Modified Atmosphere Packaging and Melatonin Treatment Extends Shelf Life and Preserves Bioactive Quality of 'Tayfi' (Vitis vinifera) Grapes During Cold Storage

Quality degradation and crop loss during postharvest storage are important factors affecting the shelf life and marketing of grapes. This study evaluated the individual and combined effects of melatonin and modified atmosphere packaging (MAP) as integrated bioprocess strategies to extend the shelf life and maintain the quality, biochemical, and organic acid content of 'Tayfi' (Vitis vinifera) grapes during storage. Among all treatments, MAP most effectively limited weight loss (6.63% at day 27 vs. 22.06% in control), while melatonin treatment provided the best preservation of fruit flesh firmness at the end of the storage period. The melatonin + MAP combination proved superior in maintaining skin color parameters (L*, chroma, hue), total phenolic content (2.95% change), antioxidant activity (3.22% change), and organic acid profile, including tartaric, malic, oxalic, and fumaric acids. Principal component analysis and hierarchical heatmap analysis confirmed distinct clustering of MAP-based treatments from the control, highlighting the process efficiency of packaging-based interventions. These findings demonstrate that MAP, particularly when combined with melatonin, represents a cost-effective, scalable, and commercially viable bioprocess approach for extending the cold storage life of grapes while preserving their nutritional and sensory quality.