Quality of 'Conference' Pears as Affected by Initial Low Oxygen Stress, Dynamically Controlled Atmosphere and 1-MCP Treatment

摘要

'Conference' pears in Italy are often subjected to superficial scald in cold storage, impairing their marketing. Among the postharvest methods employed to control scald, some include treatment at harvest with 1-methylcyclopropene (1-MCP), dynamically controlled atmosphere (DCA) and initial low O2 stress (ILOS). This research aimed at studying the influence of these treatments on the quality of 'Conference' pears. Treated (300 nl/L 1-MCP, Smartfresh) and untreated pears (control), after 4 weeks at -0.5°C, were stored in controlled atmosphere (CA, 2 kPa O_2 + 0.7 kPa CO_2), with or without ILOS (0.3-0.5 kPa O_2) and in DCA (0.3-0.5 kPa O_2 + 0.45 kPa CO_2). ILOS was applied twice for 2 weeks with a 3 weeks interval, while monitored with fluorescence sensors (HarvestWatch~(TM)). After 4 months of storage, fruit were put at 20°C up to 7 days and evaluated for skin color, pulp mechanical properties (firmness, stiffness, energy-to-rupture), ethylene production (EP), sensory characteristics and storage disorders. Fruit softening and EPwere strongly reduced by 1-MCP. Skin yellowing was slowed down by 1-MCP, especially in DCA and ILOS+CA pears which maintained the greenest color throughout the shelf life period. Control fruit stored in DCA and in ILOS+CA at dl of shelf life had a skin color similar to that of treated pears, showing a quick yellowing with the progress of shelf life period. Treated pears were perceived as firmer and less juicy than control ones regardless of the storage atmosphere. DCAtreated pears were more grainy and astringent, and less sweet and aromatic than control DCA fruit. Treated ILOS+CA fruit were perceived as grainy and astringent as control ILOS+CA pears, but less sweet and aromatic. Two types of storage disorders were detected: blackening which was distinguished in two forms (early blackening and black spot) differing for the color and the severity of the disorder. Black spot was developed only in treated DCA fruit (4); early blackening and black speck were developed in all atmospheres, the former more pronounced in control fruit, with DCA treated pears showing the lowest percentage of early blackening.