Abstract:

Existing sugar juice decolorizers have food safety hazards and low adsorption capacity. To address these issues, we have developed a green, non-toxic, and efficient hyperbranched polyethyleneimine-functionalized chitosan aerogel (HPCA) for sugar juice decolorization and conducted preliminary investigations into its ability to adsorb melanoidin (MLD) from sugar juice. However, it is necessary to further explore the theoretical mechanisms of adsorption in order to apply efficient HPCA to industrial settings. In this study, we systematically investigated the potential mechanisms of MLD adsorption by HPCA from a molecular perspective using multiple quantum chemical theoretical calculations. Our findings on the electrostatic potential, average local ionization energy, and electrostatic potential interactions suggested that MLD capture by HPCA was primarily mediated by the charge interaction between protonated amine group on HPCA and carboxylate group on MLD. Three visualized optimal capture configurations were proposed at the molecular level, with Configuration I demonstrating the highest stability due to the strong electrostatic interactions formed from the close contact between HPCA and MLD. Frontier molecular orbitals, independent gradient model, and Hirshfeld surface analysis revealed that the MLD adsorption by HPCA involved weak interactions, such as hydrogen bond and van der Waals force. Notably, the MLD mainly acted as hydrogen bond receptor in various capture configurations. These multiple quantum chemical theory calculations provide valuable insights into the molecular-level mechanisms of adsorption and are significant for advancing the study of adsorption micro-mechanisms.

Key words: computational chemistry, adsorption, gels, melanoidin, sugar juice decolorization

摘要：

现有糖汁脱色剂存在食品安全隐患及吸附量低等局限性。开发一款绿色无毒且具有高吸附量的超支化聚乙烯亚胺功能化壳聚糖气凝胶（HPCA）用于糖汁脱色，并初步探究其吸附美拉德色素（MLD）性能。为将高效糖汁脱色吸附剂投入到工业化应用中，还需对吸附理论机制进行更深层次探索。通过多重量子化学理论计算，从分子角度系统揭示HPCA吸附MLD潜在机理。静电势、平均局部电离能、静电势相互作用分析结果表明，HPCA捕获MLD主要由质子化胺基与羧酸根之间电荷作用介导。在分子水平上优化出三种可视化最优捕获构型，分析结果表明强的静电相互作用使得构型Ⅰ中HPCA与MLD紧密接触成为最稳定的构型。前沿分子轨道、独立梯度模型和Hirshfeld表面分析揭示HPCA捕获MLD存在氢键和范德华力等弱相互作用，且MLD在不同捕获构型中均主要充当氢键受体。多重量子化学理论计算研究方法可为探究分子水平上吸附相互作用机制提供可行研究方向，对研究吸附微观机制具有重要意义。

关键词: 计算化学, 吸附, 凝胶, 美拉德色素, 糖汁脱色