The present invention refers to a process for preparing a biomaterial scaffold said method comprising, (a) providing a hydrogel comprising a fibrin network and a polysaccharide network; (b) subjecting the hydrogel of step a) to a freeze-thawing process to physically crosslink the hydrogel; and (c) subjecting the physically cross-linked hydrogel obtained after conducting the step b), to a lyophilization. The invention also relates to the biomaterial scaffold obtainable by the process as defined above, as well said biomaterial scaffold for its use to partially or completely increase, restore or replace the functional activity of a diseased or damaged oral mucosa.