Analysis of the Thermal Degradation of the Individual Anthocyanin Compounds of Black Carrot (Daucus carota L.): A New Approach Using High-Resolution Proton Nuclear Magnetic Resonance Spectrosco
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- 作者：Ioanna Iliopoulou ; Delphine Thaeron ; Ashley Baker ; Anita Jones ; Neil Robertson
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2015
- 出版时间：August 12, 2015
- 年：2015
- 卷：63
- 期：31
- 页码：7066-7073
- 全文大小：450K
- ISSN：1520-5118
文摘
The black carrot dye is a mixture of cyanidin molecules, the nuclear magnetic resonance (NMR) spectrum of which shows a highly overlapped aromatic region. In this study, the p>1 p>H NMR (800 MHz) aromatic chemical shifts of the mixture were fully assigned by overlaying them with the characterized p>1 p>H NMR chemical shifts of the separated compounds. The latter were isolated using reverse-phase high-performance liquid chromatography (RP-HPLC), and their chemical shifts were identified using p>1 p>H and two-dimensional (2D) correlation spectroscopy (COSY) NMR spectroscopy. The stability of the black carrot mixture to heat exposure was investigated at pH 3.6, 6.8, and 8.0 by heat-treating aqueous solutions at 100 掳C and the powdered material at 180 掳C. From integration of high-resolution p>1 p>H NMR spectra, it was possible to follow the relative degradation of each compound, offering advantages over the commonly used ultraviolet/visible (UV/vis) and HPLC approaches. UV/vis spectroscopy and CIE color measurements were used to determine thermally induced color changes, under normal cooking conditions.