Chitosan-hydroxypropyl methylcellulose and sodium alginate bilayer edible films for chestnut preservation

To address the challenge of preserving fresh chestnuts, chitosan (CS), hydroxypropyl methylcellulose (HPMC), nisin (N), and sodium alginate (SA) were utilized in the preparation of a bilayer edible film named CS-HPMC-N/SA, which was compared to the monolayer films CS-HPMC and CS-HPMC-N. In comparison to the CS-HPMC film, the CS-HPMC-N and CS-HPMC-N/SA films exhibited increased water vapor permeability (WVP), oxygen permeability, and thickness, while transparency, tensile strength (TS), and elongation at break (EAB) were reduced. The bilayer film CS-HPMC-N/SA showed higher WVP, transparency, thickness, and EAB, but lower TS than the monolayer film CS-HPMC-N. The chestnuts coated with CS-HPMC-N/SA showed lower respiratory intensity and decay rate compared to those coated with CS-HPMC and CS-HPMC-N. These results suggested that the bilayer film CS-HPMC-N/SA, containing nisin, has potential as an edible material for preserving fresh chestnuts.