Oxidation of whey proteins during thermal treatment characterized by a site-specific LC-MS/MS-based proteomic approach

ABSTRACT: Thermal treatment is often employed in food processing to tailor product properties by manipulating ingredient functionality. However, due to the presence of oxidants in many food products, these elevated temperatures may accelerate oxidation and lead to the loss of nutrients. In the present study, oxidation of different whey protein systems (pure alpha-lactalbumin (a-LA), pure beta-lactoglobulin (b-LG), a mix of a-LA and b-LG (as a whey model) and a commercial whey protein isolate (WPI)) was investigated during heat treatment at 60-90 degreeC and a UHT-like condition by LC-MS-based proteomic analysis. The relative modification levels of each oxidation site were calculated and compared among different heat treatments and sample systems. The temperature- and time-dependent oxidation was detectable in protein systems after heating at and higher than 90 degreeC, while the extent of oxidation decreased with increasing complexity of the system (a-LA > b-LG > whey model > WPI). Trp residues in a-LA were found to be the amino acid residues most prone to oxidation during heat treatment. In b-LG-containing protein systems, Cys residues were suggested to scavenge most of the reactive oxidants and undergo oxidation-mediated disulfide rearrangement. The rearranged disulfide bonds contributed to protein aggregation (as confirmed by SDS-PAGE analysis), which was suggested to provide further physical protection against oxidation. However, no significant loss of amino acid residues was detected in the heated protein systems after acidic hydrolysis followed by HPLC analysis, which shows only a minor effect of heat treatment on protein oxidation in these pure protein systems.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Bos Taurus (ncbitaxon:9913)

SUBMITTER: Marianne Nissen Lund  

PROVIDER: MSV000088520 | MassIVE | Mon Dec 06 02:38:00 GMT 2021

SECONDARY ACCESSION(S): PXD030201

REPOSITORIES: MassIVE