Analysis of film-forming properties of chitosan with different molecular weights and its adhesion properties with different postharvest fruit surfaces.

In this work, the film-forming properties of chitosan with different molecular weights (MW) (30, 100, 200 and 300 kDa) and its adhesion properties with different postharvest fruit surfaces were analyzed. The viscosity of 30 and 300 kDa chitosan film-forming solution gradually increased from 0.007 to 1.16 Pa.s at a shear rate of 10 s. Compared to 30 kDa chitosan films, higher MW chitosan films showed enhanced water resistance, water vapor barrier properties and mechanical properties, mainly due to the different strength of interaction forces within the chitosan films, which can be confirmed by microstructural observations and FTIR results of the films. It can be found that different MW chitosan film surfaces with bananas, apples, pears, oranges and strawberries all have a similar adhesion work of about 70-80 mN m, and 100 and 200 kDa chitosan film had higher adhesion work with different fruit surfaces compared to 30 and 300 kDa.