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Science Update
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| Mouth-Watering
Mangoes for Mass-Marketing
The perfect mango melts in your mouth. But many aren't perfect because this
tropical fruit is susceptible to injury during cold storage. At temperatures
below 50 °F, mango's skin becomes pitted and discolored and its flesh
darkens and becomes susceptible to decay.
ARS and Mexican scientists recently
discovered that methyl jasmonate prevents such chilling injury. This
sweet-smelling compound derived from the essential oils of
plants—especially jasmine and honeysuckle—is safe and relatively
inexpensive. Fifty dollars' worth could treat truckloads of fruit.
Studies showed how to use methyl jasmonate to prevent chilling injury and
dramatically improve overall fruit quality. The treatment worked on mangoes at
various stages of maturity and didn't alter normal ripening and softening
processes or increase water loss.
The researchers also learned to preserve fresh-cut mangoes by treating slices
with a combination of hexylresorcinol, isoascorbic acid, and potassium
sorbate—all food-safe compounds derived from natural products—and
storing the slices in plastic containers to prevent drying.
Mangoes could be an attractive addition to the growing market for fresh-cut
produce, but browning and drying have prevented such marketing. In 1998, the
U.S. population consumed 412 million pounds of mangoes—an increase of 77
percent from 1993.
Chien Y. Wang, USDA-ARS
Horticultural Crops
Quality Laboratory, Beltsville, Maryland; phone (301) 504-6128. |
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Clearing the Air With Biodiesel
Buses and other diesel-burning vehicles will run cleaner if they mix soy-based
biodiesel with their regular diesel fuel. To test the feasibility of switching
to this fuel blend, ARS began a year-long demonstration at the Beltsville
(Maryland) Agricultural Research Center in January. BARC has 65 vehicles
operating on "B20," a 20-percent biodiesel/80-percent diesel mix.
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| This test is part of a
federal effort to reduce reliance on petroleum and create new markets for U.S.
crops. There is interest in permanently switching as many federal government
vehicles as possible nationwide to alternative diesel fuels, using biodiesel
from soybean and other seed oils or animal fat.
One goal is to increase the federal purchases of biobased fuel and other
products by 10 percent each year for the next 5 years.
The demonstration may help encourage local governments and the private sector
to do the same—especially in areas where air quality is an issue.
Crop-based diesel burns cleaner and produces less soot, and vehicles don't need
modification before being switched to the fuel.
Recent changes in the Energy Policy Act of 1992 allow for credits for biodiesel
usage in existing vehicles, reducing the number of alternative fuel vehicles
that must be purchased.
Future changes could also affect large municipal vehicle fleets, such as buses
and public works vehicles.
Ronald F. Korcak,
Associate Director of
Beltsville Area, USDA-ARS, Beltsville, Maryland; phone (301) 504-5193.
Processing Alfalfa and Soybeans—on the Spot
New products and increased markets for alfalfa and soybeans may be on the
horizon for Midwest farmers, thanks to innovative research by ARS and
University of Wisconsin scientists in Madison. Following a concept long used by
the petroleum industry—the separating, or fractionating, of crude oil into
a variety of products of increasing value—researchers have tested the
fieldside processing of harvested crops.
Until now, wet fractionation of alfalfa and soybeans has been performed at a
central processing facility. But that necessitates transporting the herbage,
containing about 80 percent water, from the field to the facility and then
dehydrating the plant material and transporting the waste liquid back to the
field as liquid fertilizer.
Last summer, under a cooperative research and development agreement with
industry, a group of machines was used in the first fieldside demonstration of
wet fractionation of soybean herbage. Commercially available machines, plus a
modified hammermill—normally used to pulverize grain by forcing it through
screens—were used to rupture the herbage without reducing fiber size.
Demonstrating the feasibility of the concept was the first step toward further
development of a mobile field processor. Working like a combine, it would cut
and wet-fractionate the crop while juice was being processed at the edge of the
field.
Products such as cattle feed, chemical feedstocks, mats for filtering
pollutants from water, enzymes derived by growing fungi on the fiber, and
building materials can be made from the fiber portion. Products from the juice
fraction might include food- and feed-grade protein concentrates, carotenoids,
antioxidants, and industrially valuable enzymes.
Richard G. Koegel, USDA-ARS
Dairy Forage Research Center,
Madison, Wisconsin; phone (608) 264-5149. |
| "Science
Update" was published in the
April 2000
issue of Agricultural Research magazine.
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