Whey Protein-Quercetin-Gellan Gum Complexes Prepared Using pH-Shift Treatment: Structural and Functional Properties

Area of Science:

• Food Science
• Biochemistry
• Materials Science

Background:

• Whey protein and quercetin are valuable bioactive compounds with limited stability and bioavailability.
• Gellan gum can be used to form complexes with proteins and polyphenols.
• Understanding protein-polyphenol interactions is crucial for developing functional food ingredients.

Purpose of the Study:

• To prepare whey protein-quercetin-gellan gum conjugates using the pH-shift method.
• To investigate the effects of pH and quercetin concentration on conjugate formation and properties.
• To evaluate the functional characteristics, including antioxidant activity, of the prepared conjugates.

Main Methods:

• Preparation of whey protein-quercetin-gellan gum conjugates via pH-shift method.
• Spectroscopic analyses (fluorescence, UV-vis, FT-IR) to characterize complex formation.
• Particle size and zeta potential measurements to assess complex stability.
• Evaluation of foaming capacity, emulsification properties, and radical scavenging activity (DPPH, ABTS).

Main Results:

• Complex formation was confirmed under alkaline conditions.
• Increased quercetin concentration reduced particle size and increased zeta potential, especially under alkaline conditions.
• Alkaline-prepared conjugates showed enhanced foaming, emulsification, and significantly improved DPPH (41.57%) and ABTS (57.69%) radical scavenging activity.
• Optimal conditions yielded a particle size of 425.7 nm and a zeta potential of -30.00 mV at 15 umol/g protein.

Conclusions:

• The pH-shift method effectively formed stable whey protein-quercetin-gellan gum conjugates.
• Alkaline conditions and optimized quercetin concentration enhance the functional properties and antioxidant capacity of the conjugates.
• These findings support the development of novel protein-polyphenol systems for functional foods and supplements.