Transparent Biocompatible Polyelectrolyte Multilayer Coatings on Apples: Formation and Properties

Area of Science:

• Food Science and Technology
• Materials Science
• Surface Chemistry

Background:

• Polyelectrolyte multilayers (PEMs) are advanced nanocoatings with diverse applications.
• PEMs are increasingly explored as protective food coatings to prevent fruit decay during storage and transport.
• Chitosan (CS) and carboxymethyl cellulose (CMC) are biocompatible polyelectrolytes suitable for food applications.

Purpose of the Study:

• To fabricate and characterize PEMs composed of chitosan and carboxymethyl cellulose on apple surfaces.
• To correlate fundamental PEM build-up aspects with their practical food coating applications.
• To evaluate the utility of contact angle measurements for monitoring PEM formation on fruit.

Main Methods:

• Fabrication of polyelectrolyte multilayers (PEMs) using chitosan (CS) and carboxymethyl cellulose (CMC) on both apple and model silica surfaces.
• Systematic investigation of experimental conditions, including pH, influencing PEM build-up and properties.
• Utilizing contact angle measurements to assess PEM formation and surface characteristics.

Main Results:

• PEM build-up and properties (thickness, hydrophobicity) are significantly influenced by experimental conditions like pH.
• Contact angle measurements were successfully employed to verify PEM build-up on apple surfaces, a novel finding.
• Optimal conditions for PEM formation, indicated by a distinct zigzag pattern, were identified at pH(CS) = 5.0 and pH(CMC) = 3.0.

Conclusions:

• Contact angle measurements provide an effective method for monitoring polyelectrolyte multilayer formation on fruit surfaces.
• Optimized PEMs using chitosan and carboxymethyl cellulose offer potential for developing advanced, biocompatible food coatings.
• This research lays the groundwork for enhancing fruit preservation through tailored nanocoatings in food technology.