linoleic-acid and trilinolein

High-purity trilinolein and triolein were prepared by Novozym 435-catalyzed esterification reaction combined with column chromatography purification in this study. Firstly, linoleic acid and oleic acid were respectively extracted from safflower seed oil and camellia seed oil by urea adduct method. Secondly, trilinolein and triolein were synthesized through Novozym 435 catalyzed esterification of glycerol and fatty acids. The best synthesis conditions were obtained as follows: reaction temperature 100°C, residual pressure 0.9 kPa, enzyme dosage 6%, molar ratio of glycerol to linoleic acid 1:3 and reaction time 8 h. Crude trilinolein and triolein were further purified by silica gel column chromatography. Finally, highpurity trilinolein (95.43±0.97%) and triolein (93.07±1.05%) were obtained.

Topics: Camellia; Carthamus tinctorius; Chromatography, Liquid; Enzymes, Immobilized; Esterification; Fungal Proteins; Glycerol; Linoleic Acid; Lipase; Oleic Acid; Safflower Oil; Temperature; Triglycerides; Triolein

Trilinolein, with or without additives, was placed in glass ampoules and subjected to thermal treatment at 180 °C or 240 °C for 8h. Thermal treatment of trilinolein at 180 °C and 240 °C produced twice the amount of trans nonconjugated linoleic acids (NLAs) compared to conjugated linoleic acids (CLAs), and nitrogen stream reduced the amount of both trans NLA and CLA products. The presence of additives resulted in the suppression or induction of trans NLAs and CLAs, depending on the type of additive, the concentration of the additive, and the heating temperature. Our analysis indicates that TBHQ is an effective additive for reducing trans NLA formation and inducing trans CLA formation in frying oil. Glutathione and L-cysteine at 0.1% may also be used as additives for frying oil. At suitable concentrations, Fe(3+) and Al(3+) ions derived from oils can reduce trans NLAs and induce trans CLAs during frying.

Topics: Butylated Hydroxyanisole; Butylated Hydroxytoluene; Chromatography, Gas; Cooking; Cysteine; Hot Temperature; Hydroquinones; Isomerism; Linoleic Acid; Linoleic Acids, Conjugated; Trans Fatty Acids; Triglycerides; Vitamin E

Now it is recognized that DHA is oxidatively stable fatty acid compared with linoleic acid (LA) in emulsified system, although DHA is oxidatively unstable in a bulk system. In fact, an emulsified mixture of DHA and LA behaves as in a bulk system, namely the oxidative stability of DHA becomes lower than that of LA. Therefore, in this study, tridocosahexaenoate (DDD) and glycerol trilinoleate (LLL) were separately emulsified using TritonX-100 as an emulsifier and DDD emulsion was mixed with the oxidizing LLL emulsion using a water-soluble radical initiator, 2,2'-azobis(2-aminopropane) dihydrochloride. As a result, DHA suppressed the oxidation of LA, while DHA was not significantly oxidized. This suppression ability was examined using glycerol trieicosapentaenoate, glycerol trilinolenate, or glycerol trioleate instead of DDD and it was found that this activity was increased with the increasing number of double bonds in the structure. Furthermore, the same type of experiment was carried out using a lipid-soluble radical initiator, 2,2'-azobisisobutyronitrile and the similar result was obtained. These results indicated that a highly polyunsaturated fatty acid might act as an antioxidant in an emulsion system oxidized by an azo compound.

Topics: Amidines; Antioxidants; Docosahexaenoic Acids; Emulsions; Linoleic Acid; Octoxynol; Solubility; Triglycerides

Lipid hydroperoxides are important factors in lipid oxidation due to their ability to decompose into free radicals. In oil-in-water emulsions, the physical location of lipid hydroperoxides could impact their ability to interact with prooxidants such as iron. Interfacial tension measurements show that linoleic acid, methyl linoleate, and trilinolein hydroperoxides are more surface-active than their non-peroxidized counterparts. In oil-in-water emulsion containing surfactant (Brij 76) micelles in the continuous phase, linoleic acid, methyl linoleate, and trilinolein hydroperoxides were solubilized out of the lipid droplets into the aqueous phase. Brij 76 solubilization of the different hydroperoxides was in the order of linoleic acid > trilinolein > or = methyl linoleate. Brij 76 micelles inhibited lipid oxidation of corn oil-in-water emulsions with greater inhibition of oxidation occurring in emulsions containing linoleic acid hydroperoxides. Surfactant solubilization of lipid hydroperoxides could be responsible for the ability of surfactant micelles to inhibit lipid oxidation in oil-in-water emulsions.

Topics: Alkanes; Chemical Phenomena; Chemistry, Physical; Emulsions; Kinetics; Linoleic Acid; Linoleic Acids; Lipid Bilayers; Lipid Peroxidation; Lipid Peroxides; Micelles; Surface-Active Agents; Triglycerides; Water

To determine sources of desirable deep-fried flavor in frying oils, degradation products from heated triolein and trilinolein with 5-31% polar compounds representing low to high deterioration were evaluated by purge-trap gas chromatography-mass spectrometry-olfactometry. (E,E)-2,4-Decadienal, 2-heptenal, 2-octenal, 2,4-nonadienal, and 2,4-octadienal produced deep-fried odor at moderate-strong intensities in heated trilinolein. However, unexpected aldehydes-2,4-decadienal, 2,4-undecadienal, 2,4-nonadienal, and 2-octenal (all <15 ppm)-were produced in triolein heated for 6 h. These dienals possibly were produced by hydroperoxidation and/or hydroxylation followed by dehydration of 2-alkenals. The 2-alkenals were produced from thermal decomposition of hydroperoxides, epoxides, and keto and dimeric compounds produced during the heating of triolein. These aldehydes produced low intensities of deep-fried odor in triolein. This information helps to explain sources of the deep-fried flavor that is characteristic of high linoleic frying oils but which is only at low intensity levels in high oleic frying oils.

Topics: Chromatography, High Pressure Liquid; Cooking; Gas Chromatography-Mass Spectrometry; Hot Temperature; Humans; Linoleic Acid; Odorants; Oleic Acid; Taste; Triglycerides; Triolein; Volatilization

In soybean (Glycine max L.) vegetative tissue at least five lipoxygenase isozymes are present. Four of these proteins have been localized to the paraveinal mesophyll, a layer of cells that is thought to function in assimilate partitioning. In order to determine the role of the lipoxygenase isozymes within the soybean plant, the leaf lipoxygenases were cloned into bacterial expression vectors and expressed in Escherichia coil. The recombinant lipoxygenases were then characterized as to substrate preference, pH profiles for the most common plant lipoxygenase substrates, linoleic acid, and alpha-linolenic acid, and the reaction products with the substrates linoleic acid, alpha-linolenic acid, arachidonic acid, gamma-linolenic acid, and the triacylglycerol trilinolein. All five enzymes were shown to be (13S)-lipoxygenases against linoleic acid. The results of these assays also indicate that two of these isozymes are highly active against esterified fatty acid groups, such as those found in triacylglycerols. Lipid analysis of leaves from plants subjected to sink limitation conditions indicates that the soybean leaf lipoxygenases are active in vivo against both free fatty acids and esterified lipids, and that the quantities of lipoxygenase products found in leaf tissue show a positive correlation with the level of lipoxygenase in the leaf. Implications for the putative role of these enzymes in the paraveinal mesophyll are discussed.

Topics: Arachidonic Acid; Chromatography, High Pressure Liquid; Cloning, Molecular; Electrophoresis, Polyacrylamide Gel; Escherichia coli; Fatty Acids; gamma-Linolenic Acid; Glycine max; Hydrogen-Ion Concentration; Linoleic Acid; Lipoxygenase; Microscopy, Electron; Nitrogen; Protein Isoforms; Recombinant Fusion Proteins; Recombinant Proteins; Substrate Specificity; Time Factors; Triglycerides

Analysis of the kinetic behaviour of a two-enzyme-system carrying out two consecutive reactions was investigated in macroheterogeneous biphasic media (octane/buffer pH 9.6, v/v = 1:1). The lipase-catalysed hydrolysis of trilinolein and the subsequent lipoxygenation of the liberated linoleic acid, were coupled in a modified Lewis cell with a well-defined liquid/liquid interfacial area. Trilinolein was dissolved in the organic phase and hydrolysed in the presence of Mucor javanicus lipase at the organic/aqueous interface. Linoleic acid, liberated after hydrolysis was transferred to the aqueous phase and reacted with lipoxygenase. This reaction consumed linoleic acid and produced hydroperoxides, which favoured the transfer of residual linoleic acid, since they possess surface active properties. Catalysis and transfer influenced each other reciprocally. At low substrate concentrations, cooperativity phenomena were observed in the experimental and also the modelled two-enzyme systems. When the initial substrate concentration was high, the kinetic behaviour of the two-enzyme system in a compartmentalised medium, seemed to be independent of the substrate concentration, unlike that observed in homogeneous monophasic enzymology. The numerical integration program used to model the two-enzyme system was based on results obtained in separate studies of the following three phenomena: (1) trilinolein hydrolysis in biphasic medium. (2) linoleic acid transfer across a liquid/liquid interface and (3) lipoxygenation in an aqueous media. Results obtained by modelling were similar to the results observed experimentally.

Topics: Glycine max; Hydrolysis; Kinetics; Linoleic Acid; Linoleic Acids; Lipase; Lipoxygenase; Models, Chemical; Mucor; Solutions; Triglycerides; Water

The reactivity of cucumber cotyledon lipoxygenase with trilinolein was examined. The activity of the enzyme against linoleic acid rapidly decreased with increasing pH of the assay solution, and essentially no activity could be detected above pH 8.5. The rapid decrease in activity was not the result of an inactiveness of the enzyme at alkaline pH, because with trilinolein, the enzyme showed a broad pH-activity profile, and substantial activity could be detected even at pH 9.0. Rather, the decrease in activity was due to the dissociation of the linoleic acid emulsion into acid-soap aggregates and/or the monomeric form, depending on the ionization of the terminal carboxylic group. This suggests that cucumber cotyledon lipoxygenase acts only on an insoluble substrate at the lipid/water interface but not on a soluble one. High-performance liquid chromatography analyses of the products formed from trilinolein revealed that the enzyme inserted oxygen into the acyl moiety of trilinolein without hydrolysis of the ester bonds. Preincubation of the enzyme with triolein emulsions effectively abolished its activity against trilinolein added afterward. Furthermore, the enzyme was adsorbed on the trilinolein or triolein emulsion droplets in an essentially irreversible manner. A reaction velocity curve of the enzyme with trilinolein showed saturation kinetics. This is thought to be due to a regional substrate deficiency as the reaction proceeds. These lines of evidence indicate that the enzyme, once bound to the lipid/water interface, is unable to break free and bind to other emulsions.

Topics: Adsorption; Chromatography, High Pressure Liquid; Cotyledon; Cucumis sativus; Emulsions; Hydrogen Peroxide; Hydrogen-Ion Concentration; Kinetics; Linoleic Acid; Linoleic Acids; Lipoxygenase; Substrate Specificity; Triglycerides; Water

The effects of incremental amounts of dietary t,t-18:2 on liver microsomal delta 5 and delta 6 acyl desaturase activities were studied. The hepatic concentration of t,t-18:2 increased linearly from 0 to 1.6 mg/g liver as dietary t,t-18:2 was increased from 0--50% of dietary fat. This apparently inhibited the conversion of linoleic to arachidonic acid in liver tissue because linoleic acid increased from 1.2 to 3.1 mg/g liver, while arachidonic acid concurrently decreased from 3.9 to 1.9 mg/g liver tissue. This reflected the inhibition of delta 6 desaturase by t,t-18:2. The delta 6 desaturase activity in liver microsomes of rats fed 10, 20, and 50% of t,t-18:2 in their dietary lipids was 97, 75, and 51% of the activity of rats fed no t,t-18:2. In vitro tests showed that t,t-18:2 specifically inhibited liver delta 6 desaturase. The delta 5 desaturase activities did not increase significantly as dietary t,t-18:2 levels increased. This study showed that dietary t,t-18:2 by depressing delta 6 desaturase activity may affect essential fatty acid metabolism.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Delta-5 Fatty Acid Desaturase; Fatty Acid Desaturases; Fatty Acids; Fatty Acids, Unsaturated; Linoleic Acid; Linoleic Acids; Linoleoyl-CoA Desaturase; Liver; Male; Microsomes, Liver; Rats; Rats, Inbred Strains; Triglycerides

Topics: Biochemical Phenomena; Fats; Glycine max; Linoleic Acid; Lipid Metabolism; Lipoxygenase; Oxidoreductases; Triglycerides