The consumption of fresh-cut apples has grown rapidly due to consumers' increasing willingness to enjoy prepared and ready-to-eat fruits. But fresh-cut apples tend to experience severe enzymatic browning which discourages people to taste. Chitosan (CS) coating containing ascorbic acid (AA) or calcium chloride (CaCl 2) were applied on fresh-cut apples in this work to observe their preservation effects. Their appearance, weight change were evaluated during the storage at room temperature, besides, AA content, soluble solid content were analyzed at the end of storage. CS-CaCl 2 coating has better preservation effect than CS-AA coating when they were applied on fresh-cut apples. CS-CaCl 2 coating showed lower weight loss and higher AA content of apple slices than CS-AA coating. CS-CaCl 2 coating was also good at anti-browning in terms of the appearance of coated apple slices.

The consumption of fresh-cut fruits is limited because of the oxidation browning and pathogenic bacteria's growth on the fruit surface. Besides, crack of the fresh-keeping film may shorten the preservation time of fruit. In this work, polyelectrolyte multilayer (PEM) film was fabricated by layer-by-layer (LBL) electrostatic deposition method. The film was made by carboxy methylcellulose sodium (CMC) and chitosan (CS). The as-prepared PEM film had good anti-oxidative and antibacterial capability. It inhibited the growth of Gram-negative bacteria and the antibacterial rate was more than 95%. The stratified structure and linear increase of the absorbance in the film verified a linear increase of film thickness. The slight scratched film could self-heal rapidly after the stimulation of water whatever the layer number was. Moreover, the film could heal cracks whose width was far bigger than the thickness. The application of PEM film on fresh-cut apples showed that PEM film had good browning, weight loss and metabolic activity inhibition ability. These results showed that the PEM film is a good candidate as edible film in fresh-cut fruits applications.

Self-healing process occurring when a self-healing Co–CS/PAA PEM film is integrated (I), damaged (II), self-healing (III), and self-healed (IV).

In this study, we report highly transparent self-healing films based on Schiff base linkages between DF-PEG and CS via a layer-by-layer technique.

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