How to Test Saliva pH for an Experiment

The acidity of a substance is measured by pH; the pH scale is used to assign a value to that substance using numbers 0 to 14, where 0 is the most acidic and 14 is the most basic. Neutral pH between 6.8 and 7.2 is ideal for your mouth, according to dentist Dr. William Reuss, but various foods you eat can affect the acidity of saliva.


Create a hypothesis for your experiment. You might theorize that eating alkaline foods will raise your saliva’s pH and acidic foods will lower the pH.


Test your pH to determine overall saliva acidity before you change your diet. The best time to test saliva is right after you wake up in the morning -- before you eat, drink or brush your teeth. Swallow the saliva currently in your mouth. Collect more saliva in your mouth and spit it out. Collect additional saliva and spit into a cup or spoon. Dip the end of a strip of litmus paper in the saliva and compare its color to the pH chart. Record the pH in a data journal.


Eat a diet of mostly alkaline foods, including almonds, pineapples, radishes, grapes, greens and avocados for a week, and keep a food diary. Test your pH three times a day by spitting on a spoon and dipping litmus paper into the saliva; do not brush your teeth before testing. Record the results.


Eat a diet of mostly acidic foods in the following week and record your food intake. Acidic foods include soft drinks, pickles, chocolate, sweetened fruit juice, grains and cooked beans. Test your saliva pH three times a day and write down the results.


Return to your regular diet for a week and continue to test pH three times a day.


Compare data from the three weeks of testing. You'll likely noticed your saliva became more alkaline as you introduced more alkaline foods into your diet, and more acidic as you ate more foods with lower pH, results that support your hypothesis.


Photo Credits

  • Jupiterimages/ Images

About the Author
