Cheese Lab

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

Observation Write Down key concepts of making cheese. http://www.youtube.com/watch?v=jBPYopcoeqs http://videos.howstuffworks.com/discovery/30257-some-assembly-required-milk-into-cheddar-cheese-video.htm

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

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

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

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

Materials Rennin, bovine

Material Chymosin Recombinant DNA

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

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

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.

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

Data Analysis