This work focuses on exploring the potential of using chitn nanoparticles (ChNs) for structure development and stabilization of food colloidal systems, including gels and oil-in-water emulsions subjected to different conditions encountered during processing and storage as well as conditions simulating the environment of the digestive system. Aqueous ChN dispersions (pH 3.0) exhibited a nematic gel-like behaviour with increasing solids concentration that can be attributed to associative interactions between the ChNs. With increasing ionic strength and pH, such associative interactions are enhanced yielding stronger network structures. Heating of the ChN dispersions led to further increases in the storage modulus (G'), which were irreversible upon cooling; the rate of G' increase (dG'/dt) was dependent on temperature. Mixtures of chitin nanocrystal (ChN) aqueous dispersions (pH 3.0) and soluble polysaccharides of varying molecular characteristics or whey protein isolate were also examined with small deformation oscillatory measurements and polarized optical microscopy, under varying polymeric composition, ionic strength, pH and temperature. The gel strengthening in the mixed ChN-biopolymer systems was attributed to phase separation due to thermodynamic incompatibility, whereas with oppositely charged polysaccharides, the possibility for complex formation cannot be excluded. Chitin nanocrystals were also found to form stable Pickering emulsions, with the ChN adhering at the oil/water interfaces as well as forming a particle network structure in the continuous phase. The stability of the emulsions improved with increasing ChN concentration. Raising the temperature (from 20 to 74 oC), the NaCl concentration (up to 200 mM) or the pH (from 3.0 to 6.7) led to enhancement of the emulsion’s elastic character and its creaming stability. The kinetics of enzymic lipid hydrolysis in the ChN-stabilized emulsion was slower and the plateau values of fatty acids released were lower, compared to conventional dairy protein-stabilized emulsions. Overall, incorporation of ChNs in food systems as structuring agents and/or emulsion stabilizers, apart from the improvement of their structural characteristics, may lead towards the development of functional formulations with novel nutritional properties.
Professor Costas G. Biliaderis, biliader@agro.auth.gr
