Development and Characterization of Carboxymethylated Agar-based Film for Food Packaging Applications

Document Type : Research Article-en

Authors

Farideh Falahatgar

Aria Babakhani

Eshagh Zakipour Rahimabadi

Hanieh Rostamzad

Fisheries Department, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Guilan, Iran

https://doi.org/10.22067/ifstrj.2026.95783.1488

Abstract

The aim of this study was to develop and characterize carboxymethylated agar (CMA) based films crosslinked with citric acid, polyethylene glycol (PEG), and β-cyclodextrin for sustainable food packaging applications. The inherent brittleness, high hydrophilicity, and limited thermal stability of native agar films, which restrict their practical use in food packaging systems were considered as the aim of performing this study. Five distinct film formulations were prepared using different combinations of crosslinking agents, and their physicochemical, morphological, and thermal properties were systematically evaluated. The degree of substitution (DS) of carboxymethyl agar was determined to be 0.69, indicating successful chemical modification. Water contact angle analysis revealed that the CMA-P-β-A film exhibited the highest hydrophobicity, with a contact angle in the range of 80–89°, compared to approximately 67° for the control CMA film, demonstrating enhanced moisture resistance. Differential scanning calorimetry showed a significant increase in glass transition temperature (Tg), reaching 82.08 °C for the CMA-P-β-A formulation, compared to 52.54 °C for CMA, confirming the formation of a highly crosslinked polymer network. FTIR and XRD analyses confirmed successful carboxymethylation and crosslinking, accompanied by reduced crystallinity and improved structural flexibility. SEM micrographs revealed smooth and homogeneous surfaces with interconnected polymer networks. Overall, the integrative carboxymethylation crosslinking strategy effectively enhanced the hydrophobicity, thermal stability, and structural integrity of agar-based films, highlighting the CMA-P-β-A formulation as the most promising candidate for environmentally friendly food packaging applications. These findings provide valuable insights into the design of advanced biopolymer-based packaging materials.

Keywords

Algae

Carboxymethylated agar

Crosslinking

Packaging

Thermal properties

Subjects

• Food Chemistry

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Authors retain the copyright. This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0)

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