Chitosan-caseinate bilayer coatings for paper packaging materials.

Area of Science:

• Materials Science
• Polymer Science
• Food Science

Background:

• Paper coatings are crucial for enhancing barrier properties.
• Caseinate and chitosan are biocompatible polymers with potential for paper modification.
• Developing sustainable and effective paper coatings is an ongoing research area.

Purpose of the Study:

• To develop and characterize paper coatings using caseinate and caseinate/chitosan bilayer films.
• To investigate the effects of coating parameters on the physical and mechanical properties of coated papers.
• To evaluate the barrier properties, specifically water vapor permeability (WVP), of the developed coatings.

Main Methods:

• Films of caseinate and caseinate/chitosan were prepared and characterized using FTIR spectroscopy and thermal stability analyses.
• Coated papers were prepared with varying coating weights, caseinate concentrations (7%, 10%, 12%), and application methods (single layer, bilayer).
• Physical and mechanical properties, including water vapor permeability (WVP), tensile strength (TS), and elongation at break (%E), were measured.

Main Results:

• Increasing caseinate concentration decreased the water vapor permeability (WVP) of coated papers.
• Chitosan significantly increased the elongation at break (%E) of coated paper (p<0.05).
• Applying chitosan as a bilayer on caseinate films did not significantly affect tensile strength (TS), but the greatest WVP reduction was achieved with a chitosan layer on dried caseinate.

Conclusions:

• Caseinate and caseinate/chitosan bilayer coatings can effectively modify paper properties.
• Chitosan enhances the mechanical properties, particularly elongation, of coated papers.
• Bilayer coatings, especially with chitosan applied to dried caseinate, offer superior water vapor barrier properties for paper applications.