Hebrew U invention will keep fruit and flowers fresh longer

A new compound developed in part by scientists at Hebrew University that extends the shelf life of fruits and vegetables, and allows farmers more time to harvest wheat and other crops, will be commercially developed by a subsidiary of Dow Chemicals. Dow AgroFresh, a business unit of Rohm and Haas Company, last week signed a contract with Yissum, the research and development company of the Hebrew University of Jerusalem, and North Carolina State University, for the new ethylene inhibitor developed by researchers at the two institutions.

The compound, a synthesis of a chemical called 3-cyclopropyl propanoic acid (CPA), prevents ethylene, a gas that functions as a plant hormone, from performing its natural function: causing fruit to ripen and flowers to open. Ethylene is also responsible for leaf and fruit abscission (separation) from trees, and leaf senescence (the turning of colors, the stage before leaves fall off). Once these events take place, the life cycle of fruit and flowers is basically at an end, and the rush to bring them to market and get them sold before they wither begins.

In order to impede the ripening process in fruits and flowers, farmers often use an ethylene antagonist. These antagonists consist of a gas or powder containing a cyclopropene derivative, 1-methylcyclopropene (1-MCP). However, the gas form of 1-MCP can only be used in closed systems (otherwise the gas would escape), while the powder is only effective when it is constantly kept wet — so they can’t be used in open areas, like greenhouses, open fields, or even supermarket shelves.

In a joint research project, which was supported by a research grant from the United States — Israel Bi-national Agriculture Research and Development Fund (BARD), Prof. Edward C. Sisler of North Carolina State University (Raleigh) contributed to the invention by synthesizing the novel 3-cyclopropyl propanoic acid (CPA), a derivative of the aforementioned gaseous cyclopropene. In the framework of the same research project, Professor Raphael Goren and his team at Hebrew University (Professors E E. Goldschmidt, J. Riov, A. Apelbaum and Dr. M. Huberman) used Prof. Sisler’s CPA as the basis of the invention – 3-Cyclopropyl-1-enyl-propanoic acid sodium salt (CPAS), which impedes ethylene’s effects, but is water-soluble. Unlike the gaseous ethylene antagonists, the new compound can be sprayed in fields, plantations, or greenhouses.

It could even be used on supermarket shelves and in flower shops to keep produce and flowers fresh longer, Professor Goren, leader of the Hebrew University team, told The Times of Israel, although more tests are needed to see just how effective the compound would be under such circumstances. Meanwhile, the research team has produced studies that show that “CPAS extends the vase life of cut flowers and the shelf life of flowering pot plants and some fruits, depending on their size and peel thickness,“ Goren said.

The new compound will significantly help grain farmers, Goren said. “CPAS has been shown to significantly increase the grain yield of rain-fed wheat. It might also be effective in inhibiting fruitlet and particularly pre-harvest fruit abscission and ripening, and by thus extends the picking period.” Thus, farmers will be able to keep grain in the field longer, ensuring that they harvest their crops when market conditions are most favorable.

While inhibiting a natural process of fruit ripening might seem like another example of man’s “tinkering” with nature — the kind of meddling that, in the human imagination, always leads to no good — agricultural scientists are quite emphatic about the benefits of impeding the effects of ethylene. While ethylene is associated with the development of the “signs” of ripeness, such as color and texture, say scientists at Cranfield University in the UK, it is also associated “with loss of storage potential, and the removal of ethylene and/or inhibition of the effect of ethylene in stored environments is therefore fundamental to maintaining postharvest quality of climacteric produce.” And the U.S. National Institutes of Health called ethylene inhibitor (1-MCP) “an excellent safe and commercially available ethylene antagonist for the preservation of horticultural products.” With help from Dow, Yissum officials said, this Israeli-developed advance will help farmers around the world preserve crops longer, and hopefully enable food distributors to deliver healthier, fresher food to more people.