Chitosan films incorporating Pickering emulsions stabilized by OSA-modified yeast dietary fiber for controlled citral release and berry preservation

OSA-YDF Pickering emulsions regulated film microstructure and interfaces. • Interfacial structure governed swelling–diffusion–controlled citral release. • Droplet dispersion enabled release, while aggregation hindered mass transfer. • The films exhibited enhanced UV-blocking, antioxidant and antibacterial activities. • Shelf life of strawberries and blueberries increased by 50% and 33.3%. Citral-loaded liquid high internal phase Pickering emulsions stabilized by OSA-modified yeast dietary fiber (OSA-YDF) were incorporated into a chitosan matrix to fabricate composite films for berry preservation. Compared with neat chitosan film, incorporation of the citral-loaded Pickering emulsion markedly enhanced the surface hydrophobicity, water vapor barrier properties, antioxidant and antibacterial performance. Specifically, the composite films exhibited inhibition rates exceeding 90% against E. coli , S. aureus , and B. cinerea . Citral in different food simulants showed a sustained release profile over 72 h and was strongly influenced by the interfacial characteristics of OSA-YDF-stabilized emulsion droplets dispersed within the chitosan matrix. Kinetic modeling indicated that citral release was primarily governed by chitosan matrix swelling and concentration-driven diffusion. At relatively low emulsion contents, the emulsion droplets were uniformly distributed within the chitosan matrix, allowing citral to diffuse across the OSA-YDF interfacial layer, resulting in sustained citral release. In contrast, excessive emulsion incorporation induced droplet aggregation and interfacial layer crowding, generating heterogeneous composite structure that hindered citral transport. An optimal balance between droplet dispersion and matrix integrity was achieved at 7.5% emulsion content, leading to superior overall film properties and controlled release performance. Preservation experiments further confirmed that the composite film effectively delayed berry deterioration by reducing weight loss, nutrient loss, and texture softening, extending shelf life from 4 d to 8 d for strawberries and from 12 d to 18 d for blueberries. This work provides valuable insights for active food packaging applications. Download: Download high-res image (193KB) Download: Download full-size image