Boiled Juice Greatly Increased The Respiration Of How Long Will Boiled Red Cabbage Juice Last As A PH Test?

How long will boiled red cabbage juice last as a pH test? - boiled juice greatly increased the respiration of

I do my science project in the control of the pH values of household substances. I want to change the color to show the class, but I wonder whether the solution is boiled red cabbage "to be powerful (or able to alter the color)" If I get to school. I can not cook the cabbage in the school as well as his ideas of others as a video and photos, ask how my project to the test?