Mycoproteins of medicinal mushroom from submerged fermentation of agroindustrial byproducts

The global population is constantly growing and likely to exceed 10 billion by 2060[1] , thus revising food production and its resources is necessary. Our planet is overexploited and 80% of Earth’s agricultural land is used for livestock[2] , for meat and meat derivates consumption, which have heavy environmental impact (high water consumption, production of greenhouse gases, use of territorial resources, deforestation and biodiversity loss). To overcome these problems without depriving human diet of proteins, several solutions have arisen over time, such as protein-rich plants, synthetic meat and insects. Mycoproteins can be a valid alternative. Fungi are highly prone to biotechnological applications, such as making plant matrices more digestible by degrading lignin for feed purpose, enriching plant wastes in fatty acids and proteins, including essential amino acids, and for using their biomasses as probiotics. Moreover, these processes are often coupled with production of valuable metabolites such as vitamins and pigments[3] . Although retrieving proteins from fungi has already been achieved using solid state fermentation, it arouses technological and environmental concerns. Submerged fermentation is instead a more sustainable and controlled solution, avoiding seasonal process dependance. Developing products based on this technology could be the foundation for a new ‘green’ food frontier. Five edible medicinal mushrooms (Ganoderma resinaceum, Pleurotus ostreatus, Cordyceps militaris, Pleurotus eryngii and Lentinula edodes) preserved in the Mycotheca Universitatis Taurinensis (University of Torino) were selected. To develop economic and energetic sustainable process, growth media were based on agroindustrial by-products (e.g. wheat vinasses, insects exuviae, tomato peels, etc.) coming from local companies, to identify the media yielding the more fungal biomass. Then, once selected the nine best performing media, the proximate compositions of the fungal biomasses were analyzed to identify the highest protein content biomass for future studies focused on fungal protein production. Among the experimental lines, both the highest biomass production (24 g/L dw) and protein content (51% dw) were achieved in P. eryngii grown in Hermetia illucens exuviae-based media. To the authors’ knowledge, this is the first work exploiting insect exuviae-based media to sustain fungal growth in SmF. At the same time, antioxidant activity of the extracts retrieved from these fungal biomasses was measured. Extracts were obtained via conventional 24-h maceration or fast microwave (MW) treatment, using water or ethanol as solvents. Data indicated that MW method led to comparable antioxidant activity yields, opening new possibilities in future (poly)phenolic extraction protocols with more feasible and sustainable techniques. Studies are ongoing using different fungi and by-products in respect of the circular Economy and sustainability principles. The present project leads to a better understanding of sustainable fungal fermentation, sustainable downstream processes of valuable biomasses for their potential exploitation in food and feed sector.