Sustainable production of pure L-arabinose from brewer’s spent grain biomass

The current work presents the innovative isolation and purification of a commercially valuable monosaccharide, L-arabinose, which is largely utilized as a natural sweetener and food additive, from brewers’ spent grain (BSG), one of the most abundant agri-food waste and the primary by-product of the brewing industry. The utilization of BSG for the extraction of industrially relevant compounds has recently gained significant attention due to its potential for waste reduction and natural resources optimization. Moreover, L-arabinose recovery from BSG would represent a valid green alternative to the commonly used depolymerization of gum Arabic, a high-cost raw material (35 €/kg), which requires several steps of purification and, consequently, the use of hazardous solvents, higher costs, and time. In this work, a process based on an initial water treatment followed by a selective controlled hydrolysis step is presented, with the final aim to specifically break down the glycosidic bonds between D-xylose and L-arabinose to obtain the latter one release and final recovery in high purity, leaving the remaining biomass unaffected. In order to achieve this result, the kinetic of the process has been studied and optimized, and 20% of the total L-arabinose present in BSG has been recovered. This research aims to develop a new cost-effective and environmentally friendly method for the isolation of high-purity L-arabinose from brewery residues, contributing to the advancement of circular economy practices in the brewing industry.