Starch Digestion Experiment

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Does the amount of time that orange juice is swished in a human mouth affect the pH of the saliva, which could inhibit the digestion of the starches in the orange juice?

Hypothesis: The longer 2 mL of orange juice is held in a test subject’s mouth, the greater the ability of the test subject’s saliva will become to break down starches.

Dependent Variable: pH of the saliva.

Independent Variable: time that the juice is swished in the mouth.

Controlled Variables:
Orange juice only.
The amount of orange juice tested must be the same for every trial. A 1% starch solution must be used in every test tube.
Identical iodine solutions must be used to test the starch solution. The temperature of the warm bath water must be exactly 37 degrees C.

Appoximately1 Liter of orange juice
25 test tubes
One test subject for swishing the juice
25- 1% starch solutions (95 mL)
Warm bath with water heated to 37 degrees C
Litmus paper for pH testing

1.Use an eye dropper to measure 2 mL of orange juice into a Dixie cup. 2.Measure 5 mL of starch solution into every test tube.
3. The test subject must swish the measured juice in the Dixie cup in their mouth for the trial-appropriate amount of time. 4.After the designated amount of seconds has elapsed, the test subject should spit the saliva and juice into a test tube. 5.Mark the test tube with the appropriate trial number with a grease pencil. 6.Repeat this 4 times.

7.Place the test tubes into the 37 degree C water bath.
8.Allow the test tubes to sit in the water bath for 20 minutes. 9.Remove the test tubes from the water bath.
10.Using the eyedropper, add 3 drops of iodine to each of the test tubes. 11.Observe and note the color of the solution after adding iodine. 12.Test the pH of the solution using litmus paper, and record it. 13.Determine whether or not the starch was broken down based on the color of the solution after adding...
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