Wettability, surface microstructure and mechanical properties of films based on phosphorus oxychloride-treated zein

Area of Science:

• Materials Science
• Polymer Chemistry
• Food Science

Background:

• Zein, a corn protein, is explored for edible and biodegradable packaging.
• Pure zein films exhibit brittleness, limiting their practical applications.
• Chemical modification is investigated to enhance zein film properties.

Purpose of the Study:

• To improve zein film-forming properties via chemical phosphorylation.
• To evaluate the impact of phosphorus oxychloride (POCl3) treatment on zein films.
• To compare surface, mechanical, and rheological properties of treated and untreated zein.

Main Methods:

• Zein solutions treated with POCl3 at varying pH levels.
• Rheological property analysis of zein solutions.
• Atomic Force Microscopy (AFM) for surface microstructure and roughness evaluation.
• Mechanical testing including tensile strength (TS) and elongation at break (EAB).

Main Results:

• POCl3 treatment increased zein solution viscosity, particularly at pH 7 and 9.
• AFM revealed a rougher, stone-like microstructure on POCl3-treated zein films (pH 7), correlating with increased hydrophobicity.
• Tensile strength decreased, but elongation at break significantly increased (up to 150%), indicating enhanced flexibility.

Conclusions:

• Chemical phosphorylation with POCl3 effectively modulates zein film properties.
• Optimizing pH is crucial for tailoring zein films for specific applications.
• Enhanced flexibility suggests potential for zein films in food and non-food wrapping.