Mechanical instabilities in drying protein droplets under substrate-free conditions

Area of Science:

• Materials Science
• Biophysics
• Food Science

Background:

• Protein-based materials require understanding drying dynamics for mechanical stability.
• Acoustic levitation offers controlled drying conditions, minimizing substrate effects.
• Protein origin (plant vs. animal) influences material properties.

Purpose of the Study:

• To investigate the drying behavior of plant (napin) and dairy (native phosphocaseinate) proteins.
• To link intrinsic protein properties to evaporation-driven instabilities during drying.
• To provide insights for designing protein-based materials and sustainable alternatives.

Main Methods:

• Drying dynamics of acoustically levitated protein droplets (napin and native phosphocaseinate).
• Observation of skin formation, buckling, and fracture patterns.
• Comparison with model colloid-polymer films.

Main Results:

• Both protein types formed solid skins during drying.
• Native phosphocaseinate formed ductile, crack-free shells.
• Napin formed brittle shells with surface cracking.
• Contrasting behaviors linked to interfacial activity and network formation.

Conclusions:

• Protein origin dictates drying-induced instabilities and final material structure.
• Understanding these differences is crucial for designing protein-based materials.
• This research supports the use of plant-derived proteins as sustainable alternatives.