Whey Protein Hydrolysate (WPH)

A hydrolysate is not a higher grade of isolate; it is a different material with a different tariff heading and a different buyer. ADPI defines whey protein hydrolysate as the product of chemical or enzymatic cleavage of peptide bonds in a whey protein source — usually a concentrate or an isolate — where the degree of hydrolysis is measurably higher than the starting material and that increase is verified analytically. What comes out is a mixture of fragment sizes: some intact protein, polypeptides, oligopeptides, dipeptides and free amino acids, in proportions set by the enzyme, the time and the temperature. Degree of hydrolysis is the specification that actually defines the product. Commercial hydrolysates run roughly 5–30% DH, most often 10–25%, and frequently 12–20%; published work on commercial material finds peptides clustered in the 2.5–5 kDa and 5–8 kDa ranges. Below about 10% DH the change is mainly physicochemical — better solubility, lower viscosity, less heat-induced gelation — while above it the peptide population itself becomes the point. DH is measured by pH-stat, OPA, TNBS or formol titration, and the method should be named alongside the number, because they do not all give the same answer on the same lot. Protein content follows the substrate rather than any standard of its own: a WPC 80-based hydrolysate lands near 80–82% on dry matter, a WPI-based one near 90%. The trade-off buyers negotiate is bitterness. Cleaving peptide bonds exposes hydrophobic residues, and flavour moves from bland toward distinctly bitter as DH climbs, which is why sports and clinical formulators cap DH, mask, or blend hydrolysate with intact protein rather than using it neat. Typical outlets are sports recovery formulations, clinical and enteral nutrition, hypoallergenic formula bases, ready-to-drink beverages where low viscosity at high protein matters, peptide-fortified functional foods, fermentation and culture media, and as a binding agent in the agglomeration of whey protein isolate. Hydrolysis does not remove the allergen: this is milk-derived and must be labelled as a milk allergen regardless of DH.