Encapsulation with cyclodextrins (CDs) is one of the effective means for the controlled release of aroma compounds. Nevertheless, the aroma profile of the essence or essential oil often exhibits significant differences before and after encapsulation, which seriously affected the aroma quality of steady-state products. However, the exact mechanism underlying this issue has yet to be fully elucidated. In this study, the formation and mechanism of ICs between α-, β-, γ-CD and 5 characteristic aldehydes (citral, cinnamaldehyde, benzaldehyde, citronellal, and 5-methylfurfural) were investigated through a combination of experimental methods and computer simulations. The molar inclusion ratio between each CD and 5 selected aldehydes were consistently 1:1 according to phase solubility method, equimolar continuous transformation (Job’s) method and isothermal titration calorimetry (ITC) method. Based on this, each corresponding IC was constructed and confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) spectroscopy. Molecular dynamics (MD) simulation was used to further analyze the formation and stabilization mechanisms of the ICs, and MMPBSA and independent gradient model (IGM) analysis was combined to analyze the driving force inducing the formation of ICs. The results showed that the dominant driving force for stabilizing ICs was identified as van der Waals interaction, followed by hydrophobic interaction and then coulomb interaction. Moreover, hydrogen bond (H-bond) and steric hindrance also exerted certain influence on the combination between host and guest.

中文翻译：

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醛类芳香化合物/环糊精包合物的制备、理化表征和计算研究

环糊精（CD）封装是控制释放香气化合物的有效手段之一。然而，香精或精油的香气特征在封装前后往往表现出显着差异，这严重影响了稳态产品的香气质量。然而，这一问题的确切机制尚未完全阐明。本研究通过实验和计算机模拟相结合的方法，研究了α-、β-、γ-CD与5种特征醛（柠檬醛、肉桂醛、苯甲醛、香茅醛和5-甲基糠醛）之间IC的形成和机理。根据相溶解度法、等摩尔连续变换(Job's)法和等温滴定量热法(ITC)法，每个CD与5种选定的醛之间的摩尔包合比始终为1:1。在此基础上，构建了相应的IC，并通过傅里叶变换红外光谱（FTIR）、X射线衍射（XRD）和核磁共振（NMR）光谱进行了证实。利用分子动力学（MD）模拟进一步分析IC的形成和稳定机制，并结合MMPBSA和独立梯度模型（IGM）分析来分析诱导IC形成的驱动力。结果表明，稳定 IC 的主要驱动力被确定为范德华相互作用，其次是疏水相互作用，最后是库仑相互作用。此外，氢键（H-bond）和位阻也对主客体的结合产生一定的影响。