Treatment of Asian Vegetables and Herbs with 1-MCP
Trials investigated 1-MCP (1-methylcyclopropene) as a pre-storage treatment for freshly harvested whole heads or stems of choy sum (Chinese flowering cabbage), kailaan (Chinese flowering broccoli), Shanghai buk choy, buk choy, coriander, spearmint and Thai basil. Strategies for optimising 1-MCP fumigation effects included varying both the concentration of fumigant and its application time.
All 1-MCP fumigation trials were conducted on produce which retained field heat because 1-MCP action has been shown to be more effective in warmer rather than colder tissues. Fumigation was commenced within four hours of harvest. After fumigation, products were stored in high humidity packaging at optimum storage temperature (usually 0°C) or at the sub-optimal temperature of 12°C. (Thai basil was only stored at 12°C due to the chilling sensitivity of this product). A control treatment was always included, with produce placed immediately into storage at the optimum temperature (usually 0°C) and therefore representing best cool chain practice.
Of the seven crops examined, three responded positively in some way to experimental fumigation with 1-MCP. Under some circumstances, commercial use of 1-MCP with choy sum, Shanghai buk choy and spearmint may be justified. 1-MCP can improve the general visual quality and reduce leaf yellowing of choy sum and Shanghai buk choy. These effects were partly observable under different circumstances at both of the tested storage temperatures, ie. 12°C and 0°C. Choy sum fumigated with 1-MCP also experienced less leaf loss, a benefit shared with spearmint. However, generally for all three of these crops, storage at optimum 0°C is preferable and if 1-MCP has a commercial role, it is perhaps at higher than optimum handling temperatures (like 12°C).