Improvement of water solubility and humidity stability of tapioca starch film by incorporating various gums

•Minor addition of some gums improved solubility and humidity stability of tapioca starch film during storage.•Addition of xanthan (4% of total solids) increased solubility of tapioca starch film (Around 37% solubility within 60 s).•Gellan and tapioca starch (4% of total solids) based film remained flexible and less sticky.

Various gums including gum arabic, κ-carrageenan, gellan, and xanthan were tested to improve water solubility and humidity stability of a starch-based edible film. Aqueous tapioca starch pastes containing a gum (total 5.0% solids including 0.2 or 0.5% gum solids) were cast on a glass plate, and effects of the gum addition on the water solubility, humidity stability and mechanical properties of the films were examined. Solubility of the film specimen (20 × 20 mm) in distilled water or buffer solution with α-amylase (50 mL) at 37 °C within 60 s was significantly increased by the presence of the gums. Moreover, the starch-gum films were more stable to humidity than a pure pullulan film (20% solids) which was similar to popular commercial films. Under different RH conditions (23, 52, and 85%), the starch-gum films (0.2% gum addition) exhibited tensile strength values similar to those of the pure pullulan film. Among the gums tested, gellan gum at 0.2% addition appeared most effective in improving the mechanical properties and storage stability of the starch film.