative stable under either pH4～5 and 9～11 or different concentrations of Zn2+ and Ca2+. It is unstabe in sunshine, incandescent lamp, various concentrations of NaOH, high consistency reducer Na2SO3, or adding Fe3+ for 72 h. The investigating results supply the scientific basics for the stipulated standard and the processing utilization for the raw material and products of cochineal insects.

Key words: cochineal insect, carminic acid, determination means, stability