Improvement of mechanical, barrier properties, and water resistance of konjac glucomannan/curdlan film by zein addition and the coating for cherry tomato preservation

Abstract

The mechanical, barrier properties, and water resistance of packaging materials are crucial for the preservation of fruits and vegetables. In this study, zein was incorporated as a hydrophobic substance into the konjac glucomannan (KGM)/curdlan (KC) system. The KC/zein (KCZ) showed good compatibility with the zein aggregates uniformly distributed in the network formed by an entanglement of KGM and curdlan micelles based on hydrogen bonds. The presence of zein inhibited the extension of the KC entangled structure and enhanced the solid-like behavior. The high content of zein (>6 %) increased zein aggregation and negatively affected the structure and properties of KCZ. The zein addition significantly improved the water vapor permeability, tensile strength, and elongation at break. The hydrophobicity of the KCZ films was significantly enhanced, accompanied by the water contact angle increasing from 81° to 112°, and the moisture content, swelling, and soluble solid loss ratio decreasing apparently. The K56C40Z4 coating exhibited an excellent preservation effect to inhibit the respiration of cherry tomatoes, significantly reducing the water loss and firmness decline and maintaining the appearance, total solid, total acid, and ascorbic acid content. This work provided a strategy to fabricate hydrophobic packaging for the preservation of fruits and vegetables.