Without eating feed, can beef “raised” in a test tube be delicious?

Nowadays, many people love to eat beef, because beef has higher protein content than pork and lamb, but much less fat. Therefore, whether it is to lose weight or keep fit, eating beef is the best choice. But have you ever thought that one day the meat we eat may not be grown little by little on the pasture, but "raised" in a test tube?

Letting cells grow into "meat" may sound like a plot from a science fiction movie, but in reality, cell-cultured meat has already appeared. What exactly is this meat, where does it come from, what does it taste like, and is it unsafe?

There is one thing I must make clear to you first. The cell-cultured meat we are talking about today is not "vegetarian meat" synthesized from plant protein and other raw materials, but real meat.

How to grow meat through cell culture

In 2014, the world's first "test tube burger" was launched in London, the capital of the United Kingdom. This burger is a bit special. It is not only expensive, but the cost alone is as high as 320,000 US dollars. More importantly, the meat used is different from the usual meat. How is it different? It is cell-cultured meat. The scientific name of this meat is "stem cell artificial meat", which is cultivated in a test tube by Dutch scientists using bovine stem cells. In essence, it is still meat because its basic composition is the same as meat. The difference is that it is not cut from a cow, but the bovine stem cells continue to replicate into more cells under in vitro conditions and eventually become meat. In other words, you don't need to raise cattle at all to get beef.

To understand these questions, we must first understand what the essence of meat is? Animal meat is composed of a certain amount of cells arranged in an orderly manner, and can perform specific functions in living bodies. For example, the lean meat we usually eat is the muscle tissue of animals, and tripe is the stomach of cows. Therefore, in theory, if the cells can be continuously expanded and then combined together, organs can be created, or even a living organism. I remember learning "animal cell culture technology" in high school, which is to add some cells to a culture dish, and after a period of time, you will get more. After entering college, many people's graduation projects also involve cell culture, but due to certain conditions, the pile of cells we cultured can only be called "cell lines" and cannot be eaten.

Normal beef, picture from Tuchong.com

In 1997, the successful breeding of Dolly the cloned sheep made asexual reproduction of mammals a reality, using this principle. However, the technical difficulty lies in the fact that in the path of the cell-tissue-organ-individual structure level, we either get a bunch of cells or an individual, but it is very difficult to control the direction of cell division and differentiation, so that a cell divides and differentiates to form more cells and then to tissues and organs, and then stop.

However, the discovery of Shinya Yamanaka, the winner of the 2012 Nobel Prize in Physiology or Medicine, successfully solved this problem. He successfully transformed highly differentiated fibroblasts into pluripotent stem cells, and the induced pluripotent cells, or IPS cells, cultivated after transformation can control the differentiation direction, which means that immature cells can develop into all types of cells. This also laid a technical foundation for artificially culturing cells to obtain artificial meat.

Let's go back to the production process of "stem cell artificial meat". First, cell tissues must be extracted from the cow and stem cells must be separated, because only stem cells have the ability to differentiate, while other cells cannot. Then, the stem cells are soaked in a nutrient solution containing sugars, amino acids, oils, minerals and a variety of nutrients. The cells will absorb the nutrients in these nutrient solutions, slowly grow and differentiate, and initially grow into a sticky substance. Next, this pile of sticky substances is allowed to continue to "grow" and stretch into small "meat strips" about 3 cm long, 1.5 cm wide and 0.5 cm thick. In theory, it can be eaten at this time, but it is too small to fill the gaps between teeth. Therefore, about 3,000 such strips of meat are often mixed, and about 200 pieces of laboratory-cultured animal fat are added before they can be used for cooking.

Is this meat delicious?

I believe this is a concern for many people. The technology of cell-cultured meat is gradually maturing. In 2019, the National Meat Quality and Safety Control Engineering Technology Research Center of Nanjing Agricultural University also cultivated China's first piece of artificial cultured meat. The production cost of this technology is constantly decreasing, and some local restaurants have even launched corresponding ingredients.

Since it is not directly cut from animals, but is made up of cultured cells, it does not have structures such as blood vessels, connective tissue and fat that supply nutrients. Its color is not as bright red as real meat, but slightly yellow with pink. The taste is also different from real meat, being softer and more rotten.

At present, there are different opinions on cell cultured meat. Some people think that this is a good way to save energy and can even solve problems such as food hazards. Some researchers are also thinking about how to add blood vessels to the meat to make it taste closer to natural meat. After all, meat as an organ basically contains all tissues of animals, such as epithelial tissue, muscle tissue, connective tissue, and nervous tissue. However, there are also some views that this technology is risky, especially ethical risks, and some organizations even believe that it needs to be resisted.

Personally, I think that the emergence of any technology has two sides, and we should still see its positive role. Whether it is space exploration and interstellar exploration, or for environmental protection or food shortage issues, it is still helpful. Of course, this technology can also continue to be developed for the exploration of artificial organs. However, as a commercial use, it may still require a lot of research investment and time.

This article is a work supported by Science Popularization China Starry Sky Project

Author: Zhang Yu

Reviewer: Tao Ning (Associate Researcher, Institute of Biophysics, Chinese Academy of Sciences)

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.