title: Proteomic tracking of hydrothermal Maillard and redox modification in lactoferrin and β-lactoglobulin: Location of lactosylation, carboxymethylation, and oxidation sites.
abstract: Lactoferrin and β-lactoglobulin are important protein components of mammalian milk. Maillard reactions, as well as redox chemistry, are of particular interest for dairy products because they are known to occur during common processing steps, notably heating procedures such as pasteurization. Using a redox proteomics approach, we characterized AA residue side-chain modification across a range of heating times and with or without the specific addition of lactose, to both map the key modification sites within these proteins and evaluate their sensitivity to process-induced modification. Heating in the presence of lactose resulted in significant Maillard modification (both lactosylation and carboxymethylation) to both bovine lactoferrin and β-lactoglobulin. Notably, Lys47, a key residue in the bioactive peptide lactoferricin, was particularly susceptible to modification. Lactoferrin appeared to be fairly robust to hydrothermal treatment, with relatively low levels of oxidative modification observed. In contrast, β-lactoglobulin was susceptible to significant oxidative modification under hydrothermal treatment, with the range and type of modifications observed suggesting compromised nutritional value. These results have important implications for processing applications in dairy foods where retention of biological function and optimal protein quality is desired.
authors.affiliation: Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln 7608, New Zealand; Riddet Institute at Massey University, Palmerston North 4474, New Zealand; Biomolecular Interaction Centre, University of Canterbury, Christchurch 8041, New Zealand; Wine, Food & Molecular Biosciences, Lincoln University, Lincoln 7608, New Zealand. Electronic address: jolon.dyer@agresearch.co.nz.
authors.forename: Jolon M
authors.initials: JM
authors.lastname: Dyer
authors.affiliation: Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln 7608, New Zealand; Biomolecular Interaction Centre, University of Canterbury, Christchurch 8041, New Zealand.
authors.forename: Stefan
authors.initials: S
authors.lastname: Clerens
authors.affiliation: Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln 7608, New Zealand.
authors.forename: Anita
authors.initials: A
authors.lastname: Grosvenor
authors.affiliation: Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln 7608, New Zealand.
authors.forename: Ancy
authors.initials: A
authors.lastname: Thomas
authors.affiliation: Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln 7608, New Zealand.
authors.forename: Chris
authors.initials: C
authors.lastname: Callaghan
authors.affiliation: Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln 7608, New Zealand.
authors.forename: Santanu
authors.initials: S
authors.lastname: Deb-Choudhury
authors.affiliation: Food & Bio-Based Products, AgResearch Lincoln Research Centre, Lincoln 7608, New Zealand.
authors.forename: Stephen
authors.initials: S
authors.lastname: Haines
mesh_terms: D000818:Animals; D002417:Cattle; D007781:Lactoferrin / Q000378:metabolism*; D007782:Lactoglobulins / Q000737:chemistry*; D008894:Milk Proteins / Q000378:metabolism; D010084:Oxidation-Reduction; D040901:Proteomics
chemical_list: D007782:Lactoglobulins; D008894:Milk Proteins; D007781:Lactoferrin
keywords: Maillard reaction; lactoferrin; proteomics; redox chemistry; β-lactoglobulin