The analysis of the total fatty acids and the unsaponifiable fraction of oils is usually a helpful tool for tracing their origin and detecting adulterations. The aim of this work was to study and to compare the composition of total fatty acids and the main unsaponifiable components of oils obtained from conventional and genetically modified (GM) oleaginous (high-oleic and high-linoleic rapeseeds, Turkish and Greek cottonseeds and GM and non-GM corn and soybean). Lipids were extracted from the oilseeds and transmethylated. The unsaponifiable fraction was obtained by liquid extraction after cold saponification, and was purified by silica TLC. The quantitative determination and identification of the total fatty acids (FA) and the main unsaponifiable components (linear and triterpenic alcohols, 4-methylsterols and 4-desmethyl-sterols-or sterols-) was performed by CGC and GC-MS. Qualitative and quantitative differences were evinced in the FA profile of the various oilseeds, especially between high-oleic and high-linoleic rapeseeds. No significant differences were detected between the GM and non-GM corn, whereas the GM soybean presented a larger diversity of FA than the non-GM soybean. The Greek cotton oil had twice as much w-3 FA as compared to the Turkish one and both contained cyclic FA. The 4-desmethyl-sterols were the most abundant component of the unsaponifiable fraction in all the oleaginous and there were noticeable quantitative differences between the varieties of oilseeds, especially in the corn. In addition, some components were only found in certain varieties and, thus, could be utilized as tracers: clerosterol in GM soybean, b-sitostanol in the Turkish cotton, D7-stigmastenol and D5-avenasterol in high-linoleic rapeseed. Moreover, citrostadienol was only found in the 4-methyl sterol fraction of high-linoleic rapeseed. These results confirm the importance of the composition of both total fatty acid and unsaponifiable fraction, as means for identification of different varieties of oilseeds and suggest the use of these inexpensive analysis as alternative to PCR for distinguishing between GM and non-GM oleaginous.
Comparison of the composition of the total fatty acids and the main unsaponifiable components of oils obtained from conventional and genetically modified oleaginous
RODRIGUEZ ESTRADA, MARIA TERESA;CERCACI, LUISITO;LERCKER, GIOVANNI
2004
Abstract
The analysis of the total fatty acids and the unsaponifiable fraction of oils is usually a helpful tool for tracing their origin and detecting adulterations. The aim of this work was to study and to compare the composition of total fatty acids and the main unsaponifiable components of oils obtained from conventional and genetically modified (GM) oleaginous (high-oleic and high-linoleic rapeseeds, Turkish and Greek cottonseeds and GM and non-GM corn and soybean). Lipids were extracted from the oilseeds and transmethylated. The unsaponifiable fraction was obtained by liquid extraction after cold saponification, and was purified by silica TLC. The quantitative determination and identification of the total fatty acids (FA) and the main unsaponifiable components (linear and triterpenic alcohols, 4-methylsterols and 4-desmethyl-sterols-or sterols-) was performed by CGC and GC-MS. Qualitative and quantitative differences were evinced in the FA profile of the various oilseeds, especially between high-oleic and high-linoleic rapeseeds. No significant differences were detected between the GM and non-GM corn, whereas the GM soybean presented a larger diversity of FA than the non-GM soybean. The Greek cotton oil had twice as much w-3 FA as compared to the Turkish one and both contained cyclic FA. The 4-desmethyl-sterols were the most abundant component of the unsaponifiable fraction in all the oleaginous and there were noticeable quantitative differences between the varieties of oilseeds, especially in the corn. In addition, some components were only found in certain varieties and, thus, could be utilized as tracers: clerosterol in GM soybean, b-sitostanol in the Turkish cotton, D7-stigmastenol and D5-avenasterol in high-linoleic rapeseed. Moreover, citrostadienol was only found in the 4-methyl sterol fraction of high-linoleic rapeseed. These results confirm the importance of the composition of both total fatty acid and unsaponifiable fraction, as means for identification of different varieties of oilseeds and suggest the use of these inexpensive analysis as alternative to PCR for distinguishing between GM and non-GM oleaginous.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
