A TAS1R receptor-based explanation of sweet ‘water-taste’

Bitter sweeteners Paradoxically, artificial sweeteners such as sodium saccharin and acesulfame-K taken in high concentrations are not sweet: they can even seem bitter. And if the mouth is then rinsed out with water, it takes on a sweet taste. These observations have led to new insights into the action of the TAS1R taste receptor. As well as causing the ‘sweet water’ aftertaste, saccharin at high concentrations masks the effect of other sweeteners tasted at the same time. What emerges at the molecular level is a two-site system. Saccharin and acesulfame-K elicit a perception of sweetness when they bind to a high-affinity binding site; at high concentrations they bind to a second low-affinity inhibitory site. When the sweet taste inhibitors are washed away, the sweet receptor re-activates and the perception of sweetness returns. Sweet inhibitors are used in the food industry to offset the high sweetness that results from replacing fats with sweet carbohydrates in some reduced-fat products: the sweet water taste may be a useful predictor for sweet inhibitor activity.