A new idea for how anti-aging products delay ripening of fruit and wilting of flowers

The authors propose that a chemical reaction occurs between 1-MCP and naturally-occurring copper in plant cells. This knowledge could guide researchers in their attempts to discover new ethylene-blocking chemicals for preserving the freshness of fruits, vegetables and flowers for longer than currently is possible.

Until now, researchers believed that a “complex” – a chemical structure consisting of molecules that are weakly connected to one another – formed between 1-MCP and copper.

“A complex is loose and can break apart easily – something we don’t see happening in the case of 1-MCP in plants,” Pirrung explained. “A chemical reaction, which is far stronger than a complex, accounts for why 1-MCP is so effective.”

How 1-MCP prevents ripening and wilting:

Plant cells possess copper-containing ethylene binding sites called ethylene receptors. (An ethylene receptor is a protein that sits in the cell membrane and has a site for binding ethylene on the outside of the cell.) When ethylene comes into contact with the receptor, it binds chemically with the copper, which inactivates the receptor. The inactivation results in the cell breaking down, which, in turn, initiates aging and the death of plant tissues.

1-MCP works by beating ethylene to the receptors. By binding with a sufficient number of receptors chemically and permanently, it forever makes them insensitive to ethylene. The plants do not “perceive” ethylene thereafter, preventing ripening and wilting.

Furthermore, unlike ethylene, 1-MCP does not inactivate the receptors. As a result, the cells do not break down, which prolongs the freshness of flowers and fruit after harvest, extends their shelf life, reduces waste and, ultimately, benefits producers and consumers.

Administering 1-MCP:

Because 1-MCP is an unstable gas, growers face a challenge in delivering it to fruits and flowers. Commercially, 1-MCP therefore is complexed with alpha-cyclodextrin, a ring-structured biocompatible molecule formed of six linked glucose units, to produce a stable, water-soluble powder.

When the powder is dissolved in water, 1-MCP is released as a vapor that travels through the air, making its way eventually to plants’ ethylene receptors.