Mechanical size reduction and microwave expansion pretreatment of bagasse enhances hemicellulose extraction yield to approach that of sugarcane pith

Bagasse, the primary by-product of sugarcane processing, comprises both bagasse and bagasse pith. However, in industrial applications, bagasse pith is typically discarded as waste. In this study, hemicellulose was extracted from bagasse, bagasse powder, and bagasse pith to investigate the differences in solubility between fibroblast and heteroblast hemicellulose. At a temperature of 94 °C and a duration of 60 min, the yield of hemicellulose extracted from bagasse pith was found to be 52.7 %. This yield is approximately 2 times higher than that obtained from bagasse and about 1.4 times greater than that derived from bagasse powder. The scanning electron microscopy (SEM) image of the raw material indicated a shorter solubilization pathway and lower resistance of hemicellulose within heterocytes. The yield of hemicellulose extracted from bagasse pith after microwave expansion was found to be 70.1 %, representing a significant increase of 33.8 % compared to that obtained from unexpanded raw material. This indicates that the dissolution efficiency of hemicellulose has been effectively enhanced through the application of microwave expansion. The dissolution activation energies for hemicellulose derived from expanded bagasse, bagasse powder, and pith were measured at 14.9 kJ mol⁻¹, 13.3 kJ mol⁻¹, and 7.1 kJ mol⁻¹, respectively. These values reflect reductions of 31.7 %, 30.0 %, and 49.3 % when compared to those associated with their unexpanded counterparts. This process enhances the extraction of hemicellulose from the pith and further advances the utilization of pith within the overall biomass component.