How Is Milk Used to Make Cheese?

Milk is fundamentally transformed into cheese through a series of precise steps involving curdling, cutting, and processing the milk solids to achieve the desired texture and flavor.

The Essential Steps of Cheese Making from Milk

The journey from liquid milk to solid cheese involves a fascinating biochemical process. Cheesemakers meticulously control each stage to ensure the quality and characteristics of the final product.

1. Curdling the Milk

The initial and perhaps most critical step in cheese making is curdling the milk. This process separates the solid milk proteins (casein) from the liquid whey.

• Adding Rennet: As per the reference, cheesemakers add rennet to cause a reaction that curdles the milk, creating curds. Rennet, which contains the enzyme chymosin, is commonly used to coagulate the casein proteins in milk.
• Acidification: Before or during the addition of rennet, specific starter cultures (beneficial bacteria) are often introduced. These cultures ferment the lactose (milk sugar) into lactic acid, which helps in the acidification of the milk. This acidification not only contributes to the flavor development but also aids in the rennet's action and the subsequent expulsion of whey. The combination of rennet and acidification leads to the formation of a gelatinous mass known as the "curd."

2. Cutting the Curd

Once the milk has curdled into a solid mass, the next step is to cut the curd.

• Slicing and Heating: The reference states: "Next, the cheesemaker slices the curd with knives and heats it to separate the curds and whey." This cutting increases the surface area of the curd, allowing more whey to be expelled. The size of the cuts can influence the cheese's final moisture content and texture; smaller cuts typically result in harder cheeses due to greater whey expulsion.
• Whey Separation: Heating the cut curds gently helps to shrink them and further encourages the separation of the liquid whey from the solid curds. This process, often called "cooking the curds," is crucial for firming up the cheese structure.

3. Processing the Curd

After cutting and heating, the curds undergo further processing to prepare them for aging and consumption.

• Stirring, Cooking, and Washing: According to the reference, "Cheesemakers stir, cook and wash the curd to acidify and dry them."
  • Stirring prevents the curds from clumping together too early and ensures even heating and whey expulsion.
  • Cooking (or continued heating) further reduces moisture content and helps develop the curd's texture.
  • Washing the curd, often done with water, can reduce the lactose content, impacting the final acidity and flavor profile of the cheese. This step is common in cheeses like Gouda.
• Drying and Acidification: The combined actions of stirring, cooking, and washing contribute to both the drying and continued acidification of the curds, which are vital for the cheese's structure, preservation, and flavor development.
• Salting and Pressing: After processing, the curds are typically salted (either directly or by brining) for flavor, preservation, and to further draw out moisture. They are then pressed into molds, shaping the cheese and expelling any remaining whey.

Overview of Milk-to-Cheese Transformation

The entire process is a delicate balance of biological and chemical reactions, meticulously controlled by the cheesemaker.

Following these steps, the cheese is typically aged, allowing enzymes and microorganisms to mature the flavor and texture, resulting in the vast array of cheeses we enjoy.