Increasing consumer demand for natural low-calorie sweeteners, with no organoleptic drawbacks compared to sucrose, necessitates a new quality of knowledge on the organoleptic properties as well as the molecular determinants of the sweet and bitter taste of diterpenic glycosides of Stevia rebaudiana. Therefore, we correlated in vivo data obtained from human psychophysical experiments with in vitro data from cell-based taste receptor assays on the most common steviol glycosides. While sensory evaluation clearly demonstrated the structural features causing the sweet and bitter taste of these phytochemicals, comprehensive screening experiments with human bitter taste receptors indicated their sensitivity to hTAS2R4 and hTAS2R14. Interestingly, for some analytes, we observed a decline in their sweet intensity at supra-maximum concentrations. This effect did not arise from allosteric modulation of the hTAS1R2/R3 sweet taste receptor but for the first time indicate a cross-modal suppressing effect of the associated intrinsic bitter taste. Next to the analysis of the molecular determinants of taste, a stable isotope dilution analysis with LC-MS/MS detection was developed for the first time to navigate breeding of Stevia rebaudiana effectively and to improve post-harvest down-stream processing towards the production of sweet taste-optimized Stevia extracts.

Molecular determinants of the sweet-bitter Janus head of steviol glycosides and development of novel quantitation tools

246th National Meeting (2013)

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