Fortifying cultured meat: Beta-carotene produced by cow muscle cells

16 Oct 2020 --- Cow muscle cells can be engineered to produce beta-carotene, which the human body can then usually convert into vitamin A. This method, published in Metabolic Engineering, shows how cell-cultured meat might be able to surpass the nutritional profile of conventionally farmed meat.

Andrew Stout, lead author of the study and biomedical engineering PhD student at Tufts University, tells NutritionInsight that he expects other nutrients could also be produced similarly. 

“That is one of the things about this that I am the most excited about. Putting plant genes into mammalian cells is pretty untraveled scientific territory. There is a lot of space to explore other nutrients, flavor compounds and color compounds, for example.”

A double-duty effect
In this initial research stage, beta-carotene was used due to its role as an antioxidant.

“There is significant evidence for oxidative processes being involved in meat consumption’s connection to colorectal cancer. Therefore, the antioxidant nature of beta-carotene and the other carotenoids made them promising candidates for this proof-of-concept.”

Those same oxidative processes are major contributors to meat’s quality degradation over time, for example, off-flavors and color degradation. Therefore, beta-carotene offered a “double-duty” effect.

As the scientists have not produced enough cells to eat, it is unknown whether the taste would be altered. However, Stout flags that it is a possibility and notes that there is a color change in the cells. 

“They turn slightly yellow. They are usually white-ish and need to be colored anyway for a cultured meat product.”Beef with beta-carotene would likely appeal to consumers who can pay more for better-for-you offerings. 

Slashing carcinogenicity
According to Stout, this engineering technique allows nutritional benefits to be imparted directly onto a cultured meat product in a way that is likely infeasible through animal transgenics and conventional meat production.

Rather than simply mimicking meat currently found in the grocery store, cell-cultured meat products are capable of assuming different shapes, textures, nutritional profiles and bioactivities.

Another way this can be used is to reduce carcinogenicity. The researchers saw a reduction in lipid oxidation levels when a small pellet of these cells was cooked while they were expressing and producing beta-carotene. 

“Because that lipid oxidation is one of the key mechanistic proposals for red and processed meats’ link to diseases such as colorectal cancer, I think that there is a pretty compelling argument to be made that this could potentially reduce that risk,” says Stout. 

Golden rice comparisons
The scientists used the same carotenoid pathway exploited in golden rice, prompting comparisons between the two foodstuffs. Notably, issues ranging from farmer adoption to successful vitamin A conversion have prevented golden rice’s effective use. 

While golden rice was an inspiration to Stout, he stresses that different motives and considerations are at play. 

One notable difference is that golden rice was developed to address vitamin A deficiency, which is common in many regions facing poverty. 

“This work isn’t aimed at combating vitamin A deficiency, since – at least for the foreseeable future – cultured meat (and indeed, often conventional meat) isn’t an economical option for people facing vitamin A deficiency,” adds Stout.

However, he hopes that the cost can ultimately be driven down so that the product can be widely accessible. 

Occupying a unique role
In Stout’s opinion, the “genius” of golden rice was its ability to fit into the staples of the diets of people who faced the deficiency.

“This product wouldn’t do that. Here, a comparison could be that this might fit into the diets of those who face other diet-related diseases, particularly those associated with a lot of red meat consumption like colorectal cancer.”

Additionally, a large part of the problems that golden rice ran up against was asking growers to substitute this new product for something they were already growing, selling and eating. From a farmer’s perspective, this was without much incentive to do so.

However, cultured meat is not something that people are already growing, selling and eating. In contrast, it is an as-yet-unrealized product in development. However, commercialization of several cultured meats is on the horizon as scientifically-backed start-ups around the world continue R&D and work toward scaling up. 

“Exploring ways to enhance it at this stage can go hand in hand with that development in a way that’s pretty different from the golden rice story,” says Stout. 

There is also a difference in terms of consumers as cultured meat already asks for a behavior change. “It already has to do work to convince people to buy it and has a ‘neophobia’ factor to contend with.”

Earlier this year, a survey revealed that 72 percent of Generation Z Australians viewed cultured meat with disgust, although acceptance is flourishing in France and Germany. Meanwhile, KFC’s embracing of cultured meat was lauded as being “very positive for consumer acceptance.”

Nonetheless, Stout anticipates that the portion of consumers who would be okay with cultured meat but draw the line and cultured meat plus beta-carotene would be fairly low. “Of course, it could be different from a regulatory standpoint, but that’s another story.”Issues ranging from farmer adoption to successful vitamin A conversion have prevented golden rice’s effective use.

Fatty pairings
Another issue with golden rice is in order to convert beta-carotene into vitamin A, it must be metabolized, and blood serum levels of retinol need to increase. However, vitamin A is fat-soluble, which is something that many vitamin A-deficient people lack. 

While this new type of cultured meat does not aim to address deficiency, adding beta-carotene to an animal product means it is more likely that there will be ample fat. 

“Nutrients have different bioavailability in different food matrices. There’s a lot of evidence of nutrients having higher bioavailability when plant foods are eaten alongside higher-fat foods and animal products. Therefore, engineered cultured meats could hold some interesting implications for nutrient uptake,” says Stout.

Commercialization potential?
Stout explains that the commercialization of this specific technology is predicated on the commercialization of cultured meat as a whole.

The next steps for that revolve around bringing down the cost of cell culture and bringing up the achievable scale. 

“There’s some benefit that nutritionally-enhanced cultured meats could offer the field as a whole in terms of increased product value and potentially offsetting cost disparity with conventional meat.”

David Kaplan, Stern Family Professor of Engineering at the Tufts University School of Engineering and corresponding author of the study, adds that consumers may be more willing to pay for a cultured meat product if it has added health benefits.

However, Stout acknowledges that many companies are focusing on matching conventional meat before doing anything fancy with it.

“I like to say that if we view cultured meat as meat v2.0, then this would be meat v2.1,” he concludes. 

By Katherine Durrell