Abstract: Orthogonal array design was used to optimize the extraction condition of natural red pigment from Lagerstroemia indica flowers.The stability of the extracted red pigment was also investigated.The results showed that the optimal extraction conditions were as follows:using 40% aqueous ethanol and the ratio of material to liquid of 1:40 (g/mL) to extract raw material under the assistance of ultrasonic treatment for 90 min.The red pigment was soluble in water,and had good resistance to indoor natural light,heat,and had good stability in acidic environment.Except Ca²⁺, Zn²⁺, Al³⁺, Cu²⁺, Pb²⁺ and Fe²⁺, other metal ions including Na⁺、K⁺、Mg²⁺ had no obvious effects on the pigment.

Key words: Lagerstroemia indica flowers, red pigment, extraction, stability