[关键词]
[摘要]
Ala-Lys-Arg-Ala(AKRA)是白酒中的一种非挥发性组分,其呈味特性未有报道。该研究旨在探究AKRA在乙醇体系下的滋味特性及其受乙醇浓度影响的机制。结合人工感官评价和定量描述性分析(QDA)评估AKRA的滋味,利用滋味稀释分析(TDA)测定其味觉阈值,并运用密度泛函理论、分子对接与分子动力学模拟等方法探究AKRA的活性位点以及与酸味受体PKD2L1的相互作用。结果表明,AKRA在水和不同浓度乙醇水溶液(38%、46%、54%)中均表现酸味,且味觉阈值随乙醇浓度升高而增加,分别为0.28、3.91、7.73、16.42 mg/mL;PKD2L1与AKRA的相互作用依赖于氢键、静电作用力,关键作用位点有SER264、SER30、SER257等氨基酸残基;尽管乙醇浓度的增加在理论上导致PKD2L1与AKRA结合自由能增加,其绝对值从25.620 KJ﹒mol-1增加至50.604 KJ﹒mol-1,但乙醇含量上升依然能够减弱实际情况下人们对AKRA酸味的感知。因此得出结论,AKRA的酸味感知受到乙醇浓度的显著影响,其与PKD2L1的相互作用机制涉及氢键和静电作用力,乙醇浓度的上升减弱了人们对AKRA酸味的感知灵敏度。本研究将为酒类饮品的风味研究与调控提供新的视角。
[Key word]
[Abstract]
Ala-Lys-Arg-Ala (AKRA) is a non-volatile component in Chinese Baijiu, yet its taste characteristic has not been previously reported. This study aimed to investigate the taste properties of AKRA in ethanol-water systems and the relative mechanisms to reveal the effects of ethanol concentration. The taste of AKRA was assessed using a combination of sensory evaluation and quantitative descriptive analysis (QDA) methods, and its taste thresholds were determined by taste dilution analysis (TDA). Then, the active sites of AKRA and the interactions with the sour taste receptor PKD2L1 were explored through density functional theory, molecular docking, and molecular dynamics simulations techniques. The results indicated that AKRA exhibited a sour taste both in water and ethanol solutions of varying concentrations (38%, 46%, and 54%) with taste thresholds increasing as ethanol concentration increased, which were respectively 0.28, 3.91, 7.73, and 16.42 mg﹒mL-1. The interaction between PKD2L1 and AKRA was found to be dependent on hydrogen bonding and electrostatic forces, in which the key interaction sites included amino acid residues such as SER264, SER30, SER257, et al. Although the increasing ethanol concentration theoretically leaded to an increase in the binding free energy between PKD2L1 and AKRA from -25.620 KJ﹒mol-1 to -50.604 KJ﹒mol-1, the actual sour taste perception sensitivity of AKRA in humans decreased. Therefore, it was concluded that the perception of sour taste from AKRA was significantly affected by ethanol concentration with its interaction mechanism with PKD2L1 involving hydrogen bonding and electrostatic forces, and an increase in ethanol concentration diminished the human perception sensitivity to AKRA. It will provide a novel perspective for the flavor exploration and innovation of alcoholic beverages.
[中图分类号]
[基金项目]
国家重点研发计划项目(2022YFD2101205)