For the first time, the public has been treated to the spectacle of lab-grown meat cooked and eaten via live Webcast. Backed by Google billionaire Sergey Brin, Dutch tissue engineer Mark Post unveiled his "cultured beef" at a press event on August 5, answering the question posed by a 2011 Scientific American feature: "When Will Scientists Grow Meat in a Petri Dish?"

The verdict? "It is close to meat," said nutrition scientist Hanni Rutzler. "It is not that juicy." But British chef Richard McGeowan said the lack of fat didn't affect his cooking of the five ounces of minced "meat" in a frying pan, thanks to lots of butter.

Fat is just one of the fatal flaws of this lab-grown meat. Here's how it works in a handy infographic from our 2011 feature:

In addition to a lack of fat with the meat (tissue biologists just haven't gotten that union down yet), the in vitro meat features heavy antibiotic use to keep the cells alive and growth on serum from the blood of unborn cows gathered from slaughterhouses (as well as the less gruesome sugars, proteins and fatty acids). As synthetic biologist Christina Agapakis noted in a blog critique in 2012: "Cell culture is one of the most expensive and resource-intensive techniques in modern biology."

Then the meat requires "exercise" on a scaffold. There are questions about its nutritional value as well, such as how much iron it might contain compared with traditional meat. The lab meat has to be colored red after all, by adding beet juice because it is composed of 20,000 or so thin strips of muscle cells rather than the complicated mélange of muscle, fat, blood vessels and bone found in meat from an animal.

Despite all this, the lab beef is being cultured (and feted) because of its potential to reduce the environmental impacts of the human taste for meat. As Post notes, the U.N. Food and Agriculture Organization estimates that demand for meat will swell by more than 70 percent by 2050. Already 30 percent of the world's ice-free land is devoted to feeding animals for meat thanks to the fact that cows and pigs convert only roughly 15 percent of the plants they eat into edible meat. Then there's the problem of the greenhouse gas emissions, particularly potent methane, from all those ruminant belches and their waste, often stored in massive, stinky lagoons. The FAO estimates that livestock are responsible for nearly 20 percent of all greenhouse gas emissions from human activities—more than all cars, trucks, ships and airplanes put together.

Of course, to reduce those emissions, the lab meat would have to be grown on a diet of algae, something that has never been accomplished. If that can be done on a big scale (and that's a big if), the lab meat would reduce methane pollution by 95 percent, as well as reduce the need for farmlands to feed livestock by 98 percent, according to a 2011 study by the University of Oxford published in Environmental Science and Technology. Or we could just eat the algae directly.

The other reason for the hoopla is ethical: philosopher Peter Singer and groups such as People for the Ethical Treatment of Animals extol such efforts for eliminating human cruelty to animals. Why not harvest muscle cells from a single cow to culture millions of hamburgers rather than slaughtering hundreds of thousands of cattle?

This is neither the first time lab-grown meat has been grown—that honor goes to a NASA-funded goldfish filet from the early 2000s—nor eaten publicly. Biophysicist Gabor Forgacs of the University of Missouri tasted his own lab meat, constructed by a 3-D printer out of a meat "flour," at a TED Med conference in 2011. "To increase the weight of a chicken, pig or cow by one kilogram, you have to use two, four and eight kilograms of feed, respectively," Forgacs told a New America Foundation conference on the future of food in April 2012. "If that's what is needed for me to eat meat, that is ridiculous." His spinoff company, Modern Meadow, plans to focus on 3-D printing leather first, with funding from another Internet billionaire, PayPal's Peter Thiel. Menlo Park–based outfit Sand Hill Foods also hopes to create lab-grown meat.

Researchers such as Forgacs and Post predict that it will take between 10 and 20 years to bring lab meat and meat products down in price and onto store shelves. Given that Post's first petri patty has appeared nearly two years later than was first promised, that objective will likely prove optimistic. But as Post told the Rockefeller Foundation's innovation meeting in June 2012: "It's not going to be easy, but it's doable."