Abstract:

Having been held in 10 mL/L 1-methylcyclopropene (1-MCP) or air for 18 h, seedless watermelon (Citrullus lanatus Thunb. Mansfeld, cv. Millionaire) fruit was cut to obtain pericarp cylinders (7 mm in diameter, 40 mm thick), which were rinsed with 2% CaCl₂ or deionized water and then stored at 10 ℃. Tissue firmness, electrolyte leakage and activities of phospholipase C (PLC), phospholipase D (PLD) and lipoxygenase (LOX) were determined. Results suggested that 2% CaCl₂ stimulated activities of phospholipase C (PLC), phospholipase C (PLD) and lipoxygenase (LOX), but maintained tissue firmness throughout storage. CaCl₂ alone may not be sufficient to maintain quality of fresh-cut watermelon and even would exert negative effects for stimulating lipolytic enzymes. 1-MCP counteracted CaCl₂ in regulation of PLC, PLD and LOX. Combination of 1-MCP and CaCl₂ retarded the ripening process, as illustrated by higher firmness and lower activities of lipolytic enzymes in relative to the control.

Key words: calcium chloride, 1-methylcyclopropene (1-MCP), watermelon, phospholipase, lipoxygenase