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1.
Arnar Halldorsson Bjorn Kristinsson Gudmundur G. Haraldsson 《European Journal of Lipid Science and Technology》2004,106(2):79-87
The main objective of this study was to compare the fatty acid selectivity of numerous commercially available lipases toward the most ubiquitous fatty acids present in fish oils in form of their corresponding ethyl esters. Special interest was taken in their ability to separate the n‐3 long‐chain polyunsaturated fatty acids (PUFA), mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), from the more saturated fatty acids as well as exploiting the putative discrimination between these highly valuable n‐3 PUFA. Hydrolysis of sardine oil ethyl esters in a Tris buffer solution by 12 microbial lipases is described. The results reveal that all of the lipases strongly discriminate against the n‐3 PUFA and prefer the more saturated fatty acids as substrates. Most of the lipases discriminate between EPA and DHA in favor of EPA, however, 2 bacterial lipases from Pseudomonas were observed to prefer DHA to EPA. Digestive lipolytic enzymes isolated from salmon and rainbow trout intestines displayed reversed fatty acid selectivity when their fish oil triacylglycerol hydrolysis was studied. Thus, the n‐3 PUFA including EPA and DHA were observed to be hydrolyzed at a considerably higher rate than the more saturated fatty acids. 相似文献
2.
J. L. Guil-Guerrero El-Hassan Belarbi 《Journal of the American Oil Chemists' Society》2001,78(5):477-484
The polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA, 20∶5n−3) and docosahexaenoic acid (DHA, 22∶6n−3), which
have several pharmaceutical properties, have been purified from cod liver oil. The process consisted of four main steps: (i)
saponification of the oil, (ii) use of urea inclusion adducts method to obtain PUFA, (iii) PUFA methylation, and (iv) argentation
silica gel column chromatography of the methylated PUFA. Argentation silica gel chromatography yielded highly pure DHA in
the process (100% purity, 64% yiild). For EPA, the recovery in the combined process was 29.6%, and the final purity was 90.6%,
owing to the simultaneous elution of other polyunsaturated fatty esters. The recovery in the urea inclusion method was strongly
enhanced by application of orbital agitation during the crystallization process, in which EPA yield increased from 60–70%
without agitation to 90–97% at 800 rpm; stearidonic acid (18∶4n−3) yield ranged from 60–75% without agitation to 87–95% at
800 rpm, and DHA yield varied from 53–73% without agitation to 85–99% at 800 rpm 相似文献
3.
Production of n-3 polyunsaturated fatty acid-enriched fish oil by lipase-catalyzed acidolysis without solvent 总被引:1,自引:0,他引:1
Tsuneo Yamane Tomomasa Suzuki Youko Sahashi Line Vikersveen Tamotsu Hoshino 《Journal of the American Oil Chemists' Society》1992,69(11):1104-1107
Fish oil rich in n-3 polyunsaturated fatty acid (n-3 PUFA) was prepared by nonsolvent enzymic acidolysis. n-3 PUFA-enriched
fish oil contained 25% eicosapentaenoic acid (EPA) and 40% docosahexaenoic acid (DHA). In acidolysis of cod liver oil, EPA
content of the original fish oil was reduced at 5 h, but DHA content of the fish oil increased. It was assumed that EPA in
the fish oil was replaced by DHA to reach a new chemical equilibrium. Two-stage acidolysis, which was carried out under CO2 replacement early (about 3 h) and also in vacuum at 5–24 h, was effective for reduction in the content of diacylglycerol,
which was formed by reverse reaction, hydrolysis. This method has industrial significance because PUFA-enriched triacylglycerol
is easily separated from the reaction mixture by molecular distillation.
Bioreactors for fats and their derivatives, Part XIV. 相似文献
4.
Yuji Shimada Kazuaki Maruyama Masaki Nakamura Suguru Nakayama Akio Sughihara Yoshio Tominaga 《Journal of the American Oil Chemists' Society》1995,72(12):1577-1581
Polyunsaturated fatty acids (PUFA), especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), can be concentrated
in glycerides by hydrolyzing tuna oil withGeotrichum candidum lipase, the main components in the resulting oil being triglycerides. The reaction mechanism of this selective hydrolysis
was investigated. Although the lipase acted well on the esters of oleic, linoleic, and α-linolenic acids, it did not affect
the esters of γ-linolenic acid, arachidonic acid, EPA, and DHA as much. The action of PUFA-glycerides was mono-> di- > triglycerides.
Furthermore, the condensation of PUFA-partial glycerides and PUFA occurred even in the presence of a large amount of water,
and the partial glycerides converted to the triglycerides by transacylation. These results suggested that the PUFA-rich triglycerides
were accumulated in the glyceride fraction by the following mechanism: The PUFA-partial glycerides generated by the hydrolysis
were converted to PUFA-triglycerides by condensation and transacylation reactions. As the PUFA-triglycerides formed were the
poor substrates of lipase, they were accumulated in the reaction mixture. 相似文献
5.
Chemoenzymatic synthesis of structured triacylglycerols containing eicosapentaenoic and docosahexaenoic acids 总被引:6,自引:4,他引:2
Gudmundur G. Haraldsson Arnar Halldorsson Elin Kuls 《Journal of the American Oil Chemists' Society》2000,77(11):1139-1145
There are indications in the recent literature that the location of polyunsaturated fatty acids, such as eicosapentaenoic
acid (EPA) and docosahexaenoic acid (DHA), in triacylglycerols (TAG) may influence their oxidative stability. To address that
question, two types of structured lipids were designed and synthesized: firstly, a TAG molecule possessing pure EPA or DHA
at the mid-position with stearic acid at the outer positions; and secondly, a TAG molecule possessing pure EPA or DHA located
at one of the outer positions with stearic acid at the mid-position and the remaining end position. The former adduct was
synthesized in two steps by a chemoenzymatic approach. In the first step 1,3-distearolyglycerol was afforded in good yield
(74%) by esterifying glycerol with two equivalents of stearic acid in ether in the presence of silica gel using LipozymeTM as a biocatalyst. This was followed by a subsequent chemical esterification with pure EPA or DHA using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide
as a coupling agent in the presence of 4-dimethylaminopyridine in dichloromethane in excellent yields (94 and 91, respectively).
The latter adduct was synthesized in two enzymatic steps. In the first step tristearoylglycerol was prepared in very high
yield (88%) by esterifying glycerol with a stoichiometric amount of stearic acid under vacuum at 70–75°C using an immobilized
Candida antarctica lipase without a solvent. That adduct was subsequently treated in an acidolysis reaction with two equivalents of EPA or DHA
without solvent at 70–75°C or in toluene at 40°C in the presence of Lipozyme to afford the desired product in moderate yields
(44 and 29%, respectively).
This work was presented at the Biocatalysis Symposium in April 2000, held at the 91st Annual Meeting and Expo of the American
Oil Chemists’ Society, San Diego, CA. 相似文献
6.
Betty Mbatia Bo Mattiasson Francis Mulaa Patrick Adlercreutz 《European Journal of Lipid Science and Technology》2011,113(6):717-723
PUFA from oil extracted from Nile perch viscera were enriched by selective enzymatic esterification of the free fatty acids (FFA) or by hydrolysis of ethyl esters of the fatty acids from the oil (FA‐EE). Quantitative analysis was performed using RP‐HPLC coupled to an evaporative light scattering detector (RP‐HPLC‐ELSD). The lipase from Thermomyces lanuginosus discriminated against docosahexaenoic acid (DHA) most, resulting in the highest DHA/DHA‐EE enrichment while lipase from Pseudomonas cepacia discriminated against eicosapentaenoic acid (EPA) most, resulting in the highest EPA/EPA‐EE enrichment. The lipases discriminated between DHA and EPA with a higher selectivity when present as ethyl esters (EE) than when in FFA form. Thus when DHA/EPA were enriched to the same level during esterification and hydrolysis reactions, the DHA‐EE/EPA‐EE recoveries were higher than those of DHA/EPA‐FFA. In reactions catalysed by lipase from T. lanuginosus, at 26 mol% DHA/DHA‐EE, DHA recovery was 76% while that of DHA‐EE was 84%. In reactions catalysed by lipase from P. cepacia, at 11 mol% EPA/EPA‐EE, EPA recovery was 79% while that of EPA‐EE was 92%. Both esterification of FFA and hydrolysis of FA‐EE were more effective for enriching PUFA compared to hydrolysis of the natural oil and are thus attractive process alternatives for the production of products highly enriched in DHA and/or EPA. When there is only one fatty acid residue in each substrate molecule, the full fatty acid selectivity of the lipase can be expressed, which is not the case with triglycerides as substrates. 相似文献
7.
Kuan-hsiang Huang Casimir C. Akoh 《Journal of the American Oil Chemists' Society》1994,71(11):1277-1280
The ability of immobilized lipases IM60 fromMucor miehei and SP435 fromCandida antarctica to modify the fatty acid composition of selected vegetable oils by incorporation of n−3 polyunsaturated fatty acids into
the vegetable oils was studied. The transesterification was carried out in organic solvent with free acid and ethyl esters
of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as acyl donors. With free EPA as acyl donor, IM60 gave higher
incorporation of EPA than SP435. However, when ethyl esters of EPA and DHA were the acyl donors, SP435 gave higher incorporation
of EPA and DHA than IM60. When IM60 and free acid were used, the addition of 5 μL water increased EPA incorporation into soybean
oil by 4.9%. With ethyl ester of EPA as acyl donor, addition of 2 μL water increased EPA incorporation by 3.9%. For SP435,
addition of water up to 2μL resulted in increased EPA incorporation, but the incorporation declined when the added water exceeded
this amount. The addition of water increased the EPA incorporation into Trisun 90 after 24 h reaction but not the reaction
rate at early stages of the reaction. 相似文献
8.
Casimir C. Akoh Brenda H. Jennings Dorris A. Lillard 《Journal of the American Oil Chemists' Society》1996,73(8):1059-1062
Immobilized lipase SP435 fromCandida antaractica was used as a biocatalyst for the modification of the fatty acid composition of evening primrose oil by incorporating n−3
polyunsaturated fatty acid (PUFA) and eicosapentaenoic acid (EPA). Transesterification (ester-ester interchange) was conducted
in organic solvent or without solvent, with EPA ethyl ester (EEPA) as the acyl donor. Products were analyzed by gas-liquid
chromatography (GLC). After 24-h incubation in hexane, the fatty acid composition of evening primrose oil was markedly changed
to contain up to 43% EPA. The amount of 18:2n−6 PUFA was reduced by 32%, and the saturated fatty acid content was also reduced.
The effects of incubation time, molar ratio, enzyme load, and reaction medium on mol% EPA incorporation were also studied.
Generally, as the incubation time (up to 24 h), molar ratio, and enzyme load increased, EPA incorporation also increased.
Evening primrose oil, containing EPA and γ-linolenic acid (18:3n−6) in the same glycerol backbone, was successfully produced
and may be more beneficial for certain applications than unmodified oil. 相似文献
9.
Immobilized lipase-catalyzed production of structured lipids with eicosapentaenoic acid at specific positions 总被引:4,自引:0,他引:4
Structured lipids (SL) were synthesized by the interesterification reaction between medium-chain triacylglycerols and eicosapentaenoic
acid (EPA) ethyl ester. The products were partially purified, and the fatty acid at thesn-2 position was determined after pancreatic lipase-catalyzed hydrolysis. The effect of additives (water and glycerol) on the
rate of reaction was also investigated. Mol% EPA incorporated into the triacylglycerols was increased by adding water when
trilaurin and tricaprylin were the substrates and IM 60 was the biocatalyst. With SP 435, EPA incorporation was always less
with additional water than without water. The addition of glycerol (0.005 g or 0.01 g) improved interesterification catalyzed
by IM 60 to some degree, but an excess amount (0.02 g) inhibited the reaction. The reaction with glycerol showed no significant
difference with SP 435. After scale-up and fractionation by column chromatography, we could recover approximately 0.3–0.4
g of product/g of reaction products. After hydrolysis by pancreatic lipase, we can conclude that IM 60 has a high specificity
forsn-1,3 positions. With SP 435 lipase, 34.8–39.3 mol% of EPA was found at thesn-2 position of the recovered SL. 相似文献
10.
The lipase-assisted acidolysis of high-laurate canola oil (HLCO; Laurical 25) with long-chain n−3 FA (DHA and EPA) was studied.
Response surface methodology was used to obtain a maximal incorporation of DHA or EPA into HLCO. The studied process variables
were the amount of enzyme (2–6%), reaction temperature (35–55°C), and incubation time (12–36 h). The amount of water added
and the mole ratio of substrates (oil to DHA or EPA) were kept at 2% and 1∶3, respectively. All experiments were conducted
according to a face-centered cube design. Under optimal conditions (4.79% of enzyme; 46.1°C; 30.1 h), the incorporation of
DHA into HLCO was 37.3%. The corresponding maximal incorporation of EPA (61.6%) into Laurical 25 was obtained using 4.6% enzyme,
a reaction temperature of 39.9°C, and a reaction period of 26.2 h. Examination of the positional distribution of FA on the
glycerol backbone of modified HLCO with DHA showed that the DHA was primarily located in the sn-1,3 positions of the TAG molecules. However, lauric acid also remained mainly in the sn-1,3 positions of the modified oil. For EPA-modified Laurical 25, lauric acid was present mainly in the sn-1,3 positions, whereas EPA was randomly distributed over the three positions. 相似文献
11.
Jesuí Vergílio Visentainer Maximiliano D’Addio Noffs Patricia de Oliveira Carvalho Vanessa Vivian de Almeida Cláudio Celestino de Oliveira Nilson Evelázio de Souza 《Journal of the American Oil Chemists' Society》2007,84(6):543-547
Lipid content and fatty acid composition were determined in edible meat of fifteen marine fish species caught on the Southeast
Brazilian coast and two from East Antarctic. Most of the fish had lipid amounts lower than 10% of their total weight. Palmitic
acid (C16:0) predominated, accounting for 54–63% of the total amount of saturated fatty acids. Oleic acid (C18:1n-9) was the
most abundant (49–69%) monounsaturated fatty acid, and docosahexaenoic acid (DHA) was the predominant polyunsaturated fatty
acid (PUFA), accounting for 31–84% of n-3 PUFA. n-3 PUFA level were highest in Antarctic fish meat, comprising 45% of the
total fatty acid content, which consisted of mainly EPA (16.1 ± 1.5 g/100 g lipids) and DHA (24.8 ± 2.4 g/100 g lipids). The
amounts of EPA + DHA in g/100 g of lipids on the Southeast Brazilian coast and Antarctic fish species investigated were found
to be similar: 42.0 ± 1.7 for Bonito cachorro, 41.0 ± 2.3 for Atum, and 39.4 ± 1.8 for peixe porco, respectively. All the
studied species exhibited an n-3/n-6 ratio higher than 3, which confirms the great importance of Southeast Brazilian coast
fish as a significant dietary source of n-3 PUFA. 相似文献
12.
Anju Chopra A. K. Tewari S. Vatsala Ravindra Kumar A. S. Sarpal B. Basu 《Journal of the American Oil Chemists' Society》2011,88(9):1285-1296
In the present work, methods based on Gas Chromatography (GC), Gas Chromatography–Mass Spectrometry (GC–MS) and 1H-NMR techniques was developed for the characterization and estimation of Polyunsaturated Fatty Esters (PUFA) in biodiesel.
The GC method enables the separation, identification and estimation of these polyunsaturated fatty acid methyl esters to be
carried out using a highly polar capillary column (100% cyanopropyl silicon). GC–MS was utilized for unambiguous identification
and estimation of esters and isomers present in biodiesel. The estimation of PUFA content is important because PUFA content
is a part of the EN 14214 specifications of biodiesel. There is no existing standard method for the estimation of total PUFA
content in biodiesel. The developed GC method also quantifies EPA and DHA (C20:5 and C22:6) fatty acid methyl esters which
can be used as markers for the estimation of fish oil biodiesel. The presence of EPA and DHA indicates the contamination of
fish oil in biodiesel. Further, the 1H-NMR technique has also been employed to identify and estimate PUFA containing ≥3 double bonds. The PUFA content was estimated
from the integral intensities of the chemical shift region corresponding to all type of double bonds in the 1H-NMR spectra. Based on the developed method, GC fingerprinting of various biodiesel samples was carried out to estimate a
PUFA content as low as 1,000 ppm. 相似文献
13.
The fatty acid (FA) profiles of edible muscle of selected commercially important freshwater and marine fish species from Turkey
were investigated. The fatty acid compositions of freshwater fish species were 23.00–29.60% saturated (SFA), 25.70–36.50%
monounsaturated (MUFAs), and 26.59–31.92% polyunsaturated acids (PUFAs), whereas the fatty acid compositions of marine fish
consisted of 21.08–36.90% (SFA), 18.03–51.45% MUFAs, and 20.92–53.17% PUFAs. There was a wide variation and significant (P < 0.05) differences among the fatty acid profiles of the freshwater and marine fish samples, including differences in the
SFA, MUFA, PUFA, EPA, DHA, DHA/EPA, total n-3 PFAs, total n-6 PUFAs and n-3/n-6 values. In addition, the cheap marine fish
species such as anchovy and European pilchard, bogue are better dietary sources of n-3 PUFAs than more expensive species such
as bluefish, Atlantic mackerel, sea bream and sea bass. Through the application of two multivariate statistical methods, Principal
Component and Hierarchical Analysis, fish species from Turkey waters were classified according to the geographical locations
categorized in terms of fatty acid profiles. Clustering by fish species also gave rise to defined groups. 相似文献
14.
Ann‐Marie Lyberg Patrick Adlercreutz 《European Journal of Lipid Science and Technology》2008,110(4):317-324
The fatty acid specificity of four lipases towards eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) was evaluated when performing ethanolysis of squid oil. During the first part of ethanolysis, no DHA ethyl esters were detected when using the lipases from Thermomyces lanuginosus, Pseudomonas cepacia or Pseudomonas fluorescens (in the case of the second and third lipases, no EPA ethyl esters were detected either). This indicates that these three lipases could not catalyse the conversion of DHA located in a triacylglycerol to ethyl ester, and that the Pseudomonas lipases could not catalyse the conversion of EPA either. This pattern was not found for the lipase from Rhizomucor miehei. The lipase from Thermomyces lanuginosus showed the lowest specificity towards DHA and the highest DHA recovery during DHA enrichment in the acylglycerol fraction. It was thus used to catalyse the ethanolysis of squid oil on a larger scale. The ethyl esters formed were removed using short‐path distillation, resulting in a product containing mainly mono‐ and diacylglycerols. The product contained 34 mol‐% DHA and 17 mol‐% EPA, compared with 19 mol‐% DHA and 12 mol‐% EPA in the original squid oil. 相似文献
15.
J. L. Guil-Guerrero J. C. López-Martínez M. A. Rincón-Cervera P. Campra-Madrid 《Journal of the American Oil Chemists' Society》2007,84(4):357-361
The fatty acids (FA) eicosapentaenoic acid (20:5ω-3; EPA) and docosahexaenoic acid (22:6ω-3; DHA), which have several health
benefits, have been concentrated from mako shark liver (Isurus oxyrinchus). The process was carried out in one single step, in which fish liver oil was simultaneously extracted, saponified and concentrated.
Additionally, the polyunsaturated fatty acids (PUFA) concentrate was winterized to crystallize the remaining saturated FA,
resulting in a further increase in the concentration of DHA and EPA. Two variables, temperature and water concentration in
the saponification mixture, were optimized to increase the concentration of ω-3 PUFA. Best results were obtained at 12 °C
and 0% water content in the mixture, obtaining 17.8% purity and 77.6% yield of EPA; DHA purity and yield were 33.3 and 82.2%,
respectively. 相似文献
16.
Separation of eicosapentaenoic acid and docosahexaenoic acid in fish oil by kinetic resolution using lipase 总被引:5,自引:0,他引:5
Gudmundur G. Haraldsson Björn Kristinsson 《Journal of the American Oil Chemists' Society》1998,75(11):1551-1556
The objective of this study was to investigate the use of lipases as catalysts for separating eicosapentaenoic acid (EPA)
and docosahexaenoic acid (DHA) in fish oil by kinetic resolution. Transesterification of various fish oil triglycerides with
a stoichiometric amount of ethanol by immobilized Rhizomucor miehei lipase under anhydrous solvent-free conditions resulted in a good separation. When free fatty acids from the various fish
oils were directly esterified with ethanol under similar conditions, greatly improved results were obtained. By this modification,
complications related to regioselectivity of the lipase and nonhomogeneous distribution of EPA and DHA into the various positions
of the triglycerides were avoided. As an example, when tuna oil comprising 6% EPA and 23% DHA was transesterified with ethanol,
65% conversion into ethyl esters was obtained after 24 h. The residual glyceride mixture contained 49% DHA and 6% EPA (8:1),
with 90% DHA recovery into the glyceride mixture and 60% EPA recovery into the ethyl ester product. When the corresponding
tuna oil free fatty acids were directly esterified with ethanol, 68% conversion was obtained after only 8h. The residual free
fatty acids comprised 74% DHA and only 3% EPA (25:1). The recovery of both DHA into the residual free fatty acid fraction
and EPA into the ethyl ester product remained very high, 83 and 87%, respectively. 相似文献
17.
Preparation of highly purified concentrates of eicosapentaenoic acid and docosahexaenoic acid 总被引:1,自引:9,他引:1
Harald Breivik Gudmundur G. Haraldsson Björn Kristinsson 《Journal of the American Oil Chemists' Society》1997,74(11):1425-1429
Because of the complexity of marine lipids, polyunsaturated fatty acid (PUFA) derivatives in highly purified form are not
easily prepared by any single fractionation technique. The products are usually prepared as the ethyl esters by esterification
of the body oil of fat fish species and subsequent physicochemical purification processes, including short-path distillation,
urea fractionation, and preparative chromatography. Lipase-catalyzed transesterification has been shown to be an excellent
alternative to traditional esterification and short-path distillation for concentrating the combined PUFA-content in fish
oils. At room temperature in the presence of Pseudomonas sp. lipase and a stoichiometric amount of ethanol without any solvent, efficient transesterification of fish oil was obtained.
At 52% conversion, a concentrate of 46% eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) was obtained in excellent
recovery as a mixture of mono-, di-, and triacylglycerols. The latter can be easily separated from the saturated and monounsaturated
ethyl esters and converted into ethyl esters either by conventional chemical means or enzymatically by immobilized Candida antarctica lipase. Urea-fractionation of such an intermediary product can give an EPA+DHA content of approximately 85%. 相似文献
18.
Yoshitsugu Kosugi Tsutomu Kunieda Naoki Azuma 《Journal of the American Oil Chemists' Society》1994,71(4):445-448
Rice bran oil containing 30–50% free fatty acid was continually converted to an oil containing more than 75% of triacylglycerol
(TG) by means of immobilized lipase. The reaction was carried out at 60°C for 24 h with dehydration and reactant mixing by
dry nitrogen flow under a positive nitrogen atmosphere. Enzymatic TG synthesis with evaporation by heating was not suitable
because of the increasing peroxide value of the oil.
Part of this article was presented at the annual meeting of the Japan Oil Chemists' Society at Sendai, Japan, October, 16,
1990. 相似文献
19.
Scientific investigation of lipids in Elasmobranchs has been conducted mainly on shark species. Because rays seem to be neglected,
this study was performed to examine the complete fatty acid (FA) composition with a particular interest for long-chain polyunsaturated
FA (PUFA) content in different tissues of three ray species including parts usually discarded. The total FA and PUFA profiles
of total lipids were determined in muscle, liver, and gonad of Rhinobatos cemiculus, Rhinoptera marginata, and Dasyatis marmorata, the most often caught ray species from the East Tropical Atlantic Ocean. Fifty FA were characterized as methyl esters and
N-acyl pyrrolidides by gas chromatography/mass spectrometry, showing significant levels of 20:5n-3 (EPA) (up to 5.3%) and 22:5n-3
(DPA) (up to 7.3%), high levels of 20:4n-6 arachidonic (ARA) (4.8–8.6% of total FA) and 22:6n-3 (DHA) (up to 20.0%). The results
show that muscle, liver and gonad of rays can provide high amounts of essential PUFA, specially DHA, for direct human nutrition
or the food processing industry. High proportions of DHA were particularly found in all samples of R. cemiculus (11.6–20.0%), and in muscle and liver of D. marmorata (11.1–16.1%). Regarding the high amounts of (n-3) PUFA, this study shows that these rays deserve a better up-grading, including
the normally discarded parts, and describes the occurrence of unusual NMID FA in all tissues studied. Five non-methylene-interrupted
dienoic fatty acids (NMID FA) (0–3.4%) were reported, including previously known isomers, namely 20:2 Δ7,13, 20:2 Δ7,15, 22:2
Δ7,13, 22:2 Δ7,15, and new 22:2 Δ6,14. These acids are quite unusual in fish and unprecedented in rays. The 22:2 Δ6,14 acid
occurred in gonads of male specimens of R. cemiculus at 2.9%. 相似文献
20.
Gudmundur G. Haraldsson Björn Kristinsson Ragnheidur Sigurdardottir Gudmundur G. Gudmundsson Harald Breivik 《Journal of the American Oil Chemists' Society》1997,74(11):1419-1424
The objective of this study was to investigate the use of lipases as catalysts for producing concentrates of eicosapentaenoic
acid (EPA) and docosahexaenoic acid (DHA) from fish oil as an alternative to conventional chemical procedures. Transesterification
of fish oil with ethanol was conducted under anhydrous solvent-free conditions with a stoichiometric amount of ethanol. Among
the 17 lipases tested, the results showed that Pseudomonas lipases had the highest activity toward the saturated and monounsaturated fatty acids in the fish oil, much lower activity
toward EPA and DHA and, at the same time, good tolerance toward the anhydrous alcoholic conditions. With 10 wt% of lipase,
based on weight of the fish oil triacylglycerol substrate (15% EPA and 9% DHA initial content), a 50% conversion into ethyl
esters was obtained in 24 h at 20°C, in which time the bulk of the saturated and monounsaturated fatty acids reacted, leaving
the long-chain n-3 polyunsaturated fatty acids unreacted in the residual mixture as mono-, di-, and triacylglycerols. This
mixture comprised approximately 50% EPA+DHA. Total recovery of DHA and EPA was high, over 80% for DHA and more than 90% for
EPA. The observed fatty acid selectivity, favoring DHA as a substrate, was most unusual because most lipases favor EPA. 相似文献