Thermocompressed Chickpea-Flour Sheets Reinforced with Cellulose Nanocrystals: Improved Water-Vapor Barrier and Thermo-Mechanical Performance

Chickpea (Cicer arietinum L.) flour is a promising raw material for the development of biodegradable packaging due to its protein and polyphenol content. In this study, thermocompressed chickpea flour sheets were reinforced with cellulose nanocrystals (CNC) to improve their barrier, mechanical, thermal, and structural properties. Preliminary trials identified 22% moisture as the most suitable condition for consistent sheet formation. CNC was incorporated at 0, 2.5, 5.0, and 7.5% (w/w), and the resulting sheets were evaluated for phenolic content, antioxidant activity, water vapor permeability (WVP), optical properties, thermal behavior, morphology, and structural characteristics. Thermocompression reduced the measurable phenolic fractions, although antioxidant activity was not significantly affected. CNC markedly reduced WVP, from 5.16x10-10 (control) to 5.93x10-12 g∙m-1∙s-1∙Pa-1 at 7.5% CNC. Tensile strength and Young's modulus increased with CNC loading, while elongation at break was highest at intermediate concentrations. SEM, DSC, XRD, and FTIR analyses indicated matrix reorganization and modified thermo-structural behavior. Overall, CNC improved the barrier and mechanical performance of thermocompressed chickpea flour sheets, supporting their potential for biodegradable packaging applications.