Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Dec;333(Pt 2):148869.
doi: 10.1016/j.ijbiomac.2025.148869. Epub 2025 Nov 7.

Structural elucidation of citric acid cross-linked pectin and its impact on the properties of nanocellulose-reinforced packaging films

Chandra Mohan Chandrasekar  1 , Daniele Carullo  2 , Francesca Saitta  2 , Tommaso Bellesia  2 , Enrico Caneva  3 , Carlo Baschieri  3 , Marco Signorelli  2 , Dimitrios Fessas  2 , Stefano Farris  2 , Diego Romano  4
Affiliations
Free article

Structural elucidation of citric acid cross-linked pectin and its impact on the properties of nanocellulose-reinforced packaging films

Chandra Mohan Chandrasekar et al. Int J Biol Macromol. 2025 Dec.
Free article

Abstract

To advance sustainable packaging development, this study investigates modifying pectin-based films with citric acid cross-linking and nanocellulose reinforcement to enhance their functional properties. Cross-linked citrus pectin (CLCP) films were obtained from film-forming solutions containing different amounts of pectin (2.5-3.5 g 100 mL-1) and citric acid (1-2 g 100 mL-1), with glycerol (1-3 mL 100 mL-1), and nanocellulose (0-2 g 100 mL-1) added as a plasticizer and reinforcing agent, respectively. CLCP films were comprehensively characterized concerning structural, mechanical, and barrier properties. FTIR confirmed successful cross-linking, whereas the structural modifications occurred in the pectin network after cross-linking were elucidated for the first time using advanced 2D-NMR. Principal component analysis (PCA) revealed that nanocellulose concentration was the most significant factor in improving mechanical properties, with strong positive correlations with tensile strength (r = 0.586) and Young's modulus (r = 0.639). Conversely, glycerol concentration showed the strongest negative correlation (r = -0.746 and -0.741, respectively), confirming its plasticizing effect. Barrier properties were also significantly influenced: higher citric acid concentration and processing temperature improved the oxygen barrier. In contrast, higher pectin and nanocellulose concentrations decreased the oxygen transmission rate (r = -0.636 and r = -0.733, respectively). This systematic analysis provides a comprehensive design map for tuning film properties, demonstrating that co-modifying pectin with citric acid and nanocellulose is a highly effective strategy for developing advanced, sustainable packaging materials with tailored performance.

Keywords: Biopolymer modification; Citric acid; Citrus pectin; Cross-linking; Nanocellulose; Packaging films; Structure-property relationship.

PubMed Disclaimer

Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.