- Raw Materials, Ingredients, & Inputs
- Cell line development
- Bioprocess design
- Cell culture media
- End product formulation & manufacturing
One of the long-touted health benefits of fish is their long-chain (LC) omega-3 polyunsaturated fatty acid (PUFA) content. Because fish consume these nutrients from other organisms such as marine algae, it is unclear how cultivated seafood will be nutritionally equivalent to conventional products unless these compounds are supplied in the culture media or added in post-processing, which may be expensive. A key question is how to introduce LC omega-3 PUFAs into cultivated seafood products. The method by which LC omega-3 PUFAs are added may impact the quality of the final product. Depending on the product and the desired fatty acid (FA) profile, producers might also add shorter-chain PUFAs and monounsaturated fatty acids. Specific omega-3 PUFAs that will be relevant to this discussion are eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and α-linolenic acid (ALA). EPA and DHA are the best-studied of the LC omega-3 FAs, while ALA is an essential FA in animals and can be converted to EPA and DHA, albeit only in small quantities. This challenge primarily applies to cultivated seafood from marine species, especially those higher on the food chain, which contain high levels of LC omega-3 PUFAs. It will also apply to a lesser extent to freshwater fish and terrestrial meat, which are lower in LC omega-3 PUFAs.
Approaches to the challenge of incorporating LC omega-3 PUFAs (which exist in several forms, including free FAs, triglycerides, and phospholipids) into cultivated seafood products can be divided into two broad categories: First, LC omega-3 PUFAs can be sourced as ingredients and (1) added into the product in a final processing step, (2) incorporated into the scaffold, or (3a) added to the culture media. Second, bioprocesses could be designed in which LC omega-3 PUFAs are produced either by (3b) co-cultured support cells or (4) by the cultivated cells that will make up the final product.
The feasibility of these various approaches should be investigated through open-access research, considering constraints such as projected cost when the method is scaled up, effects on the organoleptic properties of the product, and susceptibility of the incorporated fatty acids to oxidation.
FAs introduced by various approaches may differ in how efficiently they are taken up by cells. For example, option 1, and possibly options 2 and 3 (especially if FAs are introduced later in the culture period), might result in a product where most FAs remain in the extracellular space. It is possible that such products would have higher oxidation rates during the post-harvest period or less desirable organoleptic properties. However, it is uncertain whether and to what extent this will be the case. Adding omega-3s during a final processing step might otherwise present advantages from a cost and scalability perspective. Therefore, it will be essential to determine what conditions lead to high cellular uptake and what impact this has on the quality and stability of the final product.
Existing methods of creating scaffolds suitable for cultivated meat and seafood will need to be adapted and optimized to develop LC omega-3 PUFA-enhanced scaffolds. Spatially heterogeneous scaffolds with alternating layers featuring cues such as stiffness and groove structures optimized for muscle and fat will be important for creating whole-cut cultivated fish. Such scaffolds should ideally have PUFAs incorporated precisely into the regions designed for the growth of fat cells. Development of methods for spatially restricted deposition of PUFAs might be beneficial for the development of nutritionally and organoleptically-optimal whole-cut fish. LC omega-3 PUFA-rich shellfish will similarly benefit from PUFA-enhanced scaffolds, though the discussion of the layered structure does not apply here.
Investigation into methods for emulsifying FAs into culture media, as well as of the effects of these compounds on the health, proliferation, and differentiation of the cultured cells, will be an essential first step toward designing optimized processes for maintaining the health of cultures while producing products with high omega-3 content. High concentrations of LC omega-3 PUFAs, especially DHA, inhibited the proliferation of cell cultures from tuna. The observation that the addition of vitamin E reverses this effect suggests that toxicity is related to oxidative stress. Further optimization of FA profiles for use in cultures of particular cell lines should consider such effects and test the efficacy of antioxidant compounds to increase the acceptable LC omega-3 FA concentration. Because of the hydrophobic nature of FAs, dissolving them in culture media is a potential challenge. Previous studies have successfully incorporated LC omega-3 PUFAs into culture media by complexing them with bovine serum albumin (BSA) or by using liposomes. Both methods were able to dissolve EPA or DHA to at least 20 μM, and the BSA method worked at concentrations of 1000 μM. Recombinant albumin has recently been shown to be effective in serum-free media for the growth of bovine cells. Therefore, it will likely be a common ingredient in media formulations for cultivated meat. This will likely contribute to demand for low-cost sources of animal-free albumin, which can improve the solubility of LC omega-3 PUFAs. However, the three studies mentioned above used free FAs. Other strategies might be preferable if FAs are added as triglycerides or phospholipids, and further research is needed in this area.
Using FAs and other media inputs efficiently will be a critical mechanism for reducing the cost of cultivated meat and seafood production and reducing its environmental footprint. Therefore, it may be worth investigating how FAs could be recovered using media recycling systems, or more generally, how media recycling systems could be designed to work well with media high in FAs.
Atlantic salmon hepatocytes have been shown to convert approximately 45% of radiolabeled ALA supplied in the culture media to longer-chain or more-highly unsaturated omega-3 FAs, including 20% to DHA. Therefore, it is possible that co-cultured hepatocytes from freshwater or diadromous fish could increase the concentration of LC omega-3 FAs in cultivated meat. Cultures would need to be fed with shorter-chain omega-3 FAs such as ALA. Research into this method will be required to determine what co-culture conditions are most favorable for LC omega-3 PUFA synthesis by hepatocytes and uptake by adipocytes, whether sufficiently high LC omega-3 PUFA levels are achievable, and how an optimized version of this method compares in terms of cost and scalability to other strategies.
Finally, designing and optimizing genetic engineering strategies by which cultivated meat and seafood cells could produce omega-3s is a promising but relatively unexplored area of research. Identifying optimal strategies for producing sufficient levels of omega-3s will be the first step, followed by further optimization and assessment compared to other methods. Such an approach could reduce costs in the long term by replacing more expensive media ingredients with cheaper ones. However, but this would come at the expense of a potentially-difficult cell line engineering challenge at the beginning, as well as the regulatory hurdles associated with producing a genetically modified product.
The methods by which producers of cultivated seafood choose to incorporate LC omega-3 PUFAs and other FAs into their products and the sources chosen for these compounds (if applicable) will affect the cost of production for cultivated seafood and likely influence its organoleptic and nutritional properties. Two critical prerequisites for the potential conservation benefits of cultivated seafood to be realized are cost-competitiveness with conventional products and the quality of the product being such that it is seen as an adequate substitute for conventional products. By identifying cost-effective methods for matching conventional seafood’s nutritional profiles and organoleptic properties, these hurdles can be overcome and the transition to safe and sustainable seafood can be hastened. Producers could use these same methods to produce “nutritionally-enhanced” cultivated meat and seafood with higher LC omega-3 PUFA levels than those found in conventional products.
- Cell proliferation and long chain polyunsaturated fatty acid metabolism in a cell line from southern bluefin tuna (Thunnus maccoyii) (Scholefield & Schuller 2014)
- A comparative study: In vitro effects of EPA and DHA on immune functions of head-kidney macrophages isolated from large yellow croaker (Larmichthys crocea) (Li et al. 2013)
- Engineering carotenoid production in mammalian cells for nutritionally enhanced cell-cultured foods (Stout et al. 2020)
- Sustainable Seafood Initiative
- Cultivated Meat Research Tool and Protocol Database
- GFI’s Research Grant Program
- Collaborative Research Directory
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