Hydrolyzes chitin and may play a role in defense against fungal pathogens containing chitin. Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Causes an allergic reaction in human. Binds to IgE. It exhibits some cross-reactivity with IgE antibodies from patients sensitized to latex. Belongs to the glycosyl hydrolase 19 family. Chitinase class I subfamily.