Who doesn’t love a cold glass of orange juice in the morning? Whatever your preference, pulp or no pulp, low calorie or full on sugar, everyone loves OJ. So we thought, why not do an experiment that will leave us with lots of delicious orange juice to drink?!

Orange juice is acidic. We don’t need to test it to know that. But what we are curious to know, is whether certain types of orange juice are more acidic than others. Does pulp affect the acidity of orange juice? Is there a difference by brand? How about brands like Trop50 that contain less sugar? How does that affect the pH level of the orange juice?

See what we’re getting at here? It’s time to buy a lot of orange juice! You won’t need much for testing, so there will be plenty leftover for drinking later!

Materials

  • pH 0-7 3 pad test strips
  • A variety of orange juice (pulp, no pulp, different brands, low sugar, organic, frozen concentrate, fresh squeezed, etc.)
  • Plastic cups

Procedure

acidity of orange juice, pH, pH test strips, orange juice pHThis experiment is pretty easy and straight-forward. Start by ordering each orange juice from what you think will be least acidic to most acidic. For the experiment, simply pour a sample of each different type of orange juice you bought into a cup. Label each cup with the OJ name/type. Next, using one pH test strip for each cup of orange juice, you will dip a strip in a sample, remove and immediately compare to the color chart. Record your results in your laboratory notebook.

Using a 3-pad pH strip will give you improved testing accuracy. It is important to note that the pH levels may not differ much between the various orange juices, so it can be difficult with pH test strips to distinguish the difference between pH 4.4 and pH 4.6. The 3-pad test strip can add some improved accuracy, but it may still be difficult to truly identify some of the results.

You should find all the results to be between pH 4 and 5. Compare the results in your laboratory notebook. Which type of orange juice was the most acidic? How does this compare to your hypothesis?

Going Further

If you want to get more precise results, try using a pH meter to test your various orange juices. You could also add a taste test factor to this experiment. Sample each orange juice first, and see if you can tell which is least and most acidic based on taste.