49F-24 |
|
M. I. CANTWELL1, P. Freitas, X. Nie, and G. Hong. (1) Dept. Vegetable Crops, University of California, One Shields Avenue, Davis, CA 95616 Ethylene can have negative effects on postharvest quality of leafy vegetables such as spinach, depending on temperature, ethylene concentration and length of exposure. 1-MCP (1-methylcyclopropene, commercially formulated as SmartFresh®) blocks the ethylene-binding site in plant membranes and prevents ethylene responses. This chemical tool offers the opportunity to reevaluate the effects of ethylene and storage temperature on shelf-life and quality of spinach cultivars currently grown for the fresh market. The main objective was to determine the postharvest quality of spinach under good and poor temperature management in relation to ethylene exposure and inhibition. Five experiments were conducted using young spinach leaves obtained from processors on the day of harvest. Ethylene concentrations of 0, 0.1, 1 and 10 ppm were provided in humidified flows through the storage containers. Leaves were pretreated with 1000 ppb 1-MCP for 12 hours. Spinach was evaluated after 0, 3, 6 and 9 days at 10C and after 0, 6, 12 and 18 days at 5C for visual appearance and defects, L*a*b* color values, and concentrations of chlorophyll, carotenoids, ascorbic acid, and ammonia. Respiration rates (CO2 production) were measured in 3 experiments. Ethylene induced significant increases in respiration rates at 5 and 10C and this resulted in increased yellowing (lower hue values), most notable at 10C after 9 days, but also evident at 5C after 20 days. 1-MCP treatment prevented the increases in respiration rates caused by ethylene and prevented loss of chlorophyll and carotenoids. Ammonia concentrations remained low in all 1-MCP-treated spinach, whereas untreated spinach exposed to ethylene had 2-fold and 3-8-fold increases at 5 and 10C, respectively. 1-MCP treatment also resulted in higher ascorbic acid concentrations at 10C, but not 5C, in ethylene-exposed spinach. 1-MCP is clearly effective in reducing detrimental ethylene-induced deterioration in spinach, especially under temperature abuse conditions.
Session 49F, Fruit & Vegetable Products: Fresh vegetables
|