"While at this time, alternative protein sources are not a direct threat to the beef industry, we do see improper labelling of these products as misleading," said Lia Biondo, the association's policy and outreach director. "Our goal is to head off the problem before it becomes a larger issue." The immediate threat to the traditional US food industry is "meat" derived from plants, which simulates the taste of the real thing. But further down the track is what is known as "clean meat". Produced without animal slaughter, the meat is derived from a small number of stem cells and produced in a laboratory.

Impossible Foods was started by Patrick Brown, a former Stanford biochemistry professor who, in 2009, took an 18-month sabbatical, which he devoted to carrying out research on eliminating industrial animal agriculture. His goal was to produce a burger that would appeal to vegetarians who had given up meat on moral grounds but still yearned for the real thing. The secret, he discovered, was creating "plant blood" from a molecule known as heme, which is found in animals and plants. When the plant burger made with heme is slapped on to a grill, it turns from red to brown, like one made from beef. It also tastes identical, according to Brown and his 50-strong team of chefs, farmers and scientists. The rest of the ingredients include wheat, coconut oil and potatoes.

His target market is not just vegetarians but hardcore meat eaters whom, Brown believes, could be persuaded to try the plant-based alternative. Beyond Meat was founded in 2009 by Ethan Brown. Endorsed by the Humane Society - the US equivalent of the RSPCA - its backers include Bill Gates. Its meatless burgers are not only sold in stores but served up by restaurant chains such as TGI Fridays, which is offering them at its 469 US locations. They are served in much the same way as a traditional burger, topped with cheddar, lettuce and tomato. Beyond Meat, whose website is packed with endorsements from assorted athletes, also produces ersatz chicken strips and Beyond Sausage - the world's first plant-based sausage, which, it says, "looks, sizzles and satisfies like pork". Nielsen data released last year show why the traditional farming industry is becoming nervous as consumers turn away from animal flesh.

They showed that sales of plant-based food rose 8.1 per cent over the past year, while demand for more traditional items - from meat to dairy - fell by 0.2 per cent. Other figures produced by HealthFocus data showed that 17 per cent of US consumers ate a predominantly plant-based diet and 60 per cent said they were cutting back on meat consumption. Already the plant food market is worth $US3.1 billion ($4 billion) in sales. The word "flexitarian" has entered the lexicon of the food industry, describing somebody whose diet is primarily vegetarian, but who occasionally eats meat or fish. Not surprisingly flexitarians - along with vegetarians - are attracting the interest of venture capitalists, private equity firms and celebrity investors such as actor Leonardo Di Caprio, who took a stake in Beyond Meat last October.

Some of the corporate giants are also moving in on the market. Tyson Foods is pumping $US150 million into Tyson New Ventures, an offshoot specialising in "meatless meat". Nestle, the world's largest food company, bought Sweet Earth Natural Foods, a company that produces plant-based breakfast meats such as Benevolent Bacon and Harmless Ham. Founded in 2011 in Moss Landing, California, Sweet Earth's products - ranging from plant-based burgers to burritos and frozen meals - are already selling in more than 10,000 stores across the US. "In the United States, we're experiencing a consumer shift towards plant-based proteins," Paul Grimwood, Nestle's US chairman, said. "In fact, as many as 50 per cent of consumers are now seeking more plant-based foods in their diet and 40 per cent are open to reducing their traditional meat consumption.

"One of Nestle's strategic priorities is to build out our portfolio of vegetarian and flexitarian choices in line with modern health trends." Loading Last month, the company also bought a majority interest in Terrafertil, a Latin American company that sells its products in Britain as well. Nestle predicts the global plant-based food market could be worth $US5 billion by 2020. Experts such as Marie Molde, a dietitian with Chicago-based analysts Datassential, have also noticed the trend.

"More and more people are becoming 'flexitarian' having meat and non-meat protein in their diet. "We are seeing people becoming concerned about animal welfare and the use of antibiotics. "This has been gaining increasing traction over recent months and years. "People are also concerned about the environment and the carbon footprint of the meat industry. "But consumers still have a concern - they want the food to always taste good and that remains a hurdle and a challenge."

Loading Marcia Mogelonsky, a food and drink specialist at Mintel, expects the trend away from meat to continue. "The whole plant-based food phenomenon is really something to watch - there is a movement towards consuming more plant-based proteins - not necessarily exchanging animal-based proteins for plant-based proteins, but adding them to the diet," she says. "I have been specifically following the growth of vegan chocolate, for example, in which dairy milk is being replaced with plant-based alternatives. "Beyond Meat Burger seems to have met a number of challenges for those who want a 'burger' that tastes like a burger, looks like a burger and acts like a burger ... the products deliver on taste and appearance, and are texturally quite similar to ground beef."

Her colleague Billy Roberts says demand doubled in the first half of the decade and has continued to increase rapidly. "It is starting to take over in parts of the country where you would not expect it to, like in the south and south-west. "Some of it is on the back of Whole Foods and its partnership with Amazon, which is increasing exposure." Much of the demand is being fuelled by the millennial generation, he adds. "They are really interested in having plant-based protein on their plate."

But there are still some who remain sceptical over the long-term future of the plant-based food industry. "This has been a 40-year odyssey," says John Quelch, the dean of Miami Business School. "The first soy burgers for retail consumption - unsurprisingly, a commercial disaster - were developed by Morningstar Farms, a division of Miles Laboratories, in the late '70s. "Technically, plant protein is almost the same as meat protein. But food is about more than nutrition content, it's much more primal than that. "For most Americans, the concept of a non-meat burger has been, and will continue to be, an oxymoron.

"Impossible Food may sadly equate with impossible profits." The Telegraph, London