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Preparation of Enzyme Solution
Dilute 1 mL of your saliva with 9 mL water. Then, add 60 mL of 0.5% NaCl solution.

Effect of pH
1. Prepare 0.1 M pH buffer solutions ranging from pH = 4.5 to pH = 9.0 in increments of one pH unit.
2. Add an equal volume of one of the above buffer solutions to 5.0 mL of the 20 g/L starch solution prepared in Step 1. The resulting solution should contain 10 g/L of starch in a buffered environment.
3. Start the enzymatic digestion process by adding 1 mL of human salivary enzyme solution; shake and mix.
4. Let the hydrolysis reaction proceed for exactly 10 minutes at 25 0C.
5. Add 0.5 mL of the reacted starch solution to 5 mL of the HCl stopping solution (0.1 N).
6. Add 0.5 mL of the above mixture to 5 mL iodine solution to develop color. Shake and mix. The solution should turn deep blue if there is any residual, unconverted starch present in the solution. The solution is brown-red colored for partially degraded starch, while it is clear for totally degraded starch.
7. Meaure the absorbance with a spectrophotometer at 620 nm.

Effect of Temperature
1. Prepare the temperatures of the temporary water baths in 250 mL beakers, and adjust the temperatures ranging from 30 0C to 90 0C in increments of 20 0C.
2. Prepare the starch substrate by diluting the 20 g/L starch solution prepared in Step 1 with an equal volume of pH = 7.0 phosphate buffer solution. This results in a working starch concentration of 10 g/L. Add 5 mL of the starch solution to each of the test tubes....