The regeneration of structural biopolymers into micelles or nanoparticles suspended in water
has enabled the design of new materials with unique and compelling properties that can serve
at the interface between the biotic and the abiotic worlds. In this study, we leveraged silk fibroin
quintessential properties (i.e. polymorphism, conformability and hydrophobicity) to design a waterbased
protein suspension that self-assembles on the surface of food upon dip coating. The water-based
post-processing control of the protein polymorphism enables the modulation of the diffusion of gases
through the silk fibroin thin membranes (e.g. O2 and CO2 diffusion, water vapour permeability), which is
a key parameter to manage food freshness. In particular, an increased beta-sheet content corresponds
to a reduction in oxygen diffusion through silk fibroin thin films. By using the dip coating of strawberries
and bananas as proof of principle, we have shown that the formation of micrometre-thin silk fibroin
membranes around the fruits helps the management of postharvest physiology of the fruits. Thus,
silk fibroin coatings enhance fruits’ shelf life at room conditions by reducing cell respiration rate and
water evaporation. The water-based processing and edible nature of silk fibroin makes this approach a
promising alternative for food preservation with a naturally derived material.