Organosolv Processing of Lignocellulosic Agroindustrial Residues: Compositional Upgrading and Exploratory Solid-Phase Material-Use Assessment

Agroindustrial lignocellulosic residues represent potential secondary resources, but their response to a common fractionation process can vary substantially with feedstock composition. This study evaluated organosolv processing of coconut fiber, maize cob, coffee parchment, and cocoa parchment under identical ethanol–acetic acid conditions. Untreated and processed solids were compared for physicochemical and compositional properties, and residue-specific responses were integrated using fiber enrichment, organic-solids equivalents, and non-dominance screening. Organosolv processing increased mean crude-fiber content from 25.04% to 66.74% and pH from 5.70 to 6.35; both effects remained significant after Holm correction. COD decreased in all residues, although the treatment-level response was not significant after multiplicity adjustment. Fiber enrichment occurred in every feedstock but varied markedly, with coffee parchment showing the largest proportional increase. Material-use profiles also differed: coconut fiber reached the highest crude-fiber concentration, whereas coffee parchment combined high fiber enrichment with the highest organic-solids equivalent and lowest ash content. Coconut fiber, maize cob, and coffee parchment were non-dominated under the exploratory screening. These results show that organosolv processing can produce fiber-enriched solids from contrasting agroindustrial residues, while the broader compositional outcome remains feedstock-dependent.