Progress on Extending the Shelf Life of Melons and Beans

As melon fruit begin to ripen they produce large amounts of ethylene gas – and this gas in turn triggers a number of additional ripening reactions including fruit softening and weakening of the connection between the fruit and the rest of the plant. Although some of these ethylene responses are beneficial, they also ultimately lead the fruit to lose quality and become over mature. Unfortunately, the orange fleshed cantaloupes that do well in the short growing season available in Saskatchewan also produce more ethylene than do the green fleshed honeydews – which may explain why locally grown cantaloupes also seem to have a limited shelf life.

Aminoethoxyvinylyglycine (AVG) is a recently developed product that safely and effectively blocks ethylene production. AVG is used commercially in apples – where it is being used to supplement or substitute for very expensive controlled atmosphere storage. However, a study by Leskovar and associates (2006) suggests that AVG may be of only limited use for extending the post-harvest life span of melons. They found that application of AVG to the foliage of the melon crop 1-3 weeks prior to fruit harvest slowed ripening of the fruit and occasionally reduced fruit size without providing any beneficial effect on keeping quality. Applying the AVG through the drip system prior to harvest did improve fruit firmness after harvest, but had no effect on other key quality indicators.

1-MCP (SmartFresh) is another new ethylene inhibitor which is being tested as a tool for extending the post-harvest lifespan of horticultural crops. Jeong (et al 2008) found that mature cantaloupes treated with 1-MCP gas just after harvest retained their firmness, both during storage and after processing into a fresh cut product. However, as was observed with AVG treatment, 1-MCP treatments failed to protect the fruit from other aspects of post-harvest decline like color change and watersoaking.

Many vegetable crops like lettuce and green bean are harvested at an immature growth stage. Exposing these crops to ethylene after harvest triggers a rapid increase in respiration and accelerates the loss of quality. Cho (et al 2008) showed that treating freshly harvest green beans with 1-MCP slowed the yellowing that typically occurs following exposure to ethylene. The 1-MCP treatments also appeared to protect the beans from the adverse changes (brown spot and watersoaking) that occur during storage at low temperatures (<7°C) for extended periods of time.

Sources :

  • Leskovar et al. (2006) HortScience 41: 1249-1252
  • Jeong et al (2008). HortScience 43: 435-438.
  • Cho et al (2008). HortScience 43:427-430.