How to Test the Acidity of Oranges

You can test the acidity level of any orange with a pH strip.

Orange acidity is caused by citric acid. You can determine the acid level by using a sodium hydroxide solution (NaOH) and a pH test meter. You can do this level of testing with either scientific testing equipment or a wine testing kit and will get satisfactory results. However, the expense for the equipment and the setup hassle may be prohibitive for random testing of orange acidity. There is a better and less expensive way to do this test.

Things You'll Need

• Set of pH testing strips, 0-4 pH range
• Knife

Instructions

1. Pull a pH test strip out of its container. Find pH test strips at science stores or medical supply shops.

2. Slice an orange in half.

3. Rub the test strip thoroughly onto the exposed fruit of the orange.

4. Compare the color change to the pH chart on the container. The color will match a pH number that signifies the acidity level in the orange.

Tips & Warnings

• Always use caution when slicing an orange with a knife.

References

• Laboratory Equipment: Single-Use pH Test Strips
• University of Michigan, Flint: Determination of the Amount of Total Acidity in Orange Juice

Resources

• Indigo Instruments: Indicator Strips pH 0-2.5, Lemon Juice, Battery Acid
• Whatman: pH Indicators and Test Papers