Interactive effects of irrigation water quality and UV‐C treatment on bioactive compounds and microbial safety of saffron ( <i>Crocus sativus</i> L.)

Abstract The influence of pre‐harvest irrigation water quality on post‐harvest ultraviolet‐C light (UV‐C) treatment efficacy remains unexplored for saffron ( Crocus sativus L.), despite its importance for both safety and bioactive compound preservation. This study investigated the interactive effects of irrigation water quality (clean groundwater, treated wastewater, and chemical fertilizer‐enriched) and UV‐C exposure time (0, 60, 120, and 180 min) on saffron stigma composition and microbial contamination. Analysis of variance revealed significant effects ( p &lt; 0.01) of both irrigation source and UV‐C treatment on most quality parameters. UV‐C exposure significantly reduced safranal (40.5–22.4 E1% 330 nm) and crocin (268.9–190.8 E1% 440 nm) content, with wastewater‐irrigated samples showing the most severe degradation. Picrocrocin levels increased, reaching a peak at 120 min of UV‐C exposure (93.8 E1% 257 nm), before declining at longer exposure times. Irrigation with wastewater resulted in significantly higher microbial counts (1250 colony forming unit [CFU]/g) compared to clean water (520 CFU/g), but 180 min UV‐C effectively reduced contamination by 65%–74% across all treatments ( p &lt; 0.01). Principal component analysis revealed that moderate UV‐C exposure (60–120 min) combined with clean water irrigation provided optimal balance between microbial control and compound preservation. These findings demonstrate that while UV‐C treatment can effectively control microbial safety, prolonged exposure risks degrading key saffron bioactive compounds, with irrigation water quality significantly influencing this susceptibility. Optimizing both irrigation practices and UV‐C treatment parameters is crucial for preserving saffron quality while ensuring food safety.