In order to estimate the bitterness intensity of citrus products we applied an adaptative sensory evaluation method, using naringin as the reference for bitterness. Twenty-five untrained subjects participated in this study. Firstly they tasted and positioned 2 naringin references on an unstructured relative-to-reference scaling to define their own bitterness scales. They then evaluated the bitterness intensity of 2 types of bitter orange products (3 distillates and 2 cold-pressed essential oils of bitter orange peels) according to their own perceptions on their own scales. We observed that 2 types of scale use could be distinguished that might be related to subjects' sensitivity or/and consumption habits to bitterness. As a result, we observed a significant difference in bitterness intensity between the crude cold-pressed essential oil and the debittered one of bitter orange, whereas there was no significant difference between the 3 distillates. This approach makes it possible to take inter-individual differences in subjects' sensitivity into account. It also provides a way to very simply rate bitterness intensity with subjects who have received no prior training in sensory evaluation.