Low molar mass xylans polymerization via hydroxycinnamic acids oxidative coupling

Abstract

The lignocellulosic material utilization in the context of biorefineries complies with the current demand for more sustainable technologies, covering several integrated processes. In this context, hemicellulose, an important natural resource, is one of the main components found in lignocellulosic biomass and has great potential for biotechnological applications in several sectors of the industry. Among the most commonly used pretreatments to reduce biomass recalcitrance, the chemithermomechanical process employing alcaline-sulfite is responsible for a greater lignin solubilization and preservation of the polysaccharide fractions, which allows higher yields of cellulose hydrolysis for production of second generation ethanol, for example. The xylan fraction exploitation, the most abundant hemicellulosic polysaccharide of the plant cell wall, has been highlighted and its isolation can be conducted through the utilization of alkaline solutions or enzymatic treatment. Previous studies have shown that enzymatically extracted xylans from alkaline-sulfite-pretreated biomass have lower contamination with lignin and lower molar masses. In addition, they are possibly associated with portions of hydroxycinnamic acids through an ester bond between arabinose and hydroxycinnamic acid. The polymerization of low molecular weight xylan from the hydroxycinnamic acids phenolic termini using oxidative enzymes presents as an alternative to promote the molar mass increase and to allow the expansion of these polymeric materials applications, adding value to the use of sugarcane bagasse in biorefineries.