Cheese Production—The
Evolution of Cheese Making
Lab 1C
Biotechnology Lab
Manuel
Objectives
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Each student performs an individual trial of
producing cheese using one of three curdling agents
Students gather, process, and analyze data from
multiple replications of cheese made with various
agents
Students evaluate the cause and effect of variables
in an experiment and attempt to limit variations
between trials
Students report experimental findings in a standard
conclusion format.
Watch Tutorials of Skills
1. Reading Pipets
2. Using Pipets
3. Micro Pipeting
4. P-10 P-20 Micropipeting
5. P-100 P-200 Micropipeting
6. P-1000 Micropipeting
Timeline
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Today: Review Key Concepts
Tuesday: Procedures Quiz, Steps 1-6
Thursday: Steps 7-9, data analysis, start
conclusion write-up
The World of Cheese
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Who likes it?
How big of a business?
How is it made?
How do you get so many kinds of cheese?
How have Biotechnology improvements in
the cheese making process impacted the
industry?
Biotechnology Impact on Cheese
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Look at page 7 and 8 of lab manual
The increasing use of technology includes
enzymes: rennin and chymosin
Enzyme Info.
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No matter the origin, the enzymes are doing the
curdling; either bacterial enzymes, fungus enzymes,
or enzymes extracted from bacteria, fungi, plant or
animal cells.
The enzymes are specialized proteins, are like other
proteins, their production is coded for on DNA
molecules. Some cells produce milk-curdling
enzymes, and others do not, depending upon their
DNA code.
Enzyme activity depends on several things:
concentration, temperature, pH, agitation
Hypothesis
If we test each of these curdling agents,
buttermilk (a bacterial culture starter), rennin,
and no additional curdling agent (milk is a
negative control), which agent do you think
will produce the most cheese in the shortest
period of time? And why do you think so?
Procedures/Flow Chart
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Make sure you write your procedures with
the tips we discussed last week
Make a flow chart…see example
Changes:
no chymosin will be tested
Prep. For Lab
1 month prior:
 Check rennin supply
 Filter paper
1 week prior:
 Buy buttermilk (1ml per group) & whole milk
(22mL per group)
 Mix rennin 1mg/mL in diwater (mix .01g in
10mL
Lab Set-up: Today if time
Set-up stations with everything ACCEPT:
 whole milk, buttermilk and rennin
 1ml pipet and pump (we will use the P-1000
instead)
Lab Work: Tuesday (Day 1)
Steps 1-6 Key Points
 Measure 25mL of whole milk and take to
bench
 Bring tubes to front to get .25 mL buttermilk,
and rennin
 Looking for curds
 take home
Lab Work: Thursday (Day 2)
Steps 7-9 Key Points
 Step 7—let filter for at least 30 min.
 Use a rubber policeman to get curds out of tube
 Folding filter paper demo—don’t tear
 Whey-o-meter set-up demo
 Calculating curd volume
 When finish with your table 1.2, 1 person per group
should input it on the front lap top computer
Bar Graphs
You will need to draw (or use excel) bar
graphs for the class averages (3) and then
compare your results to those averages (3).
You will have 6 bar graphs in total. Make
sure to draw your bar graph right next to the
averages. See example
Graph Details/Reminders
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A three part title that includes the subject
tested, the independent variable and the
dependent variable
Proper data-table set-up, independent on the
left (x) and dependent on the right (y)
Label and units
Individual entries and averages
Data Analysis
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The chart seen with the bar graphs will be
filled in by each group, then posted to the
website, so you can finish the rest of the
write-up and graphs
Conclusion/REE, PE, PA
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REE=Results, Evidence, Explanation
PE=Possible Errors
PA=Possible Application
See page 10 Conclusion for further
explanation
Witnessing
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Make sure you get your lab signed by a
classmate
See page 6-7 for details
Thinking Like a Biotechnician
Helpful Hints to get you thinking
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2.
3.
temperature, timing, shaking,
measurements, etc.
Sufficient would require results to all (or
almost all) be similar
Transfer of curds, filter paper absorption