Fresh Fruit Gets a New Protective Coat
August 21, 2002
Apples and citrus are about to get a uniform new coat. But it's
not to keep the fruit warm on cold orchard nights. Instead, these coatings act
as biofungicides that keep fruit fresh longer during storage.
Service scientists have been working to improve earlier biofungicides aimed
at controlling decay of fruits and vegetables after harvest. Such fungal decay
can destroy more than 25 percent of the world's harvested fruit.
Biological products, such as friendly yeasts, are used for
environmentally safe pest control and to reduce dependence on synthetic
chemicals. They work by consuming nutrients on fruit and vegetable skins that
otherwise would allow rot-causing fungi to grow.
Charles L. Wilson, a plant pathologist with the
ARS Appalachian Fruit Research Station,
Kearneysville, W.Va., and Ahmed El Ghaouth, a postharvest plant pathologist
employed by Micro Flo Co. of
Memphis, Tenn., conducted research leading to two patents issued this year.
One of the two new patents discloses how chitosan, a natural
fungicide, can be compatibly combined with an antagonistic yeast named
Candida saitoana by adding a softener. Antagonistic yeast organisms are
normally found on fruit and vegetable skins, but are benign to people. The
other patent approved this year discloses a mixture of C. saitoana with
lysozyme, an antifungal enzyme.
Development of postharvest biological products based on
technology described in the patents is being furthered by Micro Flo, a
subsidiary of the international chemical company BASF, through a cooperative research and
development agreement. Micro Flo is pursuing the lysozyme and C.
saitoana mixture to create a product named Biocure.
The annual worldwide market for postharvest treatments is
currently more than $18 million for citrus and more than $8 million for apples,
according to El Ghaouth.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.