Oxidation of whey protein isolate after thermal convection and microwave heating and freeze-drying: Correlation among physicochemical and NIR spectroscopy analyses

• Published in: Heliyon Vol. 9; no. 7; p. e17981
• Main Authors: Bordignon, Juliany Cristiny Sonda, Badaró, Amanda Teixeira, Barbin, Douglas Fernandes, Mariutti, Lilian Regina Barros, Netto, Flavia Maria
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2023; Elsevier
• Subjects: Carbonylated protein; Dityrosine; Protein oxidation; Dityrosine; Carbonylated protein; Protein oxidation
• ISSN: 2405-8440; 2405-8440
• DOI: 10.1016/j.heliyon.2023.e17981

This study investigated the oxidative susceptibility of whey protein isolate (WPI) dispersions treated by microwave or thermal convection before freeze-drying. WPI (20 mg protein/mL) in distilled water (DW) was heated at 63 ± 2 °C for 30 min by microwave (WPI-MW) or convection heating (WPI–CH) and freeze-dried. Untreated WPI (WPI–C), WPI solubilized in DW and freeze-dried (WPI-FD), and WPI solubilized in DW, heated at 98 ± 2 °C for 2 min and freeze-dried (WPI–B) were also evaluated. Structural changes (turbidity, ζ potential, SDS-PAGE, and near-infrared spectroscopy (NIR)) and protein oxidation (dityrosine, protein carbonylation, and SH groups) were investigated. WPI-FD showed alterations compared to WPI-C, mainly concerning carbonyl groups. Microwave heating increased carbonyl groups and dityrosine formation compared to conventional heating. NIR spectrum indicated changes related to the formation of carbonyl groups and PCA analysis allowed us to distinguish the samples according to carbonyl group content. The results suggest that NIR may contribute to monitoring oxidative changes in proteins resulting from processing. •Whey proteins are susceptible to oxidation during food processing.•Freeze-drying increased susceptibility to carbonyl protein formation in WPI.•Microwave before freeze-drying increased carbonylation and dityrosine formation.•Structural changes in WPI related to chemical bonds were observed in NIR spectra.•NIR spectroscopy can monitor oxidative changes in proteins resulting from processing.