Effect of 1-MCP and Temperature on 'Songold' Plum Postharvest Quality: (1) after Refrigeration

This experiment was conducted to evaluate the effect of 1-methylcyclopropene (1-MCP) treatment and temperature on 'Songold' plums quality after refrigeration, as a strategy to save energy and reduce costs in packinghouses. Fruit harvested at commercial maturity were treated with SmartFresh (0.6 mu l L-1 of 1-MCP) at 0 or 8 degrees C for 24 h and submitted to three different storage conditions with 90-95 % relative humidity: 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 (TT15). Untreated fruit stored at 0 and 8 degrees C were used as controls (C0 and C8, respectively). Skin colour, weight loss, flesh firmness, soluble solids content and titratable acidity were assessed at harvest and after 30 and 50 days of cold storage. After 50 days of cold storage, fruit exhibited their characteristic ripening colour pattern changing from green-yellow (SF0, C0 and TT15) to yellow-orange (SF8 and C8). Regarding flesh firmness, 1-MCP treated fruit (SF0, TT15 and SF8) and C0 fruit were "ready to buy" (16-25 N), while C8 plums were too soft to be commercialised (< 5 N). Neither 1-MCP nor temperature affected soluble solids content and titratable acidity. SF8 and C0 were equally effective in delaying colour modifications, weight loss and softening throughout 30 days of cold storage, and TT15 and SF0 were the most effective treatments in maintaining fruit quality. Moreover, SF8 and TT15 treatments slightly improved colour uniformity among fruit and they represent an energy saving for packinghouses.