The Major Proteins in Whey
The protein fraction in whey is primarily a mixture of several key globular proteins, each with its own unique structure and biological functions. The relative proportion of these proteins can vary slightly depending on factors like the type of milk (cow, goat, etc.) and the processing method used.
- Beta-Lactoglobulin (β-LG): The most abundant protein, often 50–65% of total protein. Good source of essential amino acids and transports small molecules. Can be an allergen.
- Alpha-Lactalbumin (α-LA): Second most prominent, about 20–25% of protein content. Rich in tryptophan; a key component in human breast milk.
- Bovine Serum Albumin (BSA): Approximately 8% of whey protein. Binds substances like fatty acids and plays a role in immunity.
- Immunoglobulins (Igs): Accounts for 10–15% of protein. Antibodies that offer immune-enhancing benefits.
Minor but Important Constituents
Beyond the major proteins, minor substances contribute to whey's profile.
- Lactoferrin: Iron-binding glycoprotein with antibacterial, antiviral, and antifungal properties. Aids in iron absorption and immune response.
- Lactoperoxidase: Enzyme with antibacterial properties; a natural preservative.
- Glycomacropeptide (GMP): Bioactive peptide formed during cheese-making. Promotes satiety and dental health. Concentration varies by processing.
- Bioactive Peptides: Shorter amino acid chains with physiological effects like antioxidant, antimicrobial, and antihypertensive properties. Released during hydrolysis.
Other Substances in Whey Protein
Whey is not purely protein; it includes other macronutrients and micronutrients depending on processing.
- Lactose: Primary carbohydrate. Amount varies; higher in WPC, mostly removed in WPI.
- Fats and Cholesterol: Higher in WPC, nearly eliminated in WPI.
- Vitamins and Minerals: Contains essential minerals like calcium, sodium, and potassium, plus some vitamins.
Comparison of Whey Protein Types
Processing methods influence the composition of commercially available whey forms.
| Feature | Whey Protein Concentrate (WPC) | Whey Protein Isolate (WPI) | Whey Protein Hydrolysate (WPH) |
|---|---|---|---|
| Protein Content | 25–89%, typically ~80% | >90% | >90% (often 99%) |
| Lactose Content | Moderate (4–52%) | Very low (0.5–1.0%) | Very low to negligible |
| Fat Content | Moderate (1–9%) | Very low (0.5–1.0%) | Very low |
| Processing | Microfiltration | Additional processing to remove fat and lactose | Predigested into smaller peptides |
| Taste | Creamier and more flavourful | Mild and less flavourful | Can have a bitter taste |
| Absorption Rate | Fast digestion and absorption | Fast digestion and absorption | Very rapid absorption |
Bioactive Benefits and Applications
The unique composition of whey protein leads to various health benefits.
- Muscle Growth and Repair: High concentration of essential and BCAAs supports muscle protein synthesis.
- Immune System Support: Immunoglobulins, lactoferrin, and cysteine contribute to a stronger immune response.
- Antioxidant Properties: Provides precursors for glutathione, boosting antioxidant defenses.
- Cardiovascular Health: Some bioactive peptides may have antihypertensive effects.
- Weight Management: High protein promotes satiety and aids appetite control.
Conclusion
Understanding what are the substances in whey protein reveals a complex profile beyond simple protein. It offers bioavailable proteins like β-lactoglobulin and α-lactalbumin, minor proteins, bioactive peptides, and essential micronutrients. Processing methods determine concentrations, influencing suitability for various dietary needs and goals. This diverse composition makes whey a versatile supplement with many documented health benefits.
For more detailed scientific information, refer to research compiled on ScienceDirect.
