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 bio-based packaging due to its protein and polyphenol content. In this study, thermocompressed chickpea flour sheets were reinforced with cellulose nanocrystals (CNCs) to improve their barrier, mechanical, optical, 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). Thermocompression reduced the measurable phenolic fractions, although antioxidant activity was not significantly affected. CNC markedly reduced water vapor permeability from 5.16 × 10−10 in the control to 5.93 × 10−12 g∙m−1∙s−1∙Pa−1 at 7.5% CNC. Tensile strength and Young’s modulus increased with CNC loading, whereas elongation at break was highest at intermediate concentrations. Optical characterization showed changes in transmittance and opacity. Thermal analysis indicated that CNC modified the DSC thermal event, whereas only minor differences were observed in the TGA profile. SEM, DSC, XRD, and FTIR analyses suggested changes in morphology and thermo-structural organization. Overall, CNC improved barrier and mechanical performance, supporting the potential of these sheets as a material for semirigid biodegradable packaging applications.