National Cheese Lovers Day is approaching on January 20. Below is a lesson about cheesemaking that your students will enjoy.
Lesson Title: The Science of the Squeeze
Grade Level: 4th – 8th Grade (Adjustable)
Objective: Students will understand the biochemical process of curdling and the role of acid and enzymes in food science.
1. The Core Concept: How Milk Becomes Cheese
At its simplest, cheese making is the process of removing water from milk to concentrate its proteins and fats. This happens through a process called coagulation.
- The Proteins: Milk contains a protein called casein. Normally, casein molecules float around freely.
- The Catalyst: To make cheese, we must make those proteins “clump” together. This is done by adding an acid (like vinegar or lemon juice) or an enzyme (like rennet).
- The Result: The milk separates into curds (the solids) and whey (the liquid).
2. Classroom Experiment: “Quick Queso Blanco”
You can actually make a simple acid-set cheese in the classroom using a microwave or a single burner.
Materials:
- Whole milk
- White vinegar or Lemon juice
- A pinch of salt
- Cheesecloth (or a fine mesh strainer)
- A thermometer
The Process:
- Heat: Warm the milk to about 82°C (180°F). Explain that heat helps denature the proteins, making them ready to bond.
- Acidify: Stir in the vinegar slowly. Students will see the milk “break” almost instantly.
- Strain: Pour the mixture through the cheesecloth. The liquid that runs through is the whey; what remains are the curds.
- Press: Squeeze the excess liquid out. Add salt for flavor.
3. Deep Dive: The Role of Bacteria
For older students, you can discuss fermentation. Most professional cheeses aren’t just set with acid; they are aged using specific cultures of bacteria.
- Lactic Acid Bacteria: These “good” bacteria eat the lactose (milk sugar) and turn it into lactic acid.
- The “Holes” in Swiss: Explain that Propionibacterium creates carbon dioxide gas as it grows. These gas bubbles get trapped in the cheese, creating the “eyes” or holes.
4. Critical Thinking: Geography & Flavor
Cheese is a “living” food that reflects where it was made. Discuss how different environments (caves in France vs. factories in Wisconsin) affect the final taste.
| Type of Cheese | Method | Fun Fact |
| Fresh (Mozzarella/Ricotta) | High moisture, unaged | Must be eaten quickly! |
| Aged (Cheddar/Parmesan) | Pressed and dried | Can last for years; develops crystals. |
| Blue (Roquefort/Gorgonzola) | Introduction of Penicillium mold | The blue veins are actually a safe-to-eat mold. |
Suggested Student Activity: “The Cheese Log”
Have students bring in a small piece of cheese from home (or provide a variety pack). Ask them to observe the texture (crumbly vs. creamy), smell, and color, then try to guess what kind of “catalyst” or “aging” was used based on their lesson.