New Fruit Coatings Help Abate
Post-Harvest Fruit Decay
March 7, 2000
The shine that helps fruits glisten at
the local produce stand may soon be only the most visible manifestation of a
more natural way to preserve fruit34 million tons harvested in the U.S.
in 1998while on its way to market.
Agricultural Research Service
scientists and cooperators have developed fruit coatings made from reformulated
shellac and sucrose ester, a compound derived from combining sugar with a fatty
acid. These biocontrol coatings help maintain quality by promoting the growth
of beneficial bacterial and yeast populations naturally on the fruit. The
research is part of a continuing effort to decrease fruit producers
reliance on chemicals to delay post-harvest decay.
The chemicals traditionally used to preserve harvested fruitimazalil,
which costs $1,000 per liter, and thiabendazol for Florida grapefruithave
been found to kill beneficial bacterial and yeast populations. These
populations help maintain fruit quality by competing more efficiently than
pathogens for nutrients, such as sugars and proteins, at a critical early stage
in the pathogens development. In essence, these beneficial bacteria and
yeasts starve the pathogens that would otherwise feast on the fruit nutrients
and cause decay.
Raymond McGuire at ARS Subtropical Horticulture Research Station in
Miami, Fla., and cooperators from Mantrose
Haeuser Co Inc. of Westport, Conn., have also tested both reformulated
shellac and sucrose ester coatings for their ability to reduce the development
of off-flavors caused by the buildup of ethanol. Preliminary test results on
grapefruit indicate that both the reformulated shellac and, to a larger extent,
sucrose ester coatings prevented off-flavors by allowing for a better exchange
of oxygen and carbon dioxide than commercial chemicals permit.
ARS is the chief research agency of the U.S.
Department of Agriculture.
Scientific contact: Raymond G. McGuire, ARS Subtropical Horticulture
Research Station, Miami, Fla.; phone (305) 254-3641, fax (305) 238-9330,