Automatic periodical negative air ions reduce postharvest decay and maintain texture and flavor quality of ‘Fuji’ apple during long-term cold storage

The aim of this study was to explore the effect of periodical negative air ions (NAI) on the quality of 'Fuji' apple fruit after treatment at 0, 30, 60, and 90 min every 4 weeks. NAI for 60 min decreased weight loss, mitigated decay, and maintained hardness of the apple fruit during the 40 weeks of storage. Treatment of fruits with NAI for 60 min enhanced the apple defense ability against pathogens by maintaining the cell wall integrity and improving the related-enzyme activities as well as accumulation of total phenols and flavonoids. Reverse-phase HPLC and solid-phase microextraction GC-MS analysis showed that NAI treatment for 60 min increased the levels of fructose, sucrose, sorbitol, malic acid and volatiles, such as 2-hexenal, 2-methylbutyl acetate, hexyl acetate, and ethyl butanoate. Taken together, NAI is promising for improving the quality 'Fuji' apples during the cold storage.