The Cyclic Diarylheptanoid Asadanin as the Main Contributor to the Bitter Off-Taste in Hazelnuts (Corylus avellana L.)

Activity-guided fractionation and taste dilution analysis (TDA), followed by LC-MS/MS, LC-TOF-MS, and 1D/2D-NMR spectroscopy, led to the identification of the cyclic diarylheptanoid asadanin exhibiting a human bitter recognition threshold of 13 μmol/kg, as the major inducer of the sporadic bitter off-taste of hazelnut kernels (Corylus avellana L.). Sensory analysis of hazelnut samples from two origins (Ordu/2013 and Akçakoca/2014) and from Cimiciato-infected hazelnut kernels, followed by LC-MS/MS quantitation of 1 and calculation of dose-over-threshold (DoT) factors, showed established evidence for the Cimiciato infection as the major inductor of asadanin biosynthesis in hazelnut kernels and, as a consequence, as the reason for bitter off-taste development.