hi, chitin flakes is in an insoluble form therefore break down of it will be difficult to observe clearing zones. It will also be difficult to incorporate into your media. Colloidal chitin is the better option as it is more soluble and easily dispersed in your media. Colloidal chitin also sheds chitooligosaccharides that serves as an inducer for chitinase production. 

Thank you !

 how do i prepare colloidal chitin from chitin flakes??? can you please suggest me a standard protocol.

For colloidal chitin preparation : Take chitin flakes and conc. HCl in the ratio 1:20 . ie. 1 g chitin flakes in 20 mL HCl. So you have to use in a magnetic stirrer. Take 20 mL of con. HCl n a magnetic stirrer and add chitin slowly to it at 4°C overnight. Make sure the magnetic stirrer is at high speed because the solution will become very viscous. After overnight stirring, the entire solution is to be added to 20 volumes of distilled water under continuous stirring. Say you made for 20 mL then you should add it to 400mL distilled water. Then you have to centrifuge the solution ( water + colloidal chitin ). The precipitate is the colloidal chitin. You can discard the supernatant. The colloidal chitin will be in acidic pH so you have to wash it with distilled water repeatedly to bring the final pH to 7. Washing in the sense, add distilled water to the precipitate in the centrifuge tube and suspend the solution and centrifuge the solution and discard the supernatant. If you want the process to be fast you can initially use 1N NaOH and finally three washes with distilled water.