Purification of ferulic acid solubilized from agroindustrial wastes and further conversion into 4-vinyl guaiacol by Streptomyces setonii using solid state fermentation

This work deals with the screening of seven lignocellulosic residues: chestnut and pistachio shells, grass, leaf fruit, vine leaf, and, red and white grape stems as feedstocks for the release of ferulic acid by sequential pre-treatment with dilute sulfuric acid and alkaline hydrolysis with NaOH. Grass showed the highest concentration of both ferulic acid (312.0 mg/L) and p-coumaric acid (542.7 mg/L). Ferulic acid was further purified from the brown liquor by ethanol extraction, or adsorption with activated charcoal or polyvinylpolypyrrolidone (PVPP). Finally, streams coming from these treatments were fermented by Streptomyces setonii after nutrients supplementation in solid state fermentation. Ferulic acid treated with PVPP presented the best results, achieving 92.1 mg/L 4-vinyl guaiacol (3-methoxy 4-hydroxystyrene) after 30 h of fermentation (QP = 3.071 mg/L h; YP/S = 0.44 g/g), thus confirming the efficacy of the materials as renewable feedstocks, and the treatments for producing natural food additives with high add value.

► Agroindustrial wastes can be used as feedstocks of ferulic acid by hydrolysis.
► Ferulic acid can be purified by extraction or adsorption.
► Ferulic acid can be fermented by Streptomyces setonii in solid state fermentation.
► 4-Vinyl guaiacol, a high add natural food additive can be efficiently produced.