Lignocellulosic biomass pretreatment and cellulose dissolution are principal challenges for its conversion to high-value chemicals, materials and fuels. This work focused on production of soluble cellooligosaccharides (COS) from palm bunch for future use as nutraceutical supplement to enhance human's immune and digestive systems. Deep eutectic solvents (DESs) have been found as eco-friendly, renewable and promising solvents selective for lignin and hemicellulose removal from biomass. Additionally, the investigation of most suitable DES for both cellulose dissolution and subsequently cleavage of cellulose to COS is crucial. In the study, palm empty fruit bunch (EFB) was pretreated in different DES for screening of most favorable cellulose inter- and intra-molecular structural dissolution in a combination with beta,1–4 glycosidic bond cleavage by elevated reaction temperature for COS production. ChCl/urea was found to be the most promising DES for dissolving 76.83% of EFB constituents. The highest COS production yield at 90.1%w/w based on treated EFB fraction (74.7% COS yield based on cellulose in native EFB) was achieved in ChCl/urea DES from cellulose fraction extracted from EFB at 240 °C for 20 min. The study additionally provided insightful characterization and elucidation of COS molecular structure using 2D-HSQC and MALDI-TOF/MS techniques. MALDI-TOF/MS was a promising and rapid technique for simultaneously qualitative and quantitative analysis of COS at different degrees of polymerization in COS product.

木质纤维素生物质预处理和纤维素溶解是其转化为高价值化学品、材料和燃料的主要挑战。这项工作的重点是从棕榈束中生产可溶性纤维低聚糖（COS），以供未来用作营养补充剂，以增强人体的免疫和消化系统。低共熔溶剂 (DES) 被发现是一种环保、可再生且有前途的溶剂，可选择性地从生物质中去除木质素和半纤维素。此外，研究最适合纤维素溶解和随后将纤维素裂解为 COS 的 DES 至关重要。在该研究中，棕榈空果串（EFB）在不同的 DES 中进行预处理，以筛选最有利的纤维素分子间和分子内结构溶解，并结合通过升高反应温度进行 COS 生产的 β,1-4 糖苷键裂解。ChCl/尿素被发现是最有前途的 DES，可以溶解 76.83% 的 EFB 成分。基于处理过的 EFB 级分（基于天然 EFB 中的纤维素，COS 产率为 74.7%），从 EFB 中提取的纤维素级分在 240 °C 提取 20 分钟，在 ChCl/尿素 DES 中实现了最高 COS 产量，为 90.1% w/w。该研究还使用 2D-HSQC 和 MALDI-TOF/MS 技术对 COS 分子结构进行了深入的表征和阐明。MALDI-TOF/MS 是一种有前途且快速的技术，可同时对 COS 产品中不同聚合度的 COS 进行定性和定量分析。