U.S. patent application number 09/725571 was filed with the patent office on 2001-06-21 for preparation process of diglyceride.
Invention is credited to Sugiura, Masakatsu, Yamada, Naoto, Yamaguchi, Hiroaki.
Application Number | 20010004462 09/725571 |
Document ID | / |
Family ID | 18466331 |
Filed Date | 2001-06-21 |
United States Patent
Application |
20010004462 |
Kind Code |
A1 |
Sugiura, Masakatsu ; et
al. |
June 21, 2001 |
Preparation process of diglyceride
Abstract
The present invention provides a process for preparing a
diglyceride, which includes: in an enzyme-packed tower which
includes an immobilized lipase preparation, carrying out an
esterification reaction between: (1) an acyl group donor selected
from the group including a fatty acid, a lower alcohol ester
thereof, and a mixture thereof; and (2) an acyl group acceptor
selected from the group including glycerol, a monoglyceride, and a
mixture thereof; to obtain a reaction fluid from the enzyme-packed
tower; reducing a water content or a lower alcohol content in the
reaction fluid; and subsequent to the reducing, recirculating the
reaction fluid to the enzyme-packed tower, wherein a residence time
of the reaction fluid in the enzyme-packed tower is 120 seconds or
less; to obtain a diglyceride. According to the present invention,
a high-purity glyceride can be provided at a high yield in a short
period of time.
Inventors: |
Sugiura, Masakatsu;
(Kashima-gun, JP) ; Yamaguchi, Hiroaki;
(Kashima-gun, JP) ; Yamada, Naoto; (Kashima-gun,
JP) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Family ID: |
18466331 |
Appl. No.: |
09/725571 |
Filed: |
November 30, 2000 |
Current U.S.
Class: |
426/33 ; 426/417;
435/293.1; 435/303.2 |
Current CPC
Class: |
C12P 7/6454 20130101;
C12P 7/6472 20130101 |
Class at
Publication: |
426/33 ; 426/417;
435/303.2; 435/293.1 |
International
Class: |
C11C 001/04; C11C
003/02; C12M 001/40 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 1999 |
JP |
11-359794 |
Claims
1. A process for preparing a diglyceride, comprising: in an
enzyme-packed tower comprising an immobilized lipase preparation,
carrying out an esterification reaction between: (1) an acyl group
donor selected from the group consisting of a fatty acid, a lower
alcohol ester thereof, and a mixture thereof; and (2) an acyl group
acceptor selected from the group consisting of glycerol, a
monoglyceride, and a mixture thereof; to obtain a reaction fluid
from said enzyme-packed tower; reducing a water content or a lower
alcohol content in said reaction fluid; and subsequent to said
reducing, recirculating the reaction fluid to said enzyme-packed
tower, wherein a residence time of said reaction fluid in said
enzyme-packed tower is 120 seconds or less; to obtain a
diglyceride.
2. The process according to claim 1, wherein said reducing
comprises dehydrating or dealcoholizing said reaction fluid under
conditions that a volumetric mass transfer coefficient k.sub.La
(wherein k.sub.L is a mass transfer coefficient, and a is a
gas-liquid interfacial mass transfer area per unit volume) is at
least 0.0005 (s.sup.-1).
3. The process according to claim 1, wherein said reducing is
carried out in a dehydration tank.
4. The process according to claim 1, wherein said immobilized
lipase preparation comprises an immobilized, 1,3-position-selective
lipase having an esterification activity of at least 100
(unit/g-enzyme).
5. The process according to claim 1, wherein, in said
esterification reaction, the following condition is
satisfied:L/d.sup.2<25 wherein L is a packing thickness (m) in a
flowing direction in said enzyme-packed tower, and d is an average
particle diameter (mm) of said immobilized lipase preparation.
6. The process according to claim 5, wherein said average particle
diameter d is at least 0.1 mm.
7. The process according to claim 1, wherein a pressure loss of
said enzyme-packed tower is 20 kg/cm.sup.2 or smaller.
8. The process according to claim 1, wherein said fatty acid is an
saturated or unsaturated fatty acid having 2 to 24 carbon
atoms.
9. The process according to claim 1, wherein said fatty acid is
selected from the group consisting of saturated or unsaturated
fatty acids having 2 to 24 carbon atoms, butyric acid, valeric
acid, capronic acid, enanthic acid, caprylic acid, pelargonic acid,
capric acid, undecanoic acid, lauric acid, myristic acid, palmitic
acid, zoomaric acid, stearic acid, oleic acid, elaidic acid,
linoleic acid, arachidonic acid, gadoleic acid, arachic acid,
behenic acid, erucic acid, eicosapentaenoic acid, docosahexaenoic
acid, --linolenic acid; fatty acids derived from animal and
vegetable oils, rapseed oil, soybean oil, cotton-seed oil, olive
oil, corn oil, coconut oil, palm oil, perilla oil, linseed oil,
borage oil, beef tallow, lard and fish oil; fatty acids obtained by
processing fatty acids hardening, distillation or fractionation;
and mixtures thereof.
10. The process according to claim 1, wherein said lower alcohol
ester thereof is a lower alcohol ester of a fatty acid selected
from the group consisting of saturated or unsaturated fatty acids
having 2 to 24 carbon atoms, butyric acid, valeric acid, capronic
acid, enanthic acid, caprylic acid, pelargonic acid, capric acid,
undecanoic acid, lauric acid, myristic acid, palmitic acid,
zoomaric acid, stearic acid, oleic acid, elaidic acid, linoleic
acid, arachidonic acid, gadoleic acid, arachic acid, behenic acid,
erucic acid, eicosapentaenoic acid, docosahexaenoic acid,
--linolenic acid; fatty acids derived from animal and vegetable
oils, rapseed oil, soybean oil, cotton-seed oil, olive oil, corn
oil, coconut oil, palm oil, perilla oil, linseed oil, borage oil,
beef tallow, lard and fish oil; fatty acids obtained by processing
fatty acids hardening, distillation or fractionation; and mixtures
thereof.
11. The process according to claim 1, wherein said lower alcohol
ester thereof is selected from the group consisting of esters with
a lower alcohol having 1 to 3 carbon atoms, methanol, ethanol,
propanol, 2-propanol, and mixtures thereof.
12. The process according to claim 1, wherein said acyl group donor
is present in an amount ranging from at least 1 mol per mol of a
glyceryl group of said acyl group acceptor.
13. The process according to claim 1, wherein said esterification
reaction is carried out in the presence of a monoglyceride.
14. The process according to claim 1, wherein said immobilized
enzyme preparation comprises an immobilized, 1,3-position-selective
lipase is selected from the group consisting of lipases derived
from microorganisms of the genera Rhizopus, Aspergillus and Mucor,
splenic lipases, lipases derived from Rhizopus delemar, Rhizopus
japonicus, Rhizopus niveus, Aspergillus niger, Mucorjavanicus and
Mucor miehei.
15. The process according to claim 1, further comprising separating
from said diglyceride at least one selected from the group
consisting of unreacted glycerol, unreacted fatty acid, unreacted
said lower alcohol ester thereof, monoglyceride, and mixtures
thereof.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a process for preparing a
high-purity glyceride at a high yield in a short period of
time.
[0003] 2. Description of the Background Art
[0004] Glycerides are used as base materials in fields of
cosmetics, drugs, etc., and as additives for improving plasticity
of oils and fats and edible oils in a field of food. Such
glycerides are generally prepared by an esterification reaction of
glycerol with its corresponding fatty acid, an alcohol interchange
reaction of glycerol with oil or fat, or the like. These
preparation processes are roughly divided into chemical reaction
processes, which make use of an alkali catalyst or the like, and
biochemical reaction processes, which make use of a fat-hydrolyzing
enzyme such as a lipase, or the like. However, the biochemical
reaction processes are more generally used from the viewpoints of
the yield and purity of the glycerides synthesized and the energy
savings.
[0005] Conventional biochemical reaction processes include
processes in which a fatty acid or the like is reacted with
glycerol in the presence of a 1,3-position-selective lipase while
removing water formed by the reaction outside the system, thereby
obtaining a diglyceride at high yield and purity (Japanese Patent
Application Laid-Open No. 71495/1989); processes in which glycerol
is added in an equimolar amount or more to a fatty acid to react
them, the reaction is stopped when the concentration of a
diglyceride has been enhanced, insoluble glycerol is separated, and
the reaction is further conducted while dehydrating, thereby
synthesizing the diglyceride at a high esterification reaction rate
by improving dehydration efficiency (Japanese Patent Application
Laid-Open No. 330289/1992); and processes in which a mixture of a
fatty acid or the like and glycerol or the like is reacted in a
flow tube type reactor filled with a lipase while controlling the
superficial velocity of the mixture in the reactor to at least 0.05
cm/s (Japanese Patent Application Laid-Open No. 234391/1998),
etc.
[0006] Among the above-described processes, however, the technique
described in Japanese Patent Application Laid-Open No. 71495/1989
does not investigate production conditions at an industrial level;
the technique described in Japanese Patent Application Laid-Open
No. 330289/1992 involves technical difficulties such as necessity
of stopping the reaction at the time the concentration of the
diglyceride reaches a peak; and the technique described in Japanese
Patent Application Laid-Open No. 234391/1998 is easy to operate and
can improve the reaction rate to some extent, but is insufficient
in the purity of the resulting diglyceride and the industrial
scale-up technique.
[0007] Accordingly, there is a need for a process for preparing a
high-purity glyceride at a high yield in a short period of time at
an industrial level.
SUMMARY OF THE INVENTION
[0008] It is thus an object of the present to provide a process for
preparing a high-purity glyceride at a high yield in a short period
of time at an industrial level.
[0009] This and other objects of the invention have been achieved
by a process for preparing a diglyceride, which includes:
[0010] in an enzyme-packed tower which includes an immobilized
lipase preparation, carrying out an esterification reaction
between:
[0011] (1) an acyl group donor selected from the group including a
fatty acid, a lower alcohol ester thereof, and a mixture thereof;
and
[0012] (2) an acyl group acceptor selected from the group including
glycerol, a monoglyceride, and a mixture thereof;
[0013] to obtain a reaction fluid from the enzyme-packed tower;
[0014] reducing a water content or a lower alcohol content in the
reaction fluid; and
[0015] subsequent to the reducing, recirculating the reaction fluid
to the enzyme-packed tower, wherein a residence time of the
reaction fluid in the enzyme-packed tower is 120 seconds or
less;
[0016] to obtain a diglyceride.
[0017] According to the present invention, a high-purity glyceride
can be provided at a high yield in a short period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0019] FIG. 1 schematically illustrates a preparation process in
the present invention.
[0020] In the drawing, the respective reference characters have the
following meanings:
[0021] 1: dehydration tank;
[0022] 2: mixture of raw materials;
[0023] 3: stirrer;
[0024] 4: mixture of diglyceride, by-products, unreacted raw
materials and intermediates;
[0025] 5, 14: pumps;
[0026] 6: enzyme-packed tower;
[0027] 11, 12: circulation lines for the enzyme-packed tower;
[0028] 13: circulation line for the dehydration tank; and
[0029] 15,16: pressure gauges.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Various other objects, features and attendant advantages of
the present invention will be more fully appreciated as the same
becomes better understood from the following detailed description
of the preferred embodiments of the invention.
[0031] The present inventors have made various enzyme-packed towers
which are packed with an enzyme in the same amount and different in
packing thickness and sectional area to circulate a reaction fluid
in the same flow rate, thereby investigate the influence of a
superficial velocity on reaction rate and the purity of the
resulting diglyceride. However, no change has been observed
therebetween. On the other hand, analysis of compositional changes
of the reaction fluid in the flowing direction in the interior of
each enzyme-packed tower has revealed that the concentration of a
1,3-diglyceride increases in the vicinity of an inlet of the tower,
but does not very increase at the lower part from the middle of the
tower, and the concentration of a triglyceride increases on the
contrary even when a 1,3-position-selective lipase is used. From
these facts, the present inventors have found that when residence
time is long, the 1,3-position esterification reaction is
equilibrated by the influence of water formed by the reaction to
inhibit the formation of the intended diglyceride even when a
superficial velocity of a reaction fluid in an enzyme-packed tower
is high, and on the other hand the concentration of a triglyceride
is increased by the progress of a rearrangement reaction from the
1,3-diglyceride into 1,2-diglyceride, which is not affected by the
water, and the esterification thereof to incur the lowering of the
purity of the diglyceride, and that when the reaction is operated
by controlling the residence time to a certain period of time or
shorter, a high-purity glyceride is efficiently obtained at an
industrial level.
[0032] According to the present invention, there is thus provided a
process for preparing a diglyceride, which comprises, in an
esterification reaction in which a fatty acid or a lower alcohol
ester thereof, which is an acyl group donor, and glycerol or a
monoglyceride, which is an acyl group acceptor, are fed to an
enzyme-packed tower packed with an immobilized lipase preparation
to cause a reaction fluid to flow out of the enzyme-packed tower,
and a water content or lower alcohol content in the reaction fluid
is reduced in a dehydration tank to circulating the reaction fluid
to the enzyme-packed tower, conducting the feed of the reaction
fluid to the enzyme-packed tower under conditions that residence
time amounts to 120 seconds or shorter.
[0033] The residence time herein is defined as the time required
for the reaction fluid to pass through an enzyme-packed part in the
enzyme-packed tower and calculated out by dividing an enzyme
packing volume, i.e., a bulk volume (not a void volume of voids in
an enzyme preparation) filled with and occupied by the enzyme
preparation by a circulating flow rate. In the present invention,
the feed of the reaction fluid to the enzyme-packed tower is
conducted under conditions that the residence time amounts to 120
seconds or shorter, preferably 10 to 80 seconds, more preferably 20
to 50 seconds, thereby permitting preparing a high-purity
diglyceride at an industrial level and a high production rate. If
the reaction is conducted under such conditions that the residence
time exceeds 120 seconds, the purity of the diglyceride is lowered
due to increase in the concentration of a triglyceride formed.
[0034] Preferably, the reaction in the present invention is
conducted while decreasing water or a lower alcohol formed by the
reaction in a dehydration tank. In the present invention, it is
preferred from the viewpoint of enhancing the purity and production
rate of the diglyceride that the dehydration or dealcoholization of
the reaction fluid be conducted under conditions that a volumetric
mass transfer coefficient k.sub.La (wherein k.sub.L is a mass
transfer coefficient, and a is a gas-liquid interfacial mass
transfer area per unit volume) amounts to at least 0.0005
(s.sup.-1), preferably 0.0008 to 0.01 (s.sup.-1) in addition to the
conditions of the residence time in the enzyme-packed tower.
[0035] In a batch-wise reactor of gram level, the volume of a
dehydration tank may also be small, and the whole reaction mixture
in the dehydration tank becomes a high vacuum state, thereby
permitting dehydration in the whole area of the reaction mixture
even by stirring alone. However, in a batch-wise reactor at a level
of several tens kilograms to tons, high vacuum cannot be achieved
in the interior of the reaction mixture due to the own weight of
the reaction mixture in a dehydration tank even when the space area
of the dehydration tank is in the highest vacuum, and the
dehydration rate becomes insufficient because no dehydration from
the interior of the reaction mixture occurs. Therefore, the present
inventors have found that it is preferred that the volumetric mass
transfer coefficient k.sub.La be controlled to a certain value or
higher in such a reactor of industrial level in that the viewpoint
dehydration can be efficiently conducted, so that the
above-described inhibition of 1,3-position esterification reaction
by water can be avoided, and a high-purity diglyceride can be
prepared at a high production rate. From such a point of view, it
is preferred that the feed of the reaction fluid to the dehydration
tank be conducted by means of a spray nozzle and adjusted so as to
give an average droplet diameter of at most 5 mm, more preferably
at most 2 mm.
[0036] The k.sub.La value may be calculated out either by the
analysis of a dehydration rate in the reaction or by determining
only a dehydration rate under the same dehydration conditions
irrespective of reaction. For example, a water content [H.sub.2O]
in the reaction fluid within the dehydration tank is determined
with time. Supposing that a water content after a sufficient period
of time has elapsed is an equilibrium water content [H.sub.2O]* ,
and the time is t, a dehydration rate equation is represented by
d[H.sub.2O]/dt=-k.sub.La([H.sub.2O]-[H.sub.2O]*). This equation is
integrated to give 1n([H.sub.2O]-[H.sub.2O]*)=-k.sub.La.multi-
dot.t+constant. Accordingly, since 1n([H.sub.2O]-[H.sub.2O]*) has
linearity to the time, the slope (k.sub.La) of this straight line
may be found by the method of least squares.
[0037] Preferable examples of a method for the dehydration or
dealcoholization of the reaction fluid include reduction of
pressure, passing a dry inert gas, and using a water absorbent such
as a molecular sieve. Among these methods, reduction of pressure is
preferred in that the operation can be performed at a low
temperature, and there is no need to recover both inert gas and
dehydrating agent. The degree of vacuum is preferably 70 hPa or
lower, more preferably 15 hPa or lower. No particular limitation is
imposed on the form, size and number of dehydration tanks. The
superficial velocity is preferably not lower than 1 mm/s, more
preferably higher than 2 mm/s because the mass transfer resistance
between solid and liquid becomes great to slow a reaction rate when
the superficial velocity is too low.
[0038] As conditions of the interior of the enzyme-packed tower,
defined as L/d.sup.2, wherein L is a packing thickness (m) in a
flowing direction within the tower, and d is an average particle
diameter (mm) of an enzyme preparation, is preferably controlled to
at most 25, more preferably at most 20, more particularly
preferably at most 15, most preferably at most 10, and most
particularly preferably at most 3. This means "L/d.sup.2" derived
out on the basis of the Kozeny-Carman's equation:
.DELTA.P=constant.times.u.times.L/d.sup.2
[0039] wherein .DELTA.P is a pressure drop of the enzyme-packed
tower, u is a superficial velocity, L is a packing thickness in a
flowing direction within the enzyme-packed tower, and d is an
average particle diameter of an enzyme preparation, for calculating
out the pressure drop of the enzyme-packed tower.
[0040] In order to meet the above conditions, an enzyme preparation
having an average particle diameter d of at least 0.1 mm, and more
preferably 0.2 to 0.8 mm, is preferably used as the immobilized
lipase preparation. The packing thickness L of the enzyme is
preferably preset so as to be at most 1 m, and more preferably 0.05
to 0.6 m. These factors are not important in a small-scale reactor
of laboratory level, but important in a large-scale reactor of
industrial level.
[0041] The operation is preferably conducted under conditions that
the pressure drop of the enzyme-packed tower is 20 kg/cm.sup.2 or
smaller, and more preferably 10 kg/cm.sup.2 or smaller because
plant cost can be reduced from the viewpoints of design strength of
the enzyme-packed tower and load against a circulating pump. When
the reaction is conducted repeatedly under a high pressure, there
is a possibility that the immobilized enzyme may be compacted to
increase the pressure drop, or the activity of the enzyme may be
deteriorated to elongate the reaction time.
[0042] Preferable examples of the acyl group donor which is a raw
material for the reaction, i.e., a fatty acid or a lower alcohol
ester thereof, include saturated or unsaturated fatty acids having
2 to 24 carbon atoms, for example, butyric acid, valeric acid,
capronic acid, enanthic acid, caprylic acid, pelargonic acid,
capric acid, undecanoic acid, lauric acid, myristic acid, palmitic
acid, zoomaric acid, stearic acid, oleic acid, elaidic acid,
linoleic acid, arachidonic acid, gadoleic acid, arachic acid,
behenic acid and erucic acid, and besides higher unsaturated fatty
acids such as eicosapentaenoic acid, docosahexaenoic acid and
--linolenic acid; fatty acids derived from animal and vegetable
oils such as rapseed oil, soybean oil, cotton-seed oil, olive oil,
corn oil, coconut oil, palm oil, perilla oil, linseed oil, borage
oil, beef tallow, lard and fish oil; fatty acids obtained by
processing these fatty acids by a means such as hardening,
distillation or fractionation, and lower alcohol esters of these
fatty acids. Examples of the lower alcohol esters include esters
with a lower alcohol having 1 to 3 carbon atoms, i.e., methanol,
ethanol, propanol or 2-propanol. These acyl group donors may be
used either singly or in any combination thereof.
[0043] As the acyl group acceptor which is another raw material for
the reaction, i.e., glycerol, may be used a commercially available
product. No particular limitation is imposed on a mixing ratio of
the acyl group donor to the acyl group acceptor. However, the acyl
group of the acyl group donor is preferably present within a range
of at least 1 mol, and more preferably 1.6 to 2.8 mol, per mol of a
glyceryl group of the acyl group acceptor.
[0044] A monoglyceride may be added to the mixture of the raw
materials. Even when glycerol is mixed with the fatty acid or the
like, the reaction becomes a heterogeneous reaction in which a
fatty acid phase and a glycerol phase are present, since mutual
solubility between the raw materials is low. When the monoglyceride
is added, however, the solubility of glycerol in the fatty acid
phase becomes high from the initial stage of the reaction, so that
the reaction rate is enhanced.
[0045] As the immobilized enzyme preparation used in the present
invention, is preferred an enzyme (hereinafter referred to as
"immobilized, 1,3-position-selective lipase") specifically acting
on the 1- and 3-positions of glycerol. Preferable examples of such
a 1,3-position-selective lipase include lipases derived from
microorganisms of the genera Rhizopus, Aspergillus and Mucor, and
splenic lipases, more specifically, lipases derived from Rhizopus
delemar, Rhizopusjaponicus, Rhizopus niveus, Aspergillus niger,
Mucorjavanicus and Mucor miehei. The immobilized lipase preparation
is obtained by immobilizing a lipase in accordance with a publicly
known method for immobilizing an enzyme, for example, a method
described in "Immobilized Enzymes", edited by Ichiro Senhata,
published by Kodansha, pages 9 to 85, or "Immobilized
Biocatalysts", edited by Ichiro Senhata, published by Kodansha,
pages 12 to 101. The immobilized lipase preparation must exhibit
water-holding capacity to keep its properties under conditions of
reduced pressure. In order to meet such a requirement, a lipase
immobilized on an ion-exchange resin is particularly preferred. The
esterification activity of the immobilized lipase preparation is
preferably at least 100 (unit/g-enzyme), particularly at least 200
(unit/g-enzyme). Commercially-available immobilized
1,3-position-selective lipases include "Lipozyme IM" (trade name,
product of Novo Nordisk Bioindustry Co.).
[0046] Preferably, a solvent such as hexane, octane or petroleum
ether may also be used in the reaction of the acyl group donor with
the acyl group acceptor in the present invention. However, in view
of its removal and purification, it is preferred that no solvent be
added. In order to inhibit hydrolysis, it is also preferred that no
any other water than water dissolved in the lipase preparation and
raw materials for the reaction be added to the reaction system. The
reaction temperature in the present invention is preferably 20 to
100.degree. C., particularly 35 to 70.degree. C.
[0047] Unreacted glycerol, fatty acid and/or lower alcohol ester of
the fatty acid, and monoglyceride contained in the reaction mixture
after completion of the reaction can be easily removed by a
conventionally well-known, isolating and purifying means such as
molecular distillation. However, a triglyceride and a diglyceride
are difficult to be separated from each other on an industrial
level. Accordingly, the purity of the resulting diglyceride and the
yield of reaction can be represented by the expressions D/(D+T) and
D+T, respectively. In the expressions, D is a diglyceride
concentration in the reaction product, and T is a triglyceride
concentration in the reaction product.
[0048] A preparation process of a diglyceride in the present
invention is exemplified as illustrated in, for example, FIG. 1. A
mixture 2 of raw materials is placed in a dehydration tank 1 and
fed to an enzyme-packed tower 6 through a line 11 by means of a
pump 5 while suitably stirring the mixture 2 by a stirrer 3 (in
this step, the feed of the mixture to the enzyme-packed tower is
conducted under such conditions that the residence time amounts to
120 seconds or shorter). A mixture 4 of a diglyceride formed by a
reaction within the enzyme-packed tower 6, by-products and
unreacted raw materials is entered into the dehydration tank 1
through a line 12 (Although the dehydration of the mixture is
preferably conducted under conditions that a volumetric mass
transfer coefficient K.sub.La is at least 0.0005 (s.sup.-1), this
requirement is realized by using a spray nozzle in the feed of the
reaction fluid to the dehydration tank 1 through a line 13 by means
of a pump 14.). The above process is conducted repeatedly, thereby
increasing the concentration of the diglyceride. The dehydration
tank 1 is kept under reduced pressure during this process to remove
water and the like formed by the reaction for forming the
diglyceride.
EXAMPLES
[0049] Having generally described this invention, a further
understanding can be obtained by reference to certain specific
examples which are provided herein for purposes of illustration
only and are not intended to be limiting unless otherwise
specified.
[0050] In the following Examples, the volumetric mass transfer
coefficient k.sub.La was calculated out by the method of least
squares in accordance with the above-described method, in which an
oil obtained after completion of the reaction in an amount equal to
a batch size was adjusted in such a manner that a water content is
about 0.5%, and the oil was charged into the dehydration tank to
conduct circulation on the spray side at the same flow rate as that
in each Example or Comparative Example without conducting the
circulation to the enzyme-packed tower, thereby determining a water
content [H.sub.2O] with time under reduced pressure and regarding a
water content after 10 hours as an equilibrium water content
[H.sub.2O]*.
[0051] The enzymatic activity was calculated out from a consumption
rate of a fatty acid and an amount of an immobilized enzyme used as
determined from the concentration of oleic acid at the time a
reaction is started and after 15 minutes by placing oleic acid (86
g), glycerol (14 g) and the immobilized enzyme (5 g) in a 4-necked
flask and stirring the contents at 300 rpm to conduct the reaction
at 40.degree. C. and 6.7 hPa with an activity unit that consumes 1
.mu.mol of oleic acid for 1 minute regarded as 1 unit.
Example 1:
[0052] A reactor used was composed of an enzyme-packed tower
(enzyme packing volume: 0.0132 m.sup.3; bulk specific gravity of
the preparation: 0.38 g/cc) packed with a 1,3-position-selective,
immobilized lipase, Lipozyme IM (product of Novo Nordisk
Bioindustry Co.; 300 unit/g enzyme; 5 kg) and a dehydration tank
for conducting dehydration by reduction of pressure. The
dehydration tank was charged with oleic acid (86 kg) and glycerol
(14 kg), and the temperature of the reactants was preset to
40.degree. C. with stirring. The feed of the reaction fluid to the
enzyme-packed tower and the spray nozzle of the dehydration tank
was then started, and the interior of the dehydration tank was
controlled so as to give a degree of vacuum of 6.7 hPa by means of
a vacuum pump. The feed flow rate of the reaction fluid to the
enzyme-packed tower was controlled to 1.2 m3/hr, and a value
(residence time) obtained by dividing the enzyme packing volume by
the flow rate was adjusted so as to be 40 seconds. The circulating
flow rate to the spray nozzle was determined to be 1.2
m.sup.3/hr.
[0053] After a part of an oil obtained by the reaction was taken
out after 3.5 hours from the beginning of the reaction to determine
the amount of the fatty acid by alkalimetry, followed by
trimethylsilylation, the composition of a triglyceride, diglyceride
and monoglyceride was found by gas chromatography. The result
thereof is shown in Table 1.
[0054] Incidentally, the pressure drop is a difference between
numerical values read by pressure gauges provided at the inlet and
outlet of the enzyme-packed tower, respectively, the enzyme packing
thickness is a distance over which the enzyme preparation is packed
in a flowing direction of the reaction fluid within the
enzyme-packed tower, the superficial velocity is a numerical value
obtained by dividing the flow rate to the enzyme-packed tower by a
sectional area of the packed tower in a direction perpendicular to
the flowing direction.
Example 2:
[0055] An operation was conducted in the same manner as in Example
1 except that the flow rate of the reaction fluid to the
enzyme-packed tower was changed to 0.6 m.sup.3/hr, so as to find
the composition. The results are shown in Table 1.
Example 3:
[0056] An operation was conducted in the same manner as in Example
1 except that the flow rate on the spray side was changed to 0.3
m.sup.3/hr, so as to find the composition. The result thereof is
shown in Table 1.
Comparative Example 1:
[0057] An operation was conducted in the same manner as in Example
1 except that the flow rate of the reaction fluid to the
enzyme-packed tower was changed to 0.3 m3/hr, so as to find the
composition. The result thereof is shown in Table 1.
Comparative Example 2:
[0058] An operation was conducted in the same manner as in Example
1 except that the packing amount of the enzyme was increased to 4
times, and the flow rate of the reaction fluid to the enzyme-packed
tower was changed to 1 m.sup.3/hr because the pressure drop of the
enzyme-packed tower increased, so as to find the composition. The
result thereof is shown in Table 1.
Comparative Example 3:
[0059] An operation was conducted in the same manner as in Example
1 except that the 1,3-position-selective, immobilized lipase,
Lipozyme IM was ground in a mortar to make the particle diameter
thereof small, and the flow rate of the reaction fluid to the
enzyme-packed tower was changed to 0. 14 m.sup.3/hr, so as to find
the composition. The result thereof is shown in Table 1.
Comparative Example 4:
[0060] A reactor of laboratory level was used to feed a reaction
fluid at a circulating flow rate of 96 ml/min to an enzyme-packed
tower under conditions that the packing amount of the
1,3-position-selective, immobilized lipase, Lipozyme IM was 100 g,
and a batch size was 1 kg, thereby conducting a reaction without
conducting circulation on the spray side to find the composition.
The result thereof is shown in Table 1.
1 TABLE 1 Example Comparative Example 1 2 3 1 2 3 4*.sup.1 Batch
size (kg) 100 100 100 100 100 100 1 Oleic acid (kg) 86 86 86 86 86
86 0.86 Glycerol (kg) 14 14 14 14 14 14 0.14 Immobilized enzyme
IM.sup.+2 IM.sup.+3 IM.sup.+2 IM.sup.+2 IM.sup.+2 IM.sup.+2
IM.sup.+2 Average particle 0.43 0.43 0.43 0.43 0.43 0.08 0.43
diameter d (mm) Amount (kg) 5 5 5 5 20 5 0.1 Packing thickness 0.18
0.18 0.18 0.18 0.7 0.18 0.33 Superficial velocity U 4.4 2.2 4.4 1.1
3.7 0.5 2.0 (mm/s) Residence time (s) 40 79 40 158 190 351 164
=L/d.sup.2 0.95 0.95 0.95 0.95 3.80 27.50 1.80 Pressure loss P 2.6
1.5 2.6 0.7 9.5 8.5 2.5 (kg/cm.sup.2) Spray nozzle Used Used Used
Used Used Used Not used Droplet diameter (mm) 1 1 1.2 1 1 1 --
Circulation on spray 1.2 1.2 0.3 1.2 1.2 1.2 0 side (m.sup.3/hr)
k.sub.La (s.sup.-1) 0.0017 0.0017 0.0005 0.0017 0.0017 0.0017
0.0007 Reaction time (hr) 3.5 3.5 3.5 3.5 3.5 3.5 3.5 7.0 Reaction
product (wt %) Oleic acid 14.1 15.4 16.4 43.1 11.6 47.8 41.9 12.4
Glycerol 0.3 0.7 0.5 2.1 0.4 2.7 1.7 0.1 Monoglyceride (M) 14.1
18.3 16.8 15.3 15.0 16.4 15.4 9.3 Diglyceride (D) 65.6 58.1 59.5
32.8 55.7 26.8 33.1 63.0 Triglyceride (T) 5.9 7.5 6.8 6.7 17.3 6.3
7.9 15.2 Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
Yield of reaction 71.5 65.6 66.3 39.5 73.0 33.1 41.0 78.2 D + T
(wt. %) Purity of diglyceride 91.7 88.6 89.7 83.0 76.3 80.9 80.7
80.6 D/(D + T) (wt %) *1: Example 2 of Japanese Patent Application
Laid-Open No. 234391/1998. *2: Lipozyme IM (product of Novo Nordisk
Bioindustry Co.).
[0061] Each of the above references, patents, applications and
published is hereby incorporated by reference, the same as if set
forth at length.
[0062] This application is based on Japanese Patent Application No.
359794/1999, filed Dec. 17, 1999, the entire contents of which are
hereby incorporated by reference.
[0063] Having now fully described this invention, it will be
apparent to one of ordinary skill in the art that many changes and
modifications can be made thereto without departing from the spirit
or scope of the invention as set forth herein.
* * * * *