Abstract:

Nano-chitin was prepared by treating raw chitin with hydrogen chloride （HCl） vapor followed by dispersing in water at high speed for 1 min. The obtained nano-chitin has rod-like morphology with average diameter of approximately 50-60 nm and high length-diameter ratio. The nano-chitin suspension thus prepared was used to stabilize an oleogel consisting of beeswax and corn oil to fabricate oleogel-in-water Pickering emulsion, and it was confirmed that the chitin without HCl vapor treatment could not stabilize the oleogel to form Pickering emulsion. The emulsions were characterized by optical microscope, polarized microscope, fluorescence microscope, dynamic laser scattering size analyzer and rheometer. The birefringence observed by polarized microscope shows that beeswax oleogel is successfully encapsulated. The results of fluorescence microscopy show that nano-chitin is adsorbed at the O/W interface, and the emulsions keep the original morphology after water being removed for the oleogel containing more than 5% beeswax. The rheology behaviors of oleogel Pickering emulsions stabilized by 0.6% nano-chitin suspension with varied beeswax concentration show much lower storage modulus than corresponding beeswax oleogels, indicating that the nano-chitin has acted as a barrier at the O/W interface of Pickering emulsion to protect it from breaking under shearing. Oleogel containing 10% beeswax could be stabilized at an O/W ratio of 1/9 using as little as 0.2% nano-chitin suspension. The resulting Pickering emulsion is able to maintain the original morphology after complete removal of water, and its rheology behavior is similar to the oleogel containing 10% beeswax, indicating that the beeswax oleogel is released under shearing. The rheology behaviors of emulsions with oleogel containing 10% beeswax encapsulated indicate that the beeswax oleogel can be control-released under shearing by adjusting the concentration of nano-chitin.

Key words: Pickering emulsion, nano-chitin, HCl vapor, beeswax oleogel