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1.
Arunthathi Sivasothy Peter J. Reilly 《Journal of the American Oil Chemists' Society》1996,73(10):1305-1309
Soapstock from alkaline refining of coconut oil was acidified, and the resulting acid water after neutralization was subjected
to gas chromatography, electron-ionization and chemical-ionization mass spectroscopy, and high-performance liquid chromatography.
The chief low-molecular weight organic components were C4−C18 fatty acids, hydroxylated acids, and sugar alcohols. The prevalence of acids and total absence of phosphate compounds make
coconut acid water different in composition from the acid waters from other soapstocks. 相似文献
2.
Simple alkyl FA esters have numerous uses, including serving as biodiesel, a fuel for compression ignition (diesel) engines.
The use of acid-catalyzed esterification for the synthesis of FAME from acid oil, a by-product of edible vegetable oil refining
that is produced from soapstock, was investigated. Soybean acid oil contained 59.3 wt% FFA, 28.0 wt% TAG, 4.4 wt% DAG, and
less than 1% MAG. Maximum esterification occurred at 65°C and 26 h reaction at a molar ratio of total FA/methanol/sulfuric
acid of 1∶15∶1.5. Residual unreacted species under these conditions, as a fraction of their content in unesterified acid oil,
were FFA, 6.6%; TAG, 5.8%; and DAG, 2.6%. This corresponds to estimated concentrations of FFA, 3.2%; TAG, 1.3%; and DAG, 0.2%,
on a mass basis, in the ester product. In an alternative approach, the acylglycerol species in soapstock were saponified prior
to acidulation. High-acid (HA) acid oil made from this saponified soapstock had an FFA content of 96.2 wt% and no detectable
TAG, DAG, or MAG. Optimal esterification conditions for HA acid oil at 65°C were a mole ratio of FFA/methanol/acid of 1∶1.8∶0.17,
and 14 h incubation. FAME recovery under these conditions was 89% of theoretical, and the residual unesterified FFA content
was approximately 20 mg/g. This was reduced to 3.5 mg/g, below the maximum FFA level allowed for biodiesel, by washing with
NaCl, NaHCO3, and Ca(OH)2 solutions. Alternatively, by subjecting the unwashed ester layer to a second esterification, the FFA level was reduced to
less than 2 mg/g. The acid value of this material exceeded the maximum allowed for biodiesel, but was reduced to an acceptable
value by a brief wash with 0.5 N NaOH. 相似文献
3.
F. Jahaniaval Y. Kakuda M. F. Marcone 《Journal of the American Oil Chemists' Society》2000,77(8):847-852
This paper reports the fatty acid and triacylglycerol (TAG) compositions of five Amaranthus accessions (RRC1011, R149, A.K343, A.K432, and A. K433) representing two species and a cross between one of these and a third species. Seed oils of these were analyzed by
gas chromatography and reversed-phase high-performance liquid chromatography, and their compositional properties compared
with buck-wheat (Fagopyrum esculentum), corn (Zea mays), rice bran (Oryza sativa), soybean (Glycine max L. Merr.), sesame (Sesamum indicum), quinoa (Chenopodium quinoa), and cottonseed (Gossypium hirsutum) oils. All Amaranthus accessions were relatively high in palmitic (21.4–23.8%) and low in oleic (22.8–31.5%) and linolenic (0.65–0.93%) acids when
compared to most of the grain and seed oils. The fatty acid composition of Amaranthus accessions K343, K433, and K432 (group I) were different from R149 and RRC1011 (group II) in mono and polyunsaturated fatty
acids, but the saturate/unsaturate (S/U) ratios were very similar. All Amaranthus accessions were similar in TAG type, but showed slight differences in percentage. High similarities in UUU, UUS, and USS
composition were observed among Amaranthus K343, K433 and K432, and between R149 and RRC1011. The fatty acid compositions of Amaranthus oil (group I) and cottonseed oil were similar, but their TAG compositions were different. The grain and oilseed oils were
different from each other and from the Amaranthus accessions oils in terms of fatty acid composition, S/U, and TAG ratios. The UUU, UUS, and USS percentages were very diverse
in grain and seed oils. The percentages of squalene in the TAG sample from the Amaranthus accessions were 8.05% in K343, 11.10% in K433, 11.19% in K432, 9.96% in R149, and 9.16% in RRC1011. Squalene was also tentatively
identified in quinoa and ricebran oils at levels of 3.39 and 3.10%, respectively. 相似文献
4.
Rheology of vegetable oil analogs and triglycerides 总被引:10,自引:6,他引:4
The rheological properties of two complex mixtures of short-chain triglycerides were experimentally determined. Dynamic or
absolute viscosities of the mixtures were measured for shear rates of 0.32 to 64.69 s−1 at temperatures between 25 and 80°C. The compositions of the mixtures were based on the oil of the plant species Cuphea viscosissima VS-320, a natural source of short-chain triglycerides. The dynamic viscosities of these mixtures were compared to those of
a traditional vegetable oil (peanut oil) and diesel fuel. The results of this comparison were used to make estimates of the
performance of such triglyceride mixtures as diesel fuel substitutes, since viscosity can be a key indicator of fuel performance
for possible substitute diesel fuels. The crystallization temperatures of these two mixtures were also determined experimentally,
and the effects of crystallization on fuel performance were projected. Additionally, the dynamic viscosities of pure triglycerides
from C6∶0 to C18∶0 at 75°C were plotted vs. chain length. These viscosities were measured at high shear rates (>6 s−1) where dynamic viscosity is shear-independent. An obvious trend in the relationship between triglyceride chain length and
viscosity was observed. A second-order regression was used to obtain an equation for this relationship. This equation was
used as a model for composition dependence of viscosity. This model was applied to the viscosities of the triglyceride mixtures
examined here. There was good agreement between the model and the actual, measured viscosity values determined in this study. 相似文献
5.
Conversion of vegetable oil to biodiesel using immobilized Candida antarctica lipase 总被引:11,自引:8,他引:3
Yuji Shimada Yomi Watanabe Taichi Samukawa Akio Sugihara Hideo Noda Hideki Fukuda Yoshio Tominaga 《Journal of the American Oil Chemists' Society》1999,76(7):789-793
Biodiesel derived from vegetable oils has drawn considerable attention with increasing environmental consciousness. We attempted
continuous methanolysis of vegetable oil by an enzymatic process. Immobilized Candida antarctica lipase was found to be the most effective for the methanolysis among lipases tested. The enzyme was inactivated by shaking
in a mixture containing more than 1.5 molar equivalents of methanol against the oil. To fully convert the oil to its corresponding
methyl esters, at least 3 molar equivalents of methanol are needed. Thus, the reaction was conducted by adding methanol stepwise
to avoid lipase inactivation. The first step of the reaction was conducted at 30°C for 10 h in a mixture of oil/methanol (1:1,
mol/mol) and 4% immobilized lipase with shaking at 130 oscillations/min. After more than 95% methanol was consumed in ester
formation, a second molar equivalent of methanol was added and the reaction continued for 14 h. The third molar equivalent
of methanol was finally added and the reaction continued for 24 h (total reaction time, 48 h). This three-step process converted
98.4% of the oil to its corresponding methyl esters. To investigate the stability of the lipase, the three-step methanolysis
process was repeated by transferring the immobilized lipase to a fresh substrate mixture. As a result, more than 95% of the
ester conversion was maintained even after 50 cycles of the reaction (100 d). 相似文献
6.
Fast formation of high-purity methyl esters from vegetable oils 总被引:4,自引:0,他引:4
David G. B. Boocock Samir K. Konar V. Mao C. Lee Sonia Buligan 《Journal of the American Oil Chemists' Society》1998,75(9):1167-1172
Experiments have confirmed that the base-catalyzed methanolysis of vegetable oils occurs much slower than butanolysis because
of the two liquid phases initially present in the former reaction. For the same reason, second-order kinetics are not followed.
The use of a cosolvent such as tetrahydrofuran or methyl tertiary butyl ether speeds up methanolysis considerably. However,
like one-phase butanolysis, one-phase methanolysis initially exhibits a rapid formation of ester, but then slows drastically.
Experiments show that the half-life of the hydroxide catalyst is too long to explain the sudden slowing of the reaction. Similarly,
lower rate constants for the methylation of the mono- and diglycerides are not a reasonable explanation. Instead the cause
has been identified as the fall in polarity which results from the mixing of the nonpolar oil with the methanol. This lowers
the effectiveness of both hydroxide and alkoxide catalysts. Increasing the methanol/oil molar ratio to 27 in the one-phase
system raises the polarity such that the methyl ester content of the ester product exceeds 99.4 wt% in 7 min. This has obvious
implications for the size of new methyl ester plants as well as the capacity of existing facilities. 相似文献
7.
Fast formation of high-purity methyl esters from vegetable oils 总被引:16,自引:12,他引:4
David G. B. Boocock Samir K. Konar V. Mao C. Lee Sonia Buligan 《Journal of the American Oil Chemists' Society》1998,75(12):1167-1172
Experiments have confirmed that the base-catalyzed methanolysis of vegetable oils occurs much slower than butanolysis because
of the two liquid phases initially present in the former reaction. For the same reason, second-order kinetics are not followed.
The use of a cosolvent such as tetrahydrofuran or methyl tertiary butyl ether speeds up methanolysis considerably. However,
like one-phase butanolysis, one-phase methanolysis initially exhibits a rapid formation of ester, but then slows drastically.
Experiments show that the half-life of the hydroxide catalyst is too long to explain the sudden slowing of the reaction. Similarly,
lower rate constants for the methylation of the mono- and diglycerides are not a reasonable explanation. Instead the cause
has been identified as the fall in polarity which results from the mixing of the nonpolar oil with the methanol. This lowers
the effectiveness of both hydroxide and alkoxide catalysts. Increasing the methanol/oil molar ratio to 27 in the one-phase
system raises the polarity such that the methyl ester content of the ester product exceeds 99.4 wt% in 7 min. This has obvious
implications for the size of new methyl ester plants as well as the capacity of existing facilities. 相似文献
8.
Yomi Watanabe Yuji Shimada Akio Sugihara Hideo Noda Hideki Fukuda Yoshio Tominaga 《Journal of the American Oil Chemists' Society》2000,77(4):355-360
Candida antarctica lipase is inactivated in a mixture of vegetable oil and more than 1∶2 molar equivalent of methanol against the total fatty
acids. We have revealed that the inactivation was eliminated by three successive additions of 1∶3 molar equivalent of methanol
and have developed a three-step methanolysis by which over 95% of the oil triacylglycerols (TAG) were converted to their corresponding
methyl esters (ME). In this study, the lipase was not inactivated even though 2∶3 molar equivalent of methanol was present
in a mixture of acylglycerols (AG) and 33% ME (AG/ME33). This finding led to a two-step methanolysis of the oil TAG: The first-step
was conducted at 30°C for 12 h with shaking in a mixture of the oil, 1∶3 molar equivalent of methanol, and 4% immobilized
lipase; the second-step reaction was done for 24 h after adding 2∶3 molar equivalent of methanol (36 h in total). The two-step
methanolysis achieved more than 95% of conversion. When two-step reaction was repeated by transferring the immobilized lipase
to a fresh substrate mixture, the enzyme could be used 70 cycles (105 d) without any decrease in the conversion. From the
viewpoint of the industrial production of biodiesel fuel production, the two-step reaction was conducted using a reactor with
impeller. However, the enzyme carrier was easily destroyed, and the lipase could be used only several times. Thus, we attempted
flow reaction using a column packed with immobilized Candida lipase. Because the lipase packed in the column was drastically inactivated by feeding a mixture of AG/ME33 and 2∶3 molar
equivalent of methanol, three-step flow reaction was performed using three columns packed with 3.0 g immobilized lipase. A
mixture of vegetable oil and 1∶3 molar equivalent of methanol was fed into the first column at a constant flow rate of 6.0
mL/h. The eluate and 1∶3 molar equivalent of methanol were mixed and then fed into the second column at the same flow rate.
The final step reaction was done by feeding a mixture of eluate from the second column and 1∶3 molar equivalent of methanol
at the same flow rate. The ME content in the final-step eluate reached 93%, and the lipase could be used for 100 d without
any decrease in the conversion. 相似文献
9.
Physical and chemical properties of trans-free fats produced by chemical interesterification of vegetable oil blends 总被引:1,自引:0,他引:1
V. Petrauskaite W. De Greyt M. Kellens A. Huyghebaert 《Journal of the American Oil Chemists' Society》1998,75(4):489-493
Fat blends, formulated by mixing a highly saturated fat (palm stearin or fully hydrogenated soybean oil) with a native vegetable
oil (soybean oil) in different ratios from 10:90 to 75:25 (wt%), were subjected to chemical interesterification reactions
on laboratory scale (0.2% sodium methoxide catalyst, time=90 min, temperature=90°C). Starting and interesterified blends were
investigated for triglyceride composition, solid fat content, free fatty acid content, and trans fatty acid (TFA) levels. Obtained values were compared to those of low- and high-trans commercial food fats. The interesterified blends with 30–50% of hard stock had plasticity curves in the range of commercial
shortenings and stick-type margarines, while interesterified blends with 20% hard stock were suitable for use in soft tubtype
margarines. Confectionery fat basestocks could be prepared from interesterified fat blends with 40% palm stearin or 25% fully
hydrogenated soybean oil. TFA levels of interesterified blends were low (0.1%) compared to 1.3–12.1% in commercial food fats.
Presented at the 88th AOCS Annual Meeting and Expo, May 11–14, 1997, Seattle, Washington. 相似文献
10.
Gerald P. McNeill Philip E. Sonnet 《Journal of the American Oil Chemists' Society》1995,72(2):213-218
Three lipases were compared for their ability to hydrolyze high erucic acid rapeseed oil, with the objective of concentrating
the erucic acid in a single glyceride fraction. Lipase fromPseudomonas cepacia released all fatty acids rapidly and did not result in selective distribution of erucic acid.Geotrichum candidum lipase released C20 and C22 fatty acids extremely slowly, resulting in their accumulation in the di- and triglyceride fractions.
Less than 2% of the total erucic acid was found in the free fatty acid (FFA) fraction. Lipase fromCandida rugosa released erucic acid more slowly than C20 and C18 fatty acids at 35°C but only resulted in a limited accumulation of the
erucic acid in the di- and triglyceride fractions. However, when hydrolysis catalyzed byC. rugosa lipase was carried out below 20°C, the reaction mixture solidified and was composed solely of FFAs and diglycerides. The
diglyceride fraction contained approximately 95% erucic acid while about 20% of the total erucic acid was found in the FFA
fraction. It is concluded that hydrolysis at low temperature withC. rugosa lipase results in a higher purity of erucic acid in the glyceride fraction than can be obtained withG. candidum lipase, but with considerable loss of erucic acid to the FFA fraction. 相似文献
11.
Michael Trani Robert Lortie Françoise Ergan 《Journal of the American Oil Chemists' Society》1993,70(10):961-964
The lipase fromCandida rugosa has been shown to discriminate against erucic acid. Advantage of this property has been taken to produce trierucin from high-erucic
acid rapeseed (HEAR) oil. A method has been developed for extracting erucic acid from the oil as dierucin and subsequently
enzymatically converting it to trierucin. Unrefined HEAR oil was hydrolyzed with lipase fromC. rugosa to produce a mixture of free fatty acids and dierucin. Precipitation and filtration from cold ethanol gave 73% pure dierucin,
free of fatty acids. This dierucin was treated in two ways to produce trierucin. First, in the presence of an immobilized
lipase and a known amount of water, some trierucin is produced by interesterification. Second, a more efficient route to trierucin
utilizedRhizopus arrhizus lipase to completely hydrolyze dierucin to erucic acid, which was then combined with an appropriate amount of dierucin in
the presence of an immobilized lipase to produce trierucin in a quantitative yield.
Partly presented at the AOCS Annual Meeting held in Toronto, May 10–14, 1992. 相似文献
12.
B. Pérez-Vich L. Velasco J. M. Fernández-Martínez 《Journal of the American Oil Chemists' Society》1998,75(5):547-555
A methodological study was conducted to test the potential of near-infrared reflectance spectroscopy (NIRS) to estimate the
oil content and fatty acid composition of sunflower seeds. A set of 387 intact-seed samples, each from a single plant, were
scanned by NIRS, and 120 of them were selected and further scanned as husked seed, meal, and oil. All samples were analyzed
for oil content (nuclear magnetic resonance) and fatty acid composition (gas chromatography), and calibration equations for
oil content and individual fatty acids (C16:0, C16:1, C18:0, C18:1, and C18:2) were developed for intact seed, husked seed, meal, and oil. For intact seed, the performance of the calibration equations
was evaluated through both cross- and external validation, while cross-validation was used in the rest. The results showed
that NIRS is a reliable and accurate technique to estimate these traits in sunflower oil (validation r
2 ranged from 0.97 to 0.99), meal (r
2 from 0.92 to 0.98), and husked seeds (r
2 from 0.90 to 0.97). According to these results, there is no need to grind the seeds to scan the meal; similarly accurate
results are obtained by analyzing husked seeds. The analysis of intact seeds was less accurate (r
2 from 0.76 to 0.85), although it is reliable enough to use for pre-screening purposes to identify variants with significantly
different fatty acid compositions from standard phenotypes. Screening of intact sunflower seeds by NIRS represents a rapid,
simple, and cost-effective alternative that may be of great utility for users who need to analyze a large number of samples. 相似文献
13.
P. Damianl F. Santinelli M. S. Simonetti M. Castellini M. Rosi 《Journal of the American Oil Chemists' Society》1994,71(10):1157-1162
Two methods for stereospecific analysis of triacylglycerols are compared. Procedure A, based on stereospecific phosphorylation
ofsn-1,2-diacylglycerols to phosphatidic acids, and procedure B, based on separation of the diastereomeric 1,2(2,3)-diacylglycerol
urethane derivatives by high-performance liquid chromatography on silica, were applied to olive oil triacyl-sn-glycerols. Statistical evaluation of the results showed good reproducibility, and Student'st-test indicates no statistical differences between the two considered procedures, although some small differences were observed
and discussed. Fifteen samples of extra-virgin olive oil, produced in the same region (Umbria, Italy), were analyzed with
the two considered procedures. 相似文献
14.
The γ-linolenic acid (Z,Z,Z-6,9,12-octadecatrienoic acid, GLA) present in borage oil free fatty acids was concentrated in esterification reactions that
were catalyzed by several preparations of the acyl-specific lipase ofGeotrichum candidum. In this manner, a 95% recovery of the GLA originally present in borage oil (25% GLA) was obtained as a highly enriched fatty
acid fraction with a GLA content of >70%. Other fatty acids concentrated in this fraction were the monounsaturated fatty acids
with chainlengths of C-20 and longer that were present in the oil. An immobilized preparation ofG. candidum on silica gel also was used for the enrichment of GLA in borage oil. In this instance, a 75% recovery of GLA was obtained,
and the supported lipase was reusable (three cycles) with minimal loss in activity.
Presented in part at the 84th Annual Meeting of the American Oil Chemists’ Society, Anaheim, California, May 1993. 相似文献
15.
A. Estilai 《Journal of the American Oil Chemists' Society》1993,70(5):547-549
Guayule, a perennial desert plant, is being developed for domestic production of natural rubber, a strategic commodity for
which the United States presently depends totally on foreign sources. At present, rubber alone is not sufficient to make guayule
a commercial crop, and additional revenues are being sought from by-products. Because guayule flowers profusely during several
years of growth before it is harvested for rubber, seed may also contribute to the economics of guayule production. Seed from
120 plants, including 20 genotypes with 36, 37, 54 and 72 chromosomes, were analyzed for oil content and fatty acid composition.
Oil content ranged from 17.1 to 30.5%. On average, seed from diploid and aneuploid plants (with 36 and 37 chromosomes) contained
40.4% more oil than the seed from polyploid plants. The oil consisted of four fatty acids—palmitic (8.7–11.5%), stearic (3.7–6.2%),
oleic (6.5–13.9%) and linoleic (69.1–80.2%)—at all ploidy levels. Guayule seed oil was similar to the seed oil from high-linoleic
safflower varieties. The use of genetic variation to increase seed yield and seed oil will depend on the absence of negative
correlation between oil and rubber production. 相似文献
16.
Yoshinori?Hirota Toshihiro?Nagao Yomi?Watanabe Masaharu?Suenaga Seiichi?Nakai Aktohiro?Kitano Akio?Sugihara Yuji?Shimada
Soybean oil deodorizer distillate (SODD) contains steryl esters in addition to tocopherols and sterols. Tocopherols and sterols
have been industrially purified from SODD but no purification process for steryl esters has been developed. SODD was efficiently
separated to low b.p. substances (including tocopherols and sterols) and high b.p. substances (including 11.2 wt% DAG, 32.1
wt% TAG, and 45.4 wt% steryl esters) by molecular distillation. The high b.p. fraction is referred to as soybean oil deodorizer
distillate steryl ester concentrate (SODDSEC). We attempted to purify steryl esters after a lipase-catalyzed hydrolysis of
acylglycerols in SODDSEC. Screening of industrially available lipases indicated that Candida rugosa lipase was most effective. Based on the study of several factors affecting hydrolysis, the reaction conditions were determined
as follows: ratio of SODDSEC/water, 1∶1 (w/w); lipase amount, 15 U/g reaction mixture; temperature, 30°C. When SODDSEC was
agitated for 24 h under these conditions, acylglycerols were almost completely hydrolyzed and the content of steryl esters
did not change. However, study with a mixture of steryl oleate/trilinolein (1∶1, w/w) indicated that about 20% of constituent
FA in steryl esters were exchanged with constituent FA in acylglycerols. Steryl esters in the oil layer obtained by the SODDSEC
treatment with lipase were successfully purified by molecular distillation (purity, 97.3%; recovery, 87.7%). 相似文献
17.
Acid oil is a by-product in the neutralization step of vegetable oil refining and is an alternative source of biodiesel fuel.
A model substrate of acid oil, which is composed of TAG and FFA, was used in experiments on the conversion to FAME by immobilized
Candida antarctica lipase. FFA in the mixture of TAG/FFA were efficiently esterified with methanol (MeOH), but the water generated by the esterification
significantly inhibited methanolysis of TAG. We thus attempted to convert a mixture of TAG/FFA to FAME by a two-step process
comprising methyl esterification of FFA and methanolysis of TAG by immobilized C. antarctica lipase. The first reaction was conducted at 30°C in a mixture of TAG/FFA (1∶1, wt/wt) and 10 wt% MeOH using 0.5 wt% immobilized
lipase, resulting in efficient esterification of FFA. The reaction mixture after 24 h was composed of 49.1 wt% TAG, 1.3 wt%
FFA, 49.1 wt% FAME, and negligible amounts of DAG and MAG (<0.5 wt%). The reaction mixture was then dehydrated and used as
a substrate for the second reaction, which was conducted at 30°C in a solution of the dehydrated mixture and 5.5 wt% MeOH
using 6 wt% immobilized lipase. The activity of the lipase increased gradually when the reaction was repeated by transferring
the enzyme to a fresh substrate mixture. The activity reached a maximum after 6 cycles, and the content of FAME achieved was
>98.5 wt% after a 24-h reaction. The immobilized lipase was very stable in the first-and second-step reactions and could be
used for >100 d without significant loss of activity. 相似文献
18.
Purification of docosahexaenoic acid from tuna oil by a two-step enzymatic method: Hydrolysis and selective esterification 总被引:3,自引:0,他引:3
Yuji Shimada Kazuaki Maruyama Akio Sugihara Shigeru Moriyama Yoshio Tominaga 《Journal of the American Oil Chemists' Society》1997,74(11):1441-1446
Purification of docosahexaenoic acid (DHA) was attempted by a two-step enzymatic method that consisted of hydrolysis of tuna
oil and selective esterification of the resulting free fatty acids (FFA). When more than 60% of tuna oil was hydrolyzed with
Pseudomonas sp. lipase (Lipase-AK), the DHA content in the FFA fraction coincided with its content in the original tuna oil. This lipase
showed stronger activity on the DHA ester than on the eicosapentaenoic acid ester and was suitable for preparation of FFA
rich in DHA. When a mixture of 2.5 g tuna oil, 2.5 g water, and 500 units (U) of Lipase-AK per 1 g of the reaction mixture
was stirred at 40°C for 48 h, 83% of DHA in tuna oil was recovered in the FFA fraction at 79% hydrolysis. These fatty acids
were named tuna-FFA-Ps. Selective esterification was then conducted at 30°C for 20 h by stirring a mixture of 4.0 g of tuna-FFA-Ps/lauryl alcohol (1:2, mol/mol), 1.0 g water, and 1,000 U of Rhizopus delemar lipase. As a result, the DHA content in the unesterified FFA fraction could be raised from 24 to 72 wt% in an 83% yield.
To elevate the DHA content further, the FFA were extracted from the reaction mixture with n-hexane and esterified again under the same conditions. The DHA content was raised to 91 wt% in 88% yield by the repeated
esterification. Because selective esterification of fatty acids with lauryl alcohol proceeded most efficiently in a mixture
that contained 20% water, simultaneous reactions during the esterification were analyzed qualitatively. The fatty acid lauryl
esters (L-FA) generated by the esterification were not hydrolyzed. In addition, L-FA were acidolyzed with linoleic acid, but
not with DHA. These results suggest that lauryl DHA was generated only by esterification. 相似文献
19.
An infrared spectrophotometric procedure, based on the fatty acid methyl ester mixture derived from a partially hydrogenated
vegetable oil as the calibration standard, has been developed for accurate analysis of the totaltrans content of hydrogenated fats. This procedure produces more accurate results than the current official methods of Association
of Official Analytical Chemists and American Oil Chemists’ Society, both of which use methyl elaidate as the external standard.
The results obtained with this procedure were in close agreement to those determined by the combined procedure of silver-nitrate
thin-layer chromatography and capillary gas-liquid chromatography. The improved results, obtained with the partially hydrogenated
vegetable oil methyl esters as the calibration standard, may be attributable to its assortment oftrans isomers, which may have different absorptivities relative to methyl elaidate. 相似文献
20.
T. Yokochi M. T. Usita Y. Kamisaka T. Nakahara O. Suzuki 《Journal of the American Oil Chemists' Society》1990,67(11):846-851
The fungal oil extracted fromMortierella ramanniana var.angulispora (IFO 8187) was solvent winterized in order to raise the content of γ-linolenic acid (GLA). Effects of winterization conditions
(solvent, oil concentration in the solvent and temperature) and changes of glyceride compositions were discussed. The fungal
oil was separated into four diglycerides and 17 triglycerides (TG) with high performance liquid chromatography. The predominant
species were POO, POP and LOP, whose contents were 24.4, 22.9 and 9.4% of the total TG, respectively. Ethanol at 4°C gave
the highest GLA content of 10.5% in spite of lower yield than with acetone at −20°C. The highest separation efficiency for
GLA (ηGLA) was 0.27 with acetone at −20°C and 10% oil concentration, resulting in 8.3% of GLA from the fungal oil at 5.7% LGA. In case
of lower oil concentration at 5–20%, ηGLA showed higher in the following order: acetone (−20°C)>n-hexane (−20°C)>acetone (4°C)>petroleum ether (−20°C). The winterization process also proved to be effective for the separation
of TG type, Sa2U (Sa; saturated fatty acid; U, unsaturated fatty acid) into the crystallized fraction and SaU2 into the liquid fraction. Acetone at −20°C showed higher separation efficiency for triunsaturated TG than the other solvents. 相似文献