http://www.sciencedaily.com/releases/2009/05/090522180918.htmAgricultural Research Service (ARS) studies in Lane, Okla., have shown that simple sugars in watermelon juice can be made into ethanol. In 2007, growers harvested four billion pounds of watermelon for fresh and cut-fruit markets. Around 800 million pounds--or 20 percent of the total--were left in fields because of external blemishes or deformities.
Now, instead of being plowed under, such melons could get an economic "new lease on life" as ethanol. Normally, this biofuel is produced from cane crops like corn, sorghum or sugarcane as a cleaner-burning alternative to gasoline. The watermelon work reflects a national push by ARS to diversify America's "portfolio" of biofuel crops that can diminish the reliance on petroleum, especially from foreign suppliers.
Chemist Wayne Fish's ethanol studies at the ARS South Central Agricultural Research Laboratory in Lane complement ongoing research there to commercially extract lycopene and citrulline from the crop. Both are valued nutraceutical compounds thought to promote cardiovascular and other health benefits.
In publication-pending studies, Fish showed ethanol can be fermented from the glucose, fructose and sucrose in waste-stream juices--what's left after lycopene and citrulline are extracted. Making ethanol offers the potential benefits of helping to defray sewage treatment costs associated with nutraceutical extraction, and providing watermelon growers with a new market for their crop.
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Rejected Watermelons: The Newest Renewable Energy SourceWatermelon juice can be a valuable source of biofuel. Researchers have shown that the juice of reject watermelons can be efficiently fermented into ethanol.
Wayne Fish worked with a team of researchers at the USDA-Agricultural Research Service’s South Central Agricultural Research Laboratory in Lane, Oklahoma, US, to evaluate the biofuel potential of juice from ‘cull’ watermelons – those not sold due to cosmetic imperfections, and currently ploughed back into the field. He said, “About 20% of each annual watermelon crop is left in the field because of surface blemishes or because they are misshapen. We’ve shown that the juice of these melons is a source of readily fermentable sugars, representing a heretofore untapped feedstock for ethanol biofuel production”.
As well as using the juice for ethanol production, either directly or as a diluent for other biofuel crops, Fish suggests that it can be a source of lycopene and L-citrulline, two ‘nutraeuticals’ for which enough demand currently exists to make extraction economically worthwhile. After these compounds have been removed from the ‘cull’ juice, it can still be fermented into ethanol.
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