Study on Properties of Red Pigment of Alternanthera dentata cv. Ruliginosa

[Objective] This research aimed to provide reference on development and utilization of red pigment of Alternanthera dentata cv.Ruliginosa.[Method]The red pigment was extracted from the leaves of A.dentata,and its stability was studied.[Result]The maximum absorption wavelength of the red pigment was 530 nm in visible light scope.The red pigment was influenced more greatly by pH value.It showed red at pH value of 3～7 and changed from light red to yellow-green at pH 7.Along with the temperature rising,the loss rate of red pigment rose obviously and was over 1/2 of the whole red pigment when heading for 30 minutes at 70 ℃.Along with sunlight extension,the loss rate of red pigment was significantly increased and was as high as 60.0% till 4th d.The oxidants and reductants had some influence on the stability of red pigment at the concentration of 0.01%～0.20%.Some common food additives exception of saccharose and sodium benzoate had some influence on stability of red pigment,such as VC and citric acid.[Conclusion]The red pigment of A.dentata had a better stability at pH value of 3～7 and under adding saccharose and sodium benzoate additives,but was worse under the condition of the alkali,heat,light,VC and the lemon sour etc.