诺邓火腿红色素的分离纯化及结构鉴定

Isolation,Purification and Structural Identification of Red Pigment from Nuodeng Ham

为探究诺邓火腿红色素化学本质,采用75%丙酮溶液提取,结合C18固相萃取小柱进行分离纯化,通过紫外-可见光光谱(ultraviolet spectroscopy,UV-Vis)、荧光光谱、超高效液相色谱-串联质谱(ultra-high performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS)、傅里叶变换红外光谱(Fourier transform infrared,FTIR)和核磁共振(nuclear magnetic resonance,NMR)共同表征诺邓火腿红色素的化学结构。结果表明:在UV-Vis中416 nm处有1个强吸收峰,546 nm和584 nm处有2个弱对称吸收峰,符合金属卟啉特征;以420 nm激发,红色素在590 nm处有1个强荧光发射峰,644 nm处有1个弱荧光发射峰,与Zn-原卟啉IX(Zn protoporphyrin IX,ZnPP)标准品比对后高度重合,表明卟啉环中的金属离子是锌离子;在UPLC-MS/MS的正离子(m/z 625.1779[M+H]^(+))和负离子(m/z 623.1614[M-H]^(-))模式下均检测出ZnPP的存在;在FTIR中发现—CH_(3)、—CH_(2)—、C=O、羧基中—C—OH、烯烃上的C-H和卟啉环C=N等卟啉环上的特征官能团伸缩振动;分析诺邓火腿红色素的1H-NMR,发现与其目标化合物ZnPP结构一致,因此鉴定出诺邓火腿红色素的化学本质为ZnPP。研究结果可以为诺邓火腿色泽调控提供一定理论依据。

In order to explore the chemical nature of red pigment in Nuodeng ham,the red pigment was extracted with 75%acetone aqueous solution and purified using a C18 solid phase extraction column,and its chemical structure was characterized by using ultraviolet-visible(UV-Vis)spectroscopy,fluorescence spectroscopy and ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS),Fourier transform infrared(FTIR)spectroscopy and nuclear magnetic resonance(NMR)spectroscopy.The UV-Vis spectrum showed a strong absorption peak at 416 nm and two weakly symmetrical absorption peaks at 546 and 584 nm,which are characteristic of metalloporphyrins.When it was excited at 420 nm,the red pigment exhibited a strong fluorescence emission peak at 590 nm and a weak fluorescence emission peak at 644 nm,which highly coincided with those of Zn protoporphyrin IX(ZnPP)standard,indicating that the metal ions in the porphyrin ring were zinc ions.ZnPP was detected by UPLC-MS/MS in both positive(m/z 625.1779[M+H]^(+))and negative ion(m/z 623.1614[M-H]^(–))modes,and the stretching vibrations of characteristic functional groups on the porphyrin ring such as–CH_(3),–CH_(2)–,C=O,–C–OH in carboxyl groups,C–H on olefin and porphyrin ring C=N were observed in the FTIR spectrum.In addition,the 1H-NMR results of the red pigment were consistent with the structure of the target compound ZnPP.Therefore,the red pigment in Nuodeng ham was identified as ZnPP.The results of this study provide a theoretical basis for the color regulation of Nuodeng ham.