Valorisation of Agri-Food Wastes for Pleurotus Ostreatus Growth

Background: Edible mushrooms rich in bioactive compounds (also called medicinal mushrooms) are gaining popularity due to the concerns around the consumption of animal products and the demand for new protein sources. The use of agri-food wastes as substrates for mushroom production is an alternative method to reduce the environmental impact of their disposal. Within OnFoods project, this study investigates the use of fresh-cut salad waste (S) and brewer’s spent grain (B) as substrate to apply Solid State Fermentation process for the growth of Pleurotus ostreatus. Innovative analytical technologies (i.e., digital and thermal image analysis and FT-NIR spectroscopy) were used to study the growth rate. Methods: P. ostreatus ATCC 96997 was grown on S, B, and a reference medium (i.e., malt extract agar, R). After sterilisation, substrates were inoculated with P. ostreatus and incubated at 25 °C, monitoring growth with the innovative technologies. The fungal biomasses and the entire cultures were also analysed for moisture, protein, and lipid content. Results: The three innovative technologies proved effective in monitoring P. ostreatus growth. S and B guaranteed valuable biomass growth rates. The highest growth was evidenced in B (4.1% yield in dry matter, d.m.) compared to S (1.8%) and R (1.2%). A higher protein content was found in the fungal biomass grew on S (29.9% d.m.) and B (27.8% d.m.) rather than on R (16.0% d.m.). The lipid content was similar in the biomass obtained from R and S (0.4–0.7% d.m.), while higher from B (6.3% d.m.). Conclusions: The results demonstrated the potential of wastes generated from freshcut salad and beer production as valuable substrates for P. ostreatus growth. This approach contributes to resource efficiency and advancement in sustainable practices in the production of alternative proteins. Fostering the development of new protein sources is essential to encourage consumers towards nutritious and healthy diet, considering the escalating protein demand driven by population growth.