FAYETTEVILLE, Ark.--Cucumber volatiles--compounds produced by cucumbers for a variety of purposes including self-protection--may kill harmful bacteria, according to a new study published in the 2004 issue of the Journal of Food Protection (67, 5:1014-16, 2004) (http://www.foodprotection.org/Publications/JFP.htm).

Researchers investigated the effects of the cucumber volatiles (E,Z)-2-6-nonadienal (NDE) and (E)-2-nonenal (NE) on various pathogenic bacteria, including Bacillus cereus (B. cereus), Escherichia coli O157:H7 (E. coli), Listeria monocytogenes (Listeria), and Salmonella Typhimurium (Salmonella). The pathogens were exposed to various levels of the volatiles in an infusion solution. Researchers found exposure to either NDE or NE caused a reduction in the colony forming unit (CFU) of each organism. Exposure to 250 and 500 ppm NDE fully eradicated viable B. cereus and Salmonella cells, respectively. Listeria was the most resistant to eradication by NDE, though it had a significant kill rate on E. coli cells. NE was also found effective in inactivating all the pathogenic bacteria tested; however, a higher concentration of NE--1,000 ppm--was required to kill E. coli, Listeria and Salmonella, compared with NDE.

The researchers concluded both volatiles demonstrated apparent antibacterial activity against all four pathogenic bacteria.