Detoxification of chestnut burrs hydrolyzates to produce biomolecules

Abstract

Activated charcoal was proposed to detoxify the streams rich in carbohydrates generated after the acid hydrolysis of chestnut (Castanea sativa) burrs. Adsorption isotherms, kinetics and thermodynamics parameters were evaluated under different ratios of adsorbent/adsorbate (0.25–5.0% w/v). Results showed that Langmuir equations fitted better the equilibrium sorption than the Freundlich isotherm, while pseudo-second-order reaction kinetics explained the reaction mechanism most effectively. An exothermic and non-spontaneous adsorption process was defined by negative enthalpies and positive free energies; meanwhile negative entropies showed the affinity of phenolic compounds for the adsorbent. Mid temperatures (30 °C) and higher amounts of charcoal (5.0 % (w/v)) stimulated the adsorption process, with a higher percentage of phenolic compounds removal (95.50 ± 0.03%). Lactobacillus plantarum CECT-221 was unable to consume raw hydrolyzates; however, it was capable to produce bacteriocins with antimicrobial activity against Listeria monocytogenes CECT-934, cell-bond biosurfactants and lactic acid on detoxified hydrolyzates in biotechnology processes carried out in Erlenmeyer flasks and 2 L stirred tank bioreactors