Effect of Grinding and Particle Size on Some Physical and Rheological Properties of Chitosan

Abstract

The present study was conducted to prepare nano-chitosan particles (CN) by ultrafine grinding from crude chitosan powder (CC) using a ball mill with 130 numbers of zirconia beads in range from 0.5 to 1.5 mm diameter (75 beads 0.5 mm diameter, 30 beads 1.0 mm diameter and 25 beads 1.5 mm diameter). In addition, Physical and rheological properties of chitosan solutions were determined. The results revealed that ultrafine grinding has effectively milled the chitosan particles to nano-scale. Prepared chitosan nanoparticles were characterized by X-Ray Diffraction (XRD), Zetasizer particle sizes and Zeta potential of chitosan particles of (after milling for 30, 60 and 90 minutes). The particle size of nano-chitosan was distributed in a range of 250-600 nm. With a polydispersity index <1. The particle electric charge was increased to the level of +24 to +33 mV. X-ray diffractogramms showed lower intensity and a shift in the peak to the lower 2° θ angle due to the charge in particles cristllinity. The rheological parameters from power law at 25 ˚C were obtained using a rotational coaxial viscometer. The flow behavior index (n) of the different tested chitosan solutions were less than 1.0 (ranging between 0.36-0.74) indicating their pseudoplastic of chitosan solutions. The higher value of consistency coefficient (K) was recorded for CN 30 at pH 3 and lower (n) values than those of crude chitosan at pH 7. Generally, the results showed that the studied polymer solutions exhibited non-Newtonian behavior with shear-thinning. The results indicate the possibility of safe using nanoparticles of chitosan in food applications as a result of increased efficiency and use as an anti-oxidant and antimicrobial with reducing the amount used to deliver the desired purpose. Additional research is required to further investigate the potential value-added utilization of these chitosan derivatives in improving the quality and safety of food.