Corn is presently one of the most expensively cultivated cereals worldwide, resulting in significant agricultural solid residues. The corncob waste is considered a by-product due to its phenolic fraction rich in phenolic acids and flavonoids that could be substitute synthetic functional additives in various food and pharmaceutical applications. This study has been focused on investigating different extraction processes and operating conditions to recover the phenolic fraction from corncob waste, followed by an identification study to valorise the final extracts. The experiments were conducted using bath extraction with rotary agitation and ultrasound-assisted extraction. The solvent was ethanol, water, and various ethanol-water mixtures. Ultrasonication has been more effective than rotatory agitation, ensuring higher extraction yields in a much shorter contact time. The presence of kaempferol, p-coumaric acid and ethyl-ferulate has been identified in the phenolic profile of all extracts from the treatment of corncob waste with ethanol solvents. The response surface methodology with a Box-Behnken desing (BBD) has been employed to analyse the combined effect of contact time, solid waste amount and ethanol fraction in the solvent on the extraction efficiency. Kinetic experiments were also performed with the optimal solvent selected from the BBD to examine maximising extraction of p-coumaric acid, kempferol and ethyl-ferulate.
