Effect of repeated low oxygen stress (RLOS) on physiological disorders, physico-chemical properties and sensory parameters of 'Packham's Triumph' pears

'Packham's Triumph' pears are susceptible to several postharvest physiological disorders that may reduce the fruit quality during long term storage. The aim of the study was to develop a storage protocol based on repeated low oxygen stress (RLOS). Optimally harvested fruit was stored for 2, 4, 6, 8 and 10 months at -0.5°C. Pears were subjected to low oxygen stress at 0.5% O₂ for 10 d, then for 7 d for the following periods, followed by ultra-low oxygen (ULO) at 0.9% O₂ and 0.8% CO₂ or controlled atmosphere (CA) storage of 1.5% O₂ and 2.5% CO₂ for 21 d. Regular atmosphere (RA) storage served as the control. The fruits were assessed for physiological and pathogical disorders, physico-chemical properties, and sensory parameters after 6 weeks simulated shipment and handling period and at 7 d shelf life. No incidence of superficial scald was observed under RLOS treatments up to 10 months at both 0 and 7 d shelf life (p<0.0001). The colour change was significantly higher under RA in comparison to RLOS treatments for all storage durations (p<0.0001). RLOS treatments had significantly higher TSS content than the control (p=0.0035) and retained harvest firmness up to 8 months of storage (p<0.0001). RLOS treatments had significantly higher scores for most of the sensory parameters and maintained good fruit quality up to 10 months of storage. This study showed that RLOS storage inhibits the development of physiological disorders and maintains pear quality during long term cold storage.