‘The most comprehensive study on cultivated meat production published to date….’ Believer Meats data shines light on cell cultured meat metrics

One of a handful of cultivated meat startups now operating at pilot-scale (from its base in Rehovot, Israel), BELIEVER Meats​​​ is one of the top-funded players in the industry, raising $347m in its series B round last year to help commercialize Non-GMO technology it claims enables it to achieve higher-density cell cultures and more efficient use of media than rivals in the nascent space.  

It has since broken ground on a 200,000-square-foot facility in Wilson, North Carolina, that it claims will be the largest cultivated meat production facility in the world​​ with the capacity to produce at least 10,000 metric tons of cultivated meat (around 22 million lbs) per year.

Cultivated meat: Intractable technical challenges at food scale?​

While growing meat from cells in bioreactors instead of living breathing animals should logically be more efficient as resources are spent on growing only the cells that make up the meat product rather than keeping an animal alive, no one has yet proved this at scale, however.

Skepticism about the commercial viability of the technology reached new levels in late 2021 when UC Berkeley-trained chemical engineer David Humbird told The Counter​​ that the technology faced “intractable technical challenges at food scale."​

Much of this related to cell densities (too low) and media costs (too high), with Humbird concluding that it was “hard to find an angle that wasn’t a ludicrous dead end.”​

Cell densities outlined in study far higher than those in Humbird analysis​

The new paper in Nature Food​​ – published in late December and co-authored by Prof. Nahmias at Believer Meats and scientists at the Hebrew University of Jerusalem – tackles both of these issues, outlining a non-GMO process whereby Believer Meats grows fibroblasts (initially extracted from fertilized broiler embryos) in single cell suspension (ie. without having to adhere to anything, enabling higher cell densities) in animal-free serum, without the need for expensive growth factors.

Through a patented non-GMO technique, Believer Meats coaxes fibroblasts to spontaneously immortalize ​​​​or proliferate indefinitely, which means you don’t have to keep going back to the source (ie. the chicken embryo).

According to Prof. Nahmias, “Genetic modifications can introduce unintended mutations that increase risk of immunological reactions, and thus we chose to avoid them completely. One issue of concern in the field is whether the immortalization process leads to the production of cancer-forming cell lines. However, the work showed that the process developed by our group resulted in cells with normal DNA repair mechanism and without the ability to form tumors.”​

According to the study, Believer Meats is achieving cell densities of more than 100 billion cells per liter, said Prof. Nahmias, 

Believer Meats then converts the immortalized fibroblasts (which typically form connective tissue) into fat cells, he explained: “We developed a highly efficient differentiation process that uses natural soy lecithin ​[phosphatidylcholine from soy lecithin] to turn fibroblasts to fat cells in under a week."​

Animal fat is responsible for the distinct flavor and aroma of meat 

"Animal fat is responsible for the distinct flavor and aroma of meat due to the production of complex polyaromatic hydrocarbons during grilling,"​ explains the study. "In contrast, meat's fibrous texture can be mimicked by high-moisture extrusion of plant protein. We therefore developed a method to impregnate chunks of high-moisture extruded soy protein with cultured chicken fat, producing chicken strips that blend plant-based and cell-cultured proteins and fats."​

Believer Meats' chicken strips had 22% less saturated fat and 37% less cholesterol than farmed chicken but higher sodium due to the soy protein, said Prof. Nahmias.

"The paper goes to show a significant preference for lab-grown chicken product ​[over plant-based chicken] in consumer testing.”​

The Counter’s analysis assumed a maximum density of 22-65bn cells per liter, and assumed the need for expensive growth factors that are not required by Believer Meats' fibroblasts, added Prof. Nahmias. “A production density of 100bn cells/liter cuts average projected costs three-fold, to about $7.50 per pound of biomass, or $3.30 per pound of hybrid product, within the price range of commercial chicken manufacturing.”​

GFI scientist: ‘I was surprised by the level of detail provided for its protocols’​

Elliot Swartz, lead scientist cultivated meat at the Good Food Institute, told FoodNavigator-USA that the study was “the most comprehensive study on cultivated meat production published to date.”​

He added: “Believer Meats should be commended for its transparency and willingness to publish these findings in an open-access manner. I'm hopeful this will set a standard for other companies in the cultivated meat industry.​

“I was surprised by the level of detail provided for its protocols. In the supplementary data, the company provides detailed Standard Operating Procedures (SOPs) for all the methods used. In particular, the suspension adaptation protocol may be very valuable for other researchers in the field to replicate.​

“Additionally, I thought that the company went above and beyond in the characterization of the spontaneously immortalized cell lines. I think these data provide more than enough information about the safety of the cells for regulators, and some analyses were likely done to temper any consumer concern about whether the cells are transformed.”​

‘It cannot be assumed that such high cell densities will be maintained in much larger vessels’​

Asked about cell densities, he said it was still to be determined, however, if Believer Meats will be able to maintain cost-effective high cell densities in scaled production.

“Cell density is one of the most important metrics for cultivated meat manufacturers,"​ said Dr. Swartz.

"The cell density reported in this study — 360 grams per liter — is very high and would certainly make cost-competitive cultivated meat more tractable if it were able to be replicated at scale. However, this study performed experiments in 2L stirred-tank bioreactors and used high rates of perfusion to achieve the result ​[the perfusion rate is the rate of media exchange being used, expressed as unit of volume per unit of time].

“In addition to well-characterized challenges related to mixing in larger vessels,” ​said Dr. Swartz, “such high perfusion rates could also add considerable cost. Therefore, it cannot be assumed that such high densities will be maintained in vessels that are up to or more than 10,000x larger in volume.”​

‘Our rejuvenation tech can capture >70% of the lactate produced in our system. ​This would allow us to produce poly-lactic acid as a side stream’​

Dr. Swartz also observed that “high amounts of lactate are also produced ​[during the production process]. If this were to be captured, it could be a huge opportunity to offset costs and environmental impact.”​

He added: I think it will be interesting to see them publish on their continuous process and see real data for capturing lactate.”​

Prof. Nahmias told us: “We agree it's a massive opportunity. Believer Meats has developed a proprietary media rejuvenation technology that allows us to actively remove lactate from the waste produced in our system.​

“This would allow our factories to produce poly-lactic acid as a side stream of cultured meat production potentially doubling the amount of biodegradable plastic produced worldwide.”​

Asked about Dr. Swartz’s comments on cell densities at commercial scale, he said: “We achieved densities 84% higher than Humbird’s assumption… so we certainly beat expectations by a mile. ​

"Elliot is also correct that the perfusion rates shown in our Nature Food paper are too high for commercial scale. ​

“Our next papers will show how Believer Meats went beyond ATF ​[Alternating Tangential Flow] technology towards a scalable continuous process.”​

“We must ensure that we, as an industry, provide all the scientific data and information to the public. If we do not rise to this challenge, consumers will search and find disinformation from charlatans online. I want to lead this conversation.”​

Prof. Yaakov Nahmias, president and CSO, Believer Meats​

‘The Big Wall of No has been conclusively shattered’​

That said, he added, “The Nature Food paper shows that the ‘Big Wall of No’ has been conclusively shattered for several reasons: ​

“First, Wood and Humbird ​[the two experts quoted in The Counter article​​] thought cultured meat cells would never grow like CHO cells ​[Chinese hamster ovary cells, epithelial cell lines commonly used in biopharma research] in single cell suspension but modeled what they considered an unrealistic scenario in which they did.  ​

“Our Nature Food article shows cultured meat cells growing as single cell suspension for the first time, showing that assumption was not unrealistic. In fact, we can be as efficient as the best systems in the pharmaceutical industry.​

“More importantly, both Wood and Humbird assume that only three population doublings are possible in each step of the process, so if they wanted cells to double 10 times they needed to model three consecutive bioreactors…. 200L -> 2,000L -> 20,000L ​

“Our Nature Foods data shows five population doublings. This means that factories actually need only need two-thirds of the bioreactors assumed by Humbird and Wood. This massively reduces the cost of the factory.”​

‘The medium costs that we show in this paper are under $5 per liter’​

Finally, he said, “Humbird assumed the growth would require Essential 8 Media​​, which is used to grow stem cells. This is a very expensive culture medium that includes expensive growth factors such as TGFb and high amounts of insulin and FGF. His work massively overestimates the amounts of growth factors required ​[in Believer Meats' process]. 

“The work quoted in The Counter article uses a figure of $69 per liter of medium. The medium costs that we show in this paper are under $5 per liter.” ​

Further reading:​

• BELIEVER Meats breaks ground on ‘largest cultivated meat production center in the world’ in North Carolina​​
• WATCH: Future Meat rebrands as Believer Meats: ‘A cow needs about two acres of land to grow. This [pilot plant] is the size of your living room and it can make a cow a day’​​
• What is the environmental impact of cultivated meat? LCA sheds new light, says SCiFi Foods​​
• Orbillion Bio teams up with Solar Biotech to scale up cultivated meat platform in the US​​
• Vow founder: First wave of cultivated meat should delight and intrigue consumers, so why launch with chicken nuggets?​​
• ‘A watershed moment in the history of food…’ Cultivated meat edges closer to commercialization in the US as UPSIDE Foods gets FDA green light​​

Source:​ Nature Food​ ​

Spontaneous immortalization of chicken fibroblasts generates stable, high-yield cell lines for serum-free production of cultured meat​

Authors: L.​ Pasitka, M. Cohen, A. Ehrlich, B. Gildor, E. Reuveni, M. Ayyash, G. Wissotsky, A. Herscovici, R. Kaminker, A. Niv, R. Bitcover, O. Dadia, A. Rudik, A. Voloschin, M. Shimoni, Y. Cinnamon & Y. Nahmias