1-Methylcyclopropene (1-MCP) is a synthetic cyclic olefin that inhibits ethylene by blocking access to the ethylenebinding receptor (Sisler and Serek, 1997). 1-MCP has been used extensively in the apple industry since 2002 to retain fruit firmness in cold storage and extend shelf life. It is marketed as SmartFreshSM by AgroFresh, Inc. (Springhouse, PA).