Scientists from the Monell Chemical Senses Center said that their findings, published in the early online publication Nature, could provide clues as to how to inhibit sweet taste as well as enhance it.
Until recently, the food industry has been focused on replacing sugar- also known as sucrose- with artificial sweeteners that try to do what sucrose does. But as health trends sweep the nation and today's demanding consumers become increasingly skeptical of anything perceived as 'artificial,' the goal has now switched to keeping sucrose around but making it more effective.
In collaboration with colleagues at the German Institute of Human Nutrition, the scientists conducted a series of molecular studies using cultured cells expressing the human sweet taste receptor. These, they claim, have been shown to directly parallel the human cellular responses.
Key to the mechanism is an everyday phenomenon known as sweet 'water taste': experiencing an intensely sweet taste after drinking plain water. The reason this occurs is that the water rinses away sweetness inhibitors that have been previously consumed, exposing a sweet taste.
According to the scientists, certain sweeteners such as saccharin and acesulfame-K can paradoxically inhibit sweet taste when consumed at high concentrations- resulting in these losing their sweet taste.
This led the researchers to understand that there are multiple 'binding sites', or places where a sweetener can interact with taste receptors to activate or inhibit these. At high concentrations, certain sweeteners actually bind to an inhibitory site, causing the receptor to shift from an activated to an inhibitory state.
"Some of these binding sites serve the purpose of allowing you to tweak the receptor so it's more responsive or less responsive- like a volume control. This would allow you to modify how strongly the system responds to sugar," said Monell geneticist and senior author of the new study Dr Paul Breslin.
According to the scientists, who claim this is the first time that taste perception has been linked to a molecular mechanism, the findings could lead to the development of 'sweeter' sugar.
"The key now is not to develop new sweeteners but to develop systems that enhance the efficacy of sucrose," said Dr Breslin.
This could potentially be achieved by adding a substance to sucrose that enhances our perception of sweetness. And although it is still too early to say what kind of substances could be used, it is very likely that these could be naturally-occurring, even health-enhancing compounds, said Dr Breslin.
For example, zinc is a known sweet taste inhibitor, meaning it can be used to suppress the unwanted sweetness of a product. According to Dr Breslin, it is "highly likely" that similar compounds that "go the other way" could make products taste sweeter.
Equally, the science could be used to identify compounds that counteract the undesirable sweetness that results from replacing fats with sweet carbohydrates in reduced-fat products such as snack foods and salad dressings.
"Since we know that compounds that illicit sweet water taste are sweet taste inhibitors, these are easy to identify, and the process becomes a powerful and rapid screening tool for human perception," said Dr Breslin.
A next step in the research would be to apply the findings to consumers' perceptions of other tastes, such as bitter or savory tastes.
"What I find to be one of the most important attributes of this science is that we have a complex perceptual phenomenon that is explained in great detail at a molecular level. These are exciting and powerful findings," Dr Breslin told FoodNavigator-USA.com.
The results are due to be presented at the 28th annual meeting of the Association for Chemoreception Sciences, to be held from April 26-30 in Sarasota, Florida.