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

Abstract

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