1-MCP: How Useful Can It Be on 

 New England Apples? 



Sarah A. Weis and William J. Bramlage 



Department of Plant & Soil Sciences, University of Massachusetts 



Fruit ripening is initiated by ethylene, and to some 

 extent, the rate at which ripening proceeds is regulated 

 by its concentration in the fruit. Fruit generally soften 

 faster at high ethylene levels, but ethylene is also 

 needed to stimulate formation of flavor producing 

 volatiles in the fruit. Low temperature air storage 

 slows the progress of ripening but does not prevent the 

 changes it produces. Controlled atmosphere (CA) 

 storage, however, can interfere with ethylene actions 

 and alter the quality of ripened fruit. 



For ethylene to have an effect, it must first be 

 bound on the surface of the cells. 1- 



Methylcyclopropene ( 1 -MCP) i s a new compound that 

 can block this ethylene binding and prevent or 

 seriously interfere with ethylene induced fruit ripening 

 and its effects on fruit quality. Recent studies of 1- 

 MCP treatment of apples have produced some exciting 

 results, including substantial retention of firmness and 

 dramatic reduction of superficial scald. However, 

 effects have not been entirely consistent, especially on 

 Mcintosh, and further tests to characterize responses 

 to 1-MCP are clearly needed. 



1-MCP is obtained as a powder that is used to 

 generate 1-MCP gas within a closed area containing 

 harvested fruit. Following treatment the fruit can be 

 placed into air or CA storage and will require no 

 follow-up 1-MCP treatment. The material is not yet 

 commercially available, but since it does not leave any 

 residue on the fruit and is incorporated into the iruit in 

 minute concentrations, no health issues have arisen to 

 our knowledge, so its labeling might occur soon 



There are many questions surrounding potential 

 use of 1-MCP. Results do not appear to be uniform 

 across cultivars. If ripening has begun before a fi^it is 

 treated, presumably it will continue despite treatment, 

 making time of harvest a crucial concern. If ripening is 

 blocked, will a fruit recover sufficiently to develop 

 quality attributes, especially flavor? For these 

 reasons, in Fall 2001 we initiated experiments to 



evaluate 1 -MCP effects on apples under New England 

 conditions. 



We surveyed 1-MCP effects on a range of 

 cultivars from early- to late-maturing, and at different 

 harvest times for individual cultivars. Cultivars 

 reported here are Ginger Gold, Gala, Mcintosh, 

 Delicious, and Spigold. All fhiit were stored in 32F air 

 following treatment, the durations of storage varying 

 among cultivars. For all cultivars, internal ethylene 

 concentration and fruit firmness were evaluated. 

 Occurrence of storage disorders was recorded, and, for 

 Delicious, fruit weight loss was determined since there 

 IS some evidence that 1-MCP reduces it during and 

 following storage. 



Application 



The 1-MCP is provided as a powder. When mixed 

 with water, 1 -MCP is released as a gas. This is not an 

 instantaneous reaction. Apples were harvested and 

 cooled overnight at 32F. A sample of approximately 

 one bushel was then removed from the cold storage 

 and placed in a 33 gallon plastic trash barrel. A petri 

 dish with 200 mg of the 1-MCP powder was then 

 placed on top of the apples and was mixed with 5 ml of 

 warm water. The barrel was immediately covered with 

 plexiglass and sealed with silicon vacuum grease. This 

 procedure was to produce a concentration of 1 part per 

 million 1-MCP in the barrel. The barrel was then 

 returned to cold storage. After 24 hours the barrel was 

 removed from cold storage, the apples were removed, 

 returned to conventional boxes, and put back into cold 

 storage. 



We looked at only some of the known effects of 1 - 

 MCP on fruit. Internal ethylene and fruit firmness 

 were measured at harvest and following storage. Some 

 fruit were weighed at these times as well, as it had been 

 reported that I -MCP could influence weight loss in 

 apple. Background color was recorded for Royal Gala. 



Fruit Notes, Volume 67, Summer, 2002 



