Dynamics of Quality Traits During Cold Storage in ‘Annurca’ Apples: Impact of 1-MCP and the Traditional Melaio Reddening Process

The ‘Annurca’ apple (Malus domestica), a PGI-protected Italian cultivar, undergoes a mandatory postharvest reddening process (melaio). While crucial for skin color development, this process is associated with flesh softening, creating a conflict with consumer demand for crispness. To resolve this quality trade-off, this study compared different postharvest strategies over a five-month commercial cold storage. Specifically, we performed a time-series analysis of the evolution of ripening and skin color dynamics under three strategies: traditional reddening (Melaio), 1-methylcyclopropene application (MCP), and a 1-MCP treatment followed by reddening (MCP+Melaio). While 1-MCP effectively arrested firmness loss, maintaining firmness above 47 N compared to the Melaio-only treatment which dropped to 35.9 N by the end of storage, the pathways of skin color development differed profoundly. The MCP-only strategy led to a highly non-uniform and visually inconsistent appearance (average Total Color Difference, ΔE* > 12) that persisted throughout storage. In contrast, the traditional melaio process proved indispensable for guiding the fruit towards a significantly more homogeneous final coloration (∆E* ≈ 5.5). The integrated MCP+Melaio strategy successfully reconciled these divergent effects, preserving high flesh firmness (47.9 N) while achieving the superior skin color uniformity characteristic of the traditional process (final ΔE* ≈ 5.6). This study demonstrates that pre-treating ‘Annurca’ apples with 1-MCP before the melaio period offers a viable, scientifically validated approach to resolving the critical trade-off between texture and skin color, enabling the ‘Annurca’ industry to meet modern textural expectations while preserving its unique cultural and quality traditions.