U.S. patent application number 09/812973 was filed with the patent office on 2001-10-11 for partial interesterification of triacylglycerols.
This patent application is currently assigned to Cargill, Incorporated. Invention is credited to Lampert, Daniel Scott, Liu, Linsen.
Application Number | 20010029047 09/812973 |
Document ID | / |
Family ID | 25462863 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010029047 |
Kind Code |
A1 |
Liu, Linsen ; et
al. |
October 11, 2001 |
Partial interesterification of triacylglycerols
Abstract
A process for modifying a triacylglycerol stock, such as a
vegetable oil stock, to better control fluidity is provided. The
process includes interesterifying the triacylglycerol stock in the
presence of a basic catalyst while monitoring the absorbance of the
reaction mixture. A modified triacylglycerol stock produced by
partial interesterification as well as plastic spreads and
water-in-oil emulsions which include the partially interesterified
triacylglycerol stock are also provided.
Inventors: |
Liu, Linsen; (Minnetonka,
MN) ; Lampert, Daniel Scott; (Chaska, MN) |
Correspondence
Address: |
Melissa Jean Pytel
MERCHANT & GOULD P.C.
P.O. Box 2903
Minneapolis
MN
55402-0903
US
|
Assignee: |
Cargill, Incorporated
Deephaven
MN
|
Family ID: |
25462863 |
Appl. No.: |
09/812973 |
Filed: |
March 20, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09812973 |
Mar 20, 2001 |
|
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|
08932755 |
Sep 17, 1997 |
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6238926 |
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Current U.S.
Class: |
436/71 ; 436/159;
436/171 |
Current CPC
Class: |
A23D 7/001 20130101;
A23D 9/00 20130101; C11C 3/10 20130101 |
Class at
Publication: |
436/71 ; 436/159;
436/171 |
International
Class: |
G01N 021/75; G01N
033/28 |
Claims
What is claimed is:
1. A method of monitoring an interesterification reaction of a
triacylglycerol stock comprising; forming an interesterification
mixture including a triacylglycerol stock and a basic catalyst; and
determining an absorbance of the interesterification mixture at one
or more selected wavelengths.
2. The method of claim 1 comprising determining the absorbance at
one or more selected wavelengths between about 300-500 nm.
3. The method of claim 1 wherein the basic catalyst comprises
alkali metal alkoxide, alkali metal, alkali metal alloy, or alkali
metal hydroxide.
4. The method of claim 3 wherein the alkali metal alkoxide
comprises sodium methoxide, sodium ethoxide, potassium methoxide,
potassium ethoxide, or a mixture thereof.
5. The method of claim 1 comprising determining the absorbance
after heating the interesterification mixture for a sufficient time
so that a measurable property of the mixture no longer changes with
further heating.
6. The method of claim 1 wherein the triacylglycerol stock
comprises a bleached triacylglycerol stock.
7. The method of claim 6 wherein the bleached triacylglycerol stock
comprises a refined, bleached triacylglycerol stock.
8. The method of claim 1 wherein the an interesterification mixture
includes a triacylglycerol stock which has been subjected to at
least one modification process from the group consisting of
refining, bleaching, deodorizing, fractionation and
hydrogenation.
9. A process for modifying a triacylglycerol stock comprising:
forming a mixture including the triacylglycerol stock and a basic
catalyst; reacting the mixture to form a partial
interesterification product; and determining an absorbance of the
reacting mixture.
10. The process of claim 9 further comprising adding a quenching
solution to the reacting mixture, thereby stopping the
reaction.
11. The process of claim 9 wherein the triacylglycerol stock is a
blend comprising a hardstock component and a softstock
component.
12. The process of claim 11 wherein the hardstock component
comprises a saturated fatty acid stock.
13. The process of claim 11 wherein the hardstock component
comprises a hard triacylglycerol stock having an Iodine Value of no
more than about 70.
14. The process of claim 11 wherein the softstock component
includes a liquid oil, a lauric fat or a mixture thereof.
15. The process of claim 14 wherein the liquid oil comprises
soybean oil, corn oil, rapeseed oil, sunflower oil, safflower oil,
canola oil, cottonseed oil or a mixture thereof.
16. The process of claim 14 wherein the lauric fat comprises palm
kernel oil, coconut oil or a mixture thereof.
17. The process of claim 9 wherein the triacylglycerol stock has a
trans content of no more than about 30%.
18. The process of claim 9 wherein the partial interesterification
product has a solid fat content at 40.degree. C. of no more than
about 30%.
19. The process of claim 9 comprising partially interesterifying
the mixture at a temperature of about 50.degree. C. to about
150.degree. C.
20. The process of claim 9 comprising partially interesterifying
the mixture under substantially anhydrous conditions.
21. The process of claim 9 comprising partially interesterifying a
mixture of the triacylglycerol stock and a sufficient amount of the
basic catalyst to form a partial interesterification product having
a degree of interesterification of about 5% to about 95%.
22. A method of determining the amount of a basic catalyst required
to completely interesterify a triacylglycerol stock comprising the
steps of: (A) adding a first amount of the basic catalyst to a
sample of the triacylglycerol stock to form a first catalyzed
stock; (B) allowing the first catalyzed stock to undergo an
interesterification reaction until a measurable property of the
triacylglycerol stock attains a constant value; and (C) determining
an absorbance of the first catalyzed stock after the measurable
property has attained the first constant value; (D) adding a second
amount of the basic catalyst to a sample of the triacylglycerol
stock to form a second catalyzed stock; (E) allowing the second
catalyzed stock to undergo an interesterification reaction until a
measurable property of the triacylglycerol stock attains a second
constant value; and (F) determining an absorbance of the second
catalyzed stock after the measurable property has attained the
second constant value.
23. A plastic spread comprising the partial interesterification
product formed by the process of claim 8.
24. A water-in-oil emulsion having a fat phase which comprises the
partial interesterification product formed by the process of claim
8.
25. A process for modifying a triacylglycerol stock comprising:
forming a mixture including the triacylglycerol stock and a basic
catalyst, wherein the triacylglycerol stock includes a hardstock
component and a softstock component; reacting the mixture at a
temperature of at least about 50.degree. C. to form a partial
interesterification product; and determining an absorbance of the
reacting mixture at one or more selected wavelengths between about
300-500 nm.
26. A modified triacylglycerol stock produced by a process
comprising the steps of: forming a mixture including the
triacylglycerol stock and a basic catalyst; reacting the mixture to
form a partial interesterification product; and determining an
absorbance of the reacting mixture.
Description
BACKGROUND OF THE INVENTION
[0001] Fats and oils constitute an important component of human
diet. They are a source of essential fatty acids such as linoleic,
linolenic and arachidonic acids, and act as vehicles for vitamins
as well as being a source of calories. Fats and oils are also
widely used to enhance the texture and palatability of foods. Their
varied uses necessitate a wide range of melting and crystallization
properties.
[0002] The physical properties of a fat or oil are determined by
(i) the chain length of the fatty acyl chains, (ii) the amount and
type (cis or trans) of unsaturation present in the fatty acyl
chains, and (iii) the distribution of the different fatty acyl
chains among the triacylglycerols that make up the fat or oil.
Those fats with a high proportion of saturated fatty acids are
typically solids at room temperature while triacylglycerols in
which unsaturated fatty acyl chains predominate tend to be liquid.
Thus, hydrogenation of a triacylglycerol stock ("TAGS") tends to
reduce the degree of unsaturation and increase the solid fat
content and can be used to convert a liquid oil into a semisolid or
solid fat. Hydrogenation, if incomplete, also tends to result in
the isomerization of some of the double bonds in the fatty acyl
chains from a cis to a trans configuration. Concerns over potential
health implications of excessive consumption of fatty acids with
trans double bonds (e.g., via margarines, shortenings or frying
oils), has led to interest in the manufacture of low- or zero-trans
spreadable fats.
[0003] By altering the distribution of fatty acyl chains in the
triacylglycerol moieties of a fat, randomization can produce
changes in the melting, crystallization and fluidity
characteristics of a triacylglycerol stock. As well as leaving the
overall degree of unsaturation (e.g., as measured by the Iodine
Value) of a triacylglycerol stock unchanged, interesterification
reactions typically do not generate additional trans double
bonds.
[0004] With rising concerns over potential dietary effects of trans
unsaturated fatty acids, interesterification provides an important
alternative to partial hydrogenation in the production of plastic
fats such as shortenings and margarines. Interesterification has
been used in the oil industry for about a century, although the
mechanism is still not well understood by the industry. Currently,
interesterification is conducted with experimentally determined
catalyst dosages and reaction times to reach a thermodynamic
equilibrium (i.e., complete randomization) of the distribution of
fatty acyl chains in a triacylglycerol stock. In practice,
interesterifications are run with an excess of catalyst to ensure
completion interesterification and the randomized product is then
characterized by measurement of its physical properties, such as
melting point and solid fat content. Herein the terms
"randomization," "complete interesterification" and "complete
randomization" are used interchangeably.
[0005] Interesterification has been demonstrated as a method to
prepare plastic fats and modify fat crystals. Stock oils and fats
commonly available as raw materials for interesterification have
varying qualities and levels of purity. Because of this, the
experimental dosage of catalyst required for initiating or
completing interesterification can vary widely. In some cases,
because of inactivation reactions, the catalyst dosage may be
insufficient to initiate or complete interesterification, resulting
in production delays and cost increases. To overcome this
limitation, interesterification reactions are typically run using a
substantial excess of catalyst. The physical properties and/or
composition of the reaction product must be assayed upon completion
of the interesterification. While this approach can ensure
initiation and completion of the reaction, it does not permit the
degree of control of the reaction rate necessary to reproducibly
achieve a specific level of partial esterification.
SUMMARY OF THE INVENTION
[0006] The present invention relates to triacylglycerol stocks,
such as triacylglycerol mixtures derived from oilseeds, rendered
beef tallow, fish oil, palm oil or other plant or animal sources.
It particularly concerns modifications of selected triacylglycerol
stocks to provide products with preferred properties for use, for
example in the preparation of plastic fats such as shortenings and
margarine.
[0007] A process for modifying a triacylglycerol stock, such as a
vegetable oil stock, to enhance its physical properties (e.g.,
hardness or fluidity) in a controlled manner is provided herein.
The process includes interesterifying the triacylglycerol stock in
the presence of a basic catalyst. The triacylglycerol stock turns a
reddish brown color upon initiation of the interesterification
reaction. There is a direct correlation between the absorbance of
the reaction mixture and the degree of interesterification which
has been achieved, i.e., the absorbance is a reflection of the
degree of interesterification of the mixture. While throughout this
application reference is made to measuring the absorbance of a
reacting interesterification mixture, it should be understood that
in practical terms the transmittance of the mixture could also be
measured. Since the absorbance and transmittance of a sample are
arithmetically related (Absorbance=log(1/Transmittance)), either
value could be measured and the second value calculated from the
measurement of the first value. Throughout this application, it is
to be understood the phrase "determining the absorbance"
encompasses any measurement which involves the determination of the
intensity of light passing through a sample relative to the
intensity of the incident light source. Due to reactions with
impurities in the triacylglycerol stock which can consume and/or
inactivate the catalyst, the amount of active catalytic species
generated from a fixed amount of catalyst can vary widely over
different lots of triacylglycerol stock. Thus, although the same
amount of catalyst can give different amounts of
interesterification with different lots of starting triacylglycerol
stock, by determining the absorbance of the mixture formed by
addition of the basic catalyst to the triacylglycerol stock, it is
possible to predict and monitor the degree of interesterification
(partial or complete randomization) which will occur. Thus,
according to the present invention, the partial interesterification
of a triacylglycerol stock may be carried out by forming a mixture
which includes the triacylglycerol stock and a basic catalyst. As
the mixture is allowed to react, the absorbance of the reacting
mixture is determined. The absorbance may be monitored at selected
time intervals or continuously as a function of time. The reaction
is allowed to proceed until the absorbance of the mixture reaches a
preselected value, thereby forming a partial interesterification
product. Once the absorbance has reached the preselected value, the
reaction is typically stopped by the addition of a quenching
solution.
[0008] Herein, when reference is made to the term "triacylglycerol
stock," the intent is to refer to a material comprising
triacylglycerols, whether altered or not, derived from various
plant, animal and synthetic sources, such as oil seed sources. The
term at least includes within its scope: (a) such materials which
have not been altered after isolation; (b) materials which have
been refined, bleached and/or deodorized after isolation; (c)
materials obtained by a process which includes fractionation of a
triacylglycerol stock; (d) oils obtained from plant or animal
sources and altered in some manner, for example through partial or
complete hydrogenation; and (e) blends of any such materials. While
the triacylglycerol stocks employed as starting materials in the
present interesterification process may have been treated via a
number of these processes, in most instances the starting
triacylglycerol stock will have been bleached. "Bleaching" is a
standard process used to remove color bodies from oils, typically
via an adsorption/filtration process. It will be understood that
the triacylglycerol stock typically includes a mixture of
triacylglycerols, and a mixture of triacylglycerol isomers. By the
term "triacylglycerol isomers", reference is meant to
triacylglycerols which, although including the same esterified acid
residues, may vary with respect to the location of the residues in
the triacylglycerol. For example, a triacylglycerol stock, such as
a vegetable oil stock, can include both symmetrical and
unsymmetrical isomers of a triglyeride which includes two different
fatty acyl chains (e.g., includes both stearate and oleate
groups).
[0009] The starting material for the interesterification reaction
may be a blend which includes one or more other esters in addition
to triacylglycerol(s). For example, simple esters such as long
chain alcohol esters of fatty acids and/or polyesters of sugars or
sugar derivatives may be interesterified with a triacylglycerol
stock.
[0010] Herein, the result of reacting a triacylglycerol stock, such
as a vegetable oil stock, to interesterify the fatty acyl chains
will be referenced as an "interesterification product." The term
"interesterification product" includes within its scope practices
which involve reacting the triacylglycerol stock to the extent that
thermodynamic equilibrium (i.e., complete randomization) of the
distribution of fatty acyl chains in a triacylglycerol stock has
been substantially achieved, i.e., a "randomization product" is
produced. As used herein the term, "interesterification product"
also includes triacylglycerol stocks which have been reacted to an
extent insufficient to achieve a complete thermodynamic
distribution of fatty acyl chains, i.e., a "partial
interesterification product." The partial interesterification
product is typically a modified triacylglycerol stock which has
been reacted to achieve a selected degree between about 5% and
about 95% and, preferably, from about 20% and about 80% of reaction
toward complete randomization (degree of interesterification) of
the fatty acyl chains. As described herein, the degree of
interesterification can be measured based on any of a variety of
properties of the triacylglycerol stock. The partial
interesterification product may be produced by a process which
includes determining an absorbance of a mixture including the
triacylglycerol stock and the basic catalyst; and allowing the
mixture to react for a sufficient time and at a sufficient
temperature to form the partial interesterification product. One
example of a triacylglycerol stock which is particularly suitable
for modification using this process is a triacylglycerol stock
which is a blend of a hardstock component and a softstock
component.
[0011] Plastic fats and edible products containing plastic fats,
such as margarines and low fat spreads, are also provided herein.
Such plastic fats may be produced by a process which includes
blending a partially interesterified triacylglycerol stock with
another triacylglycerol stock, e.g., a vegetable oil which has been
refined, bleached and/or deodorized. The edible products may be
produced by a process which includes emulsifying the plastic fat
with an aqueous phase. As used herein, a "plastic fat" is
semi-solid to solid, firm but not brittle, easily malleable, with
no free oil visible. Plastic fats typically have a solid fat
content of no higher than about 20% at 40.degree. C. (104.degree.
F.).
[0012] The present invention also provides a method of monitoring
an interesterification reaction. The method allows the amount of a
basic catalyst employed to completely interesterify a
triacylglycerol stock to be minimized. In many typical applications
the method includes:
[0013] (A) adding an incremental amount of the basic catalyst to
the triacylglycerol stock to form a catalyzed triacylglycerol
stock;
[0014] (B) allowing the catalyzed stock to undergo an
interesterification reaction until a measurable property of the
triacylglycerol stock remains constant; and
[0015] (C) measuring the absorbance of the catalyzed stock,
typically at a wavelength between about 300 nm and about 500 nm,
after the measurable property has attained the constant value.
[0016] The measurable property is one which depends on the
molecular composition of the triacylglycerol stock and reaches its
extreme values in the material prior to initiation of the
interesterification reaction and after randomization has been
achieved. After the interesterification has been allowed to proceed
to the point where the measurable property remains constant, the
absorbance of the mixture is determined. An additional incremental
amount of the basic catalyst may be added to form a second
catalyzed triacylglycerol stock. The second catalyzed
triacylglycerol stock allowed to interesterify until the measurable
property again attains a constant value and absorbance is then
measured. As used herein, the measurable property is considered to
no longer change (i.e., attained a constant value) when it does not
vary by more than about 5% upon further heating for a period of up
to about 1.0 hour at a temperature between 50.degree. C. and
200.degree. C. The repetition of these steps may be continued until
the measurable property no longer changes with a subsequent
addition of an incremental amount of the basic catalyst. The total
amount of catalyst required to be added to attain the equilibrium
value of the measurable property is referred to herein as the
"minimum randomization amount" of catalyst.
[0017] Alternatively, the minimum randomization amount of catalyst
may be determined by adding differing amounts of the catalyst to
separate samples of the triacylglycerol stock. For each sample, the
absorbance and the constant value of the measurable property
achieved after allowing interesterification to proceed are then
determined. As with the first alternative, the minimum
randomization amount is the level of catalyst above which higher
levels of catalyst do not produce any change in the measurable
property.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a graph showing the rate of interesterification of
a triacylglycerol stock as a function of reaction temperature and
reaction time as determined by the change of solid fat content at
40.degree. C. (0.5 wt. % NaOMe).
[0019] FIG. 2 is a graph showing the rate of interesterification of
a triacylglycerol stock as a function of reaction temperature and
reaction time as determined by the change of tristearin content
(0.5 wt. % NaOMe).
[0020] FIG. 3 is a graph of the time required for randomization of
a triacylglycerol stock and showing the semilogarithmic
relationship between reaction time and temperature.
[0021] FIG. 4 is a graph showing the effect of catalyst dosage (0.3
and 0.5 wt. % NaOMe) on interesterification of a triacylglycerol
stock at 70.degree. C.
[0022] FIG. 5 is a graph showing the effect of catalyst dosage (0.3
and 0.5 wt % NaOMe) on interesterification of a triacylglycerol
stock at 100.degree. C.
[0023] FIG. 6 depicts a typical absorption spectrum of a
triacylglycerol stock with 0.1, 0.13, 0.16 and 0.21 wt. % sodium
methoxide added.
[0024] FIG. 7 is a graph showing the dependence of absorbance (at
374.4 nm) of a refined, bleached and deodorized triacylglycerol
stock on the amount of sodium methoxide added.
[0025] FIG. 8 is a graph showing the solid fat contents of
triacylglycerol stocks partially interesterified at different
absorbencies.
[0026] FIG. 9 depicts DSC traces showing the degree of
interesterification of a triacylglycerol stock as a function of
reaction time for interesterification reaction conducted at
100.degree. C. for 15, 60 and 180 minutes (containing sufficient
NaOMe to afford an absorbance of 0.85).
[0027] FIG. 10 shows depicts DSC traces showing the degree of
interesterification of a triacylglycerol stock as a function of
temperature for interesterification reactions run for 30 minutes at
80.degree. C., 100.degree. C. and 120.degree. C. (containing
sufficient NaOMe to afford an absorbance of 0.58).
[0028] FIG. 11 shows a DSC trace of an unreacted 70:30 IMC-130/S8
oil blend (SFC at 40.degree. C.-35).
[0029] FIG. 12 shows a DSC trace of a 70:30 IMC-130/S8 oil blend
after partial interesterification at an absorbance of 0.65 (SFC at
40.degree. C.-26).
[0030] FIG. 13 shows a DSC trace of a 70:30 IMC-130/S8 oil blend
after complete randomization (SFC at 40.degree. C.-9).
DETAILED DESCRIPTION
[0031] The present method may be used to carry out the
interesterification of triacylglycerol stocks in a controlled and
reproducible manner. The present method may be utilized to provide
interesterification products with enhanced fluidity and melting
point characteristics as compared to their unmodified precursors.
For example, the method allows the controlled modification of
triacylglycerol stocks to produce fats having a reduced solid fat
content without altering the trans content of the modified stock
(relative to the trans content of the initial base stock). For
example, the present method allows the reproducible production of
partial interesterification products having increased solid fat
content compared to a fully randomized product without modifying
the trans content or the level of saturated fatty acids in the
stock.
[0032] Although the structuring properties of partially
interesterified blends may be slightly less pronounced than those
of the corresponding randomized mixture, price considerations can
favor the use of such partially interesterified mixtures. In
comparison to either a fully interesterified version of a
corresponding mixture of components or to a corresponding
uninteresterified fat blend, a partially interesterified fat blend
can also provide enhanced organoleptical characteristics.
[0033] A triacylglycerol stock includes triacylglycerol molecules
(sometimes termed triglycerides). In general, triacylglycerols
comprise three carboxylic acids esterified to glycerol; or,
alternatively phrased, glycerol esterified by addition thereto of
three carboxylic acids (typically saturated or unsaturated straight
chain carboxylic acids having from 2 to 22 carbon atoms). Herein,
the terms "triacylglycerols" and "triglycerides" are intended to be
interchangeable. In general, oils extracted from any given plant or
animal source comprise a mixture of triacylglycerols characteristic
of the specific source. The mixture of fatty acids isolated from
complete hydrolysis of the triacylglycerols in a specific source
are generally referred to as the "fatty acid composition". By the
term "fatty acid composition" reference is made to the identifiable
fatty acid residues in the various triacylglycerols. The
distribution of specific identifiable fatty acids is typically
characterized by the amounts of the individual fatty acids as a
weight percent of the total mixture of fatty acids isolated from
the triacylglycerol stock. The distribution of fatty acids in a
particular oil or fat may be readily determined by methods known to
those skilled in the art, such as by gas chromatography.
[0034] For example, a typical fatty acid composition of soybean oil
("SBO") is as shown in Table I below.
1TABLE I Typical SBO Fatty Acid Composition Fatty acid Weight
Percent.sup.1 Palmitic acid 10.5 Stearic acid 4.5 Oleic acid 23.0
Linoleic acid 53.0 .alpha.-Linolenic acid 7.5 Other 1.5
.sup.1Weight percent of total fatty acid mixture derived from
hydrolysis of soybean oil.
[0035] Palmitic and stearic acids are saturated fatty acids and
triacylglycerol acyl chains formed by the esterification of either
of these acids do not contain any carbon-carbon double bonds.
However, many fatty acids such as oleic acid, linoleic acid and
.alpha.-linolenic acid are unsaturated (i.e., contain one or more
carbon-carbon double bonds). Oleic acid is an 18 carbon fatty acid
with a single double bond; linoleic acid is an 18 carbon fatty acid
with two double bonds or points of unsaturation; and
.alpha.-linolenic is an 18 carbon fatty acid with three double
bonds. More specifically,
[0036] oleic acid is (Z)-9-octadecanoic acid;
[0037] linoleic acid is (Z,Z)-9,12-octadecadienoic acid;
[0038] .alpha.-linolenic acid is (Z,Z,Z)-9,12,15-octadecatrienoic
acid.
[0039] The degree of unsaturation of a triacylglycerol stock
strongly influences the melting point and fluidity characteristics
of the material. One measure of the average number of double bonds
present in the triacylglycerol molecules of an unsaturated
triacylglycerol stock is its Iodine Value. As referred to herein,
the Iodine Value of a triacylglycerol or mixture of
triacylglycerols is determined by the Wijs method (A.O.C.S. Cd
1-25). For example, soybean oil typically has an Iodine Value of
about 125 to about 135 and a pour point of about 0.degree. C. to
about -10.degree. C. Hydrogenation of soybean oil to reduce its
Iodine Value to about 90 or less can significantly decrease its
fluidity as evidenced by an increase in pour point to about
10.degree. C. to 20.degree. C. or higher.
[0040] Hydrogenation reactions which do not totally convert all
unsaturated fatty acids, however, tend to produce fatty acids
including a trans carbon-carbon double bond via isomerization
reactions. This is not always advantageous since concerns have been
raised over potential health implications of excessive consumption
of fats and/or oils containing "trans fatty acids." As used herein,
the term "trans fatty acid" refers to any fatty acid including a
trans carbon-carbon double bond. The "trans content" of a
triacylglycerol stock is a measure of the overall amount of trans
carbon-carbon double bonds in the stock and is defined as the wt. %
of trans fatty acids in the fatty acid composition of the stock.
The "trans content" of a triacylglycerol stock can be determined
using the method described in J.A.O.C.S., 54, 54 (1971) for
determining the trans content of a particular triacylglycerol
stock. Although the trans content of plastic fats may often run as
high as 50%, the fats, oils and other products of the present
invention typically include no more than about 30%, preferably no
more than about 10% and most preferably no more than about 1% trans
content. This may be achieved by partially interesterifying stocks
based on naturally occurring fats, oils and/or their partially and
fully hydrogenated derivatives.
[0041] The fluidity of a material is in part determined by the
ability of molecular packing, intermolecular interactions, and
molecular weight. In general, increasing branching of a
hydrocarbon, especially towards the methyl end, or introducing
unsaturation in the chain (cis typically produces a greater effect
than trans), increases fluidity since it disrupts packing. By
"increase in fluidity" in this context, reference is meant to
reduction in "pour point" or "melting point" as well as a decrease
in the viscosity at a specified temperature of a triacylglycerol
stock in a fluid state. The term "pour point" as used herein refers
to the temperature at which the material stops flowing (as measured
by ASTM method D 97). Thus pour point is a property which may
involve a phase change but generally is based on a change in the
viscosity properties of the material. The term "melting point" as
used herein refers to the temperature at which a material
transforms from a solid to a liquid, i.e., when a phase change
involving a heat of fusion occurs. In addition to pour point, the
viscosity of a triacylglycerol stock or modified version thereof at
room temperature or an elevated temperature (e.g., 40.degree. C.)
may be used to characterize its fluidity.
[0042] Another measure of the fluidity properties of a
triacylglycerol stock is the solid fat content as determined at one
or more temperatures. Solid fat content ("SFC") can be determined
by Differential Scanning Calorimetry ("DSC") using the method
described in generally in Example 1 herein. Fats with lower solid
fat contents have a lower viscosity, i.e., are more fluid, than
their counterparts with high solid fat contents.
[0043] Feedstocks employed in the present interesterification
process have generally been neutralized and bleached, and then
dried to a very low moisture content before catalyst is introduced
and the reaction is started. This is because catalysts lose some of
their activity in the presence of water, free fatty acids and
hydroperoxides. The triacylglycerol stock may have been processed
in other ways prior to interesterification, e.g., via
fractionation, hydrogenation, refining, and/or deodorizing.
Preferably, the feedstock is a refined, bleached triacylglycerol
stock.
[0044] In addition, to being generally more suitable and versatile
materials for use in producing food and beverage products, the
progress of interesterification reactions of triacylglycerol stocks
which have been bleached is typically easier to monitor via
absorbance. Unbleached oils typically include components which have
significant absorption at wavelengths between 300 nm and 600 nm.
Such components generally absorb light in the visible range and
have different absorption maxima than the reddish brown colored
species generated during interesterification. Computerized
subtraction techniques may be utilized to determine the spectrum
due to the presence of the active interesterification catalyst.
[0045] The reddish brown color which typically appears upon
initiation of a base catalyzed interesterification (generally
within minutes after the addition of the basic catalyst) absorbs at
wavelengths of spectra range from about 300 to about 500 nm and has
a peak absorption at about 370-380 nm. Interesterification
reactions may be conveniently monitored by determining the
absorbance of the reaction mixture at one or more selected
wavelengths within the range of about 300 to 500 nm. Preferably,
interestification is monitored at one or more wavelengths between
about 325 and 450 nm and, more preferably, between about 330 and
400 nm. In some instances, the reaction may be monitored by
measuring the absorbance at a single wavelength (preferably a
wavelength close to the absorption maxima, e.g., about 375 nm).
Where a significant degree of background absorbance is present,
such as with an unbleached vegetable oil, it may be preferable to
monitor a number of different wavelengths or to determine a
continuous spectrum over some or all of the 300 to 500 nm
range.
[0046] The absorbance of a reaction mixture undergoing base
catalyzed interesterification may be determined by a number of
techniques. One convenient method is to introduce a dual fiber
optic spectrometer (e.g., a PCD-1000 dual fiber optic spectrometer
available from Ocean Optics, Inc., Dunedin, Fla.) directly into the
reaction vessel. Another means of measuring the absorbance of the
reaction mixture is to employ an optical cell connected to the
reaction vessel. For example, the reaction mixture may be pumped
through a flow through optical cell connected to the reaction
vessel or the vessel may be constructed with a side arm optical
cell for monitoring the reaction.
[0047] The absorbance observed for a specified catalyst dosage can
vary somewhat for the same triacylglycerol stock under differing
experimental conditions. While the absorbance is essentially
unaffected by reaction temperature or the length of reaction time,
the configuration of the reactor, scale of the reaction, the type
and rate of mixing, air contact, as well as instrumental response
factors due to the method of determining the absorbance can lead to
minor but systematic variations in the absorbance measured. The
results reported herein, however, establish that for a fixed
reaction scale, reactor configuration and reaction conditions the
correlation between the degree of partial esterification and
absorbance is very reproducible.
[0048] Suitable basic catalysts for use in the present
interesterification include metal alkoxides (such as alkali metal
alkoxides), alkali metals (e.g., sodium metal), alkali metal
alloys, and metal hydroxides (such as alkali metal hydroxides).
Alkali metal alkoxides such as sodium methoxide, sodium ethoxide,
potassium methoxide, and potassium ethoxide are particularly
suitable for use as interesterification catalysts. Other examples
of materials which are commonly employed as an interesterification
catalyst include alkali metal alloys such as sodium/potassium alloy
and alkali metal hydroxides. When an alkali metal hydroxide such as
sodium hydroxide or potassium hydroxide is used as the catalyst, a
small amount of glycerol is also often added to the reaction
mixture. This may result in the production of alkoxides derived
from glycerol which can also act as a catalyst.
[0049] A suitable catalyst for interesterification is added to the
resulting mixture, the catalyst is activated and the temperature of
the reaction mixture is selected to bring about interesterification
at a convenient rate and is then typically maintained substantially
constant during the course of the reaction. Base catalyzed
interesterification reactions are, in general, carried out at
temperatures of about 50.degree. C. to about 150.degree. C. The
catalyst selected determines the temperature range in which the
reaction is typically carried out. Suitable reaction temperatures
for common catalyst systems are listed below.
[0050] Sodium methoxide . . . 50-120.degree. C.
[0051] Metallic sodium . . . 120-130.degree. C.
[0052] Sodium hydroxide/glycol . . . 150.degree. C.
[0053] Sodium hydroxide/water . . . 170.degree. C.
[0054] As mentioned above, the presence of water in the reaction
medium can lead to inactivation of the catalyst, particularly where
the catalyst includes a metal alkoxide, an alkali metal, or an
alkali metal alloy. Because of this, the starting triacylglycerol
stock is generally thoroughly dried prior to introduction of the
basic catalyst, preferably to a moisture content of no more than
about 0.04 wt. %, more preferably below about 0.01 wt. %, and most
preferably below about 0.005 wt. %. For example, the present
interesterification process may be conducted by heating the
triacylglycerol stock to at least about 100.degree. C. (e.g.,
110-120.degree. C.) under vacuum for at least about an hour to dry
the material. To preserve the dryness of the stock and avoid
inactivation of the catalyst, the present interesterification
reactions are preferably carried out under anhydrous conditions.
This may be achieved by running the reaction under vacuum or under
a blanket of inert gas (e.g., nitrogen or argon). The
triacylglycerol stock is then cooled to the desired reaction
temperature and an increment of the basic catalyst is added. After
a short period of time (e.g., up to about 60 minutes for reaction
temperatures between 50.degree. C. and 100.degree. C.), the
absorbance of the resulting mixture is determined and sufficient
additional amounts of the catalyst are added to achieve the desired
absorbance.
[0055] Interesterification may conveniently be carried out in batch
vessels of desired capacity. The vessels are generally be fitted
with heating/cooling coils, an agitator and a vacuum system.
Reaction can be quite rapid and will depend primarily on catalyst
loading and reaction temperature. At the end of the reaction
period, a quenching solution, typically water or dilute acid, may
be added to deactivate the catalyst completely thereby stopping the
reaction. After a short settling time the water phase may be
separated either by decantation or by centrifugation. The
interesterified oil blend is often then re-refined and/or
deodorized.
[0056] The interesterification reaction may be carried out at a
temperature (e.g., 50.degree. C. to 70.degree. C.) which causes the
reaction to proceed at a rate permitting its progress to be
continuously monitored via absorbance and stopped when a specific
desired degree of interesterification is achieved. The reaction may
be stopped at the desired point by the addition of a dilute acid
quenching solution, such as dilute sulfuric acid or phosphoric acid
solution.
[0057] The entire reaction may be performed in a single vessel
having appropriate means to vary the temperature of the reaction
mixture or, alternatively, the catalyst addition and activation may
be carried out in a first vessel, the reaction mixture cooled to
the desired interesterification temperature by passage through a
heat exchanger, for example, a plate heat exchanger and fed to a
second vessel where it is maintained at the interesterification
temperature. The latter arrangement can provide more rapid cooling
of the reaction mixture and can in some instances be used to
enhance the development of a solid fat phase during a directed
interesterification.
[0058] Interesterification may also be carried out continuously. In
this case, sodium- or potassium-alloy and/or metallic sodium are
often used as the catalyst. The triacylglycerol, stock is typically
continuously vacuum-dried to achieve a moisture content below
0.01%. Metallic sodium is introduced into the dry oil stream at a
very low level (e.g., no more than about 0.05%) and dispersed using
a high-shear mixer. The absorbance of the reaction mixture is
monitored using a flow cell. Sufficient residence time is provided
in a tubular reactor, after which catalyst may be deactivated with
steam, followed by water-washing and centrifugal separation of the
mixture.
[0059] The degree of interesterification can be measured based on a
variety of properties of the triacylglycerol stock. Suitable
examples include the amount of a specific triacylglycerol (e.g.,
tristearin), the solid fat content of the triacylglycerol stock at
a given temperature (e.g., at 40.degree. C. (104.degree. F.)),
carbon number analysis (i.e., the percentage of triglycerides
having a specified number of carbons), and the melting point of the
triacylglycerol stock.
[0060] As used herein, the term "degree of interesterification" is
defined by the formula
(Xt-Xo)/(Xeq-Xo).times.100%
[0061] wherein
[0062] X is a measurable property depending on the molecular
composition of the triacylglycerol stock that reaches its extreme
value after randomization of the composition (relative to the value
of the measurable property prior to initiation of
interesterification);
[0063] Xo is the value of X prior to initiation of the
interesterification;
[0064] Xeq is the value of X after interesterification of the
triacylglycerol stock to randomization; and
[0065] Xt is the value of X for the triacylglycerol stock for which
the degree of conversion is to be determined.
[0066] The terms "fat" and "oil" are used in this specification as
synonyms with the term "triacylglycerol stock." Triacylglycerol
stocks from which lower melting constituents have been removed will
be indicated as "stearin fractions". A stearin fraction for the
purpose of this description and claims is defined as a mixture or
fat blend from which some of the lower melting constituents
(typically at least about 10%) have been removed by of
fractionation, e.g., dry fractionation or solvent fractionation.
For example, palm oil which has had at least 10% of the lower
melting constituents removed via fractionation is referred to as
"palm stearin." Similarly, as used herein, an olein fraction is a
triacylglycerol stock from which higher melting triacylglycerols
have been removed. Typically, an olein fraction is produced by
removing at least 5% of the higher melting triacylglycerols from a
triacylglycerol stock via a fractionation process.
[0067] Crystal fractionation is one common method of modifying a
triacylglycerol mixture and can be carried out with and without
solvents, with and without agitation. The crystal fractionation can
be repeated several times. Crystal fractionation is a particularly
effective method of removing higher melting triacylglycerols.
Removal of higher melting triacylglycerols can in turn alter the
melting profile of the triacylglycerol mixture.
[0068] A triacylglycerol stock which is particularly suitable for
modification using this process is a triacylglycerol stock which is
a blend of a hardstock component and a softstock component. The
terms "hardstock" and "hardstock component" refer to
triacylglycerol stocks of which a substantial portion and,
typically, at least about 40% and often 70% or higher, of the fatty
acyl chain are saturated. Hardstocks are typically solid at room
temperature. In addition to fully hardened triacylglycerol stocks
(i.e., stocks which are essentially completely saturated and have
an Iodine Value of no more than about 10), lard and tallow are
examples of suitable triacylglycerol stocks which may make up all
or a portion of the hardstock component. The degree of saturation
of a hardstock can also be characterized in terms of the Iodine
Value of the stock. Hardstock components typically have
.alpha.-Iodine Value of no more than about 90 and preferably no
more than about 70. For example, lard typically has an Iodine Value
of 48-65, while the Iodine Value for tallow ranges from 40-55. Less
saturated fractionation products such as lard olein and tallow
olein may have Iodine Values as high as 90. Other suitable fats for
use in hardstock components include vegetable oil-based
triacylglycerol stocks having an Iodine Value of no more than about
90 and preferably no more than about 70 or tropic oils containing
high levels of saturated fatty acids (SAFAs). This latter category
includes tropic oils such as palm oil and babasu oil.
[0069] With respect to the choice of the softstock, lauric fat,
liquid oil or a mixture thereof may be used. By lauric fat is meant
a fat having a content of lauric acid residues of at least 40%,
preferably at least 45%. In practice the lauric fats will be
coconut oil or palm kernel oil, although in principle other lauric
fats can be used as well. Although the structuring effect of lauric
fats may be increased by hardening (e.g., by hydrogenation), and in
particular fully hardening before the interesterification, this
option is less preferred than using unhardened lauric fats having
regard to naturalness and other considerations mentioned herein.
For enhancing the structuring effect thereof, in a preferred
embodiment, the lauric fats are fractionated and the stearin
fraction of those fats as occurring in nature are used in the
interesterification.
[0070] The term "liquid oil" is used in this specification for
glyceride mixtures that are free of solids at 20.degree. C. and
preferably at 10.degree. C. Particularly liquid oils containing at
least 40% of unsaturated fatty acids (UFA) and in particular of
poly-unsaturated fatty acids (PUFA), especially linoleic acid, are
of importance. Preferably, the liquid oil is vegetable oil.
Specifically, the liquid oil preferably comprises sunflower oil,
soybean oil, rapeseed oil, cottonseed oil, groundnut oil, corn oil,
safflower oil, canola oil, linseed oil, high oleic acid containing
oils (e.g. high oleic sunflower oil, high oleic soybean oil or high
oleic rapeseed oil), high stearic and/or palmitic acid containing
oils (e.g. high stearic/palmitic sunflower oil, high
stearic/palmitic soybean oil or high stearic/palmitic canola oil),
or a mixture of two or more of these oils.
[0071] One example of a suitable embodiment of the invention is the
partial interesterification product of a blend which includes a
lauric fat, preferably palm kernel stearin or possibly fully
hardened palm kernel oil. The blend also typically includes a
hardstock having at least about 65% and preferably more saturated
fatty acid residues (SAFA). Most preferred is palm stearin with a
high melting point, e.g., from solvent fractionation. As an
alternative, e.g., fully hardened palm oil can be used. The
resulting fat blend is a particularly suitable for partial
interesterification together with high contents of liquid oil for
making so-called health spreads.
[0072] For certain applications, partial interesterification
products can be used as margarine fat without incorporation of
liquid oil, e.g., for bakery applications or spreads for tropical
countries if no chilled distribution is used. On the other hand,
for making soft spreads packed in tubs, very high contents of
liquid oil may be desired in the margarine fat. The present partial
interesterification method can provide triacylglycerol stocks
having a higher liquid oil content than either the fully randomized
counterpart or the starting unreacted stock (see e.g., Examples
10-12). This is especially useful for producing plastic fats such
shortenings, stick margarines and tub margarines having desirable
melting, crystallization and fluidity characteristics while
minimizing the trans content of the product (e.g., to less than
about 5% trans content). The desired solid fat and liquid oil
contents of plastic fats will vary based on their uses. For
example, while plastic fats in general have a solid fat content at
40.degree. C. of no more than about 20%, all purpose shortenings
preferably have a solid fat content at 40.degree. C. of no more
than about 15% and margarines typically have a solid fat content at
40.degree. C. of no more than about 2%.
[0073] The present partial interesterification products are useful
in a wide variety of food and beverage products. For example, the
partial interesterification products can be used in the production
of baked goods in any form, such as mixes, shelf-stable baked
goods, and frozen baked goods. Possible applications include, but
are not limited to, cakes, brownies, muffins, bar cookies, wafers,
biscuits, pastries, pies, pie crusts, and cookies, including
sandwich cookies and chocolate chip cookies. The baked goods can
contain fruit, cream, or other fillings. Other baked good uses
include breads and rolls, crackers, pretzels, pancakes, waffles,
ice cream cones and cups, yeast-raised baked goods, pizzas and
pizza crusts, baked farinaceous snack foods, and other baked salted
snacks.
[0074] In addition to their uses in baked goods, the partial
interesterification products can be used alone or in combination
with other regular and/or reduced calorie fats and oils to make
shortening and oil products. Suitable sources of regular fats and
oils include, but are not limited to: 1) vegetable fats and oils
such as soybean, corn, sunflower, rapeseed, low erucic acid
rapeseed, canola, cottonseed, olive, safflower, and sesame seed; 2)
meat fats such as tallow or lard; 3) marine oils; 4) nut fats and
oils such as coconut, palm, palm kernel, or peanut; 5) milkfat; 6)
cocoa butter and cocoa butter substitutes such as shea, or illipe
butter; and 7) synthetic fats. Shortening and oil products include
but are not limited to, shortenings, margarines, spreads, butter
blends, lards, salad oils, popcorn oils, salad dressings,
mayonnaise, and other edible oils.
[0075] Representative of fat-containing food products which can
contain, in addition to other food ingredients, the present partial
interesterification products in full or partial replacement of
another natural or synthetic fat are: frozen desserts, e.g., frozen
novelties, ice cream, sherbet, ices, and milk shakes; salad
dressings; mayonnaises and mustards; dairy and non-dairy cheese
spreads; margarine, margarine substitutes and blends; flavored
dips; flavored bread or biscuit spreads; filled dairy products such
as filled cream and filled milk; frying fats and oils; cocoa butter
replacements and blends; candy, especially fatty candies such as
those containing peanut butter or chocolate (to which antibloom
properties may be imparted); reformed and comminuted meats; meat
substitutes and extenders; egg products and substitutes; nut
products, such as peanut butter; vegetable and fruit products; pet
foods; whipped toppings; compound coatings; coffee lighteners,
liquid and dried; puddings and pie fillings; frosting and fillings;
chewing gum; breakfast cereals; bakery products, e.g., cakes,
breads, rolls, pastries, cookies, biscuits, and savory crackers and
mixes or ingredient premixes for any of these. The partial
interesterification products of this invention may also be employed
in any flavor, nutrient, drug or functional additive delivery
system.
[0076] The partial interesterification products can also be used in
combination with noncaloric or reduced calorie fats, such as
branched chain fatty acid triglycerides, triglycerol ethers,
polycarboxylic acid esters, sucrose polyethers, neopentyl alcohol
esters, silicone oils/siloxanes, and dicarboxylic acid esters.
Other partial fat replacements useful in combination with the
partial interesterification products are medium chain
triglycerides, highly esterified polyglycerol esters, acetin fats,
plant sterol esters, polyoxyethylene esters, jojoba esters,
mono/diglycerides of fatty acids, and mono/diglycerides of
short-chain dibasic acids.
[0077] The present partial interesterification products can also be
fortified with vitamins and minerals, particularly fat-soluble
vitamins. For example, U.S. Pat. No. 5,034,083 (incorporated by
reference herein) discloses polyol fatty acid polyesters fortified
with fat-soluble vitamins. Examples of suitable fat-soluble
vitamins include vitamin A, vitamin D, vitamin E, and vitamin K.
The amount of fat-soluble vitamins employed to fortify the present
partial interesterification product-containing compositions can
vary. If desired, the compositions may be fortified with a
recommended daily allowance (RDA), or increment or multiple of an
RDA, of any of the fat-soluble vitamins or combinations
thereof.
[0078] The invention will be further described by reference to the
following examples. These examples illustrate but do not limit the
scope of the invention that has been set forth herein.
EXAMPLE 1
[0079] An oil mixture, prepared from IMC-130 canola oil and fully
hydrogenated soybean oil ("S8," Iodine Value<10) at the ratio of
70:30 (w/w), was used as the starting oil mixture. The starting oil
mixture contained 6.9% palmitic ("P"), 28.3% stearic ("S"), 54.5%
oleic ("O"), 8.3% linoleic ("L") and 1.2% trans acids. Table 1
lists the main triglyceride compositions of stock oils. IMC-130, a
high oleic canola oil, contains 85% triunsaturated triglycerides,
mainly LOO and OOO. S8 (a fully hydrogenated soybean oil) was
determined to contain essentially only PSS and SSS. The IMC-130/S8
oil mixture (70:30) contains 26% trisaturated triglycerides (PSS
and SSS) and has a softening point of 60.degree. C. (140.degree.
F.).
2TABLE 1 The Triglyceride Compositions of Selected Oils Oils** LnOO
LOO LOP OOO OOP OOS PSS SSS IMC-130 7.36 19.16 1.87 58.66 5.86 2.48
0.09 --* S8 -- -- -- -- -- -- 27.49 70.59 70:30 5.15 13.41 1.31
41.06 4.1 1.74 5.28 21.18 Mixture * - not detected. ** - P -
palmitic; O - oleic; S - stearic; L - linoleic; Ln - Linolenic.
[0080] One hundred grams of the oil mixture was dried at
110-120.degree. C. for 60 min under about 10 mm Hg vacuum and then
cooled to the desired experimental temperature (60-120.degree. C.).
A controlled amount of freshly prepared sodium methoxide was added
under stirring to initiate interesterification. About 1 gram of oil
was sampled at various time intervals during the reaction for
analyses of melting curves and triglyceride profiles.
[0081] The interesterifications were conducted at various
temperatures with two levels of catalyst: 0.3% and 0.5% (w/w) of
freshly prepared sodium methoxide. The oils were sampled during the
reaction and their solid fat contents and triglyceride profiles
were measured by differential scanning calorimetry (DSC) and
high-performance liquid chromatography (HPLC), respectively. The
solid fat contents were calculated and expressed as the percentage
of integrated areas of total melting curves at 10, 21.1, 26.7, 33.3
and 40.degree. C. The solid fat contents (SFCS) at 40.degree. C.
were used as the indicator of the progress of interesterification.
Similarly, the triglyceride compositions were analyzed by HPLC and
calculated by the area percentage of HPLC chromatogram because the
calibration indicated that response factors were similar among the
various types of triglycerides in the experimental oils. The
concentration of tristearin was used to indicate the progress of
reaction.
[0082] Spectroscopic analysis and the progress of
interesterification:
[0083] A reddish brown color always appears in the reaction mixture
upon initiation of interesterification. The ultraviolet and visible
spectra of the reaction mixture were studied to quantitate the
color change. A PCD-1000 Dual Fiber Optic Spectrometer (Ocean
Optics, Inc., Dunedin, Fla., USA) was used as on-line monitor. The
peak absorbance developed with a given amount of sodium methoxide
during interesterification was determined; solid fat contents and
triglyceride compositions of these oils interesterified at certain
absorption values were determined to evaluate the degree of
interesterification. The effects of time and temperature on the
degree of interesterification at the defined absorption values were
also studied.
[0084] Scaled partial interesterification:
[0085] One kilogram of oil mixture was dried and partially
interesterified at a certain peak absorbance. The interesterified
oils were evaluated by DSC and HPLC for their solid fat contents
and triglyceride profiles. A group of experiments was conducted to
test the reproducibility of partial interesterification.
[0086] Melting Curves by Differential Scanning Calorimetry
(DSC):
[0087] About 10 mg of oils were loaded into stainless steel pans.
The DSC was programmed as the following and the melting curves from
-30 to 70.degree. C. were used to calculate the solid contents. The
solid fat contents were calculated by percentage of area at the
temperature over the total area.
3TABLE 2 DSC Heating and Cooling Program Temperature (.degree. C.)
Time (Minute) Rate (.degree. C./Min) 30 0 50 75 0.5 20 -30 10 10 70
-- --
[0088] HPLC:
[0089] The triglyceride profiles were analyzed under the following
conditions: Spherisorb C18 column, 15 cm.times.4.6 mm S3 ODS2;
Waters Alliance 2690 pump; ELSD IIA detector (Varex, Md.). The
mobile phase was a mixture of dichloromethane and acetonitrile at
0.7 mL/min. The peaks were identified by triglyceride standards and
oils with known triglyceride compositions. The area percentage was
used to quantiate the composition of triglycerides. The column
temperature was 40.degree. C.
4TABLE 3 HPLC Solvent Gradient Time (min) Dichloromethane
Acetonitrile 0 20 80 1 30 70 30 60 40 31 20 80 35 20 80
[0090] Interesterification was conducted at various temperatures
with 0.3 or 0.5 wt. % sodium methoxide. The lower amount, 0.3 wt.
%, represents the commonly used dosage in industrial
interesterification reactions and supplies an excess of catalyst to
guarantee full randomization in case inactivating factors are
present in the reaction mixture. Therefore, 0.5 wt. % sodium
methoxide provides an additional excess of catalyst to ensure fast
randomization.
[0091] The rate of interesterification increased with increasing of
reaction temperature as determined by solid fat content ("SFC") and
tristearin ("SSS") content (FIGS. 1 and 2). The SFC at 40.degree.
C. is an indirect measurement of tristearin; therefore, both data
have the similar pattern. The time required for randomization
ranges from 20 min at 60.degree. C. to 1 min at 100.degree. C.
Reaction time and temperature have a semilograthmic relationship
(FIG. 3). Therefore, increased temperature is effective in reducing
the reaction time required to achieve complete randomization.
[0092] The rate of interesterification also depends on the amount
of sodium methoxide. Interesterification proceeds more slowly at a
low dosage than at a high dosage of catalyst (see e.g., FIGS. 4-5).
The reaction was only 65% and 50% of complete with 0.3 wt. % NaOMe
compared to 100% with 0.5 wt. % NaOMe after 6, 3 and 1 minute at
70.degree. C. and 100.degree. C. With either catalyst dosage,
interesterification was faster at the higher temperature.
EXAMPLE 2
Absorption Spectrum and its Utilization
[0093] A reddish brown color always appeared upon initiation of
sodium methoxide catalyzed interesterification. It was observed
that the color density increased with the dosage of catalyst. The
UV/Visible spectra of oils with at various levels of catalyst added
were measured--minutes after the addition of sodium methoxide. The
wavelengths of spectra range from 300 to 500 nm and show a peak at
374.4 nm as determined by PCD-1000 dual fiber optic spectrometer
(FIG. 6). Within this range, the oil will absorb blue light and has
a characteristic reddish brown color.
[0094] The intensity of color induced was linearly related to the
amount of sodium methoxide added to the reaction mixture at
60-120.degree. C. (see FIG. 7). Sodium methoxide is reactive to
moisture and acidic chemicals in air and oil, so any change in the
environments such as oil quality and drying system efficiency would
significantly affect the amount of active sodium methoxide, which
then determines the amount of real catalyst in the reaction
mixture. The amount of active sodium methoxide is very difficult to
be measured in situ; therefore, this technique overcomes this
difficulty and provides a measure of the amount of catalyst
present.
[0095] Interesterifications were then conducted in which the
absorbance at 374.4 nm was held constant at various levels (FIG.
8). Initiation of interesterification was observed at absorbencies
above 0.4 and randomization occurred in reaction mixtures in which
enough catalyst was present to bring the absorbance to above 1.0.
This observation provides a technique to monitor
interesterification on-line for quality control and to minimize the
amount of catalyst employed.
EXAMPLE 3
Effect of Temperature and Reaction Time
[0096] A series of partially interesterified oils was prepared by
controlling oil absorbencies below the peak absorbency of 1.0
(corresponding to the minimum minimum randomization amount of
catalyst). The degree of partial interesterification depended on
the absorbance and did not change with increased reaction time or
temperature (see FIGS. 9 and 10). FIG. 10 shows DSC traces of the
70:30 IMC-130/S8 mixture containing sufficient NaOMe to afford an
absorbance of 0.58 after interesterification for 30 minutes at
80.degree. C., 100.degree. C. and 120.degree. C.
EXAMPLE 4
Kilogram Scale Partial Interesterifications
[0097] Three separate partial interesterifications were conducted
at one kilogram scale by controlling oil absorbencies. The close
correspondence of the solid fat contents and triacylglycerol
profiles of the three runs (Tests #1-3) indicate that the use of
absorbance to monitor partial interesterification is a very
reproducible technique (see Table 4 and 5). The absorbances
measured for sufficient catalyst to initiate reaction and achieve
randmization with the larger scale reaction were slightly different
from those observed on a small scale. The experiments demonstrated,
however, that when run under the same conditions, the degree of
partial interesterification was reproducible for a given set of
conditions.
5TABLE 4 The SFCs of Oils Interesterified at an Absorbance of 0.9 %
SFC by DSC Test # 10.degree. C. 21.1.degree. C. 26.7.degree. F.
33.3.degree. C. 40.degree. C. 1 49 28 26 18 12 2 48 30 28 20 13 3
46 28 26 19 12
[0098]
6TABLE 5 Triacylglycerol Profiles of Oils Interesterified at an
Absorbance of 0.9 STARTING SAMPLE TAG BLEND TEST 1 TEST 2 TEST 3
RANDOMIZED LnOO 3.96 3.36 3.51 3.43 1.61 LOO 11.63 9.67 9.96 9.94
5.32 LOP 1.09 1.88 1.84 1.84 2.39 OOO 45.03 36.38 37.29 38.01 17.76
LOS -- -- -- -- 6.93 OOP 3.74 5.26 5.29 5.23 6.04 OOS 1.63 13.43
12.33 12.71 33.32 OPS -- 2.12 1.87 1.94 4.52 PPS -- 0.77 0.75 0.75
0.74 OSS -- 7.28 6.48 6.57 14.96 PSS 6.84 4.11 4.11 4.15 1.11 SSS
24.09 12.86 13.04 13.35 1.99
EXAMPLE 5
[0099] Three one hundred gram lots of the 70:30 IMC-130/S8 oil
mixture were dried at 110-120.degree. C. for 60 min under about 10
mm Hg vacuum and then cooled to 90.degree. C. Interesterification
was conducted at absorbances of 1.0, 1.1 and 1.3 respectively at
374.4 nm for 30 min by adding the proper amount of sodium methoxide
under stirring. The reaction was stopped by addition of 10 ml of 1%
sulfuric acid. After drying, the oil was sampled for DSC
measurement. The solid fat contents at at 10, 21.1, 26.7, 33.3 and
40.degree. C. were determined. The results are listed in Table
6.
7TABLE 6 Solid Fat Contents of Interesterified Oil Mixtures. Wt. %
% SFC by DSC Sample NaOMe Absorb. 10.degree. 21.1.degree.
26.70.degree. 33.3.degree. 40.degree. 0 0 0 42 38 38 37 35 5A 0.30
1 47 25 22 15 9 5B 0.35 1.1 47 25 22 15 9 5C 0.5 1.3 47 25 22 15
9
EXAMPLE 6
[0100] A 100 gram sample of the 70:30 IMC-130/S8 oil mixture was
dried at 110-120.degree. C. for 60 min under about 10 mm Hg vacuum
and then cooled to 100.degree. C. Interesterification was conducted
at an absorbance of 0.75 at 374.4 nm after adding the proper amount
of sodium methoxide under stirring. Aliquots were removed after 15,
60 and 180 minutes and each aliquot was quenched by addition of 10
ml of 1% carbonate. After drying, the solid fat contents of each
aliquot was determined at at 10, 21.1, 26.7, 33.3 and 40.degree. C.
by DSC. The results are listed in Table 7. FIG. 9 shows DSC traces
of the 70:30 IMC-130/S8 mixture after interesterification for 15,
60 and 180 minutes and demonstrates that the reaction product was
not altered by heating for longer times.
8TABLE 7 Solid Fat Contents of Interesterified Oil Mixtures.
Reaction % SFC by DSC Time 10.degree. 21.1.degree. 26.7.degree.
33.3.degree. 40.degree. 15 min 45 33 32 24 18 60 min 45 32 30 23 17
180 min 45 32 30 23 17
EXAMPLE 7
[0101] Table 8 shows the solid fat contents of samples of a 50:50
mixture of canola oil (Clear Valley 65--"CV65") and a fully
hydrogenated soybean oil ("S8"). 100 gram samples were
interesterified at 110.degree. C. for 30 minutes following the
procedure generally described in Example 5. Sufficient sodium
methoxide was added to each sample to achieve the indicated
absorbance.
9TABLE 8 Interesterified Canola Oil/Hydrogenated Soybean Oil
Mixtures. % SFC by DSC Absorb. 10.degree. C. 21.1.degree. C.
26.7.degree. C. 33.3.degree. C. 40.degree. C. 7-1 0 50 45 45 45 45
7-2 0.56 49 46 46 42 40 7-3 0.65 51 40 40 37 31 7-4 0.76 51 38 38
35 29 7-5 0.88 50 33 29 28 21 7-6 0.93 51 33 28 27 20 7-7 1.01 50
33 28 26 19 7-8 1.25 50 32 26 24 18
[0102] To determine the reproducibility of the correlation between
absorbance and the degree of partial interesterfication (as
determined by % SFC by DSC), additional 100 gram samples were
interesterfied under the same conditions at an absorbance of about
0.57 (Samples 7-9, 7-10 and 7-11) or 0.78 (Samples 7-12, 7-13 and
7-14). The degree of interesterification (based on % SFC by DSC)
observed for these latter samples agrees well with that predicted
from the results obtained with samples 7-1 through 7-8 shown in
Table 9 below.
10TABLE 9 Interesterified Canola Oil/Hydrogenated Soybean Oil
Mixtures. % SFC by DSC Sample Absorb. 50.degree. F. 70.degree. F.
80.degree. F. 90.degree. F. 104.degree. F. 7-9 0.57 51 44 44 40 36
7-10 0.57 51 46 46 42 38 7-11 0.57 49 45 45 43 39 7-12 0.78 52 37
36 35 28 7-13 0.79 51 37 36 35 27 7-14 0.78 52 39 39 33 30
EXAMPLE 8
[0103] Table 10 shows the solid fat contents of samples of a 50:50
mixture of palm stearin and palm kernel stearin. 100 gram samples
were interesterified at 110.degree. C. for 30 minutes following the
procedure generally described in Example 5. Sufficient sodium
methoxide was added to each sample to achieve the indicated
absorbance.
11TABLE 10 Interesterified Palm Stearin/Palm Kernel Stearin
Mixtures. % SFC by DSC Sample Absorb. 10.degree. C. 21.1.degree. C.
26.7.degree. C. 33.3.degree. C. 40.degree. C. 8-1 0 100 81.3 56.2
20.1 4.1 8-2 0.54 95 76 51 19 0.8 8-3 0.62 96 79 54.7 20.9 0.8 8-4
0.66 93.4 76.5 52.3 19 0.3 8-5 0.78 92.4 76.8 53.9 20.1 0.3 8-6
0.88 90.7 75.3 53.1 18.8 0.1 8-7 0.98 89.9 74.3 52.3 17.8 0.1 8-8
1.04 89.7 73.2 50.5 15.7 0.1
[0104] To determine the reproducibility of the correlation between
absorbance and the degree of partial interesterfication (as
determined by % SFC by DSC), additional 100 gram samples were
interesterfied under the same conditions at an absorbance of about
0.8 (Samples 8-9 and 8-10), 0.57 (Samples 8-11 and 8-12) or 0.77
(Samples 7-13 and 7-14). The degree of interesterification (based
on % SFC by DSC) observed for these latter samples (shown in Table
11 below) agrees well with that predicted from the results obtained
with samples 8-1 through 8-8.
12TABLE 11 Interesterified Palm Stearin/Palm Kernel Stearin
Mixtures. % SFC by DSC Sample Absorb. 10.degree. C. 21.1.degree. C.
26.7.degree. C. 33.3.degree. C. 40.degree. C. 8-9 0.8 92.1 75.4
51.3 17.3 0.1 8-10 0.8 92.3 76 52.3 18.2 0.1 8-11 0.56 96.4 76.5
50.4 17.5 0.8 8-12 0.58 95.3 77.2 52 18.8 0.6 8-13 0.78 92.4 76.8
53.9 20.1 0.3 8-14 0.76 94.5 78.1 53.8 20.1 0.3
EXAMPLE 9
[0105] Table 12 shows the solid fat contents of samples of a 50:50
mixture of palm stearin and CV65 canola oil. 100 gram samples were
interesterified at 110.degree. C. for 30 minutes following the
procedure generally described in Example 5. Sufficient sodium
methoxide was added to each sample to achieve the indicated
absorbance.
13TABLE 12 Interesterified Palm Stearin/ Canola Oil Mixtures. % SFC
by DSC Sample Absorb. 10.degree. C. 21.2.degree. C. 26.7.degree. C.
33.3.degree. C. 40.degree. C. 9-1 0 46 37.1 28.4 18.4 7.2 9-2 0.54
43.2 33.6 24.5 14.6 3.6 9-3 0.76 43.1 30.3 21.1 11.5 1.5 9-4 0.86
42.6 23.8 14.8 6 0 9-5 0.96 41.5 20.4 11.6 3.5 0 9-6 0.98 40.9 19.8
11.1 3.1 0 9-7 1.01 40.9 19.9 11.2 3.2 0
[0106] To determine the reproducibility of the correlation between
absorbance and the degree of partial interesterfication (as
determined by % SFC by DSC), additional 100 gram samples were
interesterfied under the same conditions at an absorbance of
0.86-0.89 (Samples 9-8 and 9-9). The degree of interesterification
(based on % SFC by DSC) observed for these latter samples (shown in
Table 13 below) agrees well with that predicted from the results
obtained with samples 9-1 through 9-7.
14TABLE 13 Interesterified Palm Stearin/ Canola Oil Mixtures. % SFC
by DSC Sample Absorb. 10.degree. C. 21.2.degree. C. 26.7.degree. C.
33.3.degree. C. 40.degree. C. 9-8 0.89 42.8 23.8 14.7 5.9 0.1 9-9
0.86 42.6 23.8 14.8 6 0
EXAMPLE 10
[0107] Table 14 shows the solid fat contents (as % determined by
DSC) of a number of commercial fats. Examples of stick margarine,
soft spread tub margarine and shortening are included.
15TABLE 14 Solid Fat Contents of Commercial Fats % SFC by DSC
Product 10.degree. C. 21.1.degree. C. 26.7.degree. C. 33.3.degree.
C. 40.degree. C. Soft Margarine* 50.2 30.7 18.1 5.2 0 Stick
Margarine 71.5 42.7 23.5 5.4 0.1 (Imperial .TM.) Crisco All 55 50
41 31 18 Vegetable Shortening Cargill All 57.2 44 34 24 14.5
Purpose Shortening *I Can't Believe It's Not Butter .TM. Tub
Spread
[0108] Commercial All Purpose Shortenings such as the two listed in
Table 14 typically have trans contents on the order of 30-40%. To
explore the potential of interesterification to permit the
production of lower trans content shortenings, two very low trans
content shortenings (<4% trans content) were prepared. Sample
10-1 was an 85:15 mixture of the 0.88 absorbance partially
interesterified oil stock described in Example 7 ("7-5 Basestock")
and palm kernel oil. Sample 10-2 was an 78:22 mixture of (i) a
completely interesterified mixture of canola oil and palm kernel
oil described in Example 7 ("7-8 Basestock") and (ii) palm kernel
oil. The total liquid oil portion of the blend containing the
partially interestified stock was 9% higher than the formulation
based on a completely interesterified stock and thus has a lower
total saturate content while still achieving the desired solid fat
content profile.
16TABLE 15 All Purpose Shortenings % SFC by DSC Product 10.degree.
C. 21.2.degree. C. 26.7.degree. C. 33.3.degree. C. 40.degree. C.
Crisco .TM. 55 50 41 31 18 Cargill 57.2 44 34 24 14.5 All Purpose
10-1 58 43 37 25 18 10-2 60 46 38 22 14 7-5 50 33 29 28 21
Basestock 7-8 50 32 26 24 18 Basestock
EXAMPLE 11
[0109] Commercial soft spread margarines, such as the example
listed in Table 16, typically have trans contents on the order of
8-15%. To explore the potential of interesterification to permit
the production of lower trans content soft spread margarines, two
very low trans content soft spread margarines (<4% trans
content) were prepared. Sample 11-1 was an 90:5:5 mixture of (i)
the 0.86 absorbance partially interesterified oil stock described
in Example 9 ("9-4 Basestock"), (ii) palm kernel oil, and (iii)
palm kernel stearin. Sample 11-2 was an 80:10:10 mixture of a
completely interesterified 50:50 CV65 canola oil/palm stearin oil
blend stock described in Example 9 ("9-7 Basestock"), (ii) palm
kernel oil, and (iii) palm kernel stearin. The blend containing the
partially interesterified stock (11-1) had 12.5% more liquid oil
than the formulation based on a completely interesterified stock
(11-2) and thus has a lower total saturate content while still
achieving the desired solid fat content profile.
17TABLE 16 Soft Spread Margarines % SFC by DSC Product 10.degree.
C. 21.2.degree. C. 26.7.degree. C. 33.3.degree. C. 40.degree. C.
Comm'l Spread 50 31 18 5 0 Ex 11-1 48 29 19 6.5 0 Ex 11-2 52 33 20
5 0 9-4 42.6 23.8 14.8 6 0 Basestock 9-7 40.9 19.9 11.2 3.2 0
Basestock
EXAMPLE 12
[0110] Commercial stick margarines, such as Imperial.TM. margarine,
typically have trans contents on the order of 20-30%. To explore
the potential of interesterification to permit the production of
lower trans content stick margarine, two very low trans content
stick margarines (<4% trans content) were prepared. Sample 12-1
was an 30:35:35 mixture of (i) CV65 canola oil, (ii) the 0.56
absorbance partially interesterified oil stock described in Example
8 ("8-11 Basestock"), and (iii) coconut oil. Sample 12-2 was an
25:25:50 mixture of (i) CV65 canola oil, (ii) palm kernel oil, and
(iii) a completely interesterified 50:50 blend palm kernel oil and
palm kernel stearin. The blend containing the partially
interesterified stock (12-1) had 20% more liquid oil than the
formulation based on a completely interesterified stock (12-2) and
thus has a lower total saturate content while still achieving the
desired solid fat content profile.
18TABLE 17 Stick Margarines % SFC by DSC Product 10.degree. C.
21.2.degree. C. 26.7.degree. C. 33.3.degree. C. 40.degree. C.
Imperial .TM. 71 43 24 5 0 12-1 69 47 24 6 0.3 12-2 70 49 23 5 0
8-11 96.4 76.5 50.4 17.5 0.8 Basestock
EXAMPLE 13
[0111] Table 18 shows the solid fat contents (as % determined by
DSC) of a number of stock oils. Examples of hardstock, liquid oil
and lauric fat are included.
19TABLE 18 Solid Fat Contents of Stock Oils % SFC by DSC Oil
10.degree. C. 21.2.degree. C. 26.7.degree. C. 33.3.degree. C.
40.degree. C. Coconut Oil 100 57 4 0 0 CV65 Canola Oil 0 0 0 0 0 S8
Hydrogenated 100 100 100 100 100 Soybean Oil Palm Oil 33 32 22 11 1
Palm Stearin 53 53 53 43 28 Palm Kernel Oil 96 60 18 0 0 Palm
Kernel 99 97 91 22 0 Stearin Palm Kernel 88 32 1 0 0 Olein
[0112] The invention has been described with reference to various
specific and preferred embodiments and techniques. The invention is
not to be construed, however, as limited to the specific
embodiments disclosed in the specification. It should be understood
that many variations and modifications may be made while remaining
within the spirit and scope of the invention.
* * * * *