Lactase Synthesis

Background:

The sugar molecule lactose is found in dairy products and people with Lactose Intolerance are unable to digest lactose because the enzyme lactase is unable to split the sugar molecule into glucose. Lactase is an enzyme that breaks lactose down into galactose and glucose. Lactase functions best between 21 and 48 degrees Celsius (or 70 and 120 degrees Fahrenheit). Cooler temperatures will slow down lactase’s function, whereas high temperatures can denature it or lactase will lose its shape. If lactase is rendered nonfunctional because of temperature or pH extremes, the breakdown of lactose stops. Lactose intolerance occurs when this breakdown fails due to insufficient or ineffective lactase. The experiment will stimulate the process

of hydrolysis of lactose to glucose in samples of fat-free milk, fat-free lactose-free milk, vanilla ice cream, and plain yogurt. They will be tested to indicate which substance has the highest concentration of glucose, as indicated by the amount of lactose the product contains. This raises the question as to how the amount of lactase affects the amount of glucose present in the four samples.

Personal Statement:

Research Question:
How does adding 4 drops of lactase solution to 20 mL samples of fat- free milk, fat- free lactose- free milk, vanilla ice cream, and plain yogurt affect the amount of glucose present, measured by a glucose test strip?

Hypothesis:

If the amount of lactase is higher in plain yogurt, than the amount of glucose will also increase because lactase is an enzyme that breaks up the milk sugar lactose to produce the sugar glucose. If more lactase is present in a substance, such as the plain yogurt, than it will be easier and more efficient to break down the lactose into glucose. Therefore, if higher levels of lactase are present, then there will be more glucose present.

Variables:

Independent: 20 mL of a substance (fat- free milk, fat- free lactose- free milk, vanilla ice cream, and plain yogurt)

Dependent: Amount of glucose which will be measured using a glucose test strip

Controls:

• Amount of Lactaid original lactase drops (4)

• Initial temperature of each substance (23 degrees

Celsius)
• Each sample size (20 mL)
• Type of glucose test strip (Diastix Reagent strips for Urinalysis to test urine glucose)
• Amount of time the test tube is rolled in hand (2 minutes)

Procedure:
Make positive and negative control solutions.

The positive control solution is 2% glucose in water. This is necessary to make sure the glucose strips are able to detect glucose. The negative control solution is water. This is necessary in making sure the glucose test strips don’t react to plain water.

1. In a beaker, grind one glucose tablet (4 grams) with a spoon.

2. Add 200 mL of water and stir until the tablet is dissolved.

3. Fill a test tube with the 2% glucose water and label it with tape and a marker. This is the positive control solution.

4. Fill another test tube with 200 mL of plain water and label it Negative Control.

5. Test both the positive and negative control solutions with the glucose strips.

6. Dip separate strips into the glucose solution (positive control) and water (negative control).

7. Wait for the length of time specified by the test strip directions.

8. Record any color changes of the strip and determine the glucose concentration according to the key on the bottle.

9. Record any observations made. (A clear positive reaction for the 2% glucose control and a clear negative reaction for the water control should be seen).

10. Create the lactase solution.

11. Take 5 lactase caplets and grind them into a powder.

12. Measure out 200 mL of water in a beaker.

13. Add the lactase powder to the 200 mL of water and stir until completely

dissolved.
14. Determine the level of glucose in regular milk and the level of glucose in lactose-free milk.
15. Measure out 20 mL of fat-free white milk and 20 mL of fat-free lactose-free milk into clean, separate test tubes and let them sit until they reach room temperature (23°C). Label accordingly.
16. Use a stirring rod to stir each individual sample to combat any separation that might have occurred while they were left alone to reach room temperature.
17. Dip a glucose test strip into the regular milk sample. Wait for the length of time specified by the test strip directions.
18. Determine the glucose concentration according to the key on the bottle.
19. Repeat steps 14 and 15 for lactose-free milk and record results.
20. Determine the level of glucose in regular milk and the level of glucose in lactose-free milk after adding the lactase solution.
21. Add one drop of the lactase solution to the regular milk sample.
22. Expedite the reaction by rolling the tube back and forth in the hands for 2 minutes. Use the stopwatch to keep track of time.
23. Repeat the glucose test with a fresh test strip and record the results.
24. Repeat steps 17-19 with the lactose-free milk.
25. Repeat steps 12-19 two more times so that three trials have been completed for each milk sample, both before and after adding lactase. Be sure to clean out the test tubes carefully before beginning any new trials. Always use fresh test strips.
26. Perform steps 12-19 three times for the vanilla and plain yogurt samples. Again be sure to clean out the test tubes before every trial and use new test strips. Record the results for all three trials.