Enhancing Acacia dealbata valorization through microwave-assisted autohydrolysis: An energy-efficient approach to oligosaccharides and bioethanol production

Microwave-assisted autohydrolysis (MAA) has gained attention as an alternative to conventional hydrothermal treatment (CHT) to solubilize hemicellulosic-derived compounds, such as oligosaccharides, within shorter residence times. MAA assays were conducted on Acacia dealbata wood, an invasive species, at severities (S 0 ) ranging from 3.63 to 4.64 to optimize xylooligosaccharides (XO) recovery and assess the enzymatic susceptibility of the spent solids for bioethanol production. S 0 between 3.77 and 4.15 yielded XO concentrations >9.8 g/L corresponding to a recovery of >80% regarding initial xylan. Besides, at S 0 =3.77, a bioethanol yield of 71% was attained (26.25 g/L). Furthermore, CHT was performed at S 0 values of 3.80 and 4.44 to compare the impact of both heating strategies under optimal conditions for (i) XO production and (ii) higher enzymatic susceptibility of the spent solid. MAA resulted in higher bioethanol yields and, particularly under harsher conditions, lower by-products formation and higher oligosaccharides content. Additionally, MAA consumed 2.60–2.75-fold less energy than CHT.