Detection ofcis-vaccenic acid in palm oil by13C NMR spectroscopy

Oleic Acid Is not the Only Relevant Mono-Unsaturated Fatty Ester in Olive Oil

(1) Background: Extra-virgin olive oil (EVOO) is a precious and universally studied food matrix. Recently, the quantitative chemical composition was investigated by an innovative processing method for the nuclear magnetic resonance (NMR) experiments called Multi-Assignment Recovered Analysis (MARA)-NMR. (2) Methods: Any EVOO 13-carbon NMR (¹³C-NMR) profile displayed inconsistent signals. This mismatch was resolved by comparing NMR data to the official gas-chromatographic flame ionization detection (GC-FID) experiments: the analyses concerned many EVOOs but also the "exotic" Capparis spinosa oil (CSO). (3) Results: NMR and GC-FID evidenced the overwhelming presence of cis-vaccenic esters in the CSO and, more importantly, cis-vaccenic ¹³C-NMR resonances unequivocally matched the misunderstood ¹³C-NMR signals of EVOOs. The updated assignment revealed the unexpected relevant presence of cis-vaccenic ester (around 3%) in EVOOs; it was neglected, so far, because routine and official GC-FID profiles did not resolve oleic and cis-vaccenic signals leading to the total quantification of both monounsaturated fatty esters. (4) Conclusions: The rebuilt MARA-NMR and GC-FID interpretations consistently show a meaningful presence of cis-vaccenic esters in EVOOs, whose content could be a discrimination factor featuring specific cultivar or geographical origin. The study paves the way toward new quantification panels and scientific research concerning vegetable oils.

Characterization of Mesocarp and Kernel Lipids from Elaeis guineensis Jacq., Elaeis oleifera [Kunth] Cortés, and Their Interspecific Hybrids

Morphological traits, total lipid contents, and fatty acid profiles were assessed in fruits of several accessions of Elaeis oleifera [Kunth] Cortés, Elaeis guineensis Jacq., and their interspecific hybrids. The latter featured the highest mesocarp-to-fruit ratios (77.9-78.2%). The total lipid contents of both E. guineensis mesocarp and kernel were significantly higher than for E. oleifera accessions. Main fatty acids comprised C16:0, C18:1n9, and C18:2n6 in mesocarp and C12:0, C14:0, and C18:1n9 in kernels. E. oleifera samples were characterized by higher proportions of unsaturated long-chain fatty acids. Saturated medium-chain fatty acids supported the clustering of E. guineensis kernels in multivariate statistics. Hybrid mesocarp lipids had an intermediate fatty acid composition, whereas their kernel lipids resembled those of E. oleifera genotypes. Principal component analysis based on lipid contents and proportions of individual fatty acids permitted clear-cut distinction of E. oleifera, E. guineensis, and their hybrids.

Recognition and quantitation of cis-vaccenic and eicosenoic fatty acids in olive oils by 13C nuclear magnetic resonance spectroscopy

The presence of 11-cis monoenoic fatty acids was detected in olive oil samples by means of 13C nuclear magnetic resonance spectroscopy, and the positional isomery on the glycerol backbone was derived. The 11-cis vaccenic and eicosenoic fatty acid resonances were recognized and the amounts of the fatty acids quantified. For comparison purposes, a quantitative analysis was also made by gas chromatography.

High-resolution nuclear magnetic resonance spectroscopy--applications to fatty acids and triacylglycerols

During the past two decades, nuclear magnetic resonance spectroscopy (NMR) has played an ever-increasing role in the structural determination of fatty acids, fatty acid derivatives and analogues, and in the analysis of the structures of triacylglycerols including the quantitative analysis of lipid mixtures. This article discusses some of the results obtained through the application of the NMR technique to lipid molecules and reviews the literature. To maintain brevity, this article does not cover the underlying theory of NMR spectroscopy as numerous books devoted to modern NMR spectroscopy have been published.