Analysis of the Dynamic Decomposition of Unsaturated Fatty Acids and Tocopherols in Commercial Oils During Deep Frying

The decomposition of unsaturated fatty acids and tocopherols in 10 commercial edible oils during deep frying was investigated. The dominant tocopherol in oils rich in polyunsaturated fatty acids (PUFAs) was γ-tocopherol, except for natural perilla oil (δ-tocopherol dominant), and the main tocopherol in oleic acid-rich oils was α-tocopherol. The PUFA-rich oils had higher tocopherol contents than the oleic acid-rich oils. Both the reduction rate of total unsaturated fatty acid (TUFA) and total tocopherol (TToc) were linear with frying time (t). The decomposition rate of TToc is faster than that of TUFA since the slope values obtained from fitting equations (Y?=?k t) k_TToc (1.520–14.483) were obviously larger than for k_TUFA (0.155–0.270). By establishing a dynamic decomposition index, unsaturated fatty acids and tocopherol in oils showed dynamic decomposition over multiple frying cycles. The obtained results showed that decomposition characteristics of oils are related to their fatty acid compositions.     

大果白刺游离脂肪酸的柱前衍生高效液相色谱-荧光检测法分析

采用2-（11H-苯[a]咔唑）乙基对甲苯磺酸酯（BCETS）为柱前荧光衍生试剂,通过梯度洗脱使得18种脂肪酸在BDS-C8柱上得到良好的分离.方法应用于大果白刺不同部位中游离脂肪酸的分析,结果表明大果白刺的果皮果肉和叶子中均含有大量的不饱和脂肪酸,其总不饱和脂肪酸含量分别为70.74%和73.47%.大果白刺种子中不饱和脂肪酸的含量相对较少,仅占总脂肪酸含量的57.21%,其不饱和脂肪酸组成主要是C18∶1（油酸）和C18∶2（亚油酸）.其中,大果白刺的果皮果肉中,不饱和脂肪酸主要是C18∶1、C18∶2和C18∶3（亚麻酸）.其叶子中的不饱和脂肪酸主要是C18∶3,所占总脂肪酸比例为48.34%.首次对大果白刺中的脂肪酸进行了分析,可以为大果白刺在食品、药品中的进一步开发应用和质量控制提供一定的数据支持.     

Purification and monolayer study of the thylacoid lipids of moss marchantia polymorpha

The original lipid content of the thylakoid membranes of moss Marchantia polymorpha has been determined for the first time. In particular, the content of SQDG is almost 3 times higher than those for both of the other classes. The ratios for DGDG and MGDG are just a little bit lower than those for green algae, but almost 2 times less than those for plants. The distribution of unsaturated bonds has changed in C₁₈ -residues of fatty acids. The total content of C₁₈-residues in thylacoid lipids have been almost the same but the content of C_18:1, C_18:2 and C_18:3 are altered in the fractions of DGDG, PG and PE. The light stress produces only the quantitative, but no qualitative, changes of the thylakoid lipid composition. The properties of the thylakoid lipids and corresponding fatty acids in the monolayers at the liquid/gas interfaces have been studied. The changes in distribution of unsaturated bonds in C₁₈ residues of fatty acids at light stress have been confirmed by Langmuir method.     

Monolayer properties of fatty acids : II. Surface vapor pressure and the free energy of compression

The properties of monolayers spread at the air-water interface were measured for saturated, unsaturated, and hydroxy fatty acids, differing in the type and degree of unsaturation, geometric isomerism, and position of unsaturated and hydroxy groups. Surface vapor pressures, reflecting the equilibrium between “gaseous” and “liquid” monolayer states were determined, as were the free energies of compression, ΔF_c, from essentially infinite dilution (100,000 Ų/molecule) to the area per molecule, A_e at the equilibrium spreading pressure, π_e. Surface vapor pressures and free energies of compression for saturated and unsaturated fatty acids with a double bond, or bonds, change in a manner expected because of chain-chain interactions. Hydroxy and acetylenic acids produce relatively high surface vapor pressures, despite their tendency for strong chain-chain interaction. It is concluded that chain-water interactions are very significant for the acetylenic and hydroxy acids and less so for the saturated and ethylenic acids.     

Influence of oleic acid on the structure of a mixture of hydrated model stratum corneum fatty acids and their soaps

The phase behaviour of a hydrated (32% (w/w) water) mixture of saturated and unsaturated fatty acids and their soaps has been examined. By progressively increasing the proportion of oleic acid, it could be shown that this unsaturated component exists partly as a separate phase within the others. The unsaturated fatty acids form an H_II phase at 25°C, whereas the saturated fatty acids form a fatty acid—soap crystal under the conditions employed. The results help to explain the role played by the fatty acids (and also cholesterol) within the lipid fraction of human stratum corneum. A feature of this study is a comparison of the results obtained by X-ray diffraction, differential scanning calorimetry and Fourier transform infrared spectroscopy.     

Synthesis of Gb3 Glycosphingolipids with Labeled Head Groups: Distribution in Phase‐Separated Giant Unilamellar Vesicles

The receptor lipid Gb₃ is responsible for the specific internalization of Shiga toxin (STx) into cells. The head group of Gb₃ defines the specificity of STx binding, and the backbone with different fatty acids is expected to influence its localization within membranes impacting membrane organization and protein internalization. To investigate this influence, a set of Gb₃ glycosphingolipids labeled with a BODIPY fluorophore attached to the head group was synthesized. C₂₄ fatty acids, saturated, unsaturated, α‐hydroxylated derivatives, and a combination thereof, were attached to the sphingosine backbone. The synthetic Gb₃ glycosphingolipids were reconstituted into coexisting liquid‐ordered (l_o)/liquid‐disordered (l_d) giant unilamellar vesicles (GUVs), and STx binding was verified by fluorescence microscopy. Gb₃ with the C_24:0 fatty acid partitioned mostly in the l_o phase, while the unsaturated C_24:1 fatty acid distributes more into the l_d phase. The α‐hydroxylation does not influence its partitioning.     

Analysis of long-chain fatty acids in grey wastewater with in-vial derivatisation

The presence and levels of long-chain fatty acids (C₆–C₂₀) in grey wastewater from bathrooms have been investigated. The acids were purified and concentrated by solid-phase extraction on strong anion exchange discs, in-vial derivatised to their corresponding methyl ester and subsequently analysed by GC-MS. The method was able to quantify the acids at concentration <1?µg/L with a recovery of 31–97%. The levels of fatty acids were found in the range of <0.5 to 27?100?µg/L and the highest levels were found for the saturated lauric (C₁₂), palmitic (C₁₆) and stearic (C₁₈) acids. The treatment efficiency of a local treatment plant was evaluated by comparing concentrations of fatty acids at the inlet and the outlet. It was found that the treatability decreases with increasing chain length for the saturated acids (19–100% degradation) whereas the corresponding mono unsaturated acids were more easily degraded.     

Determination of fatty acids in atmospheric samples via GC/MS

Summary Atmospheric precipitation and aerosol samples are characterized by a complex mixture of several organic compounds. A simple method for the simultaneous determination of the main compound classes by GC/MS is presented. In detail, seasonal variations of C₈–C₃₂ fatty acids in precipitation in a semirural area have been studied. Total fatty acids concentrations of 7–53 g/l were detected. Summer rain is characterized by high amounts of fatty acids >C₂₀ and lower amounts of C₁₁–C₂₀ species. Two effects may be responsible: larger emission rates of fatty acids during vegetation periods and an increased influence of vapour phase due to higher temperatures during summer. CPI values showed no general trend; lower CPI values for winter rain could not be observed. This would be expected if anthropogenic sources play an important role. Monounsaturated fatty acids (C_16:1, C_18:1) were more abundant during winter than in summer. High concentrations of polyunsaturated fatty acids (C_18:x) could be detected during summer. High relative concentrations of the potential oxidation products of the unsaturated species, nonanedioic acid and w-oxononanoic acid, are associated with relatively low concentrations of their precursors.     

Analytical characterization of mannosylerythritol lipid biosurfactants produced by biosynthesis based on feedstock sources from the agrofood industry

Mannosylerythritol lipids (MELs) are currently one of the most promising biosurfactants because of their multifunctional applications and good biodegradability. Depending on the yeast strain and the feedstock used for the fermentation process, structural variations in the MELs obtained occur. Therefore, MELs produced by Pseudozyma aphidis DSMZ 70725 with a soybean oil feedstock were characterized by chromatography and mass spectrometry (MS). Column chromatography with silica provided fractionation of the different types of MEL. High-performance liquid chromatography combined with MS was employed for the analysis of the MEL fractions and crude mixtures. A characteristic MS pattern for the MELs was obtained and indications of the presence of new MEL homologues, showing the incorporation of longer and more unsaturated fatty acid chains than previously reported, were given. Gas chromatography?CMS analysis confirmed the presence of such unsaturated fatty acid chains in the MELs, demonstrating the incorporation of fatty acids with lengths ranging from C₈ to C₁₄ and with up to two unsaturations per chain. The incorporation of C₁₆ and C₁₈ fatty acid chains requires further investigation. MS/MS data allowed the unambiguous identification of the fatty acids present in the MELs. The product ion spectra also revealed the presence of a new isomeric class of MELs, bearing an acetyl group on the erythritol moiety.     

Lipids of the vegetative and generative organs ofHibiscus sp.

The lipids of the leaves, stems, and roots ofHibiscus sp. have been studied. Their fatty acid compositions have been determined. The greatest amount of unsaturated fatty acids was present in the glycolipids of the leaves and the stems. More than 25% of low-molecular-mass C₁₀-C₁₂ fatty acids have been found in the neutral lipids of the roots.Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 705–708, September–October, 1996. Original article submitted March 11, 1996.     

Synthetic Polyester from Algae Oil

Current efforts to technically use microalgae focus on the generation of fuels with a molecular structure identical to crude oil based products. Here we suggest a different approach for the utilization of algae by translating the unique molecular structures of algae oil fatty acids into higher value chemical intermediates and materials. A crude extract from a microalga, the diatom Phaeodactylum tricornutum, was obtained as a multicomponent mixture containing amongst others unsaturated fatty acid (16:1, 18:1, and 20:5) phosphocholine triglycerides. Exposure of this crude algae oil to CO and methanol with the known catalyst precursor [{1,2‐(tBu₂PCH₂)₂C₆H₄}Pd(OTf)](OTf) resulted in isomerization/methoxycarbonylation of the unsaturated fatty acids into a mixture of linear 1,17‐ and 1,19‐diesters in high purity (>99 %). Polycondensation with a mixture of the corresponding diols yielded a novel mixed polyester‐17/19.17/19 with an advantageously high melting and crystallization temperature.     

Docosahexaenoic acid and eicosapentaenoic acid induce changes in the physical properties of a lipid bilayer model membrane

We investigated the effect of fatty acids such as stearic acid (SA, 18:0), oleic acid (OA, 18:1), eicosapentaenoic acid (EPA, 20:5), and docosahexaenoic acid (DHA, 22:6) on a dipalmitoylphosphatidylcholine (DPPC) bilayer by determining the phase transition temperature, fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH), and detergent insolubility. Treatment with unsaturated fatty acid broadened and shifted the phase transitions of the DPPC bilayer to a lower temperature. The phase transition temperature and the value of fluorescence anisotropy of DPH at 37 degrees C decreased progressively with increasing treatment amounts of unsaturated fatty acid. A large amount of the DPPC bilayer treated with unsaturated fatty acid was dissolved in Triton X-100, obtaining a low level of detergent insolubility. These modifications of the bilayer physical properties were most pronounced with DHA and EPA treatment. These data show that unsaturated fatty acids, particularly DHA and EPA, induce a marked change in the lipid bilayer structure. The composition of fatty acids in the DPPC bilayer was similar after treatment with various unsaturated fatty acids, suggesting that the different actions of unsaturated fatty acids are attributed to change in the molecular structure (e.g., kinked conformation by double bonds). We further explored the change in physical properties induced by fatty acids dispersed in a water-in-oil-in-water multiple emulsion and found that unsaturated fatty acids acted efficiently on the DPPC bilayer, even when incorporated in emulsion form.     

2-氨基-2-甲基丙醇化学修饰试剂用于气相色谱-质谱分析不饱和脂肪酸

以2-氨基-2-甲基丙醇为脂肪酸的化学修饰试剂，将不饱和脂肪酸羧基化学修饰成含氮杂环，从而避免了链烯基中碳碳双键在EI源中的移动，并使质谱呈现显示双键位置的规范信息。通过解析不饱和脂肪酸2-氨基-2-甲基丙醇化学修饰产物的EI质谱图，得到了不饱和脂肪酸中碳碳双键的定位规则，从而为分析不饱和脂肪酸精细结构提供了手段。用脂肪酸2-氨基-2-甲基丙醇化学修饰气相色谱-EI质谱法分析了螺旋藻脂肪酸，鉴定出9种不饱和脂肪酸，确定了螺旋藻脂肪酸中碳碳双键的位置，结果与文献一致。     

黑蚂蚁的脂肪酸及抗氧化性能的分析

对黑蚂蚁中脂肪酸的组成和含量进行测定。采用索氏提取法提取其脂肪酸,再进行甲酯化处理,以气相色谱-质谱联用仪进行了分离和鉴定。由黑蚂蚁中分离鉴定出11种脂肪酸,占脂肪酸总量的99.78%,不饱和脂肪酸占脂肪酸总量的80.65%,饱和脂肪酸占脂肪酸总量的19.13。通过流动注射化学发光法分析了黑蚂蚁的抗氧化性能,结果表明,黑蚂蚁具有较强的抗氧化性能。     

Enorme Unterschiede in der qualitativen und quantitativen Zusammensetzung der Fettsäurefraktion von rohem und gekochtem Gemüse

Summary Potato tubers und vegetables, introduced into the body contain — in dependance if boiled or not — very different amounts of multiple unsaturated fatty acids. In boiled vegetables linoleic and linolenic acid remain unchanged. In contrast, if the vegetable is shred and then analysed, the content of multiple unsaturated fatty acids is lowered for a factor of 2–5. If vegetable is shred, lipoxygenases are liberated, resulting in oxidizing the multiple unsaturated acids. The lipoxygenases are destroyed if vegetable is cooked before shreding. An easy comparison of the effect of lipoxygenases on fatty acid can be made by gas chromatography. The effect is especially strong incruciferae e.g. in cabbage or cauliflower.

     

A Novel Labeling Reagent of 2-(12-Benzo[b]acridin-5-(12H)-yl)-acetohydrazide for Determination of Saturated and Unsaturated Fatty Acids in Traditional Chinese Herbs by HPLC-APCI-MS

A new fluorescence labeling reagent 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) has been designed for fatty acids labeling. Eleven fatty acids containing seven saturated and four unsaturated fatty acids were used to evaluate the analytical potential of this reagent. The labeling reaction of BAAH with fatty acids was completed at 85?°C for 60?min using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC·HCl) as the condensing agent. Separation of the derivatized fatty acids was carried out on a reversed-phase Thermo Hypersil Gold C18 column (4.6?mm?×?250?mm, 5?μm) in combination with a gradient elution with a good baseline resolution. The fluorescence excitation and emission wavelengths were set at λ_ex 280 and λ_em 510?nm, respectively. The identification was carried out by the online APCI-MS in positive-ion detection mode. Linear correlation coefficients for all fatty acid derivatives were of >0.9994. Detection limits, at a signal-to-noise ratio of 3:1, were 3.89–12.5?nmol?L^?1 for the labeled fatty acids. The developed method was successfully applied to the accurate determination of fatty acids in five traditional Chinese herbs with satisfactory results.     

A Novel Labeling Reagent of 2-(12-Benzo[b]acridin-5-(12H)-yl)-acetohydrazide for Determination of Saturated and Unsaturated Fatty Acids in Traditional Chinese Herbs by HPLC-APCI-MS

A new fluorescence labeling reagent 2-(12-benzo[b]acridin-5(12H)-yl)-acetohydrazide (BAAH) has been designed for fatty acids labeling. Eleven fatty acids containing seven saturated and four unsaturated fatty acids were used to evaluate the analytical potential of this reagent. The labeling reaction of BAAH with fatty acids was completed at 85 °C for 60 min using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC·HCl) as the condensing agent. Separation of the derivatized fatty acids was carried out on a reversed-phase Thermo Hypersil Gold C18 column (4.6 mm × 250 mm, 5 μm) in combination with a gradient elution with a good baseline resolution. The fluorescence excitation and emission wavelengths were set at λ_ex 280 and λ_em 510 nm, respectively. The identification was carried out by the online APCI-MS in positive-ion detection mode. Linear correlation coefficients for all fatty acid derivatives were of >0.9994. Detection limits, at a signal-to-noise ratio of 3:1, were 3.89–12.5 nmol L⁻¹ for the labeled fatty acids. The developed method was successfully applied to the accurate determination of fatty acids in five traditional Chinese herbs with satisfactory results.

     

Elucidation of the double-bond position of long-chain unsaturated fatty acids by multiple-stage linear ion-trap mass spectrometry with electrospray ionization

Linear ion-trap (LIT) MS2 mass spectrometric approach toward locating the position of double bond(s) of unsaturated long-chain fatty acids and toward discerning among isomeric unsaturated fatty acids as dilithiated adduct ([M-H+2Li]+) ions are described in this report. Upon resonance excitation in a LIT instrument, charge-remote fragmentation that involves beta-cleavage with gamma-H shift (McLafferty rearrangement) is the predominant fragmentation pathway seen for the [M-H+2Li]+ ions of monoenoic long-chain fatty acids. The fragmentation process results in a dilithiated product ion of terminally unsaturated fatty acid, which undergoes consecutive McLafferty rearrangement to eliminate a propylene residue, and gives rise to another dilithiated adduct ion of terminally unsaturated fatty acid. In addition to the above-cited fragmentation process, the [M-H+2Li]+ ions of homoconjugated dienoic long-chain fatty acids also undergo alpha-cleavage(s) with shift of the allylic hydrogen situated between the homoconjugated double bonds to the unsaturated site. These fragmentation pathways lead to two types of CC bond cleavages that are allylic (alpha-cleavage) or vinylic, respectively, to the proximal CC double bond, resulting in two distinct sets of ion series, in which each ion series is separated by a CH2CHCH (40 Da) residue. These latter fragmentations are the predominant processes seen for the polyunsaturated long-chain fatty acids. The spectrum feature dependent on the position of unsaturated double bond(s) affords unambiguous assignment of the position of double bond(s) of long-chain unsaturated fatty acids.     

Chemistry and Biochemistry of Unsaturated Fatty Acids

Although unsaturated fatty acids have long been known to accompany saturated fatty acids in most lipids, qualitative and quantitative determination of fatty acid patterns only became possible with the advent of modern analytical methods. Present day knowledge of the chemical structure, physical properties, and metabolism of unsaturated fatty acids provides the basis for the development of new concepts of their function. Thus unsaturated fatty acids crucially determine the properties of biological membranes. Moreover, essential fatty acids are precursors of prostaglandins.     

Interrelation between parameters of isotherms of adsorption of fatty acids on the surface of magnetite and volume effects of their dissolution in n-hexane and carbon tetrachloride at 298.15 K

The adsorption of unsaturated C_18:n fatty acids on magnetite and volume effects of their dissolution in n-hexane and carbon tetrachloride are studied. It is established that an increase in the values of limiting adsorption of a series of oleic, linolic, and linolenic acids corresponds to positive volume effects of their dissolution in CCl₄. Opposite picture of the adsorption behavior of studied acids in n-hexane corresponds to negative volume effects of the dissolution of the acids in this solvent.