Influence of malondialdehyde-induced modifications on physicochemical and digestibility characteristics of whey...

Area of Science:

• Food Chemistry
• Protein Science
• Dairy Science

Background:

• Lipid oxidation is a major concern in food products, affecting nutritional quality and safety.
• Whey protein isolate (WPI) is a valuable dairy protein with diverse applications.
• Understanding the interaction between lipid oxidation products and proteins is crucial for food quality.

Purpose of the Study:

• To investigate the effects of malondialdehyde (MDA), a lipid oxidation product, on the physicochemical and structural properties of WPI.
• To assess the impact of MDA modification on WPI's susceptibility to enzymatic digestion.

Main Methods:

• Modification of WPI with MDA.
• Analysis of protein carbonyls, sulfhydryls, intrinsic fluorescence, and surface hydrophobicity.
• Gel electrophoresis and immunoblotting to visualize protein modifications.
• Scanning electron microscopy (SEM) for microstructural analysis.
• In vitro digestibility assays.

Main Results:

• MDA incorporation led to increased protein carbonyls and surface hydrophobicity, with a loss of sulfhydryls and impaired fluorescence.
• MDA targeted major WPI components (β-lactoglobulin, α-lactalbumin), causing cross-linking and aggregation.
• SEM confirmed abnormal protein aggregation in MDA-modified WPI.
• MDA modification significantly reduced WPI's in vitro digestibility.

Conclusions:

• Malondialdehyde substantially modifies whey protein isolate, affecting its structure, functionality, and digestibility.
• These findings are relevant for dairy products incorporating lipids, emphasizing the need to consider protein changes alongside lipid oxidation.
• The food industry should implement preventive strategies to mitigate the negative impacts of lipid oxidation products on dairy proteins.