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Effects of thermal stressing on saturated vegetable oils and isolated triacylglycerols ‐ product analysis by MALDI‐TOF mass spectrometry, NMR and IR spectroscopy
Author(s) -
Schiller Jürgen,
Süß Rosemarie,
Petković Marijana,
Hanke Göran,
Vogel Alexander,
Arnold Klaus
Publication year - 2002
Publication title -
european journal of lipid science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.614
H-Index - 94
eISSN - 1438-9312
pISSN - 1438-7697
DOI - 10.1002/1438-9312(200208)104:8<496::aid-ejlt496>3.0.co;2-6
Subject(s) - chemistry , mass spectrometry , infrared spectroscopy , saponification , organic chemistry , nuclear magnetic resonance spectroscopy , fatty acid , chromatography , double bond , spectroscopy , unsaturated fatty acid , physics , quantum mechanics
It is well‐known that triacylglycerols in vegetable oils undergo slow oxidative modifications upon storage particularly at elevated temperatures. This has been shown primarily for oils with unsaturated fatty acid residues that are most sensitive towards oxidation. Saturated oils, however, were by far less investigated. In the present study saturated oils (coconut oil) as well as isolated triacylglycerols were exposed to defined thermal stressing and the resulting products were investigated in dependence on temperature and the heating period. Matrix‐assisted laser desorption and ionization spectrometry, 13 C and 31 P nuclear magnetic resonance spectroscopy and infrared spectroscopy were used for the characterization of the native as well as the thermally stressed oil samples. These methods were used since they provide both, fast and reliable information on oil composition and can be performed faster than other more established methods. We found that the degradation mechanism of saturated fatty acids is completely different from unsaturated fatty acids. Whereas unsaturated oils are primarily depleted under the cleavage of the double bonds, saturated oils undergo a conversion of one methylene group into a carbonyl group. This was independently demonstrated by all applied methods for the triacylglycerols as well as for the free fatty acids derived after saponification.