Abstract:

Red pigment was extracted from fruits of Myrica rubra using 1, 0.1 mol/L and 0.01 mol/L hydrochloric acid, citric acid, tartaric acid and ascorbic acid. Different pigment solutions were obtained by filtration. Pigment solutions were subjected to heating treatment at 70 ℃ for 5 hours and ultrasonic treatment for 1 hour. The treated pigment solutions were placed in the natural light for 3 days. The absorbance change of pigment solutions was determined to evaluate the stability of pigment. Results showed that red pigment was not stable in acidic systems. The pigment was very unstable to heating, ultrasonic and light treatments in ascorbic acid system. However, the pigment exhibited relative stability to heating treatment in hydrochloric acid system with the minimum absorbance change in 1 mol/L hydrochloric acid. Moreover, the pigment also exhibited the relative stability to ultrasonic treatment in hydrochloric acid, citric acid and tartaric acid. Meanwhile, the minimum absorbance change of pigment after ultrasonic treatment was observed in 0.01 mol/L citric acid. Furthermore, the minimum absorbance change of pigment after natural light treatment was revealed in 0.1 mol/L hydrochloric acid.

Key words: acid systems, red pigment, Myrica rubra, stability