Pre and postharvest application of regulators enhances bell pepper quality and antioxidant levels during cold storage

Post-harvest quality maintenance of bell peppers (Capsicum annuum L.) presents significant challenges in commercial agriculture due to their high perishability and sensitivity to cold storage conditions. While ethylene regulators show promise in extending storage life, the optimal timing and method of application remain unclear. To evaluate the effectiveness of two ethylene regulators (1-methylcyclopropene (1-MCP) and sodium nitroprusside (SNP) as a nitric oxide donor) applied at different developmental stages on quality retention and antioxidant preservation in bell peppers during cold storage. Green Bianca and Red California Wonder bell pepper cultivars were treated with either 1 µmol L^-1 1-MCP or 5 µmol L^-1 SNP at three timing intervals: pre-harvest, post-harvest, or both. Following a factorial design with three replications, fruits were stored at 7 ± 0.5 °C with 80-85% relative humidity for 28 days. Comprehensive analysis included physical attributes (firmness, weight loss, shape index), chemical properties (pH, titratable acidity, soluble solids), bioactive compounds (vitamin C, phenolics, flavonoids), pigments (chlorophylls, carotenoids, lycopene), and physiological responses (chilling injury, ion leakage, antioxidant capacity). Pre-harvest application of SNP proved most effective for both cultivars, with Green Bianca showing superior retention of vitamin C (73.19 mg100g^-1), antioxidant capacity (61.06%), and minimal weight loss (0.19%). Red California Wonder demonstrated optimal response to pre-harvest NO treatment, maintaining high antioxidant activity (45.16%) and vitamin C content (99.92 mg100g^-1). Treatment timing significantly influenced effectiveness, with pre-harvest applications showing particular efficacy in maintaining membrane integrity and reducing chilling injury while preserving bioactive compounds. This study establishes the timing-dependent efficacy of ethylene regulators in bell pepper preservation and provides valuable insights for developing cultivar-specific post-harvest protocols. The findings offer practical solutions for extending market life and maintaining nutritional quality of bell peppers during cold storage, with potential applications in commercial post-harvest management systems.