Sustainable Valorization of Tsipouro Liquid Waste via Fermentation for Hericium erinaceus Biomass Production

This study investigates the potential of tsipouro liquid waste (TLW) as a sustainable substrate for cultivating the edible–medicinal mushroom Hericium erinaceus under static liquid fermentation. TLW naturally contains high glycerol levels and significant quantities of phenolic compounds; therefore, five media (0–50% v/v TLW) with varying phenolic concentrations and a standard initial glycerol level (~20 g/L) were prepared to simulate TLW-type substrates. Throughout fermentation, physicochemical parameters in the culture medium (pH, electrical conductivity, total sugars, free amino nitrogen, proteins, laccase activity, total phenolics, ethanol, glycerol) and biomass composition (intracellular polysaccharides, proteins, lipids, phenolic compounds, flavonoids, triterpenoids, antioxidant activity) were determined. Results showed that increasing TLW concentration enhanced biomass production and bioactive metabolite accumulation. The highest dry biomass (22.8 g/L) and protein (4.06 g/L) content were obtained in 50% v/v TLW, while maximum polysaccharides (6.8 g/L) occurred in 17% v/v TLW. Fungal growth led to a reduction of up to 74% in total phenolic content, indicating simultaneous bioremediation potential. Fruiting body formation—rare and uncommon in liquid cultures—occurred at the end of fermentation period. Fruiting bodies contained higher protein (24.5% w/w) and total phenolic compounds (13.36 mg GAE/g), whereas mycelium accumulated more polysaccharides (49% w/w). This study demonstrates that TLW can serve as a cost-effective, ecofriendly medium for producing high-value H. erinaceus biomass and bioactive metabolites, supporting circular bioeconomy applications in the alcoholic beverage sector.