As food pioneers continue investigating the planet-conserving and health properties of new cell-based meat components, researchers at Tufts University in the US have managed to bulk-produce fat tissue that has a similar texture and make-up to fat tissue naturally occurring in animals. 

Their findings are deemed a key step forward in a “third epoch in human harvesting of food – from hunting to domesticated animal farming to cellular agriculture.”

“It’s the fat that contributes not only texture, but also to its delicious flavor to the meat,” the researchers underscore. “Consumer tests with natural beef of varying fat content showed the highest scores for beef containing 36% fat.”

The results, described in a study published in the journal nclick="updateothersitehits('Articlepage','External','OtherSitelink','Scientists cultivate cell-based animal fat for accentuated texture and flavor in alt-meats','Scientists cultivate cell-based animal fat for accentuated texture and flavor in alt-meats','334024','https://elifesciences.org/articles/82120', 'article','Scientists cultivate cell-based animal fat for accentuated texture and flavor in alt-meats');return no_reload();">eLife, could be applied to the production of cultured meat grown entirely from cells, giving it a more realistic texture and flavor.

“Our goal was to develop a relatively simple method of producing bulk fat. Since fat tissue is predominantly cells with few other structural components, we thought that aggregating the cells after growth would be sufficient to reproduce the taste, nutrition and texture profile of natural animal fat,” comments John Yuen Jr., a graduate student working at the Tufts University Center for Cellular Agriculture (TUCCA).

“This can work when creating the tissue solely for food, since there’s no requirement to keep the cells alive once we gather the fat in bulk.”

Cultivating a new industry
Start-up companies around the world are developing cultivated meat – cell-grown chicken, beef, pork and fish. Most are in early stages of development, not ready for large-scale production and, with a couple of exceptions, not yet approved for commercial sale.

The movement is primarily driven by cell-based production’s ability to significantly reduce foods’ footprint, while eliminating the need for growth hormones and antibiotics entering the food chain through consumed livestock.

But most of those products in development are in the form of an unstructured mixture of cells, which are more conducive to forming chicken nuggets instead of a slice of chicken breast, the Tufts University researchers highlight. “What is lacking is the real texture of a filet or steak – a texture created by muscle fibers, connective tissue and fat,” they note.

“Producing cultured fat tissue in sufficient quantities has been a major challenge, because as the fat grows into a mass, the cells in the middle become starved of oxygen and nutrients.”

In nature, blood vessels and capillaries deliver oxygen and nutrients throughout the tissue. Scientists still have no way to replicate that vascular network at large scale in lab-grown tissue, so they can only grow muscle or fat to a few millimeters in size.

To get around this limitation, the Tufts University researchers grew fat cells derived from mice and pigs first in a flat, 2D layer, then harvested those cells and aggregated them into a 3D  mass with binders such as alginate (developed from seaweed) and microbial transglutaminase (MTG), which are both already used in some commercial foods.

Reproducing features of native fat
The aggregated fat cells immediately had the appearance of fat tissue, but to see if they truly reproduced the features of native fat from animals, the team carried out a further series of experiments.

First, they explored the texture, by compressing the fat tissue and seeing how much pressure it could withstand compared to natural animal fat.

They found that cell-grown fat bound with alginate was able to withstand a similar amount of pressure as fat tissue in livestock and poultry, and that the cell-grown fat bound with MTG behaved more like rendered fat, similar to lard or tallow. 

This suggests it could be possible to fine-tune the texture of cultured fat using different types and amounts of binders, so that it most closely resembles the real-life texture of fat within meat.

The molecular composition of fat is also important, the researchers highlight. Cooking releases hundreds of compounds that add flavor and aroma to the meat, and most of those compounds originate from fat, including lipids and their component fatty acids.

Supplementing cultivated fats with other lipids
The Tufts research team examined the composition of molecules from the cell-grown fat and found that the mix of fatty acids from cultured mouse fat differed from native mouse fat, but that cultured pig fat had a much closer fatty acid profile to the native tissue.

The team’s preliminary research suggests it might be possible to supplement growing fat cells with different lipids to ensure that they more closely match the fatty acid composition of natural meat.

“This method of aggregating cultured fat cells with binding agents can be translated to large-scale production of cultured fat tissue in bioreactors – a key obstacle in the development of cultured meat,” explains David Kaplan, Stern Family professor of biomedical engineering at Tufts and director of TUCCA. 

“We continue to look at every aspect of cultured meat production with an eye toward enabling mass production of meat that looks, tastes, and feels like the real thing.”

Cell-based food aisle of the future
TUCCA is continuing to run projects toward the development of a growing cellular agriculture industry. Along with a consortium of academic and corporate members – the TUCCA Consortium – it is focused on solving key technological challenges in cell grown meat production.

While the burgeoning sector has made significant strides in this past year – not limited to the creation of a wooly mammoth meatball and Japanese eel – it has been met with some backlash from traditional livestock producers feeling a push against cultural farming heritage, particularly in Italy.

But while cultured meat is anticipated to play a pivotal role in the transformation of the global food system, it is notable that industry cannot harness this opportunity effectively without the help of farmers.

With this in mind, cultured meat companies have a significant opportunity to collaborate with farmers at early stages of production, involving them in cell sourcing and cell feedstock.