Low-calorie artificial sweeteners used in popular fizzy drinks are often criticized for leaving a metallic flavour in the mouth, but the "bitter blocker," which is tasteless in itself, prevents tart tastes being sensed by the tongue.

It raises the prospect of diet drinks that delight the tastebuds -- and even cough mixture and medicines that are easier to swallow.

In taste tests, the compound known as GIV3616 made drinks, yogurts, sweets and cough medicines all seem more enjoyable.

Just a sprinkling of GIV3616 among a million particles of food takes away the bitter taste of the artificial sweeteners commonly used in low-calorie drinks, the American Chemical Society's annual conference heard. Ioana Ungureanu, of the research team that developed the compound with a flavor house in Cincinnati, Ohio, said, "A lot of people are very sensitive to bitter taste in medicines, calorie-free sweeteners and foods.

"Blocking these flavors, which we call off-notes, could help consumers eat healthier and more varied diets. It could encourage them to switch to low-calorie soft drinks and help children and seniors swallow bitter-tasting medicines."

The bitter blocker is expected to be of most use to the 25% of the population labelled "super-tasters," because their genetic make-up makes bitter foods taste particularly sharp.

The compound is expected to go on sale in the U.S. this summer, with the first products to contain it likely to include diet drinks.

The conference heard that the food and drug industries traditionally relied on salt, fat and sugar to hide unpleasant flavors, but health concerns have shifted the focus to compounds that change how the tongue senses tastes.

From the April 4, 2011, Prepared Foods E-dition