Effects of HHAIB combined with FIR-PVFD on drying characteristics, microstructure, physicochemical properties, and pesticide residues of celery stalks (Apium graveolens L.).

This study innovatively combined high-humidity hot air impingement blanching (HHAIB) with far-infrared radiation assisted pulsed vacuum freeze-drying (FIR-PVFD) and systematically investigated the effects of pretreatment duration (0-150 s) and drying temperature (55-70 °C) on the quality of celery stalks. Results showed that HHAIB destroyed the cellular structure, shortened drying time, reduced FIR-PVFD-specific energy consumption by 16.67%-44.50%, promoted the release of bioactive compounds, and enhanced in vitro antihypertensive activity. Comprehensive multi-index analysis identified the optimum condition as 90 s of HHAIB pretreatment combined with FIR-PVFD at 65 °C, achieving a good balance between drying efficiency and physicochemical quality. Furthermore, this pretreatment effectively decreased carbendazim, procymidone, pyrimethanil, and imidacloprid residues by 62.54%-88.04% and reduced the chronic dietary exposure risk (% ADI) for dried celery to 0.55%-13.17%. This composite technology demonstrates outstanding advantages in quality improvement and energy conservation for celery processing, with promising industrial application prospects.