Kroll Helena, Friedrich Julia, Menzel Michael, Schreier Peter
Lehrstuhl fur Lebensmittelchemie, Universitat Wurzburg, Wurzburg, Germany.
J Agric Food Chem. 2008 Jun 11;56(11):4198-204. doi: 10.1021/jf8002575. Epub 2008 May 14.
Considering the increasing nutritional and commercial importance of carotenoids, there is an interest in developing a reliable method for authenticity assessment of these compounds. Applying isotope ratio mass spectrometry using elemental analysis in the "combustion" (C) and "pyrolysis" (P) modes (EA-C/P-IRMS), the delta (13)C V-PDB and delta (2)H V-SMOW values of selected carotenoids and alpha/beta-carotene-based commercial dietary supplements were determined in comparison to those of synthetic and "natural" references. The delta (13)C V-PDB and delta (2)H V-SMOW values of synthetic beta-carotene samples ( n = 4), ranging from -25.3 per thousand to -26.4 per thousand and from -144 per thousand to -155 per thousand, respectively, differed clearly from the data determined for carotenoids from various natural sources, including C 3 plant material ( n = 9; delta (13)C V-PDB ranging from -28.5 per thousand to -32.8 per thousand and delta (2)H V-SMOW from -180 per thousand to -275 per thousand) and microalgae Dunaliella salina ( n = 1; delta (13)C V-PDB value of -15.6 per thousand and delta (2)H V-SMOW value of -191 per thousand). From five commercial dietary supplements under study, two revealed delta (13)C V-PDB and delta (2)H V-SMOW values in areas as found for synthetic references, and the other three had values near those of biotechnological beta-carotene produced by D. salina. The delta (13)C V-PDB and delta (2)H V-SMOW values recorded for natural lycopene ( n = 4) and lutein ( n = 5) ranged from -31.1 per thousand to -31.8 per thousand and from -180 to -201 per thousand, as well as from -28.8 per thousand to -32.2 per thousand and from -186 per thousand to -245 per thousand, respectively. Synthetic canthaxanthin ( n = 3) exhibited delta (13)C V-PDB and delta (2)H V-SMOW values ranging from -25.0 per thousand to -28.6 per thousand and from -133 per thousand to -153 per thousand, respectively. The EA-C/P-IRMS application of this study showed that the natural stable isotopic composition of carotenoids is a powerful tool for determining their origin.
鉴于类胡萝卜素在营养和商业方面的重要性日益增加，人们对开发一种可靠的方法来评估这些化合物的真实性产生了兴趣。采用“燃烧”（C）和“热解”（P）模式下的元素分析联用同位素比质谱法（EA-C/P-IRMS），测定了所选类胡萝卜素和基于α/β-胡萝卜素的商业膳食补充剂的δ(13)C V-PDB和δ(2)H V-SMOW值，并与合成和“天然”参考物的相应值进行了比较。合成β-胡萝卜素样品（n = 4）的δ(13)C V-PDB值在-25.3‰至-26.4‰之间，δ(2)H V-SMOW值在-144‰至-155‰之间，与从各种天然来源获得的类胡萝卜素的数据明显不同，这些天然来源包括C3植物材料（n = 9；δ(13)C V-PDB值在-28.5‰至-32.8‰之间，δ(2)H V-SMOW值在-180‰至-275‰之间）和微藻盐生杜氏藻（n = 1；δ(13)C V-PDB值为-15.6‰，δ(2)H V-SMOW值为-191‰）。在所研究的五种商业膳食补充剂中，有两种的δ(13)C V-PDB和δ(2)H V-SMOW值处于合成参考物的范围内，另外三种的值接近盐生杜氏藻生产的生物技术β-胡萝卜素的值。天然番茄红素（n = 4）和叶黄素（n = 5）的δ(13)C V-PDB值分别在-31.1‰至-31.8‰之间和-28.8‰至-32.2‰之间，δ(2)H V-SMOW值分别在-180‰至-201‰之间和-186‰至-245‰之间。合成角黄素（n = 3）的δ(13)C V-PDB和δ(2)H V-SMOW值分别在-25.0‰至-28.6‰之间和-133‰至-153‰之间。本研究中EA-C/P-IRMS的应用表明，类胡萝卜素的天然稳定同位素组成是确定其来源的有力工具。
