Moisture Microenvironment-Regulating Electro spun Membranes for Extending Litchi Shelf Life

To address post-harvest issues of litchi, including browning, water loss, and nutrient degradation, a moisture microenvironment-regulating electro spun membrane was prepared by incorporating hydrophobic carnauba wax (CW)@nano silica (SiO₂) composite powder into a polyethylene terephthalate (PET) matrix via electro spinning. The dynamic water penetration equilibrium was evaluated by monitoring the water vapor absorption of the electrospun membrane within 12 h, while the effects of CW@SiO₂ on the micro-structure, mechanical properties, hydrophobicity, and thermal stability were investigated. Results showed that the tensile strength of the PET-2.5%CW@SiO₂ electro spun membrane increased from 4.64 MPa to 8.49 MPa, the elongation at break rose from 34.67% to 67.56%, and the water contact angle (WCA) improved from 116.53° to 140.82°. Furthermore, the PET-2.5%CW@SiO₂ electro spun membrane exhibited excellent thermal stability, effectively blocked moisture evaporation (water vapor absorption of only 0.33 g in 12 h), and maintained the moisture dynamic equilibrium. Freshness preservation experiments on litchi at 25°C revealed that compared to the Control group, PET-2.5%CW@SiO₂ electro spun membrane packaging extended the shelf-life of litchis for five days by reducing the weight loss (19.35%), total solids content (15.90%), titratable acid (TA) content (0.12%), and vitamin C content (1080.02 mg/L), inhibiting the polyphenol oxidase (PPO) and peroxidase (POD) activities as well as reducing cell membrane permeability and lipid peroxidation. Magnetic resonance imaging (MRI) and low-field nuclear magnetic resonance (LF-NMR) analyses confirmed that the PET-2.5%CW@SiO₂ electro spun membrane effectively delayed browning and spoilage by inhibiting water loss in litchis. PRACTICAL APPLICATIONS: Fresh litchi is prone to browning after harvesting. In this study, a moisture microenvironment-regulating electro spun membrane was prepared by incorporating hydrophobic powder CW@SiO₂ into the PET matrix, and its structural and physicochemical properties were explored to further validate its post-harvest preservation efficacy for litchis. Compared with the control group, the PET-2.5% CW@SiO₂ electro spun membrane extended the shelf-life of litchi by five days by inhibiting water loss, thereby delaying browning and maintaining nutritional quality. This finding provides a new perspective on the post-harvest preservation of litchi.