In this issue


Maleinisation of MUFA by Rh-catalysis

Fatty acid based 3,6-disubstituted-1,2,3,6-tetrahydro-phthalic acid (THPA) derivatives can be used in polycondensation processes. They are commonly synthesized by Diels-Alder reaction of conjugated fatty acids and maleic anhydride. Eschig, Schirp and Salthammer report a rhodium-catalyzed maleinisation of monounsaturated fatty acids such as oleic and elaidic, rather than conjugated fatty acids, selectively leading to cyclic anhydrides. They show that in terms of yield and selectivity Rh(OAc)2 is a better catalyst than RhCl3 for the production of cyclic products. Detailed analysis mainly by NMR was performed and expected products were confirmed. The reaction mechanisms are thoroughly discussed.

Eschig, S. et al. Maleinisation of monounsaturated fatty acids by Rh-catalysis, Eur. J. Lipid Sci. Technol. 2014, 116, 943–951.

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Authenticating eggs

Eggs are an excellent source of nutrients and a variety of eggs from different birds are commercially available. While consumers will not have problems distinguishing petite quail eggs from large ostrich eggs, distinguishing eggs from other species is a difficult task, and an unwitting consumer may be tricked into buying relatively cheap quail eggs mislabeled as the more expensive pigeon eggs. The situation is even more difficult when eggs are used as an ingredient in other foods. Wang, He and colleagues report a chemometric approach for discriminating duck, free-range chicken, silky chicken, quail, pigeon, goose, and chicken eggs. The fatty acid profiles and yolk volatiles were compared using HS-SPME/GC–MS and electronic nose. The major volatile constituents including ethyl acetate, pathalic acid butyl isohexyl ester, N-isopropylbenzamide, O-methylisourea hydrogen sulfate, and 1-butanol were identified as useful markers to distinguish the eggs.

Wang, Q. et al. Discriminating eggs from different poultry species by fatty acids and volatiles profiling: Comparison of SPME-GC/MS, electronic nose, and principal component analysis method.Eur. J. Lipid Sci. Technol. 2014, 116, 1044–1053.

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Combining MALDI and Raman to image lipids in tissues

In this Short Communication, Jadoul, De Pauw et al. use Raman spectroscopy to complement matrix-assisted laser desorption/ionization mass spectrometry imaging of lipids in tissue sections. The study focuses on important experimental issues such as the influence of MALDI matrix (1,5-DAN, 2,5-DHB, and CHCA) and the surrounding environment on the MALDI signal intensity. Despite a strong overlap with the spectrum of the native tissue, an intensity profile constructed along the diameter of the section clearly shows that the signature of glycerophosphocholine can be detected on a doped biological sample allowing detection of 18fmol PC in the probed volume. This work is a first step along the long road to a quantitative analysis.

Jadoul, L. et al. Matrix-assisted laser desorption/ionization mass spectrometry and Raman spectroscopy: An interesting complementary approach for lipid detection in biological tissues. Eur. J. Lipid Sci. Technol. 2014, 116, 1080–1086.

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