Reject watermelon juice can be valuable source of biofuel

In a new research, scientists have shown that the juice of reject watermelons can be efficiently fermented into ethanol, which means that watermelon juice can be a valuable source of biofuel.

The research was conducted by Wayne Fish and a team of researchers at the USDA-Agricultural Research Service's South Central Agricultural Research Laboratory in Lane, Oklahoma, US.

It was done to evaluate the biofuel potential of juice from 'cull' watermelons - those not sold due to cosmetic imperfections, and currently ploughed back into the field.

According to Fish, "About 20 percent 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," he said.

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.

"At a production ratio of 0.4 g ethanol/g sugar, as measured in this study, approximately 220 L/ha of ethanol would be produced from cull watermelons," the researchers concluded.