European reassessment of MIB and geosmin perception in drinking water

Earthy-musty flavors are a prevalent customer complaint for drinking water utilities. Sensory analysis can be used as an inexpensive early warning system to signal a taste and odor (T&O) event and to define the water quality objectives the treatment process has to achieve. T&O threshold concentrations of both 2-methylisoborneol (MIB) and trans-1, 10-dimethyl-trans-9-decalol (geosmin) were reassessed using a French and a Spanish panel, using a flavor-by-mouth protocol. Results of the 2 panels were found consistent and lower than those reported in the literature. Additional sensory testing experiments were performed to investigate the resulting perception when the two compounds (geosmin and MIB) are both present in solution and to clarify the effect of chlorine on both geosmin and MIB (masking or confusion in the perception).