Improving disinfection and packaging strategies for the effective preservation of welsh onion (Allium fistulosum L.)

This study aimed to improve postharvest preservation strategies for Welsh onion (Allium fistulosum L.) by optimizing disinfection techniques and packaging methods. This study pioneers the combination of cold plasma treatment and nanocomposite packaging as a novel approach to enhance shelf life and preserve quality in Welsh onion. The research was conducted in two phases. In the first phase, disinfection was performed using gamma irradiation (1, 3, and 5 kGy) and cold plasma (15, 20, and 25 kV for 5, 10, and 15 min). In the second phase, four gas-barrier nanocomposite films were tested under both ambient and vacuum-sealed storage conditions for 4, 8, and 12 months. Volatile compounds were analyzed using gas chromatography (GC and GC/MS). Cold plasma treatment was more effective than gamma irradiation in preserving key postharvest quality parameters. The highest phenolic content and antioxidant activity were observed in samples treated with cold plasma at 25 kV for 5 min, with a phenolic content of 196.84 mg GAE/g DW and an IC₅₀ value of 78.74 μg/mL. Nonetheless, all packaging treatments showed declines in total phenolics, essential oil yield, and L* color values over time. The major volatile compounds in the essential oil included dipropyl disulfide (9.0%-18.3%), dipropyl trisulfide (9.4%-16.4%), dimethyl trisulfide (5.3%-11.1%), diallyl disulfide (6.8%-11.4%), and d-limonene (4.0%-9.1%). These findings provide valuable insights into the postharvest management of leafy vegetables such as Welsh onion.