Growing Nutrition on Waste: Exploring Pleurotus columbinus as a Sustainable Functional Food

The present study investigated the cultivation of Pleurotus columbinus on alternative substrates derived from spent mushroom substrate combined with spent coffee grounds or wheat straw, with or without supplementation with wheat bran and soybean flour, in comparison to conventional wheat straw. All substrates were evaluated for their effects on the nutritional composition, amino acid profile, lipid, carbohydrate contents and bioactive compounds of the harvested carposomes. Protein content ranged from 15.6 to 21.4% w/w. Methionine was identified as the first limiting amino acid and the essential amino acid index was up to 60.9%. Carbohydrate content exceeded 63.3% w/w in all samples, with glucose identified as the major monosaccharide. Lipid content was low (1.7–3.4% w/w), with polyunsaturated fatty acids predominating. Ash content ranged from 5.7 to 6.3% w/w and the energy value varied between 36.2 and 37.1 kcal/100 g f.w. Bioactive compounds, including β-glucans (35.9–44.4% w/w) and ergosterol (3.3–4.7 mg/g d.w.), along with their metabolites, were successfully quantified. Non-supplemented substrates enhanced β-glucan levels; most of them were further isolated, whereas lovastatin was not detected in any sample. Overall, P. columbinus cultivated on alternative substrates exhibited improved nutritional quality and higher bioactive compound content compared to conventional cultivation, demonstrating the potential of agro-industrial by-products as sustainable substrates for high-value mushroom production.