Storage stability of konjac glucomannan/curdlan films at low temperature and its coating for the preservation of cucumbers

Fruits and vegetables suffer severe moisture loss during cold storage. To explore the mechanism of water transfer, this study investigated the properties of konjac glucomannan (KGM)/curdlan (KC) composite films after cold storage treatment, the preservation of KC-coated cucumbers, and the water transfer. The results showed that the weight, thickness, free water content, and enthalpy (ΔH) of endothermic peak of the film increased after cold storage, mainly because of the water adsorption and diffusion. K₆C₄ (the KGM/curdlan mass ratio in 6:4) maintained uniform and dense and showed the lowest dissolution loss of 21.92%. Moreover, the water content of K₆C₄ film changed by 1.1% on day 15, and K₆C₄ exhibited excellent gas barrier and mechanical properties. These were attributed to the optimal matrix formed by the assembly of KGM and curdlan in K₆C₄, contributing to the stability of structure and performance. K₆C₄ coating significantly maintained the quality of cucumbers. At the end of storage, the firmness and weight loss of the coating group were 19.3% and 24.4% higher than the control group, respectively. The color, total solid content, acid, and VC were maintained for coating group. The low-field nuclear magnetic resonance revealed that K₆C₄ coating inhibited the water transfer from the center to the epidermis of cucumbers by blocking the water produced by respiration and the free water in the tissues. The storage stability and water transfer analysis will contribute to the understanding of the mechanism of coating inhibiting moisture loss of fruits and vegetables.