Download Cheese Lab

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=j
BPYopcoeqs
• http://videos.howstuffworks.com/dis
covery/30257-some-assemblyrequired-milk-into-cheddar-cheesevideo.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 Time to
Agent
Curdling
(hours)
Observatio Volume Volume of
ns every 5 of Whey Curds (g)
(min)
(mL)
pH of Milk
(1-14)
Data Analysis