title: Whey protein isolate polydispersity affects enzymatic hydrolysis outcomes.
abstract: The effects of heat-induced denaturation of whey protein isolate (WPI) on the enzymatic breakdown of α-La, caseinomacropeptide (CMP), β-Lg A and β-Lg B were observed as hydrolysis proceeded to a 5% degree of hydrolysis (DH) in both unheated and heat-treated (80 °C, 10 min) WPI dispersions (100 g L(-1)). Hydrolysis of denatured WPI favoured the generation of higher levels of free essential amino acids; lysine, phenylalanine and arginine compared to the unheated substrate. LC-MS/MS identified 23 distinct peptides which were identified in the denatured WPI hydrolysate - the majority of which were derived from β-Lg. The mapping of the detected regions in α-La, β-Lg, and CMP enabled specific cleavage points to be associated with certain serine endo-protease activities. The outcomes of the study emphasise how a combined approach of substrate heat pre-treatment and enzymology may be used to influence proteolysis with attendant opportunities for targeting unique peptide production and amino acid release.
authors.affiliation: Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
authors.forename: I B
authors.initials: IB
authors.lastname: O'Loughlin
authors.forename: B A
authors.initials: BA
authors.lastname: Murray
authors.forename: A
authors.initials: A
authors.lastname: Brodkorb
authors.forename: R J
authors.initials: RJ
authors.lastname: FitzGerald
authors.forename: A A
authors.initials: AA
authors.lastname: Robinson
authors.forename: T A
authors.initials: TA
authors.lastname: Holton
authors.forename: P M
authors.initials: PM
authors.lastname: Kelly
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000737:chemistry; D002417:Cattle; D006358:Hot Temperature; D006868:Hydrolysis; D007768:Lactalbumin / Q000737:chemistry; D007782:Lactoglobulins / Q000737:chemistry; D013058:Mass Spectrometry; D008894:Milk Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010449:Peptide Mapping; D012697:Serine Endopeptidases / Q000737:chemistry*; D000067816:Whey Proteins
chemical_list: D002364:Caseins; D007782:Lactoglobulins; D008894:Milk Proteins; D010446:Peptide Fragments; D000067816:Whey Proteins; C065989:caseinomacropeptide; D007768:Lactalbumin; D012697:Serine Endopeptidases
keywords: Enzymatic hydrolysis; Essential amino acids; Heat-treatment; Peptide analysis; Whey protein isolate