The heterogeneous nature of the production process renders chitosan heterogeneous. The chitosan derived from similar starting materials or preparations can be quite different in terms of the average molecular mass, molecular mass dispersity and DD. The differences in these parameters can greatly affect the physical properties and the biological functions of chitosan, such as the solubility and the ability to stimulate plants. Therefore, these parameters should be well characterized prior to its application. The differences in the starting material can be reduced or eliminated by NaOH pretreatment to modulate DD, and chemical or enzymatic hydrolysis to modulate the size and polydisperisity. Modification methods for these parameters have been well documented elsewhere (Jung and Park, 2014, Kubota et al., 2000 and Thadathil and Velappan, 2014).