Structural, viscoelastic, and emulsifying properties of shrimp chitin nanowhisker dispersions as a function of acidic pHs

Ultrastructural, hydrodynamic, rheological, and emulsifying properties of chitin nanowhisker dispersions from commercial (C) and laboratory (L) origin were analyzed at pHs 2-3.5. Nanowhiskers were rod-like shaped and their hydrodynamic properties changed in range: particle size: 90-560 nm; zeta potential: 26-42 mV; polydispersity 0.175-0.850. Flow curves indicated a shear-thinning behavior for both samples. At pH 2 dispersions were more consistent than at pH 3.5, but in both cases L showed higher consistency than C. Both C and L exhibited a non-stationary (thixotropic) flow at pH >= 2.5. The coexistence of two shear-induced domains was found in the oscillatory tests. The emulsifying ability of both C and L samples at a low (0.5%) concentration was dependent on pH. So, at pH 2, the L sample showed a greater emulsifying ability (98%) and emulsion stability (92-90%) than the C sample (emulsion stability approximate to 74%).