Historical data suggests that the leading cause of consumer dissatisfaction with tap water quality
involves chlorinous taste and odors. In this work, chlorinous flavor sensitivity testing was
conducted in France and in the U.S. with untrained panels to confirm the taste thresholds of free
chlorine and chloramine. This was compared to the results with a French Flavor Profile Analysis
(FPA) panel.
The answers of untrained panelists were found to be more heterogeneous than those of trained
panelists. In other words, the free chlorine concentration had to be significantly increased to be
detected by the majority of the untrained panelists. The heterogeneity in human sensitivity of
both untrained panels were similar, but the U.S. consumer panel was 5 to 10 times less sensitive
than the French consumer panel to free chlorine and monochloramine, respectively (0.2 +/- 0.05
vs. 0.9 +/- 0.25 mg/L for free chlorine and 0.18 +/- 0.05 vs. 1.8 +/- 0.4 mg/L for monochloramine).
This result may be linked to chlorination residuals practice in the different countries (0.1 - 0.2
mg/L in France vs. 1.0 - 3.0 mg/L in the U.S.). In the background Total Dissolved Solids (TDS)
experiments, no significant influence of water characteristics on panelist sensitivity to free
chlorine or chloramine was noticed. In addition, there was no significant influence of changes in
temperature (in a range between 15 - 25C) on free chlorine taste perception by untrained
panelists.
It is difficult to define a common target in terms of free chlorine residual based on consumer
perception and almost impossible in terms of consumer tolerance.
Geographical/cultural differences may be partly explained by the difference in local free
chlorination practices.
For practical reasons, it is easier for water utilities to rely on a laboratory panel rather than a
consumer panel for the monitoring of drinking water organoleptic quality. When interpreting
panelist data, utilities should keep in mind that a trained panel may significantly overestimate the
chlorine perception of average consumers, whatever the taste testing method. Includes 7 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 330 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 8 |
| Published : | 11/02/2003 |
