Propose a hypothesis and experimental procedure to test the effect of microbial growth on milk quality using a redox indicator.

a) Propose a hypothesis for your experiment:
If the microbial count in milk increases, then the reductase enzymes will increase, leading to a faster decolorization of a redox indicator dye.

b) Procedure:

1. Obtain several samples of fresh milk.
2. Incubate these milk samples at a constant warm temperature (e.g., $30\,^{\circ}\text{C}$) for different durations (e.g., 0 hours, 6 hours, 12 hours, 24 hours, 36 hours) to create varying microbial counts. Keep one sample as fresh milk (0 hours incubation).
3. Label five (or more) test tubes.
4. Add a fixed volume of each milk sample (e.g., $10\,\text{mL}$) to its respective test tube.
5. Add a fixed volume of methylene blue solution (e.g., $1\,\text{mL}$ of 0.005% methylene blue) to each test tube.
6. Gently mix the contents of each test tube to ensure uniform blue color.
7. Place all test tubes in a water bath maintained at a constant temperature (e.g., $37\,^{\circ}\text{C}$).
8. Immediately start a stopwatch for each test tube after adding methylene blue and mixing.
9. Record the time taken for the methylene blue in each test tube to completely decolorize (turn colorless).
10. Repeat the experiment at least three times for each milk sample to ensure reliability and calculate the average decolorization time.