Gas Conduction Functional Units (GCFUs) Enable Quantitative Equilibrium Modified Atmosphere Packaging to Suppress Respiration and Pectin Degradation in Strawberries.

Postharvest strawberry softening is driven by rapid pectin depolymerization, a process accelerated by the fruit's inherently high respiration rate. Although equilibrium modified atmosphere packaging (EMAP) can suppress respiration, conventional systems lack the precision required to dynamically align gas permeability with fruit metabolism. Herein, we engineer a tunable EMAP system by incorporating gas conduction functional units (GCFUs) into a polyether sulfone matrix, enabling quantitatively adjustable CO2/O2 selectivity. The optimized film (P2) spontaneously established an optimal equilibrium atmosphere (5.5% O2, 12.5% CO2) within packages, achieving 80% suppression of respiration for postharvest strawberries. This controlled hypoxic/hypercapnic environment coordinately downregulated key pectin-degrading enzymes, thereby limiting water-soluble pectin accumulation while preserving chelate- and alkali-soluble pectin fractions. Consequently, firmness retention exceeded 70%, and phenotypic deterioration was significantly mitigated. This work bridges material engineering with postharvest physiology, offering a scalable, energy-efficient strategy for extending the shelf life of highly perishable fruits.