High strength, gas barrier and hydrophobic konjac glucomannan/glutenin films with semi-interpenetrating network for cherry tomato preservation

Polysaccharide films such as konjac glucomannan (KGM) with excellent biocompatible, green, renewable, and biodegradable properties have attracted much attention as excellent candidates to replace petrochemical plastics. However, the water resistance of KGM film is poor, which can not meet the requirements of fruit and vegetable preservation in complex scenes. Herein, we utilized sodium hydroxide solution as the good solvent of glutenin and deacetylation agent of KGM to form KGM/glutenin films with semi-interpenetrating networks for fruit preservation. Compared with KGM film, the synergistic effect of deacetylated KGM and glutenin could increase the surface water contact angle of films from 65.1° to 106.7°, and increase the tensile strength from 55.6 MPa to 92.5 MPa. Surprisingly, the water vapor and oxygen permeabilities of KGM/glutenin film were as low as 2.12 × 10⁻³ g·/(m·d·KPa) and 0.52 × 10⁻⁹ m²/(d·KPa), respectively, showing excellent gas barrier performance. The changes in appearance, firmness, total sugar content, pH, and malondialdehyde content of cherry tomatoes during storage proved that the KGM/glutenin film could effectively delay the ripening and decay, and extend the freshness lifetime of cherry tomatoes for more than 6 days. Therefore, this new type of water-resistant composite film with a semi-interpenetrating network has great application prospects in fruit preservation.