Controlled atmosphere pO2 alters ripening dynamics of 1-MCP treated ‘d’Anjou’ pear (Pyrus communis L.) fruit

Authors: Mattheis, James

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2017
Publication Date: 11/8/2017
Citation: Mattheis, J.P. 2017. Controlled atmosphere pO2 alters ripening dynamics of 1-MCP treated ‘d’Anjou’ pear (Pyrus communis L.) fruit. HortScience. 52(10):1385–1389. https://doi.org/10.21273/HORTSCI12286-17.
DOI: https://doi.org/10.21273/HORTSCI12286-17

Interpretive Summary: ‘d’Anjou’ is a popular pear variety that can be stored for months after harvest. Cold storage in air or a controlled atmosphere where oxygen concentration is reduced to 1-2% slows fruit ripening and allows fruit to be commercially available over most of the year. In spite of the cold, low oxygen storage environment, peel browning can occur after several months that makes fruit cosmetically unattractive. Postharvest technologies that limit ripening as well as peel browning exist, but optimizing storage management systems to allow predictable ripening with no peel browning have been challenging storage operators. Research conducted at the USDA, ARS Tree Fruit Research Laboratory demonstrated increasing storage oxygen concentration from 1-2% to up to 5% can result in fruit that ripens better after removal from storage without developing peel browning. This information provides pear producers with another option for postharvest management that can contribute to availability of great looking, high quality pears in retail markets well into the summer the year after harvest.

Technical Abstract: Ripening and development of physiological disorders and decay were assessed in ‘d’Anjou’ pear fruit following 1-methylcyclopropene (1-MCP) treatment and cold storage in air or controlled atmosphere (CA). Fruit were exposed after harvest to 0 or 12.6 µmol•L-1 1-MCP and then stored at 0.5 oC in air or 1, 3, or 5 kPa O2 with 0.5 kPa CO2. Pears were held post-storage at 20 oC for 7 days prior to analysis. 1-MCP fruit usually had higher hue compared with controls. Softening after removal from storage was delayed in 1-MCP fruit regardless of storage atmosphere, however, control fruit stored in air or CA ripened to below 23 N, a minimum value for consumer acceptance, after all storage durations. 1-MCP fruit stored in air, 3, or 5 kPa O2 softened in the outer cortex (fruit surface to 8 mm into the cortex) to below 23 N only after 9 m, however, only fruit stored in air softened to less than 23 N in the inner cortex (8 mm to coreline). 1-MCP treatment also delayed deformation in cortex tissue tensile strength (TTS); after 6 or more months 1-MCP fruit TTS was lower compared with those for control fruit. After 9 m 1-MCP fruit stored in air had TTS values similar to those of controls while values for fruit stored in CA increased with CA O2 concentration. Titratable acidity was higher in 1-MCP treated fruit stored in air (6 m only) or 3 or 5 kPa O2 compared with controls. Superficial scald developed after 6 m on control fruit stored in air or 5 kPa O2 and on control CA fruit regardless of O2 concentration after 9 m. No 1-MCP fruit developed scald. The results indicate ‘d’Anjou’ pear ripening in response to 1-MCP is influenced by storage pO2 as well as storage duration, and at the 1-MCP treatment concentration used, softening to a consumer standard for firmness occurred only in fruit cold stored in air for 9 months plus a 7 day post-storage ripening period. These fruit had peel hue less than 100 and the yellow peel color may not be consistent with current market expectations.