Functional modification of gum Arabic with nitric oxide donor: Coating characterization with modulation of...

Postharvest quality deterioration is a major issue in citrus fruits, often driven by oxidative stress, moisture loss, and membrane degradation during prolonged storage. This study evaluated the synergistic effect of polysaccharide-based coating, gum Arabic (GA), combined with a nitric-oxide donor on maintaining lemon quality and antioxidant defence during 60 days of storage for two consecutive years. The GA polysaccharide matrix was characterized using Fourier Transform Infrared spectroscopy and rheological profiling (viscosity-shear rate profiling), confirming its suitability as a stable film-forming system. Antioxidant enzymes (SOD, POD, CAT, PAL) and radical-scavenging assays (DPPH and OH•) revealed that GA 10% + SNP 2 mM provided the strongest enhancement of both enzymatic and non-enzymatic antioxidant systems. The treatment also minimized weight loss, respiration, and membrane injury while better preserving key quality attributes (phenols, flavonoids, acidity, ascorbic acid). Furthermore, multivariate analyses, including correlation and hierarchical clustering, demonstrated strong positive linkages among antioxidant traits and their negative association with senescence indicators, confirming the coordinated protective response induced by the coating. The scanning electron microscopy (SEM) further showed a smoother, more uniform surface in GA 10% + SNP 2 mM-coated fruits, supporting its superior functional performance. Overall, the 10% GA + 2 mM SNP formulation represents a potent, synergistic coating for extending lemon shelf-life.