Surfactant-free silk fibroin–oil nanoemulsion coatings enable fruit-specific preservation pathways

Postharvest deterioration of fresh fruits is strongly influenced by moisture loss, gas exchange, and oxidative processes. Yet, many edible coatings remain sensitive to high-humidity storage conditions or require additional surfactants to stabilize functional oil phases. Here, we developed fully edible, surfactant-free silk fibroin (SF)–stabilized nanoemulsion dip coatings and employed three oils spanning hydrophobicity and antioxidant capacity (jojoba, camellia, and grape-seed oils) to investigate oil-dependent preservation performance. Oil identity regulated SF interfacial assembly and β-sheet/Silk II formation, producing films with tunable microstructure and barrier properties. In strawberries, coatings containing hydrophobic oils (jojoba and camellia) formed denser films that reduced weight loss by ∼50%, suppressed respiration, and reduced mold growth, consistent with barrier-dominated protection. In bananas, the antioxidant-rich grape-seed oil most effectively delayed peel browning and reduced mass loss, indicating an antioxidant-driven preservation pathway. These results demonstrate that SF–oil nanoemulsion architecture enables simultaneous structural reinforcement and functional antioxidant delivery, allowing preservation mechanisms to be tailored to fruit physiology. This work provides a scalable, surfactant-free strategy for fruit-specific edible coating design and sustainable postharvest preservation. • Prepared surfactant-free, fully edible SF-stabilized vegetable-oil nanoemulsions • Oil polarity regulated SF film assembly and β-sheet ordering • JO–SF/SF coating reduced strawberry weight loss by about 50% • GO–SF/SF coating reduced banana browning by about 28% and weight loss by about 26% • Proposed a preservation coating strategy tailored to different fruits.