Integrating optotracing to elucidate wheat straw delignification pathways in a one-step peracetic acid process

In this work, a one-step peracetic acid (PAA) treatment was established for wheat straw delignification, eliminating the need for conventional chemical pretreatments. By exploring sulfuric acid catalysis, we demonstrate that fiber liberation can be achieved at sulfuric acid concentrations as low as 50 mM. It is achieved by primary removal of acid-soluble lignin and arabinose while preserving xylose and mannose. Although delignification is spatially heterogeneous and requires extended reaction times, the addition of sulfuric acid significantly accelerates fiber release. Advanced imaging approaches, including scanning electron microscopy, confocal fluorescence microscopy, and optotracing, enable in situ spatial visualization of lignocellulose anatomy at sub-cellular resolution. These analyses reveal how PAA penetrates and acts within wheat straw, moving from conventional bulk chemical descriptions to anatomical mapping of fiber liberation and delignification dynamics. Notably, they showed that the lignin-rich epidermal cell layer is a limiting factor, and residual lignin can also persist within parenchyma cells. The recovered holocellulose fibers display sufficient structural integrity to form self-standing paper-like sheets.