Determination of free cholesterol oxide products in food samples by gas chromatography and accelerated solvent extraction: influence of electron-beam irradiation on cholesterol oxide formation

Optimizing accelerated solvent extraction combined with liquid chromatography-Orbitrap mass spectrometry for efficient lipid profile characterization of mozzarella cheese

In this study, a novel Accelerated Solvent Extraction (ASE) procedure combined with UHPLC-Q-Orbitrap-MS was developed for detailed untargeted lipid profile of mozzarella cheese. Response Surface Methodology and Pareto front, using a Central Composite Design (CCD), were employed to define the optimised combination of extraction temperature, number of extraction cycles and mix of solvents. LipidSearch™ software was used for a reliable and accurate lipid identification. A total of 13 subclasses, including ceramides, diacylglycerols, triacylglycerols, lysophosphatidylcholines, lysophosphatidylethanolamines, phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, sphingomyelins, bismethyl phosphatidic acids, cholesterol ester, zymosterol ester, hexosyl ceramides were measured. The elaboration of the CCD showed that the solvents ratio was the main factor affecting the extraction efficiency. The optimised ASE method, together with the Folch extraction, synergistically contributed to a complete characterization of lipid profile of mozzarella cheese, confirming ASE technique, associated with high resolution mass spectrometry detection, as an efficient tool for Lipidomics in food science.

Quantification of Cooking Method Effect on COP Content in Meat Types Using Triple Quadrupole GC-MS/MS

A diet containing cholesterol is an essential component of biological function; however, cholesterol oxidation products (COPs) remain a major public health concern. This study investigated the effects of cooking methods (boiling and frying) on the production levels of COPs in processed foods. Samples, as represented by minced beef, chicken sausages, and fish fillets, were subjected to different cooking methods followed by COP extraction using a saponification method. Then, six common COPs, 5α-cholest, α-epoxy, β-epoxy, 25-HC, triol, and 7-keto, were quantified by triple quadrupole gas chromatography-mass spectrometry (GS-MS/MS). A significantly high number of COPs were detected in minced meat, of which 7-keto and triol were detected as major oxidation products, followed by chicken sausages and fish fillets (p ≤ 0.05). Compared to boiling, frying generated significantly more COPs, specifically triol (0.001-0.004 mg/kg) and 7-keto (0.001-0.200 mg/kg), in all samples. Interestingly, cholesterol level was found to be slightly (but not significantly) decreased in heat-treated samples due to oxidation during cooking, producing a higher number of COPs. Notably, the fish fillets were found to produce the fewest COPs due to the presence of a low amount of cholesterol and unsaturated fatty acids. In conclusion, adapting boiling as a way of cooking and choosing the right type of meat could serve to reduce COPs in processed foods.

Desarrollo de un método analítico de preparación de muestras de alimentos para determinar óxidos de colesterol (COP) mediante cromatografía

Las transformaciones surgidas durante los procesos de limpieza de los alimentos grasos para determinar productos de oxidación de colesterol (COP) limitan los resultados reales en un estudio. Por tanto, el objetivo de este estudio fue comparar los COP obtenidos por distintos métodos de extracción: fase sólida (SPE) y cromatografía líquida en fase normal y reversa, comparando sus perfiles de elución. Adicionalmente, se tuvo como objetivo optimizar los procesos de limpieza para reducir las transformaciones de COP. Se usaron muestras de lomo de cerdo crudo, jamón serrano y salmón ahumado. Las transformaciones de COP se determinaron por SPE y GC–FID y se optimizaron los métodos de limpieza con la técnica SPE. Los cartuchos apolares no mostraron transformación de COP durante el tratamiento de muestras y los cambios de pH generaron transformaciones del triol a 6 ceto epóxido. Debido a que la limpieza del cartucho suele ser deficiente y genera coelución de compuestos indeseables (ácidos grasos) implicados en la transformación de epóxidos α y β en triol, estas transformaciones se evitaron con la técnica SPE, uso de cartuchos C18, con ajuste del volumen de elución de MeOH y ajustes del pH. La reducción de los pasos de la limpieza de muestras optimizó el proceso en un 73%.