Efficacy of 1-Methylcyclopropene (SmartFresh™) on Quality Retention of 'Rocha' Pear during Long-Term Storage under Controlled Atmosphere

The ban on the use of diphenylamine (DPA), effective in the harvest season of 2013, is forcing a change in the technology for long-term storage of 'Rocha' pear (Pyrus communis L.). Efficacy of 1-methylcyclopropene (1-MCP, SmartFresh (TM)), at 312 and 150 nl L-1, was evaluated in 'Rocha' pear in comparison with the standard postharvest treatments used by the Portuguese pear industry: drenching with the fungicide imazalil alone and with imazalil combined with DPA. Fruit harvested at commercial maturity from four representative orchards in the Oeste Region, Portugal, were subjected to the postharvest treatments and stored at 0 degrees C, 90-95% RH, under controlled atmosphere (CA, 3 kPa O-2 + 0.7 kPa CO2), for up to 9.4 months. The CA regime was imposed immediately after the beginning of cold storage or after an 8-week delay. 1-MCP at 312 nl L-1 reduced fruit softening, skin yellowing, and acidity loss, and increased soluble solids content in comparison with control fruit treated with fungicide alone or combined with DPA. Superficial scald appeared during the shelf-life after a storage period of 243 days (ca. 8 months). 1-MCP at 312 nl L-1 was more effective than DPA in reducing superficial scald. Delayed CA increased scald incidence in relation to immediate CA. 1-MCP at 150 nl L-1 was effective in reducing superficial scald with minimal effect on ripeningrelated changes. Internal browning disorders occurred after 243 days in CA storage. DPA reduced the incidence of internal browning after a storage period of 281 days, but not after subsequent shelf-life. 1-MCP at 312 nl L-1 was as effective as DPA in reducing the incidence of internal browning under immediate and delayed CA conditions. On average, delayed CA storage appeared to be slightly better than immediate CA in reducing internal browning disorders during storage but the effect did not persist during shelf-life. In conclusion, 1-MCP at 312 nl L-1 was an effective replacement for the conventional treatment with DPA in 'Rocha' pear stored under CA for up to 9 months. At 150 nl L-1, 1-MCP had little effect on ripening-related changes and was less effective in protecting against the physiological disorders. Delayed CA did not seem beneficial for 'Rocha' pear.