Liu Zhi, Wen Xin, Wang Chong-Zhi, Li Wei, Huang Wei-Hua, Xia Juan, Ruan Chang-Chun, Yuan Chun-Su
College of Chinese Medicinal Materials, Jilin Agricultural University, Changchun, China.
Institute of Agricultural Modernization, Jilin Agricultural University, Changchun, China.
J Ginseng Res. 2020 May;44(3):424-434. doi: 10.1016/j.jgr.2019.04.001. Epub 2019 Apr 10.
Amino acids are one of the major constituents in , including neutral amino acid, acidic amino acid, and basic amino acid. However, whether these amino acids play a role in ginsenoside conversion during the steaming process has not yet been elucidated.
In the present study, to elucidate the role of amino acids in ginsenoside transformation from fresh ginseng to red ginseng, an amino acids impregnation pretreatment was applied during the steaming process at 120°C. Acidic glutamic acid and basic arginine were used for the acid impregnation treatment during the root steaming. The ginsenosides contents, pH, browning intensity, and free amino acids contents in untreated and amino acid-treated samples were determined.
After 2 h of steaming, the concentration of less polar ginsenosides in glutamic acid-treated was significantly higher than that in untreated during the steaming process. However, the less polar ginsenosides in arginine-treated increased slightly. Meanwhile, free amino acids contents in fresh , glutamic acid-treated , and arginine-treated significantly decreased during steaming from 0 to 2h. The pH also decreased in samples at high temperatures. The pH decrease in red ginseng was closely related to the decrease in basic amino acids levels during the steaming process.
Amino acids can remarkably affect the acidity of sample by altering the pH value. They were the main influential factors for the ginsenoside transformation. These results are useful in elucidating why and how steaming induces the structural change of ginsenoside in and also provides an effective and green approach to regulate the ginsenoside conversion using amino acids during the steaming process.
氨基酸是人参的主要成分之一，包括中性氨基酸、酸性氨基酸和碱性氨基酸。然而，这些氨基酸在蒸煮过程中是否参与人参皂苷的转化尚未阐明。
在本研究中，为阐明氨基酸在鲜人参到红参的人参皂苷转化中的作用，在120℃蒸煮过程中采用氨基酸浸渍预处理。酸性的谷氨酸和碱性的精氨酸用于根部蒸煮过程中的酸浸渍处理。测定未处理和氨基酸处理样品中的人参皂苷含量、pH值、褐变强度和游离氨基酸含量。
蒸煮2小时后，谷氨酸处理的人参在蒸煮过程中极性较小的人参皂苷浓度显著高于未处理的人参。然而，精氨酸处理的人参中极性较小的人参皂苷略有增加。同时，鲜人参、谷氨酸处理的人参和精氨酸处理的人参在蒸煮0至2小时期间游离氨基酸含量显著下降。高温下人参与样品的pH值也下降。红参的pH值下降与蒸煮过程中碱性氨基酸水平的下降密切相关。
氨基酸可通过改变pH值显著影响人参样品的酸度。它们是人参皂苷转化的主要影响因素。这些结果有助于阐明蒸煮为何以及如何诱导人参中人参皂苷的结构变化，并且还提供了一种在蒸煮过程中使用氨基酸调节人参皂苷转化的有效且绿色的方法。
