Whey Protein

Whey protein is a high-biological-value protein derived from the liquid fraction (whey) that separates from milk during cheese production. It is composed mainly of globular proteins (β-lactoglobulin, α-lactalbumin, serum albumin, immunoglobulins, and lactoferrin) and is widely used as a dietary supplement to support muscle repair, growth, and overall nitrogen balance.

• Whey protein is not a single molecule but a mixture of globular proteins with average molecular weights of 14–70 kDa.
• β-lactoglobulin: The dominant component, β-lactoglobulin (C₁₁₉H₁₈₈N₃₄O₂₈S₁, 18 kDa, 162 aa) has the IUPAC name [α-]‑β‑lactoglobulin.
• α-lactalbumin: α-lactalbumin (C₂₈₈H₄₅₈N₈₈O₈₄S₆) weighs ~14 kDa.
• BCAA content: Both are rich in branched-chain amino acids (Leu, Ile, Val) and contain disulfide bonds that stabilize their tertiary structures.
• Bioactive peptides: Whey also contains bio-active peptides (e.g., lactoferrin, C₈₉₈H₁₄₈₅N₂₇₅O₂₇₇S₁₁) with iron-binding domains and antimicrobial motifs.
• Physical properties: The collective protein mixture exhibits high solubility (pH 2‑8), a neutral to slightly acidic pI (~5.3), and a rapid digestion rate due to its minimal secondary structure and high water-binding capacity.

• Origin: Commercial whey protein originates from dairy milk, primarily bovine (cow) milk, as the liquid whey generated during cheese or casein production.
• Processing: The liquid is filtered (micro-filtration, ultrafiltration) to concentrate proteins, then spray-dried to produce whey protein concentrate (WPC; 30–80 % protein) or whey protein isolate (WPI; >90 % protein). Hydrolyzed whey (WPH) undergoes enzymatic hydrolysis to pre-digest proteins, reducing allergenicity and enhancing absorption.
• Quality considerations:
  • Protein purity: % protein, nitrogen-to-protein conversion factor (6.38 for whey).
  • Amino-acid profile: must meet ≥30 % leucine of total EAAs.
  • Microbial/heavy-metal testing: third-party certifications (NSF, Informed-Choice).
  • Processing: low-heat processing preserves bio-active peptides.
• Alternative sources: Alternative sources (e.g., goat, sheep, or camel milk) exist but are less common; they share similar protein structures but may differ in immunoglobulin content.
• Labeling: High-quality supplements typically list the source (e.g., “grass-fed, non-GMO cow milk”) and processing method (e.g., “cold-filtered, micro-filtered”) to assure purity and bio-activity.