Hundreds of thousands of tons of watermelons are lost every year. They are grown and then left in the ground because of superficial imperfections. About 20% of each annual crop is left in the field because of surface blemishes or because they are misshapen; currently these are lost to growers as a source of revenue. Due to imperfections, bad spots, or weird shapes, these watermelons are left in the field and then ploughed right back into the ground.
However, according to the authors of a new study (Benny Bruton and Vincent Russo from the USDA-ARS, South Central Agricultural Research Laboratory, and Wayne Fish), these watermelons could be used to produce ethanol. According to these researchers:
“The results of this investigation indicate that watermelon juice as a source of readily fermentable sugars represents a heretofore untapped feedstock for ethanol biofuel production. The 8.4 t/ha of unmarketable watermelons left in the field at harvest would produce about 220 L/ha of ethanol for on-farm use or as an additional revenue stream for the grower.”
The watermelon juice can be fermented and used directly or it can be used as a “diluent, supplemental feedstock, and nitrogen supplement” with other biofuel crops. If it is used as a supplement to other crops, it could first be used in neutraceutical production and serve an economic and health purpose in that capacity as well. Watermelons could be used to produce the neutraceuticals lycopene (found to be important to prostrate health) and L-arginine (an amino acid that is critical for the production of nitric oxide). After being used to produce these, the waste juice can be used for ethanol production.