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1.
Production of specific-structured lipids by enzymatic interesterification: Elucidation of acyl migration by response surface design 总被引:3,自引:0,他引:3
X. Xu A. R. H. Skands C. -E. Høy H. Mu S. Balchen J. Adler-Nissen 《Journal of the American Oil Chemists' Society》1998,75(9):1179-1186
Production of specific-structured lipids (SSL) by lipase-catalyzed interesterification has been attracting more and more attention
recently. However, it was found that acyl migration occurs during the reaction and causes the production of byproducts. In
this paper, the elucidation of acyl migration by response surface design was carried out in the Lipozyme IM (Rhizomucor miehei)-catalyzed interesterification between rapeseed oil and capric acid in solvent-free media. A five-factor response surface
design was used to evaluate the influence of five major factors and their relationships. The five factors, water content,
reaction temperature, enzyme load, reaction time and substrate ratio, were varied at three levels together with two star points.
All parameters besides substrate ratio had strong positive influences on acyl migration, and reaction temperature was most
significant. The contour plots clearly show the interactions between the parameters. The migration rates of different fatty
acids were also compared from three different sets of experiments during the lipase-catalyzed reaction. The best-fitting quadratic
response surface model was determined by regression and backward elimination. The coefficients of determination (R
2) of the model were 0.996 and 0.981 for Q
2 value. The results show that the fitted quadratic model satisfactorily expresses acyl migration for the enzymatic interesterification
in the batch reactor used. 相似文献
2.
Parameters affecting diacylglycerol formation during the production of specific-structured lipids by lipase-catalyzed interesterification 总被引:2,自引:0,他引:2
X. Xu H. Mu A. R. H. Skands C. E. Høy J. Adler-Nissen 《Journal of the American Oil Chemists' Society》1999,76(2):175-181
Diacylglycerols (DAG) are important intermediates in lipase-catalyzed interesterification, but a high DAG concentration in
the reaction mixture results in a high DAG content in the final product. We have previously shown that a high DAG concentration
in the reaction mixture increases the degree of acyl migration, thus adding to the formation of by-products. In the present
study we examined the influence of water content, reaction temperature, enzyme load, substrate molar ratio (oil/capric acid),
and reaction time on the formation of DAG in batch reactors. We used response surface methodology (RSM) to minimize the numbers
of experiments. The DAG content of the product was dependent on all parameters examined except reaction time. DAG formation
increased with increasing water content, enzyme load, reaction temperature, and substrate ratio. The content of sn-1,3-DAG was higher than that of sn-1,2-DAG under all conditions tested, and the ratio between the contents of the former compounds and the latter increased
with increasing temperature and reaction time. The water content, enzyme load, and substrate ratio had no significant effect
on this ratio. The DAG content was positively correlated with both the incorporation of acyl donors and the degree of acyl
migration. 相似文献
3.
Production of specific-structured lipids by enzymatic interesterification in a pilot continuous enzyme bed reactor 总被引:8,自引:8,他引:0
X. Xu S. Balchen C. E. Høy J. Adler-Nissen 《Journal of the American Oil Chemists' Society》1998,75(11):1573-1579
Production of specific-structured lipids (interesterified lipids with a specific structure) by enzymatic interesterification
was carried out in a continuous enzyme bed pilot scale reactor. Commercial immobilized lipase (Lipozyme IM) was used and investigations
of acyl migration, pressure drop, water dependence, production efficiency, and other basic features of the process were performed.
The extent of acyl migration (defined as a side reaction) occurring in the present enzyme bed reactor was compared to that
in a pilot batch reactor. The continuous enzyme bed reactor was better than the batch reactor in minimizing acyl migration.
Generally the former produced about one-fourth the acyl migration produced by the latter at a similar extent of incorporation.
Pressure drop and production efficiency were evaluated in order to obtain a suitable yield in one reaction step. High incorporation
was favored by high substrate ratios between acyl donors and oils, requiring long reaction times on the enzyme bed. Under
these conditions, the pressure drop of the reactor was modeled statistically and theoretically. Residence time, water content,
and effects of mass transfers were also investigated. Incorporation of medium-chain fatty acids increased with increased residence
time. Approximately 40% of lipase activity was lost after a 4-wk run. External mass transfer was not a major problem in the
linear flow range, but internal mass transfer did impose some transfer limitations. 相似文献
4.
X. Xu S. Balchen C. -E. Høy J. Adler-Nissen 《Journal of the American Oil Chemists' Society》1998,75(2):301-308
Effects of water content, reaction time, and their relationships in the production of two types of specific-structured lipids (sn-MLM- and sn-LML-types: L-long chain fatty acids; M-medium chain fatty acids) by lipase-catalyzed interesterification in a solvent-free system were studied. The biocatalyst used was Lipozyme IM (commercial immobilized lipase). The substrates used for sn-MLM-type were fish oil and capric acid, and medium chain triacylglycerols and sunflower free fatty acids for sn-LML-type. The observed incorporation with the time course agrees well with the Michaelis-Menten equation, while the acyl migration is proportional to time within the range of 20 mol% acyl migration (MLM-type: M f =0.2225 T, R2=0.98; LML-type: M f =0.5618 T, R2=0.99). As water content (wt%, on the enzyme basis) increased from 3.0 to 11.6% for MLM-type and from 3.0 to 7.2% for LML-type in the solvent-free systems, the incorporation rates in the first 5 h increased from 3.34 to 10.30%/h, and from 7.29 to 11.12%/h, respectively. However, the acyl migration rates also increased from 0.22 to 1.12%/h and from 0.56 to 1.37%/h, respectively. Different effects in the production of two totally position-opposed lipids can be observed. Presumably these are caused by the different chain length of the fatty acids. The relationships between reaction time and water content are inverse and give a quantitative prediction of incorporation and acyl migration in selected reaction conditions and vice versa. The acyl migration can not be totally avoided in present systems, but can be reduced to a relatively low level. Acyl migration during the downstream processing has also been observed and other factors influencing the acyl migration are briefly discussed. 相似文献
5.
Xuebing Xu Lydia B. Fomuso Casimir C. Akoh 《Journal of the American Oil Chemists' Society》2000,77(2):171-176
Structured lipids from menhaden oil were produced by enzymatic acidolysis in a packed bed reactor. Response surface methodology
was applied to optimize the reaction. Lipozyme IM from Rhizomucor miehei lipase was the biocatalyst, and caprylic acid was the acyl donor. Parameters such as residence time, substrate molar ratio,
and reaction temperature were included for the optimization. High incorporation of acyl donor and retention of high levels
of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in the original menhaden oil were obtained. Good quadratic models
were obtained for the incorporation of caprylic acid and for the content of EPA plus DHA retained, by multiple regression
with backward elimination. The coefficients of determination (R
2) for the two models were 0.91 and 0.87, respectively. The regression probabilities (P) were below 0.003 for both models. Also, the predicted values from the two models had linear relationships with the observed
responses. All parameters studied had positive effects on the incorporation of caprylic acid, but only residence time and
substrate molar ratio had negative effects on the content of EPA plus DHA retained. The optimal conditions generated from
models were temperature =65°C, substrate molar ratio=4–5, and residence time=180–220 min. Incorporated caprylic acid did not
replace DHA, but the content of EPA decreased somewhat with an increase in caprylic acid incorporation. 相似文献
6.
Anders F. Vikbjerg Huiling Mu Xuebing Xu 《Journal of the American Oil Chemists' Society》2006,83(7):609-614
Elucidation of acyl migration was carried out in the Lipozyme RM IM (Rhizomucor miehei)-catalyzed transesterification between soybean phosphatidylcholine (PC) and caprylic acid in solvent-free media. A five-factor
response surface design was used to evaluate the influence of five major factors and their relationships. The five factors—enzyme
dosage, reaction temperature, water addition, reaction time, and substrate ratio—were varied on three levels together with
two star points. Enzyme dosage, reaction temperature, and reaction time showed increased effect on the acyl migration into
the sn-2 position of PC, whereas increased water addition and substrate ratio had no significant effect in the ranges tested. The
best-fitting quadratic response surface model was determined by regression and backward elimination. The coefficient of determination
(R
2) was 0.84, which indicates that the fitted quadratic model has acceptable qualities in expressing acyl migration for the
enzymatic transesterification. Correlation was observed between acyl donor in the sn-2 position of PC and incorporation of acyl donor into the intermediate lysophosphatidylcholine. Furthermore, acyl migration
into the sn-2 position of PC was confirmed by TLC-FID, as PC with caprylic acid was observed on both positions. Under certain conditions,
up to 18% incorporation could be observed in the sn-2 position during the lipase-catalyzed transesterification. 相似文献
7.
Seda Demirkol H. Ayse Aksoy Melek Tüter Guldem Ustun Dursun Ali Sasmaz 《Journal of the American Oil Chemists' Society》2006,83(11):929-932
Enzymatic methanolysis of refined soybean oil with methanol was investigated using Rhizomucor miehei lipase, Lipozyme RM IM, in n-hexane for reaction times of 30 min. Response surface methodology (RSM) based on three-level, three-factor (variable) face-centered
cube design was used for the optimization of methanolysis. The independent variables that affect the methanolysis reaction
conducted in n-hexane are temperature (°C), enzyme/oil weight ratio, and oil/methanol molar ratio. A good quadratic model was obtained for
the methyl ester production by multiple regression and backward elimination. A linear relationship was observed between the
observed and predicted values (R2−0.9635). The effects of temperature and enzyme amount, which affected methyl ester content of the product (response) positively,
were significant (P<0.01). The quadratic term of temperature and the interaction term of enzyme amount with temperature affected the response
negatively (P<0.01). The interaction term of enzyme amount with substrate mole ratio had a positive effect on the response (P<0.05). Critical conditions for the response at which methyl ester content of the product was 76.9% were determined to be
50°C, 2.37 methanol/oil mole ratio, and 0.09 enzyme/oil weight ratio. 相似文献
8.
Structured lipids were synthesized by the acidolysis of corn oil by caprylic acid in supercritical carbon dioxide (SCCO2) with Lipozyme RM IM from Rhizomucor miehei. The effects of pressure and temperature on the reaction were studied. To compare the degrees of acyl migration in the SCCO2 and solvent-free reaction systems, the effects of reaction time on the degree of acyl migration were also studied. The highest
mole percentage incorporation of caprylic acid (62.2 mol%) occurred at 24.13 MPa in SCCO2. The overall incorporation of caprylic acid in the SCCO2 system remained higher than that in the solvent-free system at every temperature tested. This trend was observed more clearly
at lower temperatures (35–55°C) than at higher temperatures (65–75°C). Acyl migration with both reaction systems was low,
with a negligible difference between them up to 12 h, after which the degree of acyl migration in the solvent-free system
increased rapidly with time up to 24 h compared with the SCCO2 system. 相似文献
9.
Structured lipids: Lipase-catalyzed interesterification of tricaproin and trilinolein 总被引:2,自引:0,他引:2
Structured lipids were synthesized by interesterification of trilinolein and tricaproin with sn-1,3-specific (IM 60) and nonspecific (SP 435) lipases. The interesterification reaction was performed by incubating a 1:2
mole ratio of trilinolein and tricaproin in 3 mL hexane at 45°C for the IM 60 lipase from Rhizomucor miehei, and at 55°C for the SP 435 lipase from Candida antarctica. Reaction products were analyzed by reverse-phase high-performance liquid chromatography with an evaporative light-scattering
detector. The fatty acids at the sn-2 position were identified after pancreatic lipase hydrolysis and analysis with a gas chromatograph. IM 60 lipase produced
53,5 mol% dicaproyllinolein (total carbon number = C33) and 22.2% monocaproyldilinolein (C45). SP 435 lipase produced 41%
C33 and 18% C45. When caproic acid was used in place of tricaproin as the acyl donor, the IM 60 lipase produced 62.9% C33.
The effects of variation in mole ratio, temperature, added water, solvent polarity, and time course on the interesterification
reaction were also investigated. In the absence of organic solvent, IM 60 lipase produced 52.3% C33. 相似文献
10.
Production of specific-structured triacylglycerols by lipase-catalyzed interesterification in a laboratory-scale continuous reactor 总被引:1,自引:0,他引:1
A laboratory-scale continuous reactor was constructed for production of specific structured triacylglycerols containing essential
fatty acids and medium-chain fatty acids (MCFA) in the sn-2 and sn-1,3 positions, respectively. Different parameters in the lipase-catalyzed interesterification were elucidated. The reaction
time was the most critical factor. Longer reaction time resulted in higher yield, but was accompanied by increased acyl migration.
The concentration of the desired triacylglycerol (TAG) in the interesterification product increased significantly with reaction
time, even though there was only a slight increase in the incorporation of MCFA. Increased reactor temperature and content
of MCFA in the initial reaction substrate improved the incorporation of MCFA and the yield of the desired TAG in the products.
Little increase of acyl migration was observed. Increasing the water content from 0.03 to 0.11% (w/w substrate) in the reaction
substrate had almost no effect on either the incorporation or the migration of MCFA, or on the resulting composition of TAG
products and their free fatty acid content. Therefore, we conclude that the water in the original reaction substrate is sufficient
to maintain the enzyme activity in this continuous reactor. Since the substrates were contacted with a large amount of lipase,
the reaction time was shorter compared with a batch reactor, resulting in reduced acyl migration. Consequently, the purity
of the specific structured TAG produced was improved. Interesterification of various vegetable oils and caprylic acid also
demonstrated that the incorporation was affected by the reaction media. Reaction conditions for lipase-catalyzed synthesis
of specific structured TAG should be optimized according to the oil in use.
Presented in part at Food Science Conference, Copenhagen, Denmark, January 30–31, 1997. 相似文献