Cucumber Flavor in Philadelphia's Drinking Water

Abstract

Since 1981, when the use of free chlorine was curtailed to control trihalomethanes at the Baxter Treatment Plant in Philadelphia, Pa., a seasonal cucumber flavor problem occurred. Flavor profile analysis was the only tool available to guide treatment. During 1990, the cucumber odor was tracked more than 250 mi (402 km) up the Delaware River to the Cannonsville Reservoir, and the odor‐causing compound was identified as trans,2‐cis, 6‐nonadienal. Algae growth beneath the winter ice produced the compound. Other treatment plants on the river that used free chlorine for disinfection and a final residual never had a problem with trans,2‐cis,6‐nonadienal. Therefore, use of chlorine was increased at the Baxter plant to control the cucumber flavor. Studies were conducted on trans,2‐cis, 6‐nonadienal to describe its sensory characteristics and analytical detection limit.