Effect of 1-MCP and Temperature on 'Songold' Plum Postharvest Quality (2) after Shelf-Life

The effect of temperatures higher than the usual refrigeration temperatures on 'Songold' plums treated with 1-methylcyclopropene (1-MCP; Smartfresh) has been evaluated, to assess if this method could be used to save energy and to achieve uniformity of fruit ripening. Plums (Prunus salicina Lindl.), harvested at commercial maturity, were treated with 600 ng L-1 1-MCP and stored for 30 and 50 days at 95% relative humidity at 0 degrees C (SF0), 8 degrees C (SF8), and 10 days at 0 degrees C, followed by 15 days at 8 degrees C and then 5 and 25 days at 0 degrees C to reach 30 and 50 days of storage, respectively (SF0/8). Untreated plums were stored at 0 degrees C (C0) and 8 degrees C (C8) and used as control. Fruit were removed from cold storage after 30 and 50 days and kept for 5 days at 20 degrees C (shelf-life). After that, they were analyzed for weight loss, flesh firmness, soluble solids content (SSC), titratable acidity (TA) and skin colour. 1-MCP treatment did not affect weight loss but it retained flesh firmness. After 30 days plus shelf-life, 1-MCP treated fruit stored at 0 degrees C showed a "ready to buy" flesh firmness, while SF8 were "ready to eat" and control plums were too soft. SF0/ 8 fruit exhibited the highest SSC and TA after 50 days of storage. 1-MCP helped to maintain characteristic fruit colour, regardless of temperature, for up to 30 days storage plus shelf-life. After 50 days, SF0/ 8 and SF0 fruit still had acceptable colour. At 30 days of cold storage at 8 degrees C plus 5 days of shelf-life, 1-MCP maintained plum quality assuming an energy saving for packinghouses. At the end of storage only SF0 and SF0/8 fruit were still commercially acceptable.