Rejected watermelons valuable source of energy

Wayne Fish worked with researchers at the US Department of Agriculture (USDA) lab in Lane, Oklahoma, to evaluate the biofuel potential of juice from 'cull' watermelons -- those not sold due to cosmetic imperfections. "About 20 percent of each annual watermelon crop is left in the field because of surface blemishes or because they are misshapen," said Fish.

"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," said Fish.
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, according to an USDA release. These findings were published in BioMed Central's open access journal Biotechnology for Biofuels.