Analytical Methods for Quantification of Modified Fatty Acids and Sterols Formed as a Result of Processing

Strategies for UHPLC-MS/MS-Based Analysis of Different Classes of Acyl Chain Oxidation Products Resulting from Thermo-Oxidation of Sitostanyl Oleate

Phytostanyl fatty acid esters, which are being added to a variety of foods owing to their cholesterol-lowering properties, are susceptible to thermally induced oxidation reactions. Using sitostanyl oleate as an example, we, in this study, aimed at developing strategies for the detection and the quantitation of acyl chain oxidation products (ACOPs). The elaborated ultra high performance liquid chromatography-mass spectrometry MS/MS-based approach involves (i) derivatizations of hydroxy and oxo groups, (ii) combined use of atmospheric pressure chemical ionization and electrospray ionization as ionization techniques, and (iii) establishment of selective multireaction monitoring transitions. These strategies allow the identification of a broad spectrum of nonpolar short-chain as well as polar short- and long-chain hydroxy, epoxy, and oxo ACOPs. Semiquantitative assessments showed that sitostanyl 9,10-epoxystearate was the predominating ACOP resulting from thermo-oxidation of sitostanyl oleate at 180 °C for 30 min. The elaborated analytical approach paves the way to narrow the existing knowledge gap on the fate of phytostanyl fatty acid esters upon heat treatments.

Oxidation and Polymerization of Triacylglycerols: In-Depth Investigations towards the Impact of Heating Profiles

The stability of refined, bleached, and deodorized palm olein (RBDPO) was studied under controlled heating conditions. RBDPO was heated continuously for 24 h at 160, 170, and 180 °C, with oil sampled at four hour intervals. Thermo-oxidative alterations were measured through various parameters, such as monomeric oxidized triacylglycerols (oxTAG), total polar compounds (TPC), polymerized triacylglycerols (PTG), oxidative stability, and fatty acid composition. After 24 h of heating, the TPC and triacylglycerol oligomers showed a linear increase with heating time at all heating temperatures. At the end of the heating study, more epoxy acids were formed than keto and hydroxy acids. Moreover, caprylic acid, which was not present in fresh oil, was formed in significant amounts. The increase in oxTAG was strongly correlated with the increase in the p-anisidine value and total oxidation value. The decreases in diacylglycerol and free fatty acids were strongly correlated with an increase in PTG.

Dual analysis of triglycerides from certain common lipids and seed extracts

A number of reference oils, two commercial oils, and several oil extracts from seeds of Nicotiana species were analyzed for the fatty acid content and also for triglyceride composition. The seed oils were obtained using an accelerated solvent extraction procedure, which was proven to be very efficient and reproducible. The fatty acids were analyzed after the hydrolysis of the oils, using trimethylsilylation and gas chromatography/mass spectrometry (GC/MS) analysis. The levels of sixteen molecular species of triglycerides in the oils were measured after GC separation using MS for identification and flame ionization detection (FID) for quantitation. The results for the fatty acids and those for triglycerides were combined to generate uniform information regarding the composition of the analyzed oils. For a number of oils, the individual triglyceride quantitation and mass spectra were reported for the first time. The study showed that in some cases, oils with similar fatty acid content do not have the same triglycerides profile. The fatty acids and triglycerides profile for selected Nicotiana species were described for the first time in the literature.