Structures, sensory activity, and dose/response functions of 2,5-diketopiperazines in roasted cocoa nibs (Theobroma cacao)
Structures, sensory activity, and dose/response functions of 2,5-diketopiperazines in roasted cocoa nibs (Theobroma cacao)
复制标题
DOI：
10.1021/jf051313m
复制
发表时间：
2005-09-07
影响因子：
6.1
通讯作者：
Hofmann, T
中科院分区：
文献类型：
--
作者：
Stark, T;Hofmann, T
最近报道的从烘烤的可可豆制备的二氯甲烷提取物的味道化合物诱导的血液样，金属苦味的感觉被确定为一系列的25 diketopiperazines通过HPLC degustation，LC-MS/MS，和独立的合成。在这25个化合物中，13个顺式构型的哌嗪二酮，即CYCIO，（L-IIe-L-Phe），CYCIO（L-Val-L-Leu），CYCIO（L-Pro-L-Pro），CYCIO（L-IIe-L-Pro），CYCIO（L-Val-L-Tyr），CYCIO（L-Ala-L-Tyr），CYCIO（L-Phe-L-Ser），CYCIO（L-Ala-L-IIe），CYCIO（L-LeU-L-Phe）、环（L-Pro-L-Val）、CYCIO（L-Pro-L-Thr）、CYCIO（L-PrO-L-Tyr）和CYCIO（L-Val-L-Val）首次在可可中被鉴定出来。此外，测定了二酮哌嗪的金属味和苦味的味觉识别阈值，并在通过使用两种非对映体二酮哌嗪作为内标物进行定量分析后，基于以化合物的浓度与阈值浓度的比率计算的接近阈值（DoT）因子来评价二酮哌嗪的感官影响。这些数据显示，仅顺式-环状（L-Pro-L-Val）、顺式-环状（L-Val-L-Leu）、顺式-环状（L-Ala-L-IIe）、顺式-环状（L-Ala-L-Leu）和顺式-环状（L-IIe-L-Pro）的DoT因子高于1.0，而所有其他二酮哌嗪均低于其各自的苦味阈值浓度，因此不应有助于可可味道。由于DoT因素不考虑单个化合物的浓度和味觉反应之间的非线性关系，我们第一次报道了更精确地描述二酮哌嗪类化合物的人类苦味感知的剂量/反应函数的记录。
The taste compounds inducing the blood-like, metallic bitter taste sensation reported recently for a dichloromethane extract prepared from roasted cocoa nibs were identified as a series of 25 diketopiperazines by means of HPLC degustation, LC-MS/MS, and independent synthesis. Among these 25 compounds, 13 cis-configured diketopiperazines, namely, CYCIO(L-IIe-L-Phe), CYCIO(L-Val-L-Leu), CYCIO(L-Pro-L-Pro), CYCIO(L-IIe-L-Pro), CYCIO(L-Val-L-Tyr), CYCIO(L-Ala-L-Tyr), CYCIO(L-Phe-L-Ser), CYCIO(L-Ala-L-IIe), CYCIO(L-LeU-L-Phe), cyclo(L-Pro-L-Val), CYCIO(L-Pro-L-Thr), CYCIO(L-PrO-L-Tyr), and CYCIO(L-Val-L-Val) were identified for the first time in cocoa. In addition, the taste recognition thresholds for the metallic as well as the bitter taste of the diketopiperazines were determined, and after quantitative analysis by using two diastereomeric diketopiperazines as the internal standards, the sensory impact of the diketopiperazines was evaluated on the basis of their close-over-threshold (DoT) factors calculated as the ratio of the concentration and the threshold concentration of a compound. These data revealed DoT factors above 1.0 exclusively for cis-cyclo(L-Pro-L-Val), cis-cyclo(L-Val-L-Leu), cis-cyclo(L-Ala-L-IIe), cis-cyclo(L-Ala-L-Leu), and cis-cyclo(L-IIe-L-Pro), whereas all of the other diketopiperazines were present below their individual bitter taste threshold concentrations and should therefore not contribute to the cocoa taste. Because the DoT factors do not consider the nonlinear relationship between the concentration and gustatory response of an individual compound, we, for the first time, report on the recording of dose/response functions describing the human bitter taste perception of diketopiperazines more precisely.