How to Measure the Amount of Ascorbic Acid in Juice

Fruit jucie provides the body with some of the vitamins it needs.

A healthy diet helps the body stay strong and energetic. A recommended amount of fruit daily provides the body with essential nutrients such as vitamin C. Vitamin C helps repair tissue in the body daily; therefore, the body needs a daily intake of the vitamin. Many fruits contain the vitamin C, or ascorbic acid, the body craves. You are able determine roughly how much ascorbic acid is in the fruit you select, helping to ensure you are getting the daily recommended amount for a healthy body.

Things You'll Need

• 3 glass cups
• Cornstarch
• 1/2 tsp. cold water
• Fruit juice
• 1/2 cup boiling water
• 3 eyedroppers
• Iodine
• Spoon

Instructions

1. Mix 1 tsp. cornstarch with 2 tbsp. cold water to create a paste.

2. Stir in 1/2 cup boiling water with spoon until cornstarch mixture has dissolved.

3. Add 10 drops, using the eyedropper, of cornstarch mixture to a glass containing 1 cup of room-temperature water.

4. 

   Iodine can be used to check the level of ascorbic acid in fruit.

   Add drops of iodine, using second eyedropper, to water until it turns dark blue or purple. Wait between drops for the color to change.

5. Pour 5ml of iodine and cornstarch solution into third cup.

6. 

   An eyedropper is used to control the amount of fruit juice added.

   Add 10 drops of fruit juice, using third eyedropper.

7. Check the clarity of the solution to determine the amount of ascorbic acid in the fruit. If the solution is completely clear, the fruit has a high level of ascorbic acid. If the blue or purple color of the water barely changed, then the fruit has a very low amount of ascorbic acid.

Tips & Warnings

• Always use clean equipment, when performing an experiment, and keep items and substances separate until mixing is called for. These steps help ensure a process that is not contaminated and more likely to yield the desired results.

• Iodine can stain clothing. Be careful while using it.

• This test does not give an exact numerical amount of ascorbic acid in fruit. The closest one can get to an exact number is by using a laboratory testing kit. This costs $50 to $100.

References

• Newton Ask a Scientist: Iodine and Vitamin C Test

Resources

• Inside the Pyramid: How much fruit is needed daily