Natural Compounds Protect Fresh-Cut Produce

Sweet-smelling methyl jasmonate, a natural compound in certain plants, protects produce from pathogens and doubles shelf life, Agricultural Research Service scientists report.

It is thought that the chemical elicits proteins in living plants and harvested produce that make them more resistant to temperature changes and attack by insects, bacteria, and fungi, according to scientists at the ARS Horticultural Crops Quality Laboratory in Beltsville, MD. The proteins lead to production of antifungal or antibacterial compounds.

Methyl jasmonate is in a class of compounds called jasmonates, first found in plants of the genus Jasminum. Most plants contain small amounts of jasmonates, but jasmine and honeysuckle contain high levels.

Scientists found that strawberries exposed to methyl jasmonate vapor for 24 hours at 68 degrees F resisted gray mold, Botrytis cinerea, a major fungal disease of harvested fruits and vegetables, for 14 days with no change in fruit firmness. Treatment of fresh- cut celery and green peppers eliminated browning and decreased bacterial growth a thousandfold for up to 2 weeks at 50 degrees F. The treatment also controlled soft rot on the peppers. Another plus: Methyl jasmonate slowed grey mold on grapes.

Methyl jasmonate is available commercially and is inexpensive. Truckloads of produce can be treated with 25 milliliters (less than an ounce), which costs about $30. It acts within a couple of hours and leaves no residue.

This and other treatments are detailed in the February Agricultural Research, available on the World Wide Web at:

http://www.ars.usda.gov/is/AR/archive/feb98/fres0298.htm

Scientific contacts: J. George Buta, Harold E. Moline, and Chien Yi Wang, ARS Horticultural Crops Quality Laboratory, Beltsville, MD 20705, phone (301) 504-6128, fax (301) 504- 5107, hmoline@asrr.arsusda.gov and cwang@asrr.arsusda.gov.