Grown in-vitro from cattle stem cells at a cost of 250,000 euros ($332,000), the burger was cooked and eaten in front of television cameras to gain the greatest media coverage for the culmination of a five-year science experiment.

Resembling a standard circular-shaped red meat patty, it was created by knitting together 20,000 strands of laboratory-grown protein, combined with ingredients normally used in burgers, such as salt, breadcrumbs and egg powder. Red beet juice and saffron were added to give it colour.

The two food tasters were reserved in their judgement, perhaps keen not to offend their host at the London event, noting the burger's "absence of fat".

Food writer Josh Schonwald said the cultured beef had an "animal protein cake" like quality to it, adding that he would like to try it with some of the extras often served with traditional burgers ' salt, pepper, ketchup.

Even the scientist behind the burger's creation, vascular biologist Mark Post of Maastricht University in the Netherlands, was relatively muted in his praise of its flavour. "It's a very good start," he said.

His aim was to show the world that in the future meat will not necessarily have to come from the environmentally and economically costly rearing and slaughtering of millions of animals. "Current meat production is at its maximum ' we need to come up with an alternative," he said.

Chris Mason, a professor of regenerative medicine at University College London, who was not involved in the research, said it was "great pioneering science" with the potential to ease environmental, health and animal welfare problems.

Post said he was confident his concept can be scaled up to offer a viable alternative to animal meat production, but said it may be another 20 years before lab-grown meat appears in supermarkets. He also conceded that the flavour of his meat must be improved if it is to become a popular choice.

Sergey Brin, a co-founder of Google, announced that he funded the project, saying he was motivated by a concern for animal welfare. "We're trying to create the first cultured beef hamburger," he said in a videotaped message. "I'm optimistic we can really scale up by leaps and bounds."