Scientists are baffled by a natural protein which makes sour foods like lemon taste like sweet lemonade.
The "miracle fruit" or Miraculin comes from a West African berry and is now available in tablet form in New Zealand.
Professor Laurie Melton, Director of Food Science University of Auckland says of Miraculin, "People don't really know what's going on. It's an exciting and challenging area.
"I suspect it's really blocking the acid taste so the sweet taste is enhanced because the acid taste has disappeared," he said.
One tester said that Miraculin made lemon juice and natural yoghurt taste like cheesecake, while Guinness tasted like chocolate milk.
However, the effects of the berry only last up to an hour. Also, the protein is not heat stable, which means its properties will cease to work if it cooked or added to hot food.
The New Zealand importers of Miraculin say it could have real benefits for diabetics or weight watchers who are looking for a sweet treat without the sugar.