What is whey protein and how is it made?
Quick summary
A liquid by-product of cheese-making, whey is filtered then dried into a powder: from it a complete protein is extracted, rich in essential amino acids and rapidly absorbed. Its protein content and low lactose level depend on the degree of filtration, which sets concentrate and isolate forms apart.
Key facts
Key points
- Whey protein comes from whey, separated from casein during cheese-making.
- Several filtration steps then spray-drying turn it into a powder.
- The degree of filtration sets the concentrate apart from the isolate, which is purer and more digestible.
- Fast-digesting, it differs from casein, which is slow and better suited to long periods without a meal.
Whey protein is a protein derived from whey, obtained from the process of turning milk into cheese. Its popularity among athletes raises legitimate questions about its origin and the processes that produce it. As the entry point to our complete guide to whey protein, this article explains where the raw material comes from, how it is filtered and dried, what distinguishes the concentrate and isolate forms, why it is called a complete protein and how it differs from casein.
Which food is whey extracted from?
Whey protein is mainly extracted from milk. Milk contains two major proteins: casein and whey, the latter being the liquid fraction. During cheese-making, the coagulation process separates these two elements, leaving the whey as a liquid by-product.
Whey contains a high concentration of essential amino acids, indispensable for muscle synthesis and recovery after exercise. These amino acids cannot be produced by the body and must therefore come from the diet, which makes this source particularly valuable in a sporting context[2].
Whey’s dairy origin gives it a high bioavailability: the body absorbs and uses its nutrients efficiently. It nonetheless remains worthwhile to choose a product suited to your digestive tolerance, as some people tolerate dairy derivatives poorly. We detail this point in the article devoted to extracting whey from milk.
What are the filtration steps for whey?
Turning milk into whey protein involves a meticulous filtration process, essential to obtaining a pure and effective protein. The process begins with the separation of the whey during cheese-making. Once isolated, the whey undergoes a series of filtrations designed to remove part of the fat and lactose while preserving the proteins.
Microfiltration and ultrafiltration
Microfiltration uses porous membranes to separate the largest particles. Ultrafiltration then refines the sorting by retaining the proteins while letting part of the lactose and fat pass through. These methods concentrate an intact and highly bioavailable protein.
Nanofiltration and ion exchange
Nanofiltration targets even smaller compounds and optimises the protein concentration. Ion exchange, which uses electrically charged resins, can be used to refine the nutritional profile further by removing certain ions without altering the proteins. These processes are set out in detail in the article devoted to the filtration steps for whey.
Final separation and drying
To turn the concentrated liquid into a powder, spray-drying is used: the liquid is sprayed into a heated chamber where the water evaporates rapidly, leaving fine dry particles. The result is a uniform powder, easy to measure out and to incorporate day to day.
What is the difference between whey concentrate and isolate?
The distinction between whey concentrate and isolate rests on their protein content and their degree of filtration. Whey concentrate generally contains 70 to 80% protein, the remainder being made up of lactose, fat and minerals. It is often a more economical option while still providing a substantial protein intake.
Whey isolate goes through an additional ultrafiltration or ion-exchange step, which brings its protein concentration above 90% and markedly reduces lactose and fat. This purity makes it an option suited to people who are sensitive to lactose or who wish to maximise their protein intake without surplus calories.
The choice depends on goals and dietary sensitivities: an athlete seeking to limit lactose will favour the isolate, whereas a more economical approach will turn to the concentrate. We explore this comparison further in the article on whey concentrate compared with isolate.
Why is whey a complete protein?
Whey contains the nine essential amino acids needed for the body to function properly, which the body cannot synthesise on its own. This “completeness” sets it apart from certain plant proteins (pulses, cereals) that may lack one or more essential amino acids.
A composition rich in key amino acids
Among these amino acids are the BCAAs — leucine, isoleucine and valine. Leucine directly stimulates muscle protein synthesis, isoleucine supports endurance and tissue repair, and valine contributes to energy metabolism during exercise.
A high bioavailability
Beyond its composition, whey is rapidly digested and absorbed, which makes its nutrients quickly available to the muscles being worked. This complete profile and rapid absorption are developed in the article explaining why whey is a complete protein.
How is whey obtained in powder form?
Obtaining whey in powder form is a technical process. It all starts with the extraction of the whey, the liquid by-product of cheese-making. This protein-rich liquid then undergoes several filtration steps to remove part of the fat and lactose.
Filtration then spray-drying
The whey passes through ultrafiltration, where semi-permeable membranes retain the proteins while letting other components through. Spray-drying then turns the filtered liquid into a fine powder: the mixture is sprayed into a heated chamber, the water evaporates and only solid protein particles remain. This process preserves the nutritional qualities and ensures good solubility.
Quality controls
Each batch is subjected to checks for purity and the absence of contaminants, and the fine texture obtained makes it easy to mix into drinks or preparations. The technical details of this powdering are described in the article on obtaining whey in powder form.
What is the difference between whey and casein?
Whey and casein both come from milk, but their characteristics and their effects on recovery differ markedly. The main distinction lies in their rate of absorption.
Absorption time
Whey is digested quickly and releases its amino acids into the blood rapidly, which makes it a practical choice post-workout. Casein is digested more slowly and releases its amino acids over several hours, which makes it useful before bed or during long periods without a meal[4].
Amino acid profile
Both provide a complete spectrum of essential amino acids, but whey stands out for its leucine concentration, key to muscle protein synthesis. Casein, being slower, instead serves a sustained intake. This comparison is explored further in the article on whey compared with casein.
Frequently asked questions about how whey works
What is whey protein?
Whey protein is a liquid by-product of cheese or yoghurt making. It is rich in essential amino acids and is commonly used by athletes to improve recovery and muscle growth. Thanks to its bioavailability, it is absorbed more quickly by the body than other protein sources.
How is whey protein made?
The whey protein manufacturing process begins with heating the milk to coagulate it. Once the curd has formed, the liquid that remains is the whey. This is then filtered to remove the fat and carbohydrates. The resulting powder is dried and may be flavoured. Swilab ensures a meticulous production process to deliver a high-quality product.
What are the benefits of whey protein?
Whey protein is valued for its ability to promote protein synthesis and support muscle recovery. As well as being an excellent protein source, it may also support the immune system through its lactoferrin and immunoglobulin content, although the evidence for a direct benefit in healthy people remains limited and indirect. Swilab, for example, offers whey forms that maximise these advantages through carefully selected ingredients.
What time of day should whey be consumed?
Whey protein can be consumed at different times of the day according to individual nutritional needs. It is often taken after training to speed up recovery and muscle synthesis. However, it can also be used between meals to increase daily protein intake. Products such as those from Swilab can easily be incorporated into a balanced diet.
Is whey protein suitable for everyone?
Although whey protein is generally well tolerated, some people may experience digestive issues, especially if they are lactose intolerant. People with particular concerns or medical conditions are advised to consult a healthcare professional before adding whey to their diet. Swilab offers suitable solutions, such as lactose-free formulas, for those with dietary sensitivities.
Sources & references
4 sources- Devries MC, Phillips SM — Supplemental protein in support of muscle mass and health: advantage whey
- Jäger R, et al. — International Society of Sports Nutrition Position Stand: protein and exercise
- Regulation (EU) No 432/2012 — list of permitted health claims made on foods
- Tang JE, et al. — Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men