Cellulose nanocrystal-mediated modulation of structural conformation and rheological properties of chickpea proteins

Understanding how plant-based ingredients interact and behave structurally is essential for achieving desired qualities in food products. However, investigations into cellulose nanocrystal (CNC)-induced structural modulation in chickpea protein matrices have offered limited insight into the conformational rearrangements occurring within their secondary structural elements. This study examined the effects of CNC concentrations (0.5, 1, and 3 %) on the conformational, secondary structure, and rheological properties of chickpea protein isolate (CPI) suspensions. The incorporation of CNC promoted greater aggregation, surface hydrophobicity, and exposed free sulfhydryl groups in the proteins, resulting in an increased water absorption capacity of the CPI-CNC complexes. Protein solubility improved as the CNC content increased (reaching 51 % with 3 % CNC), possibly because of structural changes that exposed amino acid residues to interact with water. FTIR analysis indicated that hydrogen bonds and electrostatic interactions affected the complexation of CPI and CNC. At low concentrations of CNC (0.5 %–1 %), the content of anti-parallel β-sheets and β-turns was reduced to transform into pseudo-β-sheets, promoting a more disordered conformation. However, the 1:1 protein-to-nanocrystal ratio promoted more pseudo-, anti-parallel-, and parallel β-sheets from α-helices and β-turns than CPI. The viscosity, viscoelasticity, and thixotropy behavior of the protein suspensions were influenced by an increase in CNC. A high CNC content markedly increased the thixotropic response of the CPI–CNC complexes, indicating reinforcement of interparticle bonding and network cohesiveness. These results highlight the importance of nanocrystal concentration in the modulation of plant-based protein structures and microstructure of the formed colloids.