Integrated multi-analytical framework for comprehensive characterization of lignocellulosic hydrolysates for biorefinary applications

Lignocellulosic hydrolysates are promising second-generation feedstocks for sustainable bioproduction. However, their compositional complexities and a lack of analytical framework, particularly for lignin fraction (LF), have limited holistic characterization and impeded downstream valorization. In this study, we present an integrated multi-analytical framework for in-depth compositional profiling of spruce sawdust hydrolysate (SSH), designed for tandem application in microbial valorization studies. A combined high-performance anion-exchange chromatography and liquid chromatography was developed for quantification of sugars and microbial inhibitors with monomeric arabinose (78.8 ± 0.6 g/L) and acetic acid (14.9 ± 0.1 g/L) as predominant components, respectively. Understanding lignin structures and linkages in hydrolysates enables rational selection of enzymatic and microbial valorization strategies. Therefore, we developed a workflow to quantify and evaluate lignin structures and interlinkages, using a unique spectroscopic-chromatographic approach. UV–Vis spectroscopy quantified a total aromatic content of 58.2 ± 0.1 g/L, while quantitative 31 P NMR clarified the hydroxyl group distribution in the LF. HSQC NMR provided structural identification and semi-quantification of lignin units and interconnecting linkages, and gel permeation chromatography showed the molecular weight distribution of LF. Gas chromatography-mass spectrometry identified and quantified 38 lignin-derived monomers and extractives, with benzoic acid (2.7 ± 0.2 mg/L) as the most abundant. This analysis is vital for biotransformation studies emphasizing lignin-derived monomers and platform chemical recovery. The integrated approach used in this study provides a holistic biomass compositional insight and cross-validation across methods, overcomes the limitations of a single technique, and delivers a robust workflow to evaluate any lignocellulosic hydrolysate suitability for bio-valorization. • Our integrated multi-analytical framework gives holistic profiling of hydrolysates. • Quantification of lignin fractions is necessary to evaluate fermentation suitability. • A combined HPAEC-PAD and HPLC quantifies sugars and microbial inhibitors. • Quantification of lignin monomers and oligomers for platform chemical recovery. • SSH is a potential second-generation feedstock for biorefinery applications.