Cheesemaking Lab
Biotechnology
Purpose: The purpose of this lab is to employ the process of making cheese. Cheese is a
solid food made from the milk of cows, goats, sheep and other mammals. Cheese is made
by coagulating milk. This is accomplished by first acidification with a Bacterial culture
and then employing an enzyme, rennet (or rennet substitutes) to coagulate the milk to
"curds and whey." There are hundreds of types of cheese produced all over the world.
Different styles and flavors of cheese are the result of using milk from various mammals
or with different butterfat contents, different species of bacteria and molds, and varying
the length of aging and other processing treatments.
Some fresh cheeses are curdled only by acidity, but most cheeses also use rennet. Rennet
sets the cheese into a strong and rubbery gel compared to the fragile curds produced by
acidic coagulation alone. It also allows curdling at a lower acidity—important because
flavor-making bacteria are inhibited in high-acidity environments. In general, softer,
smaller, fresher cheeses are curdled with a greater proportion of acid to rennet than
harder, larger, longer-aged varieties
Supplies:
1 disposable bowl
Plastic wrap
1 Plastic Spoon
Masking Tape
1 cup of milk
1 T of Buttermilk
2 drops of Rennet
Procedure:
Day 1
1. Collect all needed supplies
2. Label your bowl with masking tape before doing experiment – much easier! 
3. Place 1 cup of milk in your bowl
4. Add 1 T of buttermilk to your milk and stir slowly and thoroughly
5. Add 2 drops of Rennet to your milk mixture and stir slowly and thoroughly
6. Cover bowl with plastic wrap and leave out at room temp for 24 hours – do not
disturb
Day 2
7. Take a spoon and attempt to cut the curd that has formed in your bowl. If the
curd is able to be cut and the cut pieces hold together you are ready to ‘pack’ your
cheese
8. Have 2 group members hold the flour sack towel over the sink and slowly dump
your curds into the middle of the towel
9. Fold the towel into a ‘bag’ and tie the cheese in with a string leaving enough
string to hang your cheese in the refrigerator.
10. Using your bowl to catch the whey transport your cheese to the fridge and secure
on the shelf. Let drain for at least 24 hours
Day 3
11. Use a pinch of salt to flavor your cheese and enjoy!
Analysis:
1. Which product acted as the acidifying bacteria in this experiment. What was this
bacteria called?
2. Which product acted as the enzyme in this experiment. What role does it play in
this experiement.
3. Why is cheesemaking considered a fermentation process?
4. Was your lab a success? Why or why not? (Include how you thought it tasted)