Mycoprotein: a way for a more sustainable food system

The seventeen Sustainable Development Goals (SDG) are the blueprint to achieve a better and more sustainable future for all. One way to reach this goal is to look and be inspired by nature biodiversity. Microbial biodiversity could be indeed a key factor to achieve several SDG, as environmental degradation, climate change, and sustainable food system. The transition to more sustainable food systems will require many changes, including the search for a new source of food or feed with a lower impact of intensive agriculture and farming. Fungal biomass, known as mycoprotein, could be an alternative source of protein. Why mycoprotein could be a sustainable novel food? First, fungal fermentation is independent of land exploitation, avoiding ethical issues by not competing with food and farm industries. Moreover, fungal growth could be handled in an economic and energetic sustainable way, as required by the principle of the green economy. Indeed, fungal fermentation may be carried out using agro-industrial by-products (AIBPs), valorizing them as valuable feedstocks for a new production system. This project was aimed to investigate the production of high-value fungal biomass with low economic and environmental impact. Medicinal mushrooms were chosen because they are known to metabolize many kinds of substrates and to produce high-value compounds. Pleurotus ostreatus, Ganoderma lucidum, Cordyceps militaris and Pleurotus eryngii were grown in different cultural conditions. Twenty-five cultural lines were set up in submerged fermentation using different by-products including AIBPs. The first goal was to assess the effects of different AIBPs, C, and N sources and ratios on the biomass production yields: results indicated the optimal growth medium was often strain-dependent. More in detail, the best yields were obtained in the presence of insect breeding and AIBPs, where the biomass recovery of some strains was comparable to the control (rich synthetic medium). Once the optimal growth condition was set for each fungus, the nutritional quality of the biomass was evaluated. It should be indeed noted that great variability in the nutritional composition may be found among fungi, due to species, strains, type of substrate used, fermentation time, type of storage, and conservation process. In this project, the chemical composition of the fungal biomasses was investigated using centesimal composition analysis. Fungal biomass was extracted using different methodologies and the extracts were analyzed through spectrophotometric analysis (Folin-Ciocalteu assay, FRAP, and DPPH assays) to assess the presence of bioactive molecules that could have a positive outcome on animal and human health. Data confirmed the major role of culture media on the nutritional value of the produced biomass. Moreover, different strains shown different biomass quality as well. G. lucidum grown on insect breeding by-product had a very high protein content, while higher lipid content was measured in C. militaris grown on cereal molasses by-products. Results are indeed very promising but, in the future, additional effort should be done to optimize fermentation conditions, in order to achieve good nutritional value and to set up the optimal conditions for biomass production scale-up.