Fats are central to our eating experience. Yet with increasing concerns over the sustainability and stability of food supply chains, the environmental harm that fat production often causes is coming under increasing scrutiny. In recent years, advances in precision fermentation technology have offered the possibility of creating functional fats with a fraction of the ecological impact.

Anastasia Krivoruchko, co-founder and CEO of Swedish designer fat firm Melt&Marble, unpacks...

Fats consist of molecules called triglycerides, each formed by three fatty acids attached to a glycerol backbone. The chemical structure of these fatty acids – specifically their length and degree of saturation (number of double bonds), as well as their positioning on the fat’s glycerol backbone – determines the fat’s physical and nutritional profile. This structure is responsible for the difference between foodstuffs such as cocoa butter and fish oil.

In the culinary world, fats impart the texture, flavour and mouthfeel of foods. In plant-based meat alternatives, fats are crucial for mimicking the mouthfeel and juiciness of animal meat, as well as acting as a carrier for flavour and aroma compounds. In dairy products like cheese, fats are equally important – they contain short-chain fatty acids that are released during the ageing process, contributing to the distinct flavours and aromas that define different cheeses. Fat also gives chocolate its smooth melt-in-the-mouth texture, which is essential for a satisfying eating experience.

Fatty challenges

Unfortunately, there are major challenges associated with both the functionality and sourcing of fats. It can be difficult to find non-animal fats with that same functionality as animal ones. These fats have unique structures that impart specific properties which can be difficult to replicate with plant-based fats. This is one reason why many meat and dairy alternatives don’t taste quite as satisfying as the real thing.

Fats are also problematic from a sourcing perspective. While animal fats are associated with the unsustainable practices of animal farming, plant-based fats are almost exclusively sourced from tropical regions, where they are associated with mass deforestation and biodiversity loss. Additionally, geopolitical and environmental supply chain instabilities exacerbate food security concerns. Legislation aimed at preventing deforestation is a welcome development. However, the lack of alternative sourcing poses formulation challenges for companies working with these fats, making the quest for sustainable fat alternatives increasingly urgent.

New technologies

Luckily, these challenges can be overcome with novel production technologies, such as fermentation, where fat-producing microorganisms are grown in bioreactors. This process is often compared to brewing, but here fat is produced instead of alcohol. The feedstock can come from a variety of sources, from refined glucose to side or waste streams from food (or other) manufacturing processes. The process is already compatible with existing production infrastructure, allowing companies to test their processes at scale without significant upfront capital expenditures.

The closed nature of fermentation-based production systems, and their compatibility with a wide array of inputs means that fermentation-based fats can be produced in a climate-, weather- and location-independent way. This also means that these fats can be produced much more sustainably than current alternatives, avoiding extensive deforestation.

The same production plant can use a wide array of microorganisms producing different products, while the microorganisms’ rapid growth rate allows quick matching of supply to market demand: while it can take years for new oil palms to become productive, a fermentation process can be completed within days. All these factors make fermentation-based technologies incredibly resilient and likely to play a major role in future food security and climate adaptation.

Precision-fermented fats

Precision fermentation goes a step further. While standard fermentation involves using a microorganism that naturally produces a certain kind of fat, precision fermentation specifically involves rewiring of the microorganism’s lipid metabolism to control exactly what fat is produced. This sort of engineering is inherently complex – since fat is not a gene product, it’s not as simple as introducing a gene for the desired fat. Instead, the fat assembly machinery of the production organism has to be reprogrammed to have it build the desired fat.

Recent years have seen significant advances that make this possible. Advanced fermentation experiments have been carried out to understand how the metabolism of different microorganisms changes during different fermentation conditions, while -omics (e.g. genomics, transcriptomics, proteomics, metabolomics) have been used to understand different cellular processes’ impact on production.

Genome-scale metabolic models (GEMs) have been developed that allow simulation of microbial metabolism in silico to help in the prediction of engineering efforts, while synthetic biology tools have been developed that allow faster generation and screening of production microorganisms. Furthermore, advances in lipid analytics allow understanding of not just the fatty acid composition, but of how these fatty acids assemble onto fat molecules, which in turn allows better understanding of the structure/function relationship of fats.

Designer fat

These advancements allow modulation of the composition and structure of the fats in the production microorganism – characteristics like chain length and saturation of the fatty acids in the fat, as well as their positioning. This enables precise modulation of the melting, texture and mouthfeel properties of the resulting fat. This precise control also allows the customisation of fats for different applications – i.e. creating true 'designer fats' to help address the taste gap between alternative meat and dairy and their animal-based counterparts to help shift towards more sustainable consumption.

Beyond controlling the functionality of the fats, precision fermentation can be used to improve foods’ nutritional profile. Fats rich in healthy fatty acids such as omega fatty acids can be produced to enhance the end product’s health profile. This opens up new possibilities for creating healthier food products that cater to the growing consumer demand for sustainable nutrition and wellness, as well as opening up interesting opportunities for personalised nutrition. With precision fermented fats, the foods of the future promise to be not just more sustainable and delicious, but also healthier!

Naturally, there are challenges to address – microbial fat metabolism is intricately linked with numerous cellular processes and can still be tricky to engineer, resulting in long development cycles. The production microorganism must be robust and scalable, and the process must meet the desired unit economics. Full deployment of the technology will require high CapEx investments, while complex regulatory frameworks might extend time to market.

However, the potential of this technology to solve a myriad of problems and tap into a substantial market (the market for palm oil alone is estimated at over $60 billion annually) makes the effort highly worthwhile.

Amidst global challenges like deforestation, supply chain disruptions and rising food insecurity, precision fermented fats offer a groundbreaking solution, promising to transform the way we think about and consume fats in our daily diets.

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