At Maastricht University in the Netherlands, Mark Post and his team of researchers are gearing up towards a groundbreaking event: preparing and cooking a hamburger.
But this is not just any hamburger. The meat for the patty will take the best part of a year to source because it is not coming from a dead animal. Instead, a tiny cube of flesh from a cow has been removed, and cells within it isolated, cultured and then grown in a liquid medium. If it works, it may be the first ‘artificial meat’ to be eaten.
If a bubbling vat of ‘meat’ – which researchers in the field tend to refer to as ‘animal-based protein products’ – sounds unappetising, there are many valid reasons for considering it. Proponents claim that it could help to feed an overpopulated world while reducing the environmental impact of raising livestock.
According to the Worldwatch Institute, global meat production has risen by 20% in the past 10 years – and may double to 465m t by 2050. In the same period, world population is likely to swell to nine billion people: raising livestock, it seems, cannot be sustained.
There are other reasons why the interest in artificial meat has increased. In a recent paper in the American Journal of Food Technology, Z. F. Bhat and Hina Bhat assess the progress – and potential future – of ‘animal-free meat fabrication’.1 ‘Biofabrication – production of complex living and non-living biological products – is a potential solution to reduce the ill effects of the current meat production system,’ say the authors. They list these as: ‘nutrition-related diseases; food-borne illness; resource use and pollution; and the use of farm animals’.
Conventional meat production, they say, is a major source of pollution: globally, 30% of the land’s surface is used for livestock production, and one-third of arable land is used to raise crops for animal feed. Further, world meat production may account for nearly a quarter of greenhouse gas emissions. ‘It no longer makes sense to contribute staple crops towards inefficient meat production, where 1kg of beef requires 7kg of grain,’ say the authors.
Post, a professor of vascular physiology and head of the department of physiology, agrees and believes that techniques like the one he is developing could allow herds to be shrunk to one-millionth of their current size.
The Maastricht technique uses stem cells, which can be relatively easily harvested from an animal, like a pig or cow. ‘Every animal with skeletal muscle has stem cells, which repair the tissue when it’s injured,’ says Post. Stem cells can be extracted from animal tissue, then fed with nutrients to make them grow. ‘These cells will eventually differentiate into skeletal muscle tissue – because that’s what they’re used to doing,’ he says.
The tools and techniques to do this are already established, although are largely confined to the medical field, explains Post. ‘We’re not the first to use these techniques, but they’ve never been used for growing meat before,’ he adds.
Post estimates that a cubic centimetre of animal flesh will provide enough stem cells to produce a decent-sized hamburger.
Each stem cell is prepared and cultured in parallel: rather than growing one single sample of meat, Post’s team is preparing small samples in a number of parallel batches, and freezing the results. ‘That way, if we make a mistake – such as getting an infection in an incubator – we don’t have to throw everything away,’ he says. Each sample takes five or six weeks to reach maturity. Post says that anything from 100 to 1,000 samples could be cultured in parallel.
His team includes a food technologist, who will carry out the necessary tests into how the material reacts to heating, cooking, freezing and other processes. In parallel, a raft of other tests will be done. Biochemical assays will determine fat and protein content – as well as identifying specific proteins. The composition will determine its similarity to ‘real’ meat, and the conditions under which it will congeal into a patty. Microbiological tests will look for any possible infections – though this is not likely, says Post, because the culture medium is ‘much more sterile than the animal itself’.
He and his team are growing small, thin pieces of meat. They are thin because this allows efficient delivery of nutrients. Thicker pieces would need to have some kind of miniature ‘irrigation’ system to deliver nutrients into the tissue – although Post says that this problem is ‘not insurmountable’. ‘It’s a technical challenge that we will solve if we spend enough time on it,’ he says.
Post’s immediate goal, however, is to achieve a ‘proof-of-concept’, which will involve producing enough meat to create a tasty (and safe) hamburger. Once this is done, he says, he has a line of volunteers willing to carry out the ceremonial eating of the burger. He fully expects this to happen within the next 12 months.
Other key issues
Once Post has his ‘proof-of-concept’ he hopes that more funding will be forthcoming, which would allow other key issues to be addressed – such as identifying nutrients of non-animal origin and improving the efficiency of the process. The nutrient question is a key problem. If solved, it could make ‘artificial meat’ acceptable to a most unlikely set of consumers: vegetarians.
Many vegetarians shun meat because of issues of animal welfare, or do not agree that animals should be killed for their meat. Producing artificial meat does not involve killing animals, so may be acceptable to some vegetarians. But the nutrients that Post is using to feed his tissues come from blood serum – from calves and horses. At the same time, serum is relatively expensive, and there is little incentive to make it any cheaper. ‘In the end, serum from blood is just a set of chemicals,’ he says. ‘To get away from animal-derived products, we need to identify which of these thousands of chemicals are actually needed to grow these cells in the most efficient way.’ Some work is already going on here, notably researchers at Amsterdam University are trying to convert protein from algae into a medium that muscle cells can grow on. ‘For now, we are giving them amino acids, and rely on the cells to build proteins from them,’ says Post.
Vegetarians have already given the concept of artificial meat a cautious welcome. The Vegetarian Society recognises that the product could bypass the issue of animal welfare, but stresses that labelling will be crucial. This leads into the second issue: that of improving the yield. Any industrial process – and this is Post’s eventual aim for the technology – needs to be efficient. While his process is currently inefficient, he believes it will eventually overtake the natural process itself. ‘Animals are very inefficient at creating proteins – they produce lots of waste,’ he says. ‘But there’s evidence that this is not at the cell level, only at the level of the animal.’ By working at cell level, and ‘outside the animal’, he believes that the vital proteins could be made far more efficiently.
Post explains that a key factor in boosting protein production is creating ‘tension’ in the cells. This, he says, is a natural process, and will even occur spontaneously in the test tube if the tissue has an ‘anchor point’. ‘This tension is the strongest stimulus for protein production,’ he says. ‘We’ve been experimenting to see if we can make even more protein, by zapping the cells with electricity.’
Rather like Galvani’s early experiments with the frog’s leg, an electric pulse will cause contraction, and, in this case, boost protein production. However, Post believes that this will not be efficient in a production environment owing to the expense of the electricity. ‘We must come up with other ways to make the process more efficient,’ he says.
Despite the revolutionary nature of the work – and Post is not alone in his quest (see Box) – he says that funding is still difficult to find. ‘I suppose it’s because people do not believe it will work, or it’s too futuristic, or they think that nobody will eat it,’ he says. But he is confident that his ‘proof-of-concept’ will unlock funding, allowing the technology to move to the next level. ‘If we can produce a burger, and show that it’s made using processes that we can all understand, then I think investors will realise that they have to start investigating this,’ he says.
It is still early days in the commercialisation of these products, says Post. While we may soon be tucking into burgers and sausages made in this way, anything more sophisticated may be some way off. ‘Our first goal is to produce “processed” meat,’ says Post. ‘It’s a large part of the market, and it’s far less challenging than a steak or a pork chop.’
The quest for artificial meat
Alongside the use of stem cells, there are other emerging methods of producing artificial meat. One, known as scaffolding, involves attaching embryonic or adult cells to a carrier, such as a collagen mesh, or micro-carrier beads, and infusing this with a culture medium. These cells can then fuse into 'myotubes', and differentiate into 'myofibres'. These could be cooked and consumed as meat. A number of researchers are looking into scaffolding, including Willem van Eelen, who holds a worldwide patent in this area, and tissue engineers Oron Catts and Ionat Zurr of Harvard University in the US.
More highly structured meats might be produced using self-organising tissue culture. This was first done around 10 years ago by researchers, including Morris Benjaminson at Touro College in New York, US. They took slices of goldfish tissue and grew it using fetal bovine serum or Maitake mushroom extract. The resulting 'explants', which looked like fresh fish fillets, were cooked and presented to a panel, who, without actually tasting them, said they 'looked and smelled good enough to eat'.
But the reality is some way off, say Bhat and Bhat:'Since crucial knowledge is still lacking, commercial production of cultured meat is not yet possible, and the focus must be on filling the gaps in this knowledge. It will only be feasible on an industrial scale when a cost-effective process is established and given government subsidy like that given to other agribusinesses.'
- Z. F. Bhat and H. Bhat, Am. J. Food Technol., 2011, 6(6), 441.
Lou Reade is a science writer based in Kent, UK.