Fatty Acid Diesters Research Articles

Effect of temperature on lutein esterification and lutein stability in wheat grain

The creamy colour of many wheat-based end-products is conferred by endogenous lutein. During post-harvest storage of grain, free lutein may be converted in part to potentially more stable lutein mono- and di-fatty acid esters. This study investigates the synthesis of lutein esters and stability of free lutein and lutein esters over a wide range of temperatures in grain of a high lutein bread wheat, Triticum aestivum L. line DM5685*B12 and a durum, Triticum durum L cv Kamilaroi. Disappearance of free lutein and lutein esterification followed first order reaction rates. The maximum rate of lutein esterification was at ≈80 °C, however, the optimum temperature for maximum synthesis with minimum degradation was between 30 °C and 60 °C. No ester synthesis was observed at temperatures higher than 120 °C. The data are consistent with an enzyme participating in the esterification reaction. Lutein esters were found to be more stable than free lutein with a longer shelf life at 60 °C whilst at temperatures ≤40 °C, lutein degradation was minimal. This study provides new information on lutein ester formation and lutein stability that should be useful to grain handlers and food manufacturers seeking to optimise retention of lutein for the benefit of consumers.

Phosphorus-based fatty acid methyl esters

With the aim of designing novel transformable fatty acid diesters, various strategies for introducing phosphorus arms to the fatty backbone have been examined. While lithiated phosphine reacts classically to brominated fatty esters to afford the mono-addition product, the synthesis of phosphorylated diesters was found to be difficult, a fact related to the bulkiness of fatty acids and phosphine reagents. A base-induced dehydrochlorination reaction using ArPCl2 and hydroxy-terminated fatty esters resulted in metastable diester for which hydrolytic cleavage undergo phosphine oxidation and expulsion of one fatty chain. Alternatively, ArPOCl2 alleviates this drawback and provides stable, phosphorylated fatty acid diesters.

Analysis of Processing Contaminants in Edible Oils. Part 2. Liquid Chromatography–Tandem Mass Spectrometry Method for the Direct Detection of 3-Monochloropropanediol and 2-Monochloropropanediol Diesters

A method was developed and validated for the detection of fatty acid diesters of 2-monochloropropanediol (2-MCPD) and 3-monochloropropanediol (3-MCPD) in edible oils. These analytes are potentially carcinogenic chemical contaminants formed during edible oil processing. After separation from oil matrices using a two-step solid-phase extraction (SPE) procedure, the target compounds are quantitated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). The first chromatographic conditions have been developed that separate intact diesters of 2-MCPD and 3-MCPD, allowing for their individual quantitation. The method has been validated for 28 3-MCPD diesters of lauric, myristic, palmitic, linolenic, linoleic, oleic, and stearic acids in coconut, olive, and palm oils, as well as 3 2-MCPD diesters, using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 88-118% (2-16% RSD) with maximum limits of quantitation of 30 ng/g (ppb).

Free Radical Mediated Formation of 3-Monochloropropanediol (3-MCPD) Fatty Acid Diesters

The present study was conducted to test the hypothesis that a free radical was formed and mediated the formation of 3-monochloropropanediol (3-MCPD) fatty acid diesters, a group of food contaminants, from diacylglycerols at high temperature under a low-moisture condition for the first time. The presence of free radicals in a vegetable oil kept at 120 °C for 20 min was demonstrated using an electron spin resonance (ESR) spectroscopy examination with 5,5-dimethylpyrroline-N-oxide (DMPO) as the spin trap agent. ESR investigation also showed an association between thermal treatment degree and the concentration of free radicals. A Fourier transform infrared spectroscopy (FT-IR) analysis of sn-1,2-stearoylglycerol (DSG) at 25 and 120 °C suggested the possible involvement of an ester carbonyl group in forming 3-MCPD diesters. On the basis of these results, a novel free radical mediated chemical mechanism was proposed for 3-MCPD diester formation. Furthermore, a quadrupole-time of flight (Q-TOF) MS/MS investigation was performed and detected the DMPO adducts with the cyclic acyloxonium free radical (CAFR) and its product MS ions, proving the presence of CAFR. Furthermore, the free radical mechanism was validated by the formation of 3-MCPD diesters through reacting DSG with a number of organic and inorganic chlorine sources including chlorine gas at 120 and 240 °C. The findings of this study might lead to the improvement of oil and food processing conditions to reduce the level of 3-MCPD diesters in foods and enhance food safety.

Relative oral bioavailability of 3-MCPD from 3-MCPD fatty acid esters in rats

In order to quantify the relative oral bioavailability of 3-chloropropane-1,2-diol (3-MCPD) from 3-MCPD fatty acid diesters in vivo, 1,2-dipalmitoyl-3-chloropropane-1,2-diol (3-MCPD diester) and 3-MCPD were orally applied to rats in equimolar doses. In both cases, the time courses of 3-MCPD concentrations were measured in blood, various organs, tissues and intestinal luminal contents. The results show that 3-MCPD is released by enzymatic hydrolysis from the 3-MCPD diester in the gastrointestinal tract and distributed to blood, organs and tissues. Based on the measurements in blood, the areas under the curve (AUC) for 3-MCPD were calculated. By comparing both AUC, the relative amount of 3-MCPD bioavailable from the 3-MCPD diester was calculated to be 86% on average of the amount bioavailable following administration of 3-MCPD. In view of limited experimental data, it is justified for the purpose of risk assessment to assume complete hydrolysis of the diesters in the gastro-intestinal tract. Therefore, assessment of the extent of exposure to 3-MCPD released from its fatty acid esters should be performed in the same way as exposure to the same molar quantity of 3-MCPD.

Characterization of polysorbate 80 with liquid chromatography mass spectrometry and nuclear magnetic resonance spectroscopy: Specific determination of oxidation products of thermally oxidized polysorbate 80

The polysorbate species in polysorbate 80 (PS 80) have been characterized with 1H NMR, LC–UV/MS and MS/MS. The MS was operated with both negative and positive electrospray ionization (ESI). PS 80 was found to contain mono- and di-fatty acid esters of polyoxyethylene (POE) sorbitan, POE isosorbide and of POE. In addition, the same species were also present without fatty acid esters. The polysorbate species were esterified with C12:0, C14:0, C16:1, C16:0, C18:2, C18:1 and C18:0 fatty acids. The main species were polysorbate esters of C18:1. The C18:2 polysorbate species were shown, by 1H NMR, to have a large component of fatty acids with a conjugated double bond of ZE and/or EZ configuration. The positive ESI mass spectra of the polysorbate species displayed a specific in-source fatty acid fragment for each fatty acid ester. The mass chromatograms of the in-source fatty acid fragments were used to determine the degradation of specific polysorbate species in PS 80. The C18:2 polysorbate species were completely degraded after 8 weeks at 40°C under an atmosphere of air, while the main C18:1 polysorbate species were reduced to ca. 80–86% accompanied by an increase of short-chain POE C18:1 species. Polysorbate species esterified with C18:1–OH, C18:1 keto and C18:0 epoxy acids were found as degradation products of PS 80 stored at 40°C for 8 weeks under air. C18:1–OH, C18:1 keto and C18:0 epoxy acids were believed to be oxidation products of C18:1. With the present conditions, the positive ESI mass spectra of C18:1–OH and C18:0 epoxy polysorbate species displayed identical ions to the C18:2 polysorbate species due to a facile in-source loss of H2O from the protonated molecules. The presence of polysorbate esters of C18:1–OH and C18:0 epoxy acids were established using negative ESI MS. The presence of oxidized fatty acids in degraded PS 80 was also confirmed by saponification and extraction followed by negative ESI LC–MS analysis of the free fatty acids.

Formation mechanisms of Monochloropropanediol (MCPD) fatty acid diesters in refined palm (Elaeis guineensis) oil and related fractions

Monochloropropanediol (MCPD) fatty acid esters are process contaminants generated during the deodorisation of edible oils. In particular, MCPD diesters are found in higher abundance in refined palm oil than other edible oils. In the present study, a series of model reactions mimicking palm oil deodorisation has been conducted with pure acylglycerols in the presence or absence of either organic or inorganic chlorine-containing compounds. Results showed that the bulk of MCPD diesters are formed above 200°C through the reaction of organochlorines with triacylglycerols (TAG). Additional experiments confirmed that this reaction can be initiated during palm oil deodorisation by hydrogen chloride (HCl) gas evolved through the thermal degradation of organochlorines present in the oil. Therein, the majority of the ultimately produced MCPD diesters are the result of HCl reacting with TAG, via protonation, followed by the elimination of a fatty acid residue. Two possible MCPD diester formation mechanisms are highlighted, both of which involve acyloxonium ion reactive intermediates. Investigations with pure TAG regio-isomers showed that MCPD ester formation is regioselective and the sn-1(3) position of the glycerol backbone is favoured.

Factors impacting the formation of Monochloropropanediol (MCPD) fatty acid diesters during palm (Elaeis guineensis) oil production

Recently, organic and inorganic chlorinated compounds were detected in crude and commercially refined palm oils. Further, the predominant formation mechanism of monochloropropanediol (MCPD) diesters at high temperatures (>170–180°C) was revealed. The present study involved the development and comparison of solutions to mitigate MCPD diester levels in oils from various stages of palm oil production. Partially refined palm oil samples and oil extracted from fresh palm fruits were submitted to bench-top deodorisation experiments. Application of glycerol and ethanol as refining aids during the deodorisation of refined-bleached palm oil proved to be moderately effective; about 25%–35% reduction of MCPD diester levels was achieved. Washing crude palm oil with ethanol–water (1:1) prior to deodorisation was also an effective strategy yielding an ∼30% reduction of MCPD diester contents. Washing palm fruit pulp before oil extraction, however, was most impactful, resulting in a 95% reduction of MCPD diesters when compared to the deodorised control oil. This suggests that intervention upstream in the process chain is most efficient in reducing levels of these contaminants in refined oils. Following the study, a root-cause analysis was performed in order to map the parameters potentially responsible for the occurrence of MCPD diesters in refined palm oil and related fractions.

Solubility in CO2 and carbonation studies of epoxidized fatty acid diesters: towards novel precursors for polyurethane synthesis

Novel linear polyurethanes were synthesized by bulk polyaddition of diamines with two vegetable-based biscarbonates produced from oleic acid methyl ester. Internal carbonated fatty acid diester (ICFAD) and terminal carbonated fatty acid diester (TCFAD) were obtained by the reaction of their epoxide precursors with CO2. Terminal epoxy fatty acid diester (TEFAD) was found to be more soluble and more reactive in CO2 than internal epoxy fatty acid diester (IEFAD). Polyurethanes obtained by polyaddition of TCFAD and ICFAD with diamines exhibit molecular weights up to 13 500 g mol−1 and glass transitions around −15 °C. Amide linkages were not observed when secondary diamine was used as the comonomer.

Lipase‐Catalyzed Synthesis of d‐Psicose Fatty Acid Diesters and their Emulsification Activities

AbstractThe diesterification of d‐psicose (the C‐3 epimer of d‐fructose) with fatty acid vinyl esters of selected acyl chain lengths (C8, C10, and C12) was successfully carried out using Candida antarctica lipase (Novozym 435) at 45 °C for 24 h to give the 1,6‐diacyl‐d‐psicofuranoses with a high regioselectivity in good yields (83–90%). These diesters of d‐psicose have hydrophilic‐lipophilic balance (HLB) values (6.5–8.2) similar to HLB values of monoglyceride compounds which constitute the largest single type of emulsifiers employed by the food industry. Ability of the d‐psicose diesters to stabilize oil‐in‐water emulsions and the weight‐averaged oil‐droplet diameter in the emulsions was evaluated in this study. Emulsion stability of oil droplets stabilized by d‐psicose dicaprylate (0.3%, w/v in oil phase) was comparable to d‐fructose dicaprylate (0.2%, w/v). It was further confirmed that the d‐psicose diesters exhibited an emulsification activity depending on the chain length of fatty acid; d‐psicose dicaprate showed better emulsion stability than the other diesters.

Intraspecific and interspecific chemosignals in birds: a review

This review of chemosignals in birds considers intraspecific oriented chemosignals such as pheromones, interspecific chemosignals, and chemical interactions with parasites. Intraspecific chemosignals are known in some seabirds, especially burrow- or crevice-nesting auklets and petrels that breed in large colonies and are often nocturnal on land. Crested Auklets secrete a distinctive scent closely associated with courtship and important in sexual selection. Individually distinctive odours of petrels allow them to identify their own nest and can have a significant role in social relationships. Substances considered as sex pheromones, diesters of 3-hydroxy fatty acids, are produced by female mallards in their uropygial glands during the mating season. In many species of Charadriiformes during nesting monoester waxes are substituted with mixtures of less volatile diester waxes, less easily detected by mammals searching for nests. The tissues, mainly skin and feather of the New Guinean Passerines of the genus <i>Pitohui</i> and <i>Ifrita</i> contain steroidal alkaloids from the batrachotoxin group probably as a chemical defense. The variation of preen gland secretion in some other Passerines is apparently due to selective pressures caused by ectosymbionts. The auklets’ odour, considered as a signal of mate quality, has also a function as ectoparasite repellent: aldehyde constituents of this odour kill and repel ectoparasites. Parasitic nematodes influence grouse digestion and thereby scent emission, making parasitized birds more vulnerable to depredation by mammals. Conversely, scents of some mammalian predators can function as a bird repellent.

LC-MS ion maps for the characterization of aniline derivatives of fatty acids and triglycerides in laboratory-denatured rapeseed oil

In 1981 Spain went through a unique epidemic associated with a food-borne vector, affecting more than 20,000 people with over 800 deaths, which came to be known as the Toxic Oil Syndrome (TOS). Early epidemiological studies showed a link between this illness and the ingestion of rapeseed oil denatured with 2% aniline. This oil, originally aniline-denatured for industrial use, was fraudulently processed in an attempt to remove free aniline, and marketed as edible oil. Fatty acid anilides (FAA), monoesters and diesters of 3-(N-phenylamino)-1,2-propanediol (PAP) are present in oil samples as they arise in the refining process from reactions of aniline with constituent fatty acids and triglycerides of the oil matrix and are the only extraneous compounds found in these samples. To expand the search for the causative agents in TOS-associated oils and to look for new aniline-related compounds, an exhaustive characterization of laboratory-processed oils was undertaken. These oils, in the presence of aniline doped with 14C labelled aniline, were submitted to the laboratory conditions required for the generation of PAPs and FAAs. Laboratory-generated oil samples were submitted to a liquid-liquid extraction procedure to remove the unreacted aniline. The extract was processed by double solid-phase extraction to improve detection limits for minor amine-containing compounds in oils. The extracts enriched in aniline derivatives were submitted to on-line HPLC-UV-APCI-MS. Using two-dimensional ion maps, the components of several families of derivatives were readily identified. Additionally, the extracts were also fractionated by HPLC-UV and the fractions were analyzed by HPLC-APCI-MS/MS to obtain structural information. Standards of some of these compounds were synthesized and analyzed to confirm the results. A total of 115 aniline derivatives from 9 aniline-related families were identified in these oil samples. These included fatty acid anilides and an extensive array of phenylaminopropanediol esters distributed in eight major compound classes.

Molecular Composition of Nonionic Vesicles Prepared from Span 80 or Span 85 by a Two‐Step Emulsification Method

The molecular compositions of the commercial nonionic surfactants Span 80 and Span 85 were analyzed by reversed phase high performance liquid chromatography (HPLC). Both surfactants are mixtures of fatty acid esters, containing monoesters, diesters, triesters, and tetraesters. While diesters dominate in the case of Span 80, Span 85 contains mainly tetraesters. Vesicles were prepared from Span 80 (or Span 85) by a two‐step emulsification method that involved homogenization and separation steps in which a portion of the surfactants was removed. The composition of the vesicles was analyzed by HPLC with respect to the different esters present. Although commercial Span 80 and Span 85 differ considerably in their molecular compositions, the ester profiles of the vesicles formed were in both cases rather similar and dominated by diesters. Therefore, the particular vesicle preparation method leads to a molecular selection of mainly those components that are prone to form bilayers.

Microwave-assisted synthesis of deuterium labeled estrogen fatty acid esters

Deuterated analogs of estrogen fatty acid esters are needed as internal standards for isotope dilution GC/MS analyses. We have developed a rapid and efficient synthesis for 2,4,16,16-D 4-estrone palmitate, stearate, oleate, linoleate, and linolenate and the corresponding 2,4,16,16,17α-D 5-estradiol fatty acid 17-mono and 3,17-diesters using analogous fatty acid chlorides or fatty acid anhydrides and 4-(dimethylamino)pyridine under microwave irradiation. Chemoselective hydrolysis of fatty acid diesters was carried out by KOH in t-BuOH.

Production of Diglycerol Conjugated Linoleic Acid Monoester by Esterification with Penicillium camembertii Lipase

Polyglycerol fatty acid monoesters are used widely as food emulsifiers, and conjugated linoleic acid (CLA) has various physiological activities. Hence, production of polyglycerol CLA monoester was attempted through a lipase-catalyzed reaction. A commercially available free fatty acid mixture (referred to as FFA-CLA) containing 9cis,11trans (9c,11t)-CLA and 10t,12c-CLA was used as a source of CLA, and its esterification with diglycerol was studied. Screening of several lipases showed that Penicillium camembertii lipase was suitable for production of diglycerol fatty acid monoesters (DGFAMEs). When a mixture of FFA-CLA/diglycerol (1:2, mol/mol), 100 U/g-mixture of the lipase, and 2% water was agitated at 30 °C for 24 h with dehydration at 5 mm Hg using a vacuum pump, the degree of esterification reached 93%, and the ratio of DGFAMEs/diglycerol fatty acid diesters was 1.9:1 (wt/wt). The synthesized DGFAMEs were purified to 97% in a 69% yield by short-path distillation. This process comprising lipase-catalyzed esterification and short-path distillation may be effective for industrial production of an emulsifier for use in nutraceutical applications.

Separation of geometric isomers of native lutein diesters in marigold ( Tagetes erecta L.) by high-performance liquid chromatography–mass spectrometry

Lutein is found in many foods; the richest and purest plant source is marigold flower ( Tagetes erecta L.). In this plant, lutein is in the form of saturated fatty acid diesters. By using a binary mobile phase consisting of ethyl acetate and acetonitrile–methanol (9:1), improved separation was achieved on a C 18-bonded phase. The unique absorption of lutein cis isomers at 330 nm was used in combination with MS to identify the novel cis-lutein isomeric dimyristate, myristate-palmitate, dipalmitate, and palmitate-stearate diesters, as well as the rare combinations of both trans- and cis-lutein laurate-palmitate and trans- and cis-lutein myristate-stearate. The presence of the all- trans-lutein laurate-myristate, dimyristate, myristate-palmitate, palmitate-stearate, and distearate diesters, reported by others, was also confirmed.

Sucrose esterification under Mitsunobu conditions: evidence for the formation of 6- O-acyl-3′,6′-anhydrosucrose besides mono and diesters of fatty acids

A series of sucrose monoesters and homogeneous or mixed diesters, which have various chain lengths and saturation levels, were prepared under Mitsunobu conditions with good regioselectivity. Among the anhydro derivatives arising from competitive intramolecular etherification, 3′,6′-anhydrosucrose 6- O-monoesters, which have never been reported, were identified.

Facile Hydrolysis of Esters with KOH-Methanol at Ambient Temperature

A simple, rapid, and efficient method is reported for the hydrolysis of a variety of mono- and diesters of aromatic, aliphatic, fatty, and heterocyclic acids with potassium hydroxide in methanol at ambient temperature (∼35°C).

Cyclohexanediol Fatty Acid Diesters as Model Compounds for Mechanistic Studies in Silver Ion High Performance Liquid Chromatography

Series of cis‐1,2‐ and cis/trans‐1,4‐cyclohexanediol diesters of saturated, oleic and linoleic fatty acids were employed as model compounds in a study of the effect of the unsaturation and the position of the acyl moieties on the retention of acylglycerol molecules in silver ion high‐performance liquid chromatography (HPLC). cis‐1,2‐Diunsaturated cyclohexanediol diesters were retained slightly more strongly than were the respective cis/trans‐1,4‐compounds, thus indicating that formation of chelate‐type complexes between silver ions and the double bonds of two adjacent unsaturated fatty acid residues during silver ion chromatography may occur to a limited extent.

Effect of Fatty Acid Diesters on Permeation of Anti-Inflammatory Drugs Through Rat Skin

ABSTRACTFour fatty acid diesters (diethyl succinate, diethyl adipate, diethyl sebacate, and diisopropyl adipate) were used to study their enhancement effect on the permeation of four non-steroidal anti-inflammatory drugs (NSAIDs: ketoprofen, indomethacin, diclofenac sodium, and ibuprofen) through rat abdominal skin. With the diester pretreatment, drug permeation increased and the lag times decreased. No relationship was observed between the solubilities of the drugs in the diesters and the diester enhancement effects. The enhancement effect decreased with an increase of the drug lipophilicity, but increased with an increase of the lipophilic index of the diester up to about 3.5, after which the enhancement effect decreased or remained constant. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) was employed to investigate the biophysical changes in the stratum corneum lipids caused by the diesters. The FTIR results showed that treatment of the skin with diesters did not produce a blue shift in the asymmetric and symmetric C–H stretching peak positions. However, all of the above diesters showed a decrease in peak heights and areas for both asymmetric and symmetric C–H stretching absorbances in comparison with water treatment.These results suggested that the diesters were more effective for enhancing the penetration of hydrophilic drugs than lipophilic drugs, and the enhancing effect of lipophilic diesters was more effective than that of hydrophilic diesters. The enhancement effects of diesters may be due to their causing lipid extraction in the skin.