Heliotropin, Heliotrope Odor and Tahitian Vanilla Flavor: The End of a Saga?

Abstract

A targeted search for heliotropin (or piperonal) in the flower fragrance of heliotrope and in cured vanilla beans of Tahitian origin is reported. Heliotropin is not detected in the fragrance emitted by heliotrope, using dynamic headspace SBSE sampling, followed by thermal desorption and analysis by conventional GC-MS. Main constituents are anisaldehyde and benzaldehyde, which confirms previous findings. Less than one part per million of heliotropin is accurately detected in authentic Tahitian vanilla bean, in using both GC-MS and LC-MS/MS. This confirms previous observations, which had shown that 4-methoxyaromatic compounds are the characteristic elements in the flavor of Tahitian vanilla, with p-anisaldehyde as the the main aroma donator. We suggest that heliotropin was named after the discovery of piperonal by degradation of piperine, the odor of which was reminiscent of the heliotrope flower. Later, its identification in vanilla extracts was the result of either a wrong interpretation of analytical data, or, much more probably, adulterations of these extracts. As a result, heliotropin should not be cited any longer as a characteristic consituent of Tahitian vanilla.