The properties of the red pigment from purple cabbage

The pigment was extracted and separated from leaves of Purple cabbage.Analyzes the stability and the bacteriostasis of the pigment in purple cabbage by spectrophotometry.Results demonstrated that pigment is a carmine as if original plant and is better stability when the pH is 2 in water solution.As pH augment gradually the color of pigment transforms carmine to blue,blue to green gradually and a red-shift of the maximum absorption took place.The pigment by ultraviolet-visible light in 2 d preservation rates were more than 91%,the pigment by ultraviolet-visible light in 6 d preservation rates were more than 79%;Heated at the temperature below 70 ℃ in 2 h preservation rates were more than 97%,heated at the temperature at 90 ℃ in 2 h preservation rates were more than 90%.To sum up,the pigment had tolerance to light and higher tem-perature.The pigment had significantly bacteriostasis on the Staphyloccus aureus and Bacillus snbtilis,the more obvious bacteriostasis was,the higher pigment concentration increases.But the pigment did not control on the Escherichia coli growth.