Comparative Study of the Lipid Profiles of Oils from Kernels of Peanut, Babassu, Coconut, Castor and Grape by GC-FID and Raman Spectroscopy

The characterization of the lipid profiles of oils extracted from the kernel of seeds and nuts of peanut (Arachis hypogaea), babassu (Attalea speciosa), coconut (Cocos nucifera), castor (Ricinus communis) and grape (Vitis vinifera) was performed by using Raman spectroscopy and gas chromatography with flame ionization detector (GC-FID). Chromatographic analyses showed that coconut and babassu oils are composed essentially by saturated fatty acids (SFA), whereas the others are composed mainly by unsaturated fatty acids (UFA). The comparison of commercial and homemade castor oils showed the former have a lower level of ricinoleic acid at ca. 58%. Spectroscopic analyses of three distinct castor oils showed their profiles could be differentiated by marker features ascribed to carbonyl modes which were correlated with storage time. The comparison between the Raman spectra of standard samples of fatty acids with the samples of oils allowed the assignment of the spectroscopic features and the characterization of marker bands for the degree of unsaturation.本研究采用拉曼光谱法（Raman spectroscopy）与火焰离子化检测器气相色谱法（GC-FID），对花生（Arachis hypogaea）、巴巴苏棕榈（Attalea speciosa）、椰子（Cocos nucifera）、蓖麻（Ricinus communis）及葡萄（Vitis vinifera）的籽仁与果仁所提取油脂的脂质谱进行了表征。色谱分析结果显示，椰子油与巴巴苏棕榈油主要由饱和脂肪酸（SFA）构成，其余四种油脂则以不饱和脂肪酸（UFA）为主要组成成分。对市售与自制蓖麻油的对比分析表明，市售蓖麻油的蓖麻油酸含量更低，约为58%。对三种不同蓖麻油的光谱分析显示，其光谱特征可通过与羰基振动模式相关的标记特征进行区分，且该特征与油脂储存时间存在关联。通过将脂肪酸标准样品的拉曼光谱与油脂样品光谱进行比对，完成了光谱特征的归属，并确立了用于表征不饱和程度的特征谱带。