1. Cheese Lab

2. Purpose Determine which curdling agent produces cheese the fastest
Determine which curdling agent produces the most cheese
Examine numerical data to support prediction
Examine variable that can lead to invalid experiments

3. Observation Write Down key concepts of making cheese.

4. Question
What kinds of questions came to mind while watching the cheese video?
Discussion:
Lab Question:

5. Background Milk has sugar, Lactose, which is eaten by Bacteria.
Bacteria + Lactose  Lactic Acid (waste) & ATP (energy for bacteria)
Lactic acid gives cheese a bitter taste
How: Bacteria produce enzymes that breakdown lactose  Lactic Acid

6. Background
Increase in Lactic Acid makes the milk acidic Increase Hydrogen Ions
This causes Casein (Protein) to become denatured (change shape)
Once Casein is denatured it falls out of solution.
Protease (another factor) causes Casein to breakdown (cleave) into smaller pieces and fallout of solution

7. Background Casein denatured or cleaved becomes solid
Curds: lumps of denatured casein
Whey: Liquid remaining
Cheese: pressed dehydrated curds

8. Materials
Rennin, bovine

9. Material
Chymosin
Recombinant
DNA

10. Procedures
1. Pipette out 7 ml of whole milk into labeled conical tube.
2. Using a P-1000 micropipette pipette out 0.25ml of Rennin add to 7 ml whole milk.
3. Cap tube and mix by gently inverting 3 times
4. Record Initial time

11. Procedures
5. Put capped tub under armpit to incubate milk for 15 minutes at body temperature.
6. During the 15 min. incubation check for curdling every 5 min.
7. After 15 min of incubation place tub on counter resting at room temp.
8. Continue to observe curdling every 5 min for 30 min.
9. Record observation

12. Procedures
10. Separate out the curds and whey to accurately measure amount produced.
11. Place filter paper into funnel over a 10ml graduated cylinder.
12. Pour milk liquid into the funnel and let whey drain through. When completely drained record amounts.

13. Data Curdling Agent Time to Curdling (hours)
Observations every 5 (min)
Volume of Whey (mL)
Volume of Curds (g)
pH of Milk (1-14)

14. Data Analysis