Research advances based on mass spectrometry for profiling of triacylglycerols in oils and fats and their applications.

Vegetable oils and animal fats are dietary source of lipids that play critical and multiple roles in biological function. Triacylglycerols (TAGs) are the principal component of oils and fats with significant difference in profile among different oils and fats. TAG profiling is essential for nutritional evaluation, quality control and assurance of safety in oils and fats. However, analysis of TAGs is a challenging task because of the complicated composition of TAGs and their similar physicochemical properties in oils and fats. The rapid development of mass spectrometry (MS) technology in recent years makes it possible to analyze the composition, content and structure of TAGs in the study of the physical, chemical and nutritional properties of oils, fats and related products. This review described the research advancement based on MS for profiling of TAGs in oil, fat and their applications in food. The application of MS, including direct infusion strategies, and its combination with chromatography, gas chromatography-MS (GC-MS) and liquid chromatography-MS (LC-MS), in the analysis of TAGs were reviewed. The advantages and disadvantages of these analytical methods with relevant applications for TAGs analysis in food were also described.

Rapid and sensitive detection of free fatty acids in edible oils based on chemical derivatization coupled with electrospray ionization tandem mass spectrometry.

In this study, a strategy based on chemical derivatization coupled with electrospray ionizationtandem quadrupole mass spectrometry (ESI-MS/MS) for rapid and sensitive detection of FFAs in edible oils was developed. A derivative reagent (N,N-diethyl-1,2-ethanediamine, DEEA) was employed to selectively label carboxyl groups of FFAs to form an amino compound with a tertiary amino group. The DEEA derivative products could lose a characteristic neutral loss fragment of 73Da in collision-induced dissociation (CID), which enabled to discriminate and analyze the DEEA derived FFAs with neutral loss scan (NLS 73Da)under the positive ion mode of mass spectrometry. The assay was linear over the concentration range 0.5-200nmol/L with satisfactory correlation coefficients (R2≥0.9942), whilst the limit of detection and quantitation were 0.1-0.3nmol/L and 0.3-1.0nmol/L, respectively. Finally, the established method was applied to determine dynamic FFA formation in seven types of edible oils subjected to a microwave heating treatment test.

Quantitation of triacylglycerols in edible oils by off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column.

In this investigation, off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column has been applied for the identification and quantification of triacylglycerols in edible oils. A novel mixed-mode phenyl-hexyl chromatographic column was employed in this off-line two-dimensional separation system. The phenyl-hexyl column combined the features of traditional C18 and silver-ion columns, which could provide hydrophobic interactions with triacylglycerols under acetonitrile conditions and can offer π-π interactions with triacylglycerols under methanol conditions. When compared with traditional off-line comprehensive two-dimensional liquid chromatography employing two different chromatographic columns (C18 and silver-ion column) and using elution solvents comprised of two phases (reversed-phase/normal-phase) for triacylglycerols separation, the novel off-line comprehensive two-dimensional liquid chromatography using a single column can be achieved by simply altering the mobile phase between acetonitrile and methanol, which exhibited a much higher selectivity for the separation of triacylglycerols with great efficiency and rapid speed. In addition, an approach based on the use of response factor with atmospheric pressure chemical ionization mass spectrometry has been developed for triacylglycerols quantification. Due to the differences between saturated and unsaturated acyl chains, the use of response factors significantly improves the quantitation of triacylglycerols. This two-dimensional liquid chromatography-mass spectrometry system was successfully applied for the profiling of triacylglycerols in soybean oils, peanut oils and lord oils. A total of 68 triacylglycerols including 40 triacylglycerols in soybean oils, 50 triacylglycerols in peanut oils and 44 triacylglycerols in lord oils have been identified and quantified. The liquid chromatography-mass spectrometry data were analyzed using principal component analysis. The results of the principal component analysis enabled a clear identification of different plant oils. By using this two-dimensional liquid chromatography-mass spectrometry system coupled with principal component analysis, adulterated soybean oils with 5% added lord oil and peanut oils with 5% added soybean oil can be clearly identified.

Profiling of triacylglycerols in plant oils by high-performance liquid chromatography-atmosphere pressure chemical ionization mass spectrometry using a novel mixed-mode column.

In this investigation, a rapid and high-throughput method for profiling of TAGs in plant oils by liquid chromatography using a single column coupled with atmospheric pressure chemical ionization (APCI) mass spectrometry was reported. A novel mixed-mode phenyl-hexyl chromatographic column was employed in this separation system. The phenyl-hexyl column could provide hydrophobic interactions as well as π-π interactions. Compared with two traditionally columns used in TAG separation - the C18 column and silver-ion column, this column exhibited much higher selectivity for the separation of TAGs with great efficiency and rapid speed. By comparison with a novel mix-mode column (Ag-HiSep OTS column), which can also provide both hydrophobic interactions as well as π-π interactions for the separation of TAGs, phenyl-hexyl column exhibited excellent stability. LC method using phenyl-hexyl column coupled with APCI-MS was successfully applied for the profiling of TAGs in soybean oils, peanut oils, corn oils, and sesame oils. 29 TAGs in peanut oils, 22 TAGs in soybean oils, 19 TAGs in corn oils, and 19 TAGs in sesame oils were determined and quantified. The LC-MS data was analyzed by barcodes and principal component analysis (PCA). The resulting barcodes constitute a simple tool to display differences between different plant oils. Results of PCA also enabled a clear identification of different plant oils. This method provided an efficient and convenient chromatographic technology for the fast characterization and quantification of complex TAGs in plant oils at high selectivity. It has great potential as a routine analytical method for analysis of edible oil quality and authenticity control.

Preparation and characterization of novel lipid carriers containing microalgae oil for food applications.

This work investigated the suitability of lipid carriers as potential encapsulation method to improve the physical and chemical stability of microalgae oil high in docosahexaenoic acid (DHA). Lipid carriers with various oil contents were successfully prepared by a microfluidization method using stearic acid as solid lipid, microalgae oil as liquid lipid, and poloxamer 188 as surfactant. Results show that the mean particle diameter of the lipid carriers was in the range of 300 to 350 nm with the polydispersity index below 0.2. The lipid carriers were found to have spherical shape when examined under the transmission electron microscope. Data from the encapsulation efficiency and loading capacity indicate high distribution of microalgae oil throughout the lipid carriers and good physical stability as reflected by the particle size and size distribution during storage. Furthermore, the lower DPPH scavenging activity of lipid carriers compared with that of free microalgae oil suggests better chemical stability of microalgae oil encapsulated in lipid carriers. The addition of microalgae oil into lipid phase could disturb the crystalline order and form lattice defects to enable encapsulation of DHA as revealed by the results from differential scanning calorimetery. Current results suggest that this type of novel lipid carriers could be an efficient and promising carrier system for delivery of microalgae oil.

Online profiling of triacylglycerols in plant oils by two-dimensional liquid chromatography using a single column coupled with atmospheric pressure chemical ionization mass spectrometry.

The complexity of natural triacylglycerols (TAGs) in various edible oils is high because of the hundreds of TAG compositions, which makes the profiling of TAGs quite difficult. In this investigation, a rapid and high-throughput method for online profiling of TAGs in plant oils by two-dimensional (2D) liquid chromatography using a single column coupled with atmospheric pressure chemical ionization (APCI) mass spectrometry was reported. A novel mixed-mode 2D chromatographic column packed with silver-ion-modified octyl and sulfonic co-bonded silica was employed in this online 2D separation system. This novel 2D column combined the features of C8 column and silver-ion. In comparison with the traditional C18 column and silver-ion column, which are the two main columns used for the separation of complex TAGs in natural oil samples, this novel 2D column, could provide hydrophobic interactions as well as π-complexation interactions. It exhibited much higher selectivity for the separation of TAGs, and the separation was rapid. This online 2D separation system was successful in the separation of a large number of TAG solutes, and the TAG structures were evaluated by analyzing their APCI mass spectra information. This system was applied for the profiling of TAGs in peanut oils, corn oils, and soybean oils. 30 TAGs in peanut oils, 18 TAGs in corn oils, and 21 TAGs in soybean oils were determined and quantified. The highest relative content of TAGs was LLL, which was found in corn oil with the relative content up to 45.43 (%, w/w), and the lowest relative content of TAGs was LLS and OSS, which was found in soybean oil and corn oil respectively, with the relative content only 0.01 (%, w/w). In addition, the TAG data were analyzed by principal component analysis (PCA). Results of PCA enabled a clear identification of different plant oils. This method provided an efficient and convenient chromatographic technology for the fast characterization and quantification of complex TAGs in plant oils at high selectivity. It has great potential as a routine analytical method for analysis of edible oil quality and authenticity control.

Rapid magnetic solid-phase extraction based on monodisperse magnetic single-crystal ferrite nanoparticles for the determination of free fatty acid content in edible oils.

This study proposes a rapid magnetic solid-phase extraction (MSPE) based on monodisperse magnetic single-crystal ferrite (Fe(3)O(4)) nanoparticles (NPs) for determining the quantities of eight free fatty acids (FFAs), including palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2), linolenic acid (C18:3), arachidic acid (C20:0), eicosenoic acid (C20:1), and behenic acid (C22:0) in oil. The amine-functionalized mesoporous Fe(3)O(4) magnetic NPs were applied as a sorbent for MSPE of FFAs from oil samples in a process that is based on hydrophilic interaction. The extraction can be completed rapidly in a dispersive mode with the aid of vigorous vortex. Additional tedious processing steps such as centrifugation and evaporation of organic solvent were not necessary with this procedure. Furthermore, esterification of FFAs can be accomplished during the desorption procedure by using methanol/sulfuric acid (99:1, v/v) as the desorption solvent. Several parameters affecting the extraction efficiency were investigated, including the matrix solvent for extraction, the desorption solvent and desorption time, and the amount of sorbent and extraction time. The pretreatment process was rapid under optimal conditions, being accomplished within 15 min. When coupled with gas chromatography-flame ionization detection (GC-FID), a rapid, simple, and convenient MSPE-GC-FID method for the determination of FFAs in oil samples was established with a total analysis time within 25 min. The limits of detection for the target FFAs were found to be 7.22-26.26 ng/mL. Recoveries in oil samples were in the range of 81.33-117.75%, with RSDs of <6.4% (intraday) and <6.9% (interday). This method was applied successfully to the analysis of dynamic FFA formation in four types of edible oils subjected to an accelerated storage test. The simple, rapid, and cost-effective method developed in the current study offers a potential application for the extraction and preconcentration of FFAs from hydrophobic sample matrices, including edible fats and oils, fatty foods, and biological samples with high amounts of lipid.

Characterization and quantification of triacylglycerols in peanut oil by off-line comprehensive two-dimensional liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry.

The complexity of natural triacylglycerols (TAGs) in various edible oils is prodigious due to the hundreds of set is of TAG compositions, which makes the identification of TAGs quite difficult. In this investigation, the off-line 2D system coupling of nonaqueous RP and silver-ion HPLC with atmospheric pressure chemical ionization MS detection has been applied to the identification and quantification of TAGs in peanut oil. The method was successful in the separation of a high number of TAG solutes, and the TAG structures were evaluated by analyzing their atmospheric pressure chemical ionization mass spectra information. HPLC and MS conditions have been optimized and the fragmentation mechanisms of isomers have been validated. In addition, an internal standard approach has been developed for TAG quantification. Then this system was applied in peanut oil samples and there was a total of 48 TAGs including regioisomers that have been determined and quantified.

Optimisation of preparation conditions and properties of phytosterol liposome-encapsulating nattokinase.

Phytosterol liposomes were prepared using the thin film method and used to encapsulate nattokinase (NK). In order to obtain a high encapsulation efficiency within the liposome, an orthogonal experiment (L9 (3)(4)) was applied to optimise the preparation conditions. The molar ratio of lecithin to phytosterols, NK activity and mass ratio of mannite to lecithin were the main factors that influenced the encapsulation efficiency of the liposomes. Based on the results of a single-factor test, these three factors were chosen for this study. We determined the optimum extraction conditions to be as follows: a molar ratio of lecithin to phytosterol of 2 : 1, NK activity of 2500 U mL⁻¹ and a mass ratio of mannite to lecithin of 3 : 1. Under these optimised conditions, an encapsulation efficiency of 65.25% was achieved, which agreed closely with the predicted result. Moreover, the zeta potential, size distribution and microstructure of the liposomes prepared were measured, and we found that the zeta potential was -51 ± 3 mV and the mean diameter was 194.1 nm. From the results of the scanning electron microscopy, we observed that the phytosterol liposomes were round and regular in shape and showed no aggregation.

Some characteristics and functional properties of rapeseed protein prepared by ultrasonication, ultrafiltration and isoelectric precipitation.

BACKGROUND: The presence of complex protein constituents and difficulties in extracting protein from rapeseed meal limit the application of rapeseed protein in food processing. However, double-low rapeseed (low erucic acid, low glucosinolate) protein is a type of complete protein that is of potential use in the food industry. In this study the characteristics and functional properties of rapeseed protein prepared by ultrasonic-assisted extraction, ultrafiltration and isoelectric precipitation were analysed and compared with those of soybean protein. RESULTS: The extraction efficiency with the ultrasonic-assisted method was significantly higher than that obtained with the traditional method. Ultrafiltration and isoelectric precipitation yielded three different proteins: ultrafiltered protein RPs and precipitated proteins RP5.8 and RP3.6. Chromatographic separation of RPs resulted in four fractions: RPsI, RPsII, RPsIII and RPsIV. The distribution of the isoelectric point of rapeseed protein was investigated by two-dimensional electrophoresis. The amino acid composition of RPs renders it suitable for human consumption. The hydrophobic/hydrophilic amino acid ratio of rapeseed protein was higher than that of soybean protein. The functional properties (oil adsorption ability, emulsifying capacity, foaming capacity and foam stability) of RPs, RP5.8 and RP3.6 were found to be better than those of soybean protein. CONCLUSION: Ultrasonication and ultrafiltration were significantly better than the traditional method of rapeseed protein extraction. The ultrafiltered rapeseed protein RPs had superior functional properties. The results of this study provide useful indicators for rapeseed protein as a potential replacement for other proteins.

A robust sampling approach for identification and quantification of methyl jasmonate in leaf tissue of oilseed rape for analysis of early signaling in Sclerotinia sclerotiorum resistance.

INTRODUCTION: Methyl jasmonate (MJA), which is a natrual hormonal regulator, is thought to be essential for the regulation of systemic defence responses. The information about MJA levels in plant tissues is helpful for the study of the disease resistance mechanism and genetically engineered cultivars with increased resistance. Therefore, the quantification of MJA levels in plant tissues by means of a sensitive and reliable method is of interest. OBJECTIVE: Development of a film extraction method coupled with GC for determination of methyl jasmonate in leaf tissue of oilseed rape for analysis of early signalling in sclerotinia sclerotiorum resistance. METHODOLOGY: A robust polydimethylsiloxane film was prepared and used for extraction of MJA in leaf tissues. By using in-solution extraction mode, optimum extraction efficiency was achieved with methanol-water (1 : 5, v/v) as extraction medium at 40 degrees C for 60 min. RESULTS: Under the optimal conditions, a detection limit of 0.2 ng/mL was achieved. Excellent reproducibility was found over a linear range of 1-1000 ng/mL. MJA in leaves infected by sclerotinia sclerotiorum was determined, with the results showing that basal levels of MJA (15 ng/g) were present in noninfested controls, but increased to 313 ng/g 10 h after fungal attack. CONCLUSION: The film extraction method is a simple, rapid and inexpensive sampling technique for determination of endogenous MJA in plant tissues that can be applied to most plants.

Quantitative determination of oil content in small quantity of oilseed rape by ultrasound-assisted extraction combined with gas chromatography.

Accurately quantitative determination of oil content in oilseed rape plays an important role in varieties breeding for improving oil content in seeds. However, large quantity of oilseeds were needed in order to obtain accuracy and precision results by using standard Soxhlet extraction method, which may be a handicap in analysis of small, rare and precious samples in plant breeding. In the present work, ultrasound-assisted extraction was evaluated as a simpler and more effective alternative to conventional extraction method for the isolation of oil from small quantity of oilseed rape (<20 mg). The oil of oilseed rape samples was extracted by ultrasound-assisted method, and then the fatty acids and total oil content of the seeds were qualitatively and quantitatively determined by gas chromatography (GC). Extraction efficiency of total oil obtained by ultrasound-assisted extraction through an orthogonal experiment (L(9) (3(4))) were investigated to get the best extraction conditions. Statistical analysis showed that the variable with the largest effect was the ultrasound-assisted extraction time which was followed by the ultrasound-assisted extraction power, and the liquid:solid ratio. A liquid:solid ratio of 1:4 (L:g), an ultrasound-assisted extraction time of 60 min and an ultrasound-assisted extraction power of 500 W were found to be optimal for oil extraction from oilseed rape. By comparing with the conventional method, it was found that the ultrasound-assisted extraction of oil from oilseed rape was about five times faster than the traditional extraction method. By the use of ultrasound-assisted extraction combined with GC analysis, the fatty acids and total oil content in small quantity of seeds (<20 mg) were successfully qualitatively determined and the results are in agreement with that obtained by traditional standard method.