Steviol glycosides, the sweet principle of Stevia Rebaudiana (Bertoni) Bertoni, have recently been approved as a food additive in the EU. The herbal non-nutritive high-potency sweeteners perfectly meet the rising consumer demand for natural food ingredients in Europe. We have characterized the organoleptic properties of the most common steviol glycosides by an experimental approach combining human sensory studies and cell-based functional taste receptor expression assays. On the basis of their potency to elicit sweet and bitter taste sensations, we identified glycone chain length, pyranose substitution, and the C16 double bond as the structural features giving distinction to the gustatory profile of steviol glycosides. A comprehensive screening of 25 human bitter taste receptors revealed that two receptors, hTAS2R4 and hTAS2R14, mediate the bitter off-taste of steviol glycosides. For some test substances, e.g., stevioside, we observed a decline in sweet intensity at supra-maximum concentrations. This effect did not arise from allosteric modulation of the hTAS1R2/R3 sweet taste receptor but might be explained by intramolecular cross-modal suppression between the sweet and bitter taste component of steviol glycosides. These results might contribute to the production of preferentially sweet and least bitter tasting Stevia extracts by an optimization of breeding and postharvest downstream processing.

Much of our appreciation of food is due to the excitement of the perception of "sweet" and "umami" taste. With a special focus on natural products, this Review gives a summary of compounds that elicit and modulate "sweet" or "umami" taste responses. It will be discussed how the interaction of these molecules with the oral sweet and umami taste receptors stimulates receptor cells to secrete neurotransmitters to induce neural activity that is conveyed to the cerebral cortex to represent sweet and umami taste, respectively. Recent data also show that a sweet taste is metabolically relevant for fuel homeostasis and linked to appetitive ingestive behavior.

Unsere Wertschätzung für Nahrungsmittel ist weitgehend auf die Auslösung der Geschmacksempfindungen “süß” und “umami” zurückzuführen. Mit einem besonderen Schwerpunkt auf Naturstoffen wird dieser Aufsatz einen Überblick über jene Stoffe geben, die die Geschmackseindrücke “süß” oder “umami” hervorrufen und modulieren. Es wird diskutiert, wie die Wechselwirkung dieser Moleküle mit dem oralen Süß‐ oder Umamigeschmacksrezeptor die Rezeptorzellen anregt, Neurotransmitter abzusondern, um neurale Aktivität hervorzurufen, die an die Großhirnrinde weitergeleitet wird und süßen bzw. umami Geschmack übermittelt. Neue Befunde zeigen auch, dass süßer Geschmack für die Homöostase des Energiehaushalts metabolisch relevant und mit dem appetitiven ingestiven Verhalten verknüpft ist.

Review: ca. 200 refs.