Aromalab illycaffè SpA, Area Science Park, Trieste, Italy.
illycaffè SpA, Trieste, Italy.
J Mass Spectrom. 2020 Nov;55(11):e4636. doi: 10.1002/jms.4636. Epub 2020 Aug 6.
Coffee diterpenes are the main constituents of the coffee oil unsaponifiable fraction. The three most important diterpenes are cafestol, kahweol, and 16-O-methylcafestol (16-OMC), and they are produced, except for cafestol, only by plants of the Coffea genus. Recently, in addition to these three major diterpenes, another 16-O-methylated diterpene (16-O-methylkahweol: 16-OMK) has been identified and quantified, for the first time, in Robusta coffee. For many years, 16-OMC has been considered present exclusively in Robusta, and so it has been reputed an excellent authenticity marker for the presence of Robusta in coffee products. For its quantification, nuclear magnetic resonance (NMR) has proved very useful when compared with other methods. Quite recently, the detection of very low levels of the two 16-O-methylated diterpenes (16-OMD) 16-OMC and 16-OMK in roasted Arabica was reported. This finding makes the use of NMR methods in 16-OMD quantification in Arabica coffee particularly challenging in view of both the trace amounts of 16-OMD and the impossibility to discriminate between 16-OMC and 16-OMK. The ultra-high performance liquid chromatography mass spectrometry (UHPLC-MS) method, already used to detect 16-OMC and 16-OMK in Arabica roasted coffee, is then more suitable for quantitative analyses. Up to now however, no quantification of coffee 16-OMD via ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) has been carried out; this largely stimulated the present study. For the first time, a simple procedure for the quantitative detection of 16-OMD in Arabica coffee has been developed, and as far as 16-OMC is concerned, fully validated in terms of specificity, linearity, concentration range, limit of detection (LOD), limit of quantification (LOQ), and repeatability following the criteria specified in the EU Commission Decision 2002/675/EC. This method proved to be very specific and sensitive. In order to avoid the chemical complexity generated by the roasting process, the method was optimized and validated on several green Arabica samples from different geographical origins.
咖啡二萜是咖啡油不皂化物的主要成分。三种最重要的二萜是咖啡醇、卡瓦醇和 16-O-甲基咖啡醇（16-OMC），除了咖啡醇之外，它们只由咖啡属植物产生。最近，除了这三种主要的二萜外，另一种 16-O-甲基化二萜（16-O-甲基卡瓦醇：16-OMK）也首次在罗布斯塔咖啡中被鉴定和定量。多年来，16-OMC 一直被认为仅存在于罗布斯塔咖啡中，因此它一直被认为是罗布斯塔咖啡产品存在的极佳真实性标志物。为了对其进行定量，与其他方法相比，核磁共振（NMR）被证明非常有用。最近，据报道，在烘焙的阿拉比卡咖啡中检测到极低水平的两种 16-O-甲基化二萜（16-OMC 和 16-OMK）。鉴于 16-OMD 的痕量和无法区分 16-OMC 和 16-OMK 的可能性，这一发现使得 NMR 方法在阿拉比卡咖啡中 16-OMD 定量分析中变得极具挑战性。超高效液相色谱-质谱联用（UHPLC-MS）法已用于检测烘焙阿拉比卡咖啡中的 16-OMC 和 16-OMK，因此更适合定量分析。然而，迄今为止，尚未通过超高效液相色谱-串联质谱（UHPLC-MS/MS）对咖啡 16-OMD 进行定量分析；这在很大程度上激发了本研究。首次开发了一种简单的定量检测阿拉比卡咖啡中 16-OMD 的方法，就 16-OMC 而言，根据欧盟委员会第 2002/675/EC 号决定中规定的特异性、线性、浓度范围、检测限（LOD）、定量限（LOQ）和重复性标准，对其进行了充分验证。该方法被证明具有很高的特异性和灵敏度。为了避免烘焙过程中产生的化学复杂性，该方法在来自不同地理来源的几个绿色阿拉比卡样品上进行了优化和验证。
