Rhamnogalacturonans are branched pectic polysaccharides found in most plant cell walls and various agro-industrial residues. A commercial rhamnogalacturonan from soybean was selected as a model substrate to investigate the hydrolytic capacity of aqueous carboxylic acids (citric and malic acids) under subcritical water conditions as a green approach to biomass valorization. The hydrolysis was performed in batch mode at different temperatures (125–155 °C) and reaction times (10–120 min) at constant pressure (100 bar). The HPSEC-RID and HILIC-ELSD analyses showed that aqueous carboxylic acids at 125 °C/100 bar favored cleavage of neutral sugar residues from side chains of rhamnogalacturonan. At 135 °C/100 bar/60 min, scission of rhamnogalacturonan backbone was evident where fractions of 4.7 kDa, 2.1 kDa, and <1.4 kDa were prevalent. Fractions with ≤2.1 kDa were comprised of 2–9 DP (degree of polymerization) oligogalacturonides and 5–10 DP galacto-oligosaccharides. A multi-step sequential hydrolysis mechanism was proposed for rhamnogalacturonan hydrolysis in subcritical water-carboxylic acid media.

鼠李半乳糖醛酸聚糖是在大多数植物细胞壁和各种农用工业残留物中发现的分支果胶多糖。选择了以大豆为原料的鼠李糖半乳糖醛酸聚糖作为模型底物，以研究亚临界水条件下水性羧酸（柠檬酸和苹果酸）的水解能力，以此作为生物质增值的绿色方法。在不同的温度（125–155°C）下以间歇模式进行水解，并在恒定压力（100 bar）下进行反应时间（10–120分钟）。HPSEC-RID和HILIC-ELSD分析表明，在125°C / 100 bar的含水羧酸有助于从鼠李糖半乳糖醛酸聚糖侧链上裂解中性糖残基。在135°C / 100 bar / 60分钟下，鼠李糖半乳糖醛酸聚糖主链断裂明显，其中4.7 kDa，2.1 kDa和<1.4 kDa的比例普遍存在。≤2.1kDa的馏分由2–9 DP（聚合度）低聚半乳糖苷和5–10 DP的低聚半乳糖组成。提出了在亚临界水-羧酸介质中鼠李糖半乳糖醛酸水解的多步顺序水解机理。