Pigments in pitaya pulp cells exist on the cell wall. Pigments in pitaya pulp are natural, and the two most important ones are anthocyanin and betacyanin. The color of anthocyanins will change with the PH value of cell fluid, usually blue in alkaline environment and purple in acidic environment. Because the PH value of pitaya pulp is less than 7, anthocyanins and betacyanin are purplish red in this environment.