PRE-STORAGE CONDITIONING OF NON-MELTING FLESH PEACHES USING DIRECTED HEAT STRESS ALONE OR COMBINED WITH 1-METHYLCYCLOPROPENE TO MAINTAIN FRUIT QUALITY DURING POSTHARVEST HANDLING

Non-melting flesh (NMF) peaches are better suited for shipping and long-term storage than traditional melting flesh (MF) peaches due to slower texture change and lack of excessive softening at the final stage of ripeness. Pre-storage hot water and 1-methylcylopropene (1-MCP) applications have been reported separately to inhibit ripening of MF peaches; we hypothesized that hot water combined with 1-MCP may be more effective than either treatment alone in delaying softening and maintaining other sensory qualities. In this study, NMF ‘UF Sun’ peaches were immersed for 30 min in water at 25°C (Control) or 46°C (HW), 1.5 mg/L of aqueous 1-MCP solution at 25°C (1-MCP), or 1.5 mg/L of aqueous 1-MCP at 46°C (HW+ 1-MCP) then placed either directly at 20°C for 7 days or placed at 20°C after 14 days at 0°C. The HW peaches retained their initial flesh firmness better than control, 1-MCP or HW+1-MCP peaches during storage at 20°C, possibly due to inhibition of both ethylene-dependent and ethylene-independent pathways. 1-MCP and HW+1-MCP peaches had significantly lower ethylene production than the other treatments at the climacteric peak, whether the fruit were placed directly at 20°C or were first stored at 0°C. Transient retention of flesh firmness followed by rapid softening was observed for 1-MCP-treated peaches during both storage conditions. HW+1-MCP fruit exhibited the most consistent firmness retention at 20°C and after 0°C storage compared with the other treatments, thus HW+1-MCP can be con¬sidered as a potential pre-storage conditioning method for ‘UFSun’ peaches.