Innovative monitoring of medicinal mushroom growth on food by-product substrates in solid-state fermentation

The development of sustainable bioprocesses for the valorisation of food industry by-products is of growing interest, particularly through the cultivation of medicinal mushrooms. This study evaluated the growth of Pleurotus ostreatus and Ganoderma annularis under solid-state fermentation (SSF) using fresh-cut mixed salad by-product (MS) and brewer’s spent grain (BSG) as substrates, with malt extract agar (MEA) as a reference. Innovative, monitoring techniques, including digital image analysis, thermal imaging, and Fourier transform near-infrared (FT-NIR) spectroscopy, were applied to assess mycelial development during growth. Results showed that MS supported higher mycelial efficiency (695%-723%) than BSG (166%-170%). Both MS and BSG promoted the accumulation of higher concentrations of proteins (30.36-34.90 g/100 g dm) and lipids (1.03-7.60 g/100g dm) in the mycelial biomass compared to MEA (15.79-17.30 g/100 g dm proteins; 1.03-2.96 g/100 g dm lipids). Digital and thermal imaging provided accurate growth curves and insights into mycelial thermal insulation patterns, whereas FT-NIR spectroscopy effectively tracked compositional changes during fermentation. The obtained mycelial biomasses were also rich in bioactive compounds, such as ergosterol (21-104 mg/100 g dm) and β-glucans (7.35-34.3 g/100 g dm), with concentrations dependent on both substrate and species. These findings highlight the potential of integrating innovative monitoring technologies with the valorisation of food by-products for the sustainable production of functional mushroom ingredients.