The next time you make something with red cabbage, save some for a special experiment with your kids to show them about the pH of the beverages they drink and the foods that they eat.
What is pH? pH is a measure of the hydrogen ion concentration of a solution. Solutions with a high concentration of hydrogen ions have a low pH (under 7) and solutions with a low concentrations of hydrogen ions have a high pH (above 7). A pH of 7 is neutral. Let’s see how to measure the pH of your food.
Red cabbage contains an indicator pigment molecule called flavin. Very acidic solutions will turn the flavin a red color. Neutral solutions will turn it a purplish color. Basic solutions make a greenish-yellow or yellow color.
To make this natural pH test, grate a small red cabbage and place the pieces into a large bowl. Pour boiling water into the bowl to just cover the cabbage. Let the mixture sit until it is room temperature – about an hour. Stir occasionally. Pour the mixture through a strainer into a measuring up to remove the pulp and save the liquid. This is your indicator liquid!
Now you can start testing. Pour some indicator solution into a clear plastic cup. Using an eye dropper, drop some of the liquid you want to test into the indicator until it changes color. Stir after every few drops. If you want to test food, add some neutral water to it and puree it in the blender.
Help your kids to record their results in a table! For a detailed explanation of acidity in foods, click HERE. For more information like this, get Chef Cappy’s cookbook – every recipe contains a STEM tidbit!