Residual streams from industrial fermentation could potentially serve as a raw material for the production of mycoprotein. This is evident from research in which scientists tested whether the nutrients in a liquid residual stream from an existing fermentation process can be reused for the cultivation of fungal biomass.
Mycoprotein is a protein-rich food ingredient made from fungi and is considered an alternative to animal proteins. Interest stems from limited land use and the fact that production is largely independent of conventional agriculture. The organism in this study is Fusarium venenatum, the same fungus that is used for mycoprotein in meat substitutes.
The researchers looked at centrate, the liquid remaining after the fungal biomass has been separated following fermentation. This liquid still contains nitrogen compounds, carbon sources, and other nutrients, but is typically disposed of as waste. The question was whether the stream could serve again as a culture medium for a subsequent cultivation.
Ammonia and glucose determine the yield
In the trials, the residual stream indeed yielded a usable amount of new biomass. Under the most favorable conditions, the yield amounted to nearly four grams of dry biomass per liter, close to the value predicted by the calculation model. The amount of ammonia and glucose proved to be the most determining factors for the result. Carbon conversion rose to over 29 percent, which means that a substantial portion of the available nutrients was converted into biomass.
According to the authors, reuse has two advantages. The residual stream requires less processing before it can be disposed of, and additional protein-rich biomass is generated from material that would otherwise be lost. As a result, the environmental impact of the fermentation process can turn out lower.
It is not the only lead in this direction. In a related study, partly the same authors investigated whether rejected functional beverages from the beverage industry could serve as a carbon source for mycoprotein. Rapidly absorbable sugars such as glucose and sucrose yielded a high growth rate, although this was accompanied by a lower biomass yield and more by-products.
The research is still in an experimental phase and has not yet been tested on an industrial scale. However, the results suggest that a fermentation residue stream can serve as a culture medium for a subsequent cultivation, allowing the same raw materials to be used multiple times.
Source: arxiv.org
Photo: Fungus-based meat substitute, grinchh – Adobe Stock
