Overview
This lecture continues the discussion of cheese-making, focusing on moisture removal, salting, pressing, ripening, and the resulting flavor and texture diversity in cheeses.
Moisture Removal and Curd Processing
- After coagulation, cheese curds must be cut to release moisture (whey).
- Cutting is done with cheese knives to break the curd into small pieces.
- Heating curds helps shrink them, tightens proteins, and expels additional moisture.
- Heating also limits further activity of starter cultures and influences microbial development.
- The amount of heating depends on cheese style (e.g., cheddaring for cheddar).
Salting and Pressing
- Curds can be salted directly (dry salting) or by immersion in brine.
- Salting draws out moisture and flavors the cheese.
- In brining, salt migrates inward while moisture moves outward; larger cheeses require longer times.
- Pressing shapes the cheese and further removes moisture, eliminating visible curds in the final product.
Ripening and Aging
- Some cheeses are consumed fresh; others are ripened from weeks to years.
- Ripening affects texture, flavor, pH, protein content, and slicing/shredding properties.
- Flavor and texture changes result from microbial activity and enzymatic reactions, including proteolysis and lipolysis.
- Proteolysis breaks down proteins, producing peptides, amino acids, and flavor crystals (e.g., tyrosine in aged cheeses).
- Adjunct cultures (special bacteria, molds, yeasts) create strong flavors and alter cheese properties.
- In certain cheeses, microbial metabolism raises pH and forms gas (e.g., holes in Swiss cheese).
- Overripening can cause defects (e.g., excessive softness, oiliness in mozzarella, cracks in parmesan).
Cheese Style, Flavor, and Color
- Cheese style depends on production method and composition, regulated by standards of identity.
- Flavor descriptors like "sharp" are subjective and vary by region/producer.
- Some cheeses are colored with annatto; natural yellow comes from beta carotene in grass-fed cow’s milk.
- Goat milk cheeses are white due to conversion of carotene to colorless vitamin A.
Key Terms & Definitions
- Coagulation — the process of transforming liquid milk into solid curds via enzyme and acid action.
- Whey — the liquid byproduct released when curds form.
- Proteolysis — enzymatic breakdown of proteins into smaller peptides and amino acids.
- Lipolysis — enzymatic breakdown of fats into fatty acids and glycerol.
- Adjunct cultures — added microbes (bacteria, molds, yeasts) that influence flavor and ripening.
- Brine — a saltwater solution used to salt cheese and draw out moisture.
- Cheddaring — a process involving additional heating and pressing for cheddar cheese production.
Action Items / Next Steps
- Review your ongoing yogurt lab project.
- Prepare for the next module on bread and kombucha.