Note: Descriptions are shown in the official language in which they were submitted.
B,3ckqro~Jnd_of the InvPntion
The field of this invention is emulsifiers, and more
specifically a lecithin emulsifier and an improved process for
lecithin hydrogenation. The emulsifier of this invention dis-
plays improved emulsification characteristics in addition to
imparting a desirable texture to food products. Food product
improvements derived from the use of this emulsifier include:
20 the ability to produce larger and moister baked products, e.g.
caXes; improved yeast-leavened products such as breads and coffee
cakes; increased water variation, mixing time, and mixing speed
tolerance in formula mixes; lower cholesterol content in baXed
goods due to the substitution of the lecithin emulsifier for
,~.;j,i. -. . ..
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104;~709
conventional egg yolks; reduced spattering in the frying of foods;
and finally, improved sheen and stability in cake frostings.
Normally emulsifiers are defined as surface-active
agents, which when added even in small percentages to mixtures
of two or more immiscible liquids, result in the formation of
an emulsion or stable liquid suspension. Emulsifiers of the
type defined above tend to form oriented molecular structures
at interfaces of dispersed fat or oil particles thus controlling
the stability affecting the rate of coalescence (e.g. albumin
in milk, egg yolk in mayonnaise) which, in turn, allows the
suspension of the fat or oil particles in liquid. The use of
emulsifiers results in a stable substance containing a continuous
phase and a dispersed phase, for example, in an oil and water
emulsion such as milk, water is the continuous phase and butter-
fat the dispersed phase. Lecithin is, however, a unique emulsi-
fier whose properties are not as yet completely understood.
Lecithin is generally recognized as "nature's supreme emulsifier
and surface active agent".
For purposes of this application several terms must
be defined. The first is "phosphatide" which is intended to be
a broad generic term including such substances as lecithin,
cephalin, and sphingomyelin. A narrower, yet still generic
term is "lecithin". Lecithin will be used interchangeably with
"natural lecithin" and is intended to include animal, pla~t
and vegetable derived lecithin. Finally, the term "phosphatidyl
choline" is equal to and used interchangeably with the term
"chemical lecithin". Phosphatidyl cholines are the most useful
emulsifiers of this invention and are generally recognized as
10~'~7t~3
~o~sessing excc]lcnt crnulsii~ation ~roperties. ~s a rcsult,
the term lecitllin is intendcd to bc gcneric to thosc ~hosphatidyl
cholines [chemical lecithins] which are available fro~ vegetable
sourc~s. It is known that l~cithins possess both hydrophilie
and lipophilie groups which make thcm wi~ely used as emulsifying
agents or surface-active ag~nts. It is also known that specific
mixtures of lecithins derived from vegetable sources, particularly
from soybeans, corn, peanuts, safflower, sunflower, rapeseed,
and the like, are effl~ctive surface-active agents in a wide
variety of applications. Lecithin is in reality a complex mixture
containing, in addition to the phosphatidyl choline entity
~ehemical lecithin~ such other constituents as cephalin [phos-
phatidyl ethanolamine], inositol phosphatides, carbohydrates,
sterols, and the like. The composition of crude lecithin varies
according to its source and the processing steps used in its
isolation. Although usable in the crude state in a number of
instances, the results obtained leave much to be desired. The
deficiency in surface activity of the crude lecithin is due
largely to the presence of substances capable of stabilizing
water in oil emulsions as well as others capable of stabiliz-
ing oil in water emulsions. Both types of surface-active agents
being present in intimate mixture in the crude lecithin can,
in specific instances, oppose each other. The net results there-
fore when crude lecithin is used as a surface-active agent may
be a relatively unstable emulsion.
Commercial lecithins, such as derived from soybeans,
either in substantially oil-free form or in its commercial com-
,.~ ~ ,
lV~position in which t~lcre is a mi~turc o about 65% lccithin and
associatcd phosphatidcs, chic~l~ ccphalin and inositol phospha-
tides and 35% soybc~n oil, oftcn c~nnot bc convcnlen~ly uti]izcd
because thcy deteriorate at ambient tcmperaturcs or on heating
to temperatures which do not destroy ordinary oi]s (trig]ycerides).
The rate of decomposition of phosphatides is considerably more
rapid than triglycerides in the presence of moisture or oxygen
with the result that the phosphatide loses its emulsifying
properties in mixtures containing moisture.
., . I
In light of the above-mentioned problems, various
hydrogenation processes have been used to render lecithin
materials useful as emulsifiers. Lecithin materials (such as
chemical lecithin) which have been successfully hydrogenated
have been found to be extremely useful emulsifiers. They differ
from the corresponding natural phosphatides in being more stable
and more easily bleached to a light color. Although known for
years, hydrogenated phosphatides have not been available commer-
cially because the known procedures for their preparation have
been quite impractical and, therefore, commercially unattractive.
Previous publications teach that hydrogenated lecithin
can be prepared by processes employing extremely high pressures
(Cf., Chemical Abstract 280 page 7566 '1934'), while attempts
to use low pressure equipment have been unsatisfactory (Cf.,
Chemical Abstract 34, page 3380, '1940'). One such high pressure
25 process is taught by Jacini, U.S. Patent 2,870,179 (1959) which
discloses a hydrogenation process using pressures of 100 to
110 atmospheres. These procedures do not offer a practical
process for preparing hydrogenated lecithin on a commercial
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~ , -4-
(3~
basis. consequcrltly, no isolat~d hydrogenated lecithin has
been available commercially.
An additional problem with previous methods of hydro-
genation involv~sthe use of volatile and/or inedible solvents,
e.g. usually benzene (see for example, Davis, U.S. Patent
~,026,341 issued in 1962). Hydrogenation solver.ts such as
benzene may be volatile to the point of being explosive and
often deposit toxic residues. As a result such solvents are
not acceptable for use in foods. The hydrogenation process of
this invention uses solvents that are non-volatile and non-
toxic and therefore acceptable for use in foods. Sample sol-
vents which have been used successfully in practicing the process
of this invention are propylene glycol, propylene glycol esters,
or glyceride oils~
In light of the above, a primary object of this inven-
tion is to provide a lecithin emulsifier with improved emulsi-
fication stability for addition to various food products.
Another object of this invention is to provide a
lecithin emulsifier containing reduced chemical cephalin and
reduced inositidal phosphatide contents and a reduced unsatur-
ated fatty acid content.
A further object is to provide an emulsifier which
can replace the cholesterol found in the egg yolk normally
present or added to some prepared flour mixtures and thus
reduce the total cholesterol content of said mixes.
A further object is to provide an emulsifier which will
result in moister andlarger baked products and improved yeast-
leavened products ~uch as breads and coffee cakes, while at the
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lV~Z7Q~
same time permitting incre~sed water variation,mixin~ time,
and mixing speed tolerance in recipe formulation.
~ till another object is to provide an emulsifier which
will result in reduced spattering during the frying of foods
in shortenings containing said emulsifier~
Yet another objective of this invention is to provide
an improved process for hy~rogenating phosphatides, especially
lecithin, using low pressures and non-volatile, edible solvents.
These and other objects will be apparent from the fore-
going and following description of the invention.
.
SummarY of the Invention
This invention relates to the blending of hydrogenated
and solvent fractionated lecithin with unhydrogenated and
solvent fractionated lecithin for use as an improved emulsifier.
The improved emulsifiers are valuable in a broad range of products
including cakes, frostings and bread and offer improvement in
eating quality, formula tolerance and in several systems act as
an egg yolk substitute. The emulsifier product of this inven-
tion is incorporated into various food products at levels of
from 0.01% to 2.0%. The process of this invention is an improved
method for the hydrogenation of lecithin, which employs the use
of edible, non-volatile solvents in conjunction with pressures
and temperatures that allow the attainment of low Iodine Values
in the final emulsiier product. More specifically, palladium
on carbon may be used as a catalyst with non-volatile edible
solvents such as propylene glycol, propylene glycol esters or
glyceride oils at pressures of-from about 50 to 200 pounds per
7~39
square inch (ap~)roxilnat~ly 3-15atl~o-;ph(r(.~) at t(~mp~r~tu~s
of 60C to 110C to yield a ~incll hy(lrog(-llated ~mul.sificr
- product having a co~bin~d saturated a~ty acid and trans fatty
aeid content of 3~/O to 7~/O whieh corresponds to an Iodine Value
of from about 4 to about 30.
The present invention, in one aspect, resides in a
process for hydrogenatin~ lecithin comprising hydrogenating said
lecithin in the presence of a palladium on carbon catalyst and an
edible, non-volatile solvent at temperatures of from about 60C
to about 110 C and under pressures in the range of from about 50
psig to about 200 psig, and maintaining said reaction for a time
suffieient to reduce the Iodine Value of the lecithin to the range
of from about 4 to about 30.
In another aspect, this invention resides in an emulsifier I
suitable for use in food products which comprises a blend of (1)
from about 20% to about 80~ of hydrogenated lecithin having a
cephalin coneentration of less than about 10% and an inositol
phosphatide concentration of less than about 8%, and (2) from about
20~ to about 80% of unhydrogenated leeithin having a eephalin
concentration of less than about 8%, wherein the total of trans and
saturated fatty aeid groups eomprise from about 30% to about 70%
of the fatty aeid groups of the emulsifier.
Detailed Deseription of the Invention
The emulsifier produet of this inventi.on is eomposed
of hydrogenated and solvent fraetionated leeithin blended wi,h
unhydrogenated and solvent fraetionated leeithin to form a
final emulsifier havlng improved emulsifieation eharaeteristies.
The aetual pereentage amount of eaeh eomponent of the blend is
not critical and may be varied to suit individual taste and
flavors so long as the final combined saturated and trans fatty
~ _ 7 _
~9,g
16)'~ V~
acid content is increased to within the range of 3~/O to 7~/O. A
preferred range is from 20% to 80% fractionated and hydrogenated
and from 20% to 8~/o fractionated and unhydrogenated.
The combined saturated and trans fatty acid content of
3~/O to 70% is critical to this invention as it directly affects
the physical properties of the emulsifier itself. In terms of
structural behavior lecithin containing less than about 30O/o
combined saturated and trans fatty acid acts like unhydrogenated
lecithin, while conversely lecithin having more than about 70O/o
~ombined saturated and trans fatty acids acts like fully hydro-
genated lecithin. A completely unhydrogenated lecithin (or a
lecithin with less than 3~/O combined saturated and trans fatty
acids) will occupy too large an area from a molecular structure
standpoint with a resulting decrease in structural strength.
15 The net result of the use of a completely unhydrogenated
7(~9
lecit})in is a ~lat cake that instead of the normal u~"l~rd
expansion ~ill cxpand out~ard resultillg in excessive lipping
or overlapping of the cake pan wal1s. On the other hand, a
fully hydrogenated ]ccithin (greater than about 70/O combined
saturated and trans fatty acid content) will result in an
emulsifier that is both immobile and inelastic. In addition,
the crystal melting point will be too hi~h to be used effectively
as an emulsifier in food products. In lecithins having the
desirable saturated fatty acid content (3~/O-70%~ it has been
shown that the molecules are arranged in a liquid crystalline
.~tate which has a lower melting point than the corresponding
solld crystalline state.
The improved performance of the emulsifier of this
invention is the result of variations in the chemical composi-
tion of the lecithin caused by the solvent fractionation andhydrogenation of the lecithin according to the process of this
invention. Generally, commercial vegetable lecithins are con- -
taminated by from 15% to 30% cephalin and, if unfractionated,
substantial portions (10% to 35%) of phosphoinositides, while
at the same time the important phosphatidyl choline component
contains less than 25% combined saturated and trans fatty acids
which is less than the most desirable level in emulsifiers.
The improved emulsification characteristics of the
lecithin is achieved by significantly reducing, through solvent
fractionation, the cephalin concentration, which is less solubl`e
and less hydrophilic than lecithin, irom about 30/O to less
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than about 10%, prefcrably to about 5%. At the same time the
inositide concentration is decreased by further fractionation
from about 33% to less than a~out 8%, preferably to about 4%.
In addition, the combined saturated and trans fatty acid level
of the phosphatidyl choline is increased by hydrogenation to
from less than 25% to within the range of 30% to 7~/0, preferably
about 60%. As explained previously, the most critical indicator
in determining the final emulsification properties is the total
level of the saturated and trans fatty acid in the ]ecithin. It
therefore is important that the correct percentage of each com-
ponent is present, hence 20% to 80% of both the hydrogenated and
fractionated component and the unhydrogenated and fractionated
component is preferred because this amount places the combined
saturated and trans fatty acid level in the desired percentage
level range.
It has been found that an effective way to achieve the
changes in composition is by a combination of:
(a) solvent fractionation in ethanol or methanol,
and
(b) hydrogenation of unsaturated lecithin in a
non-volatile edible solvent (propylene glycoi,
propylene glycol esters, glycerides).
The lecithin may be hydrogenated either before or after fraction-
ation depending on process convenience. However, it is essential
to remember that if the hydrogenation operation is performed
first the solvent fractionation must be done at temperatures
of from about 0C to about ~20C. If the fractionation is
done prior to the hydrogenation then the fractionation temper-
atures may range from about -10C to about -15C. These tem-
peratures are critical to achieve the desired clear separation.
Hydrogenated (saturated) lecithin is produced by cata-
lytic hydrogenation using a palladium on carbon catalyst and
any of the following substances as "solvents": propylene
glycol, propylene glycol esters, glyceride oils (both hydrogen-
ated and unhydrogenated). The hydrogenation is usually carried
out at pressures of 50 to 200 psig (approximately 3 to 15 atmos-
phe~res) and at temperatures of from 60C to 110C (preferably
80C) to a final lodiné Value of between 4 and 30 which cor-
responds to a total trans and saturated fatty acid content of
30O~ to 7~/o-
The unique advantages of this hydrogenation processare the use of non-volatile solvents such as propylene glycol,
propylene glycol esters, and glycerides and additionally the
use of solvents which are food approved by the FDA. In addition,
the process of this invention allows hydrogenation at low pres-
sures as opposed to previous techniques which require commer-
cially objectionable pressures.
The solvents most often used in previous hydrogenation
processes were volatile, flammable, or left toxic residues.
Furthermore, hydrogen in combination with oxygen is an explosive
gas and, therefore, it was necessary to take proper safety pre-
cautions in any attempted production of hydrogenated lecithin.
However, using the process of this invention it is possible to
protect against hydrogen explosions, thus effectively eliminat-
ing the problem of solvent related explosions or residual
toxicity in the final food product. An additional problem was
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that using t~c ~i~h pressurc systems of the prior art required
very ~xpensive and complicated equipment to reduce solvent loss
to tolerable levelsO The process of this invention eliminates
the need for such equipment. In addition, after lecithin has
been hydrogenated according to the process of this invention
it is ~e~dy for ~inal use in food products as an emulsifier.
The term "Iodine Value" as used herein refers to a
method of quantitatively measuring the unsaturation of compounds,
especially fats and oils. Many different methods for determin-
ing Iodine Values have been devised. The results commonly are
expressed as percent iodine absorbed, i.e. grams of iodine per
100 grams of sample, whether or not the halogen used actually
is iodine. For a more complete discussion of Iodine Values and
their significance see "Vegetable Fats & Oils" by E. W. Eckey,
pages 229 to 231 ~1954).
The actual amount of emulsifier and the percentages
of hydrogenated and fractionated and unhydrogenated and frac-
tionated lecithin can be varied within the disclosed ranges to
suit individual products and tastes. However, it has been
20 experimentally shown that 0.01% to 2.0% by weight represents
an emulsifier addition range that encompasses all products to
which this application is directed. Specifically, in cakes and
breads lecithin can be added to levels of from about 0.01% to
abo~t 1.0%; in frostings from about 0.01% to about 2.0% and
25 in shortenings from about 0.01% to about 2.0%.
A less preferred but nevertheless viable alternate
embodiment of this invention lnvolves the use of hydroxylated
lecithins. Hydroxylated lecithins can be hydrogenated, frac-
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1~4'~7~?9
tionated, and bl~ndcd to produce approximately the same
described composi.tion without loss in performance. It has
been noted that while there is a loss in the yield of the
desired product there is a gain in flavor and color, with
hyd~xy~tion, over the use of crude lecithin. ~ydroxylated
lecithins can be obtained commercially or can be produced by
well-known methods of hydroxylation
Furthermore, it has been found tha~ the solvent insol-
uble phosphoinositide fractions, usually separated during
fractionation, can be used in cake, cookie, or bread formula-
tion in concentrations of from about 0.01% to about 0.2% (on
the dry mix basis) providing that no egg yolk is added to the
product.
The Eollowing examples are offered to illustrate but
not to limit the described invention.
. Example 1
Two sample cake batters were prepared each according
to the following formula:
Dry Inqredients
Sugar 40.6%
Cake Flour 40.2%
Shortening (combination of 10. 8% - ~
partially and fully nydro- .
genated soybean oil)
Dextrose 2.1%
Salt . 80/o
motal94 5%
7~i~
Othcr Inq~di~nts
__ _ _
Wheat Starch 3.1%
- Vegetable gum .06%
Flavors ~34%
Leavening Agents 2 0 /
Total 5.5%
Sum Total 100.0%
The first sample was labeled batter #94 and the second sample
- batter ~103.
To sample 1 (batter ~94) a standard emulsifier was
added. The emulsifier ingredients were added to the shorten-
ing and consisted of (based on the weight of the shortening):
17% propylene glycol monostearate
. 4% propylene glycol monoester made from fully
hydrogenated rapeseed oil.
3.5% mono-diglyceride made from fully hydrogenated
rapeseed oil.
.4% stearyl propylene glycol hydrogen succinate.
To sample 2 (batter #103) was added a lecithin emulsi-
fiçr consisting of:
0.5 g. fractionated and hydrogenated lecithin
0.5 q. fractionated and unhydrogenated lecithin
1.0 g.
The lecithin must first be dispersed in approximately 10 grams
of water prior to addition to cake batter #103.
Both cake mixes are then prepared identically. Both .
are mixed with 340 yrams of water in a~Mixmaste~*at high speed
for 2 minutes and low speed for 1 minute. Two 8" round pans
are used for baking each sample. Therefore 446 g. of batter
* Trademark for
a mixing device. -13-
~t
~ ~ ,r ~ ~ ~ r
1~4;~'7'~#9~ is p~aced in each of two ~" pans and corrcspondingly 446 g.
of batter ~103 is placed in each of two 8" pans. A11 four
pans are then baked in an oven for 32-33 minutes at 350F.
Comparison upon removal from the oven revealed a
significant dip in the cakes produced from batter #94. The
dip occurred in the center of the cake which is, of course,
very undesirable from a consumer standpoint. The poor quality
of the cakes produced from batter #94 was further confirmed
by the center and edge measurements listed below in Table I.
Cakes having the center/edge ratio of batter #94 cannot be
stacked. A cake of this appearance would be totally unaccept-
able as a consumer product.
Table I
Average Center HeightHot Cold
Batter ~94 .89 in.,82 in.
Batter #103 2.43 in.2.24 in.
Average Edge Height
Batter #94 1,40 in.1.36 in.
Batter #103 2.03 in.1.96 in.
As mentioned previously, the second batter (#103) was
identical to the first (#94) with the exception that batter #103
contained lecithin emulsifier ingredients. After being removed
from the oven no dip in center height was observed in the
cake. Measurement of center and edge heights confirmed the
initial conclusions that the cake from batter #103 was a veryhigh quality cake and very much superior to that produced from
batter #94. Specifically the measurements are listed above in
Table I. The stack height for two layers of the cake was 4.2
inches which is con idered excellent for cakes of this type.
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7~
Example 2
Two commercially availa~le "flu~fy white" frosting
mixes are obtaincd, both of which contain emulsifier ingredients.
The first frosting mix is used as a "control" and no additional
ingredients are added. To the second frosting sample (hereafter
the "test sample") 0.2% fractionated and hydrogenated lecithin
in addition to 0.2% fractionated and unhydrogenated lecithin
are added (the percentages are on the shortening basis). After
preparation and use the test sample which contained the hydro-
genated and unhydrogenated lecithin combination is evaluatedas superior. Specifically the sheen and stability of the frost-
ing mix is improved.
Example 3
., 560 grams of lecithin is dried at 60F. 20 ml. of
15 acetic anhydride is added to the lecithin which is again dried.
Foaming is noted as the acetic anhydride removes the water.
- The drying reaction is allowed to run until the foaming has
subsided. The yield,from the drying reaction is 555 grams of
lecithin.
After drying, 805 grams of propylene glycol is added
to the 555 grams of lecithin. To the lecithin-propylene glycol
mixture 25 grams of palladium and 50 grams of carbon are added
as a reaction catalyst. This blend is then subjected to hydro-
genation using a steady hydrogen pressure of 183 psig; a seal
coolant pressure of 120 psig. After application of hydrogen
the temperature rises from 70F to 92F in a 4-1/2 hour period
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of time. The pressure, during the same 4-1/2 time period varies
from an initial 90 psig to a final 114 psig.
After this time period has expired a sample is taken.
The Iodine Value of the final hydrogenated product is about 7.5.
This hydrogenated sample is found to contain no toxic residues due
to the fact that an edible solvent, i.e. propylene glycol, was
used. The hydrogenated lecithin of this example exceeds in
desirable color, odor, and Iodine Value all commercially available
and tested lecithin products.
The identical procedure is repeated three times, each
time lending additional support for the fact that the hydrogena-
tion process of this invention is superior to any of the methods
previously available.
EXAMPLB 4
A cake batter is prepared exactly as batter #103 of
Example 1 was prepared with the single exception being that
instead of the emulsifier of batter #103 being added 0.3 grams of
fractionated and hydrogenated lecithin was added to the batter.
Results obtained after baking exactly as batter #103 was baked
20 in Example 1 are listed below in Table II.
TABLE I I
Hot Cold
Center Height 2. 40 in. 2.17~ in.
Edge Height 1.91 in. 1.80 in.
As indicated by these results the conclusion was reached that
fractionated and hydrogenated lecithin alone is an excellent
emulsifier.
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