Odor and taste thresholds of potential carry-over/off-flavor compounds in orange and apple juice

The odor and taste threshold values of six aroma substances known to be constituents of fruit juices and other fruit products, i.e. limonene, α-terpineol, carvone, methyl 2-methylbutanoate, ethyl 2-methylbutanoate, and γ-decalactone, were determined in various matrices, i.e. model sugar/acid solution, apple and orange juice, as well as apple and orange substitute (made by dilution of fruit juice concentrate with water). Whereas for α-terpineol thresholds in the 1.2–11 mg/l area were defined, limonene and carvone were determined to be sensorially effective each at 0.5 mg/l. Very low thresholds were measured for γ-decalactone, methyl 2-methylbutanoate and ethyl 2-methylbutanoate that showed sensory activity in the area of 20, 1.5, and 0.5 μg/l, respectively. In relation to the aroma composition determined by high resolution gas chromatography-mass spectrometry (HRGC-MS), these results provide an objective possibility to evaluate the sensory efficacy and/or an ‘off-flavor’ potential of these compounds in fruit juices.