Coupling Trends in Cultured Meat and Entomophagy
Insect Cell Culture and Tissue Engineering for Food Production
- Insect cells have unique properties that may contribute to relatively more scalable and cost-efficient manufacture of food products. © Napat/Shutterstock
- Insect muscle and fat cells can be expanded in vitro, differentiated with the help of natural insect hormones and coupled with three-dimensional biomaterials to generate edible and healthful tissues. © Tufts University
- By coupling entomoculture with cultured foods, disadvantages associated with the individual methods can be alleviated © Tufts University
- David L. Kaplan, head of Department of Biomedical Engineering, Tufts University, Medford, MA, USA
- Natalie R. Rubio, PhD student, Tufts University, Medford, MA, USA
Meat produced from cell cultures (i.e., cultured meat) rather than whole animals may be a solution to the problems surrounding our current livestock production system, but it is currently challenging and expensive to produce such food products at large volumes. Insect cells have unique properties that may contribute to relatively more scalable and cost-efficient manufacture of food products. By coupling trends in cultured meat and entomophagy (i. e., entomoculture), the future of food could include steaks composed of caterpillar tissue, rather than cow.
Driven mutually by population growth and rises in individual economic prosperity, meat consumption is projected to increase by 76% by 2050. Increased public awareness of the public health, environmental impact and animal welfare concerns associated with our current animal agriculture system has generated a demand for more sustainable alternatives to meat and other animal products.
Innovations in meat alternatives include plant-based analogs, edible insects, transgenic animals and meat produced from cell cultures (i. e., cultured meat) rather than whole animals. Each of these options proposes benefits over conventional meat production processes yet also faces challenges with development, scalability and consumer acceptance.
Cultured meat perhaps holds the most promise in terms of reducing impact while retaining most, if not all, of the desired aspects of meat. Although cultured meat has garnered attention from the media and investment communities, it has yet to be commercialized due to technical obstacles of scale and cost-efficiency.
Entomophagy, the practice of eating edible insects, though not common in Western nations, is routine throughout South America, Africa, Asia and Australia. Insect farming is accessible, affordable and sustainable and many edible species (there are over 2,000) are lauded for their rich nutrient content. The most commonly consumed insects include species of caterpillar, palm weevil and grasshopper. Entomophagy is gradually gaining popularity in America as well, based on the relatively lower environmental impact of raising bugs compared to more traditional livestock.
Advantages include lower land and water requirements, lower greenhouse gas emissions and higher feed conversion efficiencies.
So far, American insect products have largely taken the form of protein bars and baked goods made with cricket flour.
The disadvantage of insect-based products is that they are not often a culinary substitute for meat when it comes to flavor and texture. While insects can provide an alternative for protein and other nutrients, they do not satisfy a meat eater’s craving for a juicy steak or burger for the grill, thus cooking, texture and taste remain to be explored in detail.
Like edible insects, cultured meat has advantages and disadvantages when compared against conventional meat. Cultured meat could: reduce rates of foodborne illness and antibiotic resistance; require less land, water and generate less greenhouse gas emissions and improve animal welfare by reducing or eliminating the need for livestock in the food chain.
However, to date, no cultured meat products have been commercialized due to obstacles of scale-up and cost reduction. In brief, the process for generating meat from cells involves: isolating skeletal muscle and adipose precursor cells from a donor animal; formulating serum-free media to support cell growth; proliferating cells at high-density in a bioreactor, and coupling cells with a scaffold system for differentiation and tissue maturation.
The majority of the field to this point has largely piggy-backed off advances in the field of tissue engineering for medical applications. However, dissimilar to technologies for implants for clinical utility or as in vitro disease models, tissue engineered food must be incredibly scalable, affordable and free from animal derivatives (for long-term sustainability).
Insect cell culture could provide a preferable platform for large-scale cell culture for food production. Insect muscle and fat cells have previously been cultured and characterized for a number of species. These cells can be expanded in vitro, differentiated with the help of natural insect hormones and coupled with three-dimensional biomaterials to generate edible and healthful tissues.
Vertebrate vs. Invertebrate Cell Culture
The majority of cultured meat initiatives are focused on cultivating cells from traditional food animals such as cows, pigs, poultry and fish. These cell types have proven challenging to grow at large volumes for minimal cost due to stringent growth conditions, high oxygen demand, and a lack of basic research. Mammalian muscle cells are generally grown as adherent cultures and incubated at 37 °C, with humidity and 5% carbon dioxide to stabilize the pH of sodium bicarbonate-based basal media. Media is supplemented with high concentrations (10-20%) of fetal bovine serum and growth factors, and subculture requires enzymatic dissociation.
While suitable for bench-scale research, these conditions create challenges when considering large-scale cell production; serum and growth factors are expensive and varies by batch, high incubation temperatures result in increased energy requirements and adherent culture requires complex bioreactor design for high-density culture. In contrast, insect cells are more robust, adaptable and tolerant of fluctuations in growth conditions. Many insect cells can grow in adherent or suspension conditions; at ambient temperatures; without humidity or carbon dioxide exchange; without the need for serum or complex growth factors, and in the presence of higher concentrations of toxic byproducts (e. g., ammonia, lactate).
Insect Tissue Engineering
Beyond advantageous growth properties, insect cells are a useful cell culture platform due to the amount of scientific literature available. Insect cells have long been studied in regard to developmental biology and recombinant protein production which can inform culture methods, media formulation and scale-up processes. However, insect-specific knowledge is lacking when it comes to generating organized tissues from harvested cells. While tissue engineering is less of a focus for processed meat products (e.g., burgers, nuggets, sausages), it is important for creating structured meat products (e. g., steaks, chicken breast, pork chops). This process involves inducing muscle and fat cells to differentiate into mature tissues with the help of three-dimensional materials (i. e., scaffolds) to guide morphology and influence mechanics.
Tissue engineering for mammalian muscle and fat is well-reported and can inform strategies for invertebrate constructs. There is a limited amount of research on generating insect muscle in vitro for bioactuators — e. g., biological robots powered by muscles as opposed to traditional electrical actuators. This has primarily involved culturing insect muscle cells in silicone molds to create bundles of contractile muscle. Mushroom chitosan has also been explored as an edible scaffold to support three-dimensional insect cell growth, inspired by the in vivo presence of chitin within insect exoskeletons.
Texture, Flavor and Nutrition
Due to the innate properties as highlighted earlier of insect cells, entomoculture could provide a compelling opportunity for cultured foods. Through this coupled approach, disadvantages associated with the individual methods can be alleviated; cultured insect tissue can generate more consumer acceptable products than edible insects and insect cells can be easier to culture than mammalian cells.
However, cultured insect meat will undoubtedly be challenging to market to consumers. Rather than creating an entirely new type of food, one approach could be to emulate products that are already on the market. Invertebrate muscle is similar to mammalian skeletal muscle and insects have organs called fat bodies that store lipids, analogous to mammalian adipose tissue. By selectively growing insect muscle and fat tissue and leaving out the eyes, legs and wings, products would embody the appearance and texture of familiar meat products rather than of whole edible insects.
A second important factor is flavor. The flavor of insects is largely dependent on species, location and age; and they tend to soak up flavors of their own food and ambient environment. Insects are often described as tasting like seafood. For entomoculture, both flavor and nutrition can be regulated via media composition or genetic engineering. Insect muscle cells can be more dense in protein and minerals than mammalian muscle cells and intracellular iron content can be increased by media supplementation.
With appropriate product development and consumer marketing, insect cells present an important opportunity for novel and sustainable foods. However, there are technical milestones to overcome before this concept can be feasible.
First, scale-up processes that have been achieved with insect cells for recombinant protein production must be applied to and optimized for insect muscle and fat specific cells. Second, tissue engineering principles traditionally applied to mammalian cell types should be adjusted to support the three-dimensional culture of invertebrate tissues. Once these milestones have been achieved, prototypes can be further refined to mimic the desired taste, texture and nutrient properties of meat.
Even if entomoculture never catches on in the marketplace, there are still persuasive reasons to pursue this brand of research. For instance, cultured insect protein might prove to be a good additive for pet food or aquaculture feed. Insects are also evolutionarily close to crustaceans and advances in insect cell culture could be translated to generate cell and tissue cultured lobster, crab and shrimp. Furthermore, if the advantages associated with insect cell culture can be correlated with specific cellular mechanisms, these findings may inform the modification of mammalian cell culture systems to improve economics related to cultured meat production.
By using individual cells and tissue engineered cells, instead of whole animals, culinary horizons begin to broaden. As cultured meat becomes closer to reality, researchers and innovators should work on the outskirts of traditional constraints of the food industry to bring new and improved technology to our plates.