Sustainable Preservation Strategies for Prunes—The Influence of Biopolymer Coatings on the Quality and Sustainability of Prunes

The aim of this study was to estimate the influence of biopolymer coatings based on chitosan and zein on the quality and storage stability of prunes (Prunus domestica L., cv. Stanley) over a one-year period coupled with modified atmosphere conditions (5% CO2 + 95% N2). Samples were analyzed at defined intervals (every 3 months) regarding physicochemical properties, antioxidative capacity, vitamin C content, phenolic profile, headspace gas composition, microbiological status and sensory characteristics. Biopolymer coatings, modified atmosphere, and temperature play key roles in controlling oxygen availability, which consequently affects all tested properties of prunes. Application of both types of coatings significantly improves product stability compared to uncoated samples, slows moisture loss, stabilizes pH, reduces degradation of vitamin C, phenolic compounds, and antioxidant activity, and improves microbiological safety. Chitosan exhibits more pronounced effects due to its antimicrobial and antioxidant properties, while zein primarily contributes to barrier characteristics. Gradual decline in quality, significantly slowed in coated samples, is additionally mitigated at low temperature (4 °C), which further inhibits chemical, oxidative, and microbiological changes compared to storage at 23 °C. Despite zein coating providing superior preservation of several physicochemical quality parameters, chitosan-coated prunes achieved higher sensory acceptance, demonstrating that improved physicochemical stability does not necessarily correspond to better consumer acceptability.