Protein Modification Techniques in Emulsion Systems

Emulsions—mixtures of immiscible liquids such as oil and water—rely on surface‐active agents to stabilise dispersed droplets against coalescence and creaming. Proteins are among the most versatile natural emulsifiers, but their intrinsic structure often limits interfacial performance. To enhance emulsification and long‐term stability, a suite of modification techniques has been developed. Chemical approaches include pH shifting and ionic adjustments to unfold globular proteins, exposing hydrophobic regions that adsorb rapidly at oil–water interfaces. Physical methods such as high‐intensity ultrasound and high-pressure homogenisation disrupt aggregates, reduce particle size and increase surface area for faster interfacial adsorption. Enzymatic crosslinking—commonly via transglutaminase—creates covalent networks that reinforce interfacial films, improving resistance to mechanical and thermal stress. Milling or microfluidisation can generate colloidal microgels that act as Pickering stabilisers, forming rigid shells around droplets. Together, these strategies enable precise control over droplet size distribution, interfacial rheology and emulsion microstructure, with applications spanning food texture design, nutraceutical delivery and cosmetic formulations. Advances in plant‐based protein modification further support the transition to sustainable emulsifier systems without compromising functional performance.

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Research from all publishers

Recent studies have applied pH‐shift, ultrasound and combined treatments to dairy and plant proteins to fine‐tune interfacial performance. For instance, strategic use of alkalisation and rapid neutralisation followed by high‐intensity ultrasound on whey, pea and mixed whey–pea protein isolates has been shown to modify particle size, surface hydrophobicity and charge, leading to enhanced emulsification and improved droplet stability under varying ionic and pH conditions. Another body of work has focused on rice protein, where advanced compound methods—including ultrasonication, enzymatic crosslinking and glycation—overcome intrinsic hydrophobicity and low solubility. These tailored modifications yield protein fractions with superior emulsifying properties, broadening their application in dairy analogues and bakery dispersions. Foundational research on protein–polysaccharide complexes, such as soy protein isolate combined with high-methoxyl pectin, demonstrates that electrostatic complexation below the protein’s isoelectric point produces fine colloidal particles with robust interfacial films. These complexes serve as effective stabilisers in food-grade oil–water emulsions, offering a versatile route to control droplet size and improve creaming stability.

Protein Modification Techniques in Emulsion Systems publication trend

The graph below shows the total number of articles in protein modification techniques in emulsion systems across all publications each year (not limited to Nature Index journals).

Technical terms

Emulsification: The process of forming a stable dispersion of one liquid in another immiscible liquid, typically oil in water or vice versa.

Interfacial activity: The ability of a molecule to adsorb at and modify the properties of the interface between two phases, reducing interfacial tension.

pH shifting: A chemical modification involving rapid acidification or alkalisation followed by neutralisation to induce protein unfolding and reassembly.

High-intensity ultrasound: A physical treatment using acoustic cavitation to disrupt protein aggregates, reduce particle size and enhance surface reactivity.

Enzymatic crosslinking: The formation of covalent bonds between protein molecules via enzymes (e.g. transglutaminase) to strengthen interfacial networks.

Pickering stabilisation: Emulsion stabilisation achieved by solid colloidal particles (often microgels) that adsorb irreversibly at droplet surfaces, forming a mechanical barrier.

References

1. Characterization of biopolymers and soy protein isolate-high-methoxyl pectin complex. Polímeros (2017).
2. Structure and functionality of whey protein, pea protein, and mixed whey and pea proteins treated by pH shift or high-intensity ultrasound. Journal of Dairy Science (2023).
3. Modification and Solubility Enhancement of Rice Protein and Its Application in Food Processing: A Review. Molecules (2023).