Characterization of Hydroxy and Hydroperoxy Polyunsaturated Fatty Acids by Mass Spectrometry

Mass spectrometry unveils heat-induced changes in yolk oxylipins and key lipid molecules during home cooking

INTRODUCTION

Oxylipins, as a widespread class of metabolic markers following oxidative stress, and several studies have reported dietary regulation of lipid metabolism. However, there is a lack of investigation of dietary oxylipins, especially cooking-induced changes in food lipid oxidation.

OBJECTIVES

Investigated the effects of cooking methods and lipid profiles on polyunsaturated fatty acids derived oxylipins generation within egg yolks.

METHODS

The lipid profile of egg yolk was determined by UPLC-QTOF-MS/MS, oxylipins were detected by HPLC-QTRAP-MS/MS, while the total fatty acid content was quantified by GC-FID. Random Forest (RF) and Partial Least Squares (PLS) regression models were employed to explore the association between oxidized lipids and key lipid species.

RESULTS

Heating reduced egg yolk docosahexaenoic acid (DHA) content, and no consistent trends for arachidonic acid (AA), linoleic acid (LA), and linolenic acid (ALA). Yolk lipid composition affected triacylglycerol (TG), phosphatidylethanolamine (PE), and LA-monoepoxide contents after cooking. 9- and 13-HODE (hydroxyoctadecadienoic acid), 9,10,13-TriHOME (trihydroxyoctadecenoic acid), 9,10- and 12,13-EpOME (epoxyoctadecenoic acid), 9,10- and 12,13-DiHOME (dihydroxyoctadecenoic acid), 5-HETE (hydroxyeicosatetraenoic acid), and 4-HDHA (hydroxydocosahexaenoic acid) were the prevalent oxylipins with high concentrations, accounting for 1.08 %-29.58 % of the total content of 29 oxylipins. Steaming resulted in a 1.9-fold increase in oxylipin concentrations in yolks compared to raw yolks, and boiling with or without shells (poaching) resulted in a 1.30- to 1.76-fold increase in oxylipin concentrations. In contrast, pan-fried yolks exhibited the lowest and least variable levels of total oxylipins, while still retaining some epoxides, including epoxyeicosatrienoic acid (EET) and EpOME. Utilizing big data analysis, we mapped the oxylipin network in both ordinary and DHA-enriched egg yolks, revealing a strong correlation between cooking-induced oxylipin production and variations in 24 lipid species.

CONCLUSION

Revealed the potential mechanisms and key lipid molecules for heating-induced oxylipin production of yolk through lipidomics and big data analysis.

Novel theoretical database-assisted UHPLC-Q-TOF/MS strategy for profiling and identifying oxidized triglycerides in pharmaceutical excipient soybean oil

Pharmaceutical excipient soybean oil is widely used in injections. Its main components, triglycerides, are easily oxidized due to their unsaturated fatty acyls, raising safety concerns. However, it is hard to analyze those oxidized triglycerides due to their diverse compositions and low abundance. In this study, all theoretical oxidized triglycerides were predicted and a database consisting of 329 oxidized triglycerides was constructed. Then, a novel theoretical database-assisted ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) strategy was developed to finely profile and identify oxidized triglycerides in soybean oil. A total of 106 and 116 oxidized triglycerides were identified and relatively quantified in oxidized soybean oil and long-term stored soybean oil and preparations. It was found that oxidized triglycerides containing carbonyl groups were significantly more prevalent than other forms and oxidized triglycerides with two oxidized fatty acyl chains had the highest relative abundance. Fifteen markers indicating the oxidation of soybean oil were discovered. This strategy could rapidly and directly analyze the oxidized triglycerides and assign their fatty acyl compositions for the first time. This study will improve the quality control of soybean oil and its preparations.

Effect of lipid oxidation on quality attributes and control technologies in dried aquatic animal products: a critical review

Aquatic animals are viewed as a good source of healthy lipids. Although drying is an effective method for the preservation of aquatic animal products (AAPs), the whole process is accompanied by lipid oxidation. This article reviews the main mechanism of lipid oxidation in the drying process. It also summarizes the effects of lipid oxidation on the quality of dried aquatic animal products (DAAPs), including nutrients, color, flavor, and hazard components, especially for those harmful aldehydes and heterocyclic amines. In addition, it concluded that moderate lipid oxidation contributes to improving the quality of products. Still, excessive lipid oxidation produces hazardous substances and induces health risks. Hence, to obtain high-quality DAAPs, some effective control technologies to promote/prevent lipid oxidation are introduced and deeply discussed, including salting, high-pressure processing, irradiation, non-thermal plasma technology, defatting treatments, antioxidants, and edible coating. A systematic review of the effect of lipid oxidation on quality attributes and control technologies in DAAPs is presented, and some perspectives are made for future research.

Analytical and computational workflow for in-depth analysis of oxidized complex lipids in blood plasma

Lipids are a structurally diverse class of biomolecules which can undergo a variety of chemical modifications. Among them, lipid (per)oxidation attracts most of the attention due to its significance in the regulation of inflammation, cell proliferation and death programs. Despite their apparent regulatory significance, the molecular repertoire of oxidized lipids remains largely elusive as accurate annotation of lipid modifications is complicated by their low abundance and often unknown, biological context-dependent structural diversity. Here, we provide a workflow based on the combination of bioinformatics and LC-MS/MS technologies to support identification and relative quantification of oxidized complex lipids in a modification type- and position-specific manner. The developed methodology is used to identify epilipidomics signatures of lean and obese individuals with and without type 2 diabetes. The characteristic signature of lipid modifications in lean individuals, dominated by the presence of modified octadecanoid acyl chains in phospho- and neutral lipids, is drastically shifted towards lipid peroxidation-driven accumulation of oxidized eicosanoids, suggesting significant alteration of endocrine signalling by oxidized lipids in metabolic disorders.

Targeted Lipidomics Analysis of Oxylipids in Hazelnut Oil during Storage by Liquid Chromatography Coupled to Tandem Mass Spectrometry

Hazelnut oil is a high-grade edible oil with high nutritional value and unique taste. However, it is prone to oxidative degradation during storage. Herein, we used liquid chromatography coupled to tandem mass spectrometry to carry out a lipidomics analysis of the storage process of hazelnut oil. A total of 41 triacylglycerols and 12 oxylipids were determined. The contents of all oxylipids increased significantly after storage (p < 0.05). The oxylipid accumulation of hazelnut oil during storage was clarified for the first time. Nine significantly different oxylipids were further screened out. It was considered that the 15th day of storage is the dividing point. In addition, the lipoxygenase-catalyzed oxidation may be the major contributor to lipid oxidation of hazelnut oil. This study provides a new insight and theoretical basis to explore the storage oxidation mechanism of hazelnut oil and take quality control measures.