The Fundamental Process of Cheese Making
Cheesemaking starts with milk, which contains two primary protein types: casein and whey. The ultimate goal is to separate the milk into solid curds (primarily casein and fat) and liquid whey. This separation process is triggered by adding a coagulating agent to the milk, which can be an enzyme like rennet or an acid.
For most hard and semi-hard cheeses, cheesemakers add rennet to heat-treated milk. The enzymes in rennet cause the milk's casein proteins to bind together and form a gel-like substance, trapping most of the milk fat. This solidified mass is the curd. The remaining watery liquid, known as whey, contains the soluble whey proteins, lactose (milk sugar), water-soluble vitamins, and minerals. For fresh cheeses like cottage cheese or ricotta, acid (like vinegar or lactic acid bacteria) is often used instead of rennet, resulting in a slightly different type of whey.
How Cheesemakers Separate Whey from Curds
Separating the curd from the whey is a multi-step process that heavily influences the cheese's final moisture content, texture, and flavor profile. The longer and more aggressively a cheesemaker removes whey, the harder the cheese will be.
Common methods for whey removal include:
- Cutting the Curd: Once the milk has set into a solid curd, cheesemakers use special knives or wires to cut it into smaller pieces. This increases the surface area of the curd, allowing more whey to be released. The size of the cut is crucial; smaller curds lead to drier, harder cheese, while larger cuts retain more moisture.
- Heating the Curd: After cutting, the curds and whey mixture may be gently heated, a process called 'scalding' for hard cheeses. This causes the curds to shrink and expel more whey, and can also influence the flavor by managing the activity of starter cultures,.
- Stirring the Curd: Gentle stirring prevents the curds from clumping together and helps release more whey through controlled agitation. As the curds collide, they lose more moisture.
- Straining and Pressing: The curds are typically scooped from the vat and placed in molds lined with cheesecloth to drain. For harder cheeses like cheddar, the curds are subjected to pressing under weight. This pressure forces out even more liquid whey and compresses the curds into a tight, solid mass,.
Whey Content Varies by Cheese Type
While the primary goal is to remove most of the whey, the extent of this removal is what creates the vast diversity of cheeses available today. Harder cheeses have undergone a more aggressive process of whey extraction, while softer cheeses retain a higher moisture and whey content.
Hard vs. Soft Cheese Whey Content
| Feature | Hard Cheeses (e.g., Cheddar, Swiss) | Soft Cheeses (e.g., Cottage Cheese, Chevre) |
|---|---|---|
| Whey Removal | Very extensive; high amount drained and pressed out. | Partial; less whey is removed, leaving a higher moisture content. |
| Final Texture | Firm, dense, and often crumbly or elastic depending on the specific cheese. | Soft, moist, and spreadable, or lumpy like cottage cheese. |
| Whey Content | Low, containing only trace amounts of residual whey proteins. | Higher, with more liquid whey remaining in the finished product. |
| Aging Potential | Can be aged for months or years, during which more moisture is lost. | Shorter shelf life and generally consumed fresh or with minimal aging. |
It is also worth noting that some cheeses, known as whey cheeses, are actually made from leftover whey. Ricotta, for instance, is created by reheating the whey from another cheese run to coagulate the remaining milk solids.
What Happens to the Removed Whey?
For many years, whey was considered a waste product of cheesemaking and was often disposed of. However, advances in technology and a better understanding of its nutritional value have transformed whey into a highly valuable co-product. Today, the liquid whey is a crucial ingredient in a variety of other products.
- Whey Protein Powder: Whey is filtered and dried to produce various forms of whey protein powders, which are popular dietary supplements for building muscle and improving nutrition.
- Infant Formula: The high-quality proteins found in whey are an excellent component for use in infant formula.
- Food Additives: Whey and its components can be used as a source of dairy solids, protein, and emulsifiers in a wide array of foods, including bakery products, processed meats, and dressings.
- Whey Butter and Other Products: The residual cream skimmed from whey can be made into whey butter, which has a distinct, tangier flavor. Whey can also be used as a liquid in baking or as a fertilizer on farms.
The transformation of whey from an environmental burden to a profitable and useful ingredient highlights the dairy industry's ingenuity. The U.S. Department of Agriculture has documented this shift in whey's utilization over time.
Conclusion
So, is whey removed from cheese? The answer is a definitive yes, but it's a process of degrees. The act of separating curds from whey is the fundamental step in cheesemaking, and the amount of liquid whey removed directly determines the final texture and type of cheese. While most whey is expelled, particularly for hard, aged cheeses, some moisture and residual whey proteins remain in softer cheeses. Far from being a mere waste product, the removed whey is now a valuable commodity in its own right, underpinning a thriving market for nutritional supplements and other food products.
