Optimization of the preparation process for red pigment and green pigment of amaranth

Objective To explore a way to extract the red pigment and green pigment from the edible amaranth by ultrasound extraction.Methods The red pigment was water-soluble,and the solubility of the green pigment was much higher in the ethyl alcohol.Based on these characteristics,the red and green pigments were extracted and separated simultaneously by ultrasound extraction.With the orthogonal design and univariate analysis,the technological parameter and extraction effects of the ultrasound extraction were investigated,and compared with the normal solvent soaking method.Results The optimum technological parameter were as follows:red pigment with the condition of ultrasonic frequency 40%,the ratio of liquid and powder 1:10(g:ml),extraction time 20 min,temperature 50 ℃;and green pigment with the condition of ultrasonic frequency 90%,the ratio of liquid and powder 1:10(g:ml),extraction time 30 min,temperature 25 ℃.Conclusion The method of ultrasound extraction can extract the pigments with higher efficiency and lower cost than classical diffusion method,and do not change the qualities of pigment.These provide strong theoretical support for the application of ultrasonic technology.