Researchers turn sugar beet pulp into superfood

Since the 1960’s, sugar has been used as the nutrient source in fungus-based meat alternatives. However, the byproduct from sugar—known as pulp—has until now been a relatively underutilized resource, primarily used as animal feed due to its poor taste and lack of texture.

Over the past four years, René Lametsch, Associate Professor at the Department of Food Science, has led the MYCOPROTEIN project, and they have succeeded in taking the entire waste stream from sugar production and converting it into a nutritious and edible mass. This is done by adding oyster mushroom mycelium and fermenting the mixture, and especially with selected lactic acid bacteria, this has proven particularly effective.

In Denmark, between 400,000 and 450,000 tons of sugar are produced annually from 2.3–2.5 million tons of sugar beets. Therefore, the project’s results are an important step toward better utilization of our food resources.

“The fact that we can convert sugar beet pulp directly into a food product, without sending it through a cow, means we get a much more sustainable food product. The mushroom-fermented sugar beet pulp has a really good texture, similar to a meatball, and a high protein content with excellent nutritional value,” explains René Lametsch.

The project was supported by the Green Development and Demonstration Program (GUDP) with DKK 6.9 million, and besides the Department of Food Science, participants included DTU, Microbiota Food, Rootly, Perfect Season, and Nordic Sugar.

Protein rich and friable

From the start of the project, the goal was to convert the entire side stream into fungal mycelium or another part of the new product, leaving no new byproducts. This goal has largely been achieved.

95% of the added dry matter, the side stream, ends up in the fermented pulp, which is the final product. It has a neutral taste and gains a firm structure through fermentation. When fried, for example, it develops a texture similar to cooked meat - see an example here.

“Starch is often used in plant-based foods to give the product more texture, but it very quickly becomes rubbery to chew. This fermented pulp doesn’t do that. The fungi give it a firm structure, without it becoming rubbery. When it’s fried, the pulp actually resembles a meatball a lot,” says René Lametsch.

The total protein digestibility of the product was also measured, and it is largely the fungi grown in the pulp that boosts the product's protein quality. Digestibility of the fungal mycelium was five times higher than the unfermented pulp, showing that the body can absorb protein from the fermented pulp much more effectively.

Scaling up requires investments

The project has also successfully taken the process out of the lab and scaled it up to 10L and 20L fermentations with equally good results. This outcome is crucial, says René Lametsch, because it proves the viability of the method for the food production industry, which operates on a much larger scale.

“Fungal fermentation of byproducts from the food industry has enormous potential, because there’s so much of it, and most of it goes to waste. Even when it can be used as animal feed, it's highly inefficient. But now we’ve shown, using pulp from sugar production, that it can be turned into a good product. The challenge going forward, and this applies to byproducts in general, is very much about scaling up. It’s both a technological challenge and one that requires significant investment,” says René Lametsch.

Despite the challenges, MYCOPROTEIN has succeeded in demonstrating how fungal mycelium and fermentation can transform an entire side stream into a protein-rich product. This alone is an important step toward more sustainable food production - and it may very well be applicable to other waste streams, such as spent grain from beer production.