Nofima researchers use fungi as they develop sustainable solutions to transform residual biomass and food waste into valuable products

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  Jon-Are Berg-Jacobsen

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Food waste is one of the major issues of our time. In societies like our own, we throw away large amounts of food, and biomass from animals and plants. This is not sustainable and much of the present food research aims to reduce such waste. 

Food scientists in Nofima work broadly to reduce food waste. Now they have found a solution for two “problematic” categories. The intestines left over after chickens are slaughtered and non-standard potatoes. 

Produces oil in the cells of the fungus

In this bottle, the residual biomass floats around in the fungal fluid, and when the carbon in the residual biomass has been used up, the fungal cells begin to consume nitrogen and accumulate fatty acids. Photo: Jon-Are Berg-Jacobsen/Nofima

The researchers feed a particular species of fungus with this waste, and the fungus sets about producing fatty acids in their cells. Then oil is extracted from the fatty acids. This oil cannot be used as a human food, but it can become an important and nutritious ingredient in animal feed.   

In order for the fungus to produce oil in the cells, the food must contain the elements carbon and nitrogen. These criteria are fulfilled by the waste from the chicken intestines and the non-standard potatoes. 

“We use a given species of fungus and the same with food waste. We can use other food waste and other fungal species in other contexts. It depends on what fatty acids we are looking for. In this case, chicken guts and potatoes are used primarily to show the potential for making useful oils or fatty solutions”, says the chief engineer at Nofima, Dimitrios Tzimorotas.

Carbon ensures growth, nitrogen adds extra nourishment

Dimitrios Tzimorotas, together with his colleagues, has investigated the relationship between carbon and nitrogen in different types of residual biomass and food waste. It is these studies that led them to understand that the combination of chicken guts and potatoes for this particular fungal species would be perfect for the oil they wanted to produce. 

“The combination ratio is crucial for the end result. We want the fungus to grow to a given size, and then start the conversion process. It uses carbon to grow, but the carbon needs to be regulated because we don’t want uncontrolled growth. When the fungus reaches its proper size, it uses the nitrogen and converts it into fatty acids”, Tzimorotas explains. 

“It is inspiring to see how knowledge and mapping of the relationship between carbon and nitrogen can form the basis for the development of completely new and useful feed products. Developing the production process and body of rules so that such residual raw material-based products can be used for human consumption in the long term can be an important contribution towards a sustainable diet,” says Minister of Agriculture and Food Olaug V. Bollestad.

Bespoke oils

In the future, one could imagine completely different combinations of waste and fungal species, and that one can tailor solutions and produce oils that are sought after. This applies, for example, to the omega-3 fatty acids EPA and DHA. Oils based on these fatty acids have health benefits, and are costly. 

Strict regulations around the cycle of human food from residual biomass, currently prevent the production of oils for human consumption. This may change in the future, when other and more hygienic handling routines are in place. 

“Today’s oil is intended as a supplement in animal feed, but we believe it has potential as cooking oil in the long term. We believe the potential is great with new regulations and better routines for residual raw material handling”, Tzimorotas points out. 

By freeze-drying, the residual raw material is converted into a kind of powder. From the powder or various powder mixtures, Nofima’s experts produce growth medium for fungi, and proceed to the production of fatty acids. Photo: Jon-Are Berg-Jacobsen/Nofima

Easy upscaling

The research stems from a desire to recycle and to create something valuable from what is currently considered waste. 

“The method we have developed can easily be scaled up to commercial size. It is most reasonable to imagine that biotech companies that can and want to produce oil from fungi will use the method. We hope and believe that all such processes will be important in the years ahead,” says Tzimorotas.

Fast screening method with spectroscopy

The researchers use infra-red light to detect whether the fatty acid composition in the fungus is optimal. The method used is called FTIR spectroscopy.  

Usually, measuring the oil content of the fungus would be an elaborate and cumbersome process. The FTIR method is a much faster and more efficient method in which the researchers take a sample and analyse the amount and composition of fatty acids according to a prediction model.”This method gives us an indication of the quality of the oil in the fungus. This is crucial for whether we proceed to the next step in the process. We use the measurements to look at how the fatty acids are composed, so we know if we are on the right track or not. FTIR is a very useful tool throughout the process. We actively use the method as a platform to measure the quality of the products we make,” concludes Tzimorotas. 

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