ABSTRACT: In the context of measuring thresholds of orange flavor compounds in a deodorized orange juice matrix, it was found that 50% of panelists could not perceive β-ionone or β-damascenone as well as the other panelists. Orthonasal and retronasal thresholds for β-ionone were, respectively, 985 and 490 times higher for nonperceivers than perceivers. For β-damascenone, the ratios were 690 and 390 times higher for ortho- and retronasal thresholds, respectively. Panelists who could not perceive β-ionone were otherwise good perceivers of most compounds tested. There were no such differences for α-ionone, a constitutional isomer of β-ionone. All 3 compounds were retested in water using the same panelists. Differences between nonperceivers and perceivers of β-ionone were 4900 and 4600 times higher for ortho- and retronasal thresholds for nonperceivers, respectively. However, for β-damascenone, no such differences were found when measured in water. The same panelists could be classified as “perceivers” or “nonperceivers” when β-ionone was tested in deodorized orange juice or in water. A different panel was used to confirm β-ionone and β-damascenone thresholds in water. A greater difference between perceivers and nonperceivers was found for β-ionone; as with the first panel, there were no differences in sensitivity to β-damascenone between panelists when the compound was tested in water.