Functional Characterisation of Rosemary-Enhanced Alginate Films for Strawberry Preservation.

This study developed alginate-based edible films enriched with rosemary extract (RE), obtained from distillation by-products and evaluated their physicochemical, functional and preservation performance in strawberries. RE (9% v/v) was incorporated into 2% (w/v) sodium alginate film-forming solutions, which were applied both as coatings and cast into standalone films. The incorporation of RE increased film thickness (from ~0.056 to ~0.068 mm), density (from ~1.05 to ~1.12 g/cm3) and solution viscosity, while reducing moisture content (from ~12% to ~8.5%). RE also enhanced UV-Vis light protection and slightly increased water vapour permeability (from ~2.75 to ~3.0 × 10-11 g · s-1 · m-1 · Pa-1). When applied to fresh strawberries stored at 5°C, RE-enriched coatings significantly inhibited microbial growth. Total bacterial counts remained below 4.9 log10 CFU/g after 14 days compared with higher levels in uncoated controls, whereas total yeast and mould counts decreased from ~3.7 to ~3.1 log10 CFU/g. These results demonstrate that RE-infused alginate films effectively slow microbial proliferation and help maintain fruit quality during refrigerated storage. The findings point out the efficacy of rosemary distillation by-products as sustainable, natural additives for biodegradable edible coatings in fresh produce preservation.