Synergistic Noncovalent Mulberry Polysaccharide-Ovalbumin Complexes for Enhanced Functional Properties and Pickering...

Area of Science:

• Food Science
• Biopolymer Chemistry
• Materials Science

Background:

• Ovalbumin (OVA) is a key protein in egg white with functional properties.
• Mulberry polysaccharide (MP) is a natural biopolymer with potential applications in food systems.
• Understanding protein-polysaccharide interactions is crucial for developing novel food ingredients.

Purpose of the Study:

• To investigate the interaction mechanisms between ovalbumin (OVA) and mulberry polysaccharide (MP).
• To characterize the structural and functional properties of OVA-MP complexes.
• To construct and evaluate OVA-MP based Pickering emulsions.

Main Methods:

• Systematic investigation of OVA-MP complexes under varying pH and mixing ratios.
• Turbidity measurements to determine phase behavior.
• Spectroscopic analyses (e.g., fluorescence, circular dichroism) to probe conformational changes.
• Emulsifying activity, thermal stability, and foaming property assessments.
• Molecular Dynamics (MD) simulations to elucidate interaction mechanisms.
• Characterization of Pickering emulsion properties (droplet size, rheology, stability).

Main Results:

• OVA-MP complex formation was pH and ratio-dependent, with optimal aggregation near OVA's isoelectric point (pI ≈ 4.5).
• MP induced OVA conformational relaxation and hydrophobic exposure, enhancing secondary structure and hydrogen bonding.
• OVA-MP complexes showed improved emulsifying activity (ESI = 39.36 ± 0.33 min at pH 6.0, 2:1 ratio), thermal stability, and foaming properties.
• MD simulations confirmed spontaneous OVA-MP binding driven by van der Waals and hydrogen bonds (ΔG = -38.98 ± 0.89 kcal/mol).
• Resulting O/W Pickering emulsions exhibited smaller droplet size, shear-thinning behavior, higher viscoelasticity, and enhanced salt and storage stability.

Conclusions:

• Mulberry polysaccharide (MP) effectively modulates ovalbumin (OVA) conformation and interfacial behavior via synergistic hydrogen bonding and electrostatic interactions.
• The optimized OVA-MP complex forms structurally reinforced interfaces, leading to stable Pickering emulsions.
• These findings offer insights for designing food-grade biopolymer emulsifiers and delivery systems with superior stability.