# Metabolomics Reveals the Regulatory Mechanism of Antibacterial Fiber Membrane Packaging on the Postharvest Quality of Wax Apple (Syzygium samarangense)

## TL;DR

A new antibacterial packaging membrane was developed to extend the shelf life of wax apples by inhibiting bacteria and regulating fruit metabolism.

## Contribution

A novel PEO/OSG/ε-PL fiber membrane was developed and its antibacterial and metabolic regulatory mechanisms were elucidated for postharvest preservation.

## Key findings

- The membrane significantly reduced decay and weight loss in wax apples during storage.
- It inhibited bacterial growth by damaging cell walls and membranes.
- Metabolomics showed modulation of phenylalanine and linoleic acid pathways, delaying fruit senescence.

## Abstract

Wax apple (Syzygium samarangense) is highly perishable postharvest. Even under refrigerated storage conditions, its shelf life typically lasts only about one week. This study developed a novel antibacterial food packaging membrane to extend its shelf life and explored the underlying preservation mechanisms. A composite fiber membrane was fabricated via solution blow spinning (SBS) using polyethylene oxide (PEO) and oxidized sesbania gum (OSG) incorporated with ε-polylysine (ε-PL). The composite membrane demonstrated exceptional antibacterial activity against both E. coli and S. aureus by disrupting cell wall and membrane integrity, as evidenced by increased protein leakage, alkaline phosphatase activity, and electrical conductivity. Morphological observations through scanning electron microscopy confirmed extensive cellular damage and bactericidal effects. During nine days of ambient storage, the PEO/OSG/PL membrane significantly maintained the postharvest quality of wax apples. This was evidenced by a lower decay index (2.22 ± 0.19) and weight loss rate (5.32 ± 0.16%) compared to the control group, alongside better preservation of firmness (4.11 ± 0.08 N) and color stability. The treatment suppressed respiratory rate and delayed the degradation of soluble solids and titratable acidity. Furthermore, it enhanced antioxidant capacity through higher peroxidase activity and reduced malondialdehyde accumulation, indicating attenuated oxidative stress. Non-targeted metabolomics analysis revealed that the membrane treatment modulated critical metabolic pathways, particularly phenylalanine metabolism and linoleic acid metabolism. These metabolic adjustments contributed to enhanced defense responses and delayed senescence. The results show that the PEO/OSG/ε-PL fiber membrane acts as an effective active packaging material by inhibiting microbial growth and regulating metabolism. This provides a potential method to extend the shelf life of perishable fruits.