Development of a pullulan/chitosan dual-layer smart humidity-responsive material for packaging

Food loss and waste (FLW) significantly contribute to the global food crisis, with inadequate packaging among the primary causes. This study presents the development of a smart humidity-responsive packaging designed to extend the shelf life of perishable foods through the loading and the retention of the antimicrobial yeast Metschnikowia pulcherrima (MS). The packaging consists of a dual-layer electrospun fibrous structure composed of an external hydrophobic poly(lactic acid) layer, which offers mechanical strength and moisture resistance, and an internal hydrophilic layer composed of pullulan and chitosan, which responds to humidity for the loading and the retention the biocontrol agent. Morphological and wettability analyses confirmed the distinct functionality of the two layers, with the internal layer exhibiting significant swelling under humid conditions (fibers’ diameter increase of ∼52%). In vitro degradation studies showed selective degradation of the internal layer, with ∼83% weight loss after 4 weeks, while the external PLA layer maintained over 97% of its initial mass after 12 weeks, ensuring structural integrity. The internal layer also exhibited antioxidant activity, reaching ∼53% radical scavenging activity after 48 h. Cytotoxicity and pro-inflammatory assays confirmed the biocompatibility of the system, with cell viability above 95% and no significant TNF-α secretion stimulation. In vivo tests on blueberries demonstrated a significant reduction in grey mould incidence from 55% in the positive control to 20% after contact with the active packaging. These results highlight the potential of the developed material as an eco-friendly, smart packaging system capable of enhancing food preservation through biologically active mechanisms.