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Summary of full report
Graeme Thomson, Sonja Winkler,
& Ian Wilkinson
January 2003
RIRDC Publication No 02/153 RIRDC Project No DAV-189A
Executive Summary
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 o C) or at the sub-optimal temperature of 12 o C.
(Thai basil was only stored at 12 o 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 o 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 o C and 0 o 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 o C is preferable and if 1-MCP has a commercial role, it is perhaps at higher than optimum handling temperatures (like 12 o C).
For kailaan and Thai basil, treatment with 1-MCP had limited benefits. With 24 hour treatment times for kailaan, less yellowing occurred at 12 o C if fumigation included 1-MCP. At this same temperature, there was a slight trend for 1-MCP to provide some protection against Thai basil leaf loss.
1-MCP effects on coriander and buk choy were not observed with the experimental procedures employed.
The equipment and set-up required to conduct fumigation with 1-MCP is not complex and might be readily adopted by growers who do not have cooling facilities, or have limited cooling facilities in a hot environment. Recommendations were made for on-farm procedures and equipment for safe fumigation, and these were translated into Chinese and Vietnamese. However, 1-MCP remains currently available for experimental use only.
Overall, it appears that 1-MCP does not substitute for appropriate use of optimal, cool handling and storage temperatures but if these temperatures cannot be maintained there may be a role for use of 1- MCP in some circumstances, especially for choy sum, spearmint and Shanghai buk choy.
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