Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
20136
Sl~BII.IZATION OF LAr~RIC FAIS AND OILS
The present invention relates to the stabilization of lauric fats
and oils, and more particularly to the prevention of both oxidative
and hydrolytic rancidity in fats and oils.
BACKGROUND OF THE PRESENT INVENTION
_ .
When an oil becomes oxidized, it first develops hydroperoxides.
Hydroperoxides have no flavor or odor. However, they break down
rapidly to form aldehydes, which have a strong, disagreeable flavor
and odor. The overall flavor defect is called oxidative rancidity.
It is well known to subject fats and oils to final deodorization in
the process of preparing them for commercial use. Deodorization is
the process whereby odors and flavors of fats and oils are removed,
usually by blowing steam through hot oil at 200-275C (392-527F)
under low~pressure (3-10 Torr).
It is a desirable practice in deodorization, as a final step, to
add citric acid to the oil. It is usually added as a water
solution under vacuum, so that the water is evaporated off. The
6;~
citric acid functions as a metal scavenger, especially for traces
of copper and iron which act as pro-oxidants for oil. If citric
acid is not added, the oil can revert and oxidize more rapidly
Hydrolytic rancidity is the reaction of triglycerides with water,
to produce glycerin and free fatty acids. The reaction can be
exemplified by the following equation:
C3H5(00CR)3+3HO~1 = C311s~OHj3 + 3HOOCR
Prior to deodorization~ fats and oils are usually subjected to
alkali refining. Alkali refining is effective to achieve almost
complete removal of free fatty acids. The free fatty acid content
is determined by titration of a sample with a standard solution of
sodium hydroxide (AOCS method Ca5a-40).
However, after refining, oil is often held in storage tanks. Water
vapor can get into these tanks through breather pipes and oondense
on cooling. The free fatty acid content can increase again because
of the presence of such water. De~dorization, the final process
before the fat or oil is packaged, lowers free fatty acid and water
to about 0.05% or less. However, moisture in pipe lines, feed
tanks, beading towers, and flaking rolls as well as ~ank wagons
and cars, can again cause subsequent increase in moisture, in turn
causing again an increase in free fatty acid content.
Lauric fats and oils, such as coconut oil and palm kernel oil, are
particularly subject to hydrolytic rancidity. Hydrolysis of
cooonut oil or palm kernel oil, even to a small extent, liberates
shDrt-chain fatty acids, which are highly flavored and have a very
disagreeable soapy flavor.
The problem with the presence of citric-acid in lauric fats and
oils, when acco~panied by isture, is that the citric acid, in
effect, can function as a catalyst in the hydrolysis reaction,
causing an increase in percent free fatty acid. Work carried
3 73390-3
out in connection with the present invention has demonstrated that
the rancidity occurred a-t a rate proportional to the level of
citric acid present. The most stable fractionated palm kernel oil
samples obtained other than by the present invention were those
containing no citric acid and low levels o~ water (below 0001%).
As a result, citric acid is normally added only to dome-
stic fats and oils, and not lauric fats and oils.
Lecithin is a well-known additive to fats and oils for a
number of purposes, mostly involving emulsification or viscosity
reduction. For instance, lecithin is used to reduce the viscosity
o-E confectionery coatings, or as an emusifier in such products as
ice cream, bread, icings, paints, cosmetics, printing inks, and
the like. Also, it is known to have a synergistic action with
phenolic antioxidants and may be used for this purpose. In such
uses, the amount employed can be characterized as an emulsifying
amount or antioxidant amount. By way of example, in confectionery
products a reduction in viscosity is achieved by the addi~ion of
about 001-0.4% lecithin, based on the weight of the coating.
It is also known to package lauric hard butters with
about 0.1~ lecithin added as a moisture scavenger. This is said
to reduce the potential of developing hydrolytic rancidity in a
stored, deodorized fat. This disclosure can be found in the book
"Food Oils and Their Uses", Second Edition, Theodore J. Weiss, The
Avi Publishing Co., Inc. copyright 1983 (page 289).
Prior patent to Black, V.S. No. 2,494,114, issued
10 January, 1950 to Swift & Co. describes the stabilization of
fatty materials by the addition of an antioxidant known as "NDGA"
(dihydroguaiaretic acid). The patent suggests that improved
~:
~ 73390-3
stabillzation against ran~idity produced by oxidation can be
a~hieved by the use of lecithin or citric acid in combination with
NDGA. One sample reporkecl in the patent contains all three
ingredients, NDGA, .002% citric acidr and .03~ lecithin. However,
the data given with regard to rancidity produced by oxidation
(xancid in 80 days) was no better than that obtained by the use of
NDGA and citric acid alone (also 80 days). The patent makes no
mention of hydrolytic rancidity, nor the particular problems
associated with lauric fats and oils.
Appli~ants know of no disclosure that teaches treatin~
lauric fats or oils with citric acid, to sequester traces of
copper and iron, and then further adding lecithin for the purpose
: of achieving substantially complete resistance to not only
oxidative rancidity but also hydrolytic rancidity as well.
BRIEF DISCLOSURE OF THE PRESENT INVENTION
The present invention resides in an improved process for
the treatment of lauric fats and oils to reduce or prevent both
hydrolytic and oxidative rancidity comprising adding to said fat
or oil a sequestering amount of citric acid, and with said citri~
acid, lecithin in an amount effective to provide at least 30ppm
and not more than 250 ppm active phospholipids based on the weight
of ~at or oil.
The present invention is par-ticularly applicable to
deodorized lauric fats and oils.
It is necessary that the citric acid be added subsequent
to final deodorization, as the acid can decompose at deodoriza-tion
temperatures. The lecithin can be added prior to or after final
4a 73390-3
deodorization. If added before, ~he le~ithin is preferably free
of phosphatidyl ethanolamine (PE~. Alternatively, the leci~hin
can be pretrea~ed with a strongly basic compound following the
procedure
'~
~g~ 9
73390-3
of Purves U.S. patent No. 4,528,201, issued 9 July, 1985 to
Procter ~ Gamble Co..
DETAILED DESCRIPTION OF THE PRESENT INVENTION
For purposes of the present invention~ the term "lauric
fats and oils" means specifically those Eats and oils having a
high content of lauric acid (40-60%). They contain smaller
amounts of saturated acids having 8, 10, 14, 16 and 18 carbon
atoms. Their unsaturated acids are all minor in amount and con-
sist of oleic and linoleic acid. Commercially important fats and
oils in this group include palm kernel oil, coconut oil~ babassu
oil and tucum oil.
It is understood that the present invention broadly is
also applicable to blends of fats where part of the blend is a
so-called domestic fat (e.g., non-lauric soybean or cottonseed),
and part of the blend is a lauric fat or oil. Such blends are
particularly common in the confectionery field and can comprise
from 5 to 95~ lauric fat or oil. For purposes of the present
application, the term "lauric" includes such blends.
The lauric fats and oils of the present invention are
~0 primarily those which have been subjected to conventional alkali
refining, and bleaching with an absorptive clay or typical physi-
cal refining processes. These steps are conventional in the art,
and form no part of the present invention. In addition, the fats
and oils of the present invention may be subjected to fractiona-
tion, hydrogenation, acidolysis, interesteriEication or rearrange-
ment. The fats and oil may be prepared by a direct esterifica-tion
~9462~
5a 73390-3
of Eatty acids and glycerine. A final step in the processing
usually is deodorization. With regard to those fats or oils which
are fractionated, the present invention is applicable to both the
low melting point Eractions and the high mel-ting point fractions.
Typical uses for the fats and oils of the present inven-
tion are ice cream coatings, confectionery coatings or fillings,
whipped
~29~6Z9
toppings, hard butters, plastic shortenings, cocoa butter
extenders, and stearines.
Not all lauric oil or fat products require stabilization by the
present invention. By way of example, a well processed coconut oil
which melts at about 76F has, under normal circumstances, good ~OM
(Active Oxygen Method) stability and citric acid may not be
needed. The same is true for hydrogenated ooconut oil (mp
76-100F~ or hydrogenated palm kernel oil (mp 87-115F).
IIowever, the present invention could have g~od applicability in
those instances where the coconut oil or palm kernel oil, whether
or not hydrogenated, is likely to undergo iron pick-up during
processing or storage, and be subject to oxidative rancidity. The
addition of citric acid in such instances would be useful.
Applications for these products are ice creams and whipped
toppings.
The present invention has been very advantageously used with a
fractionated palm kernel or coconut oil having a Wiley Melting
Point in the range of about 89-93F, or one that is also
hydrogenated having a Melting Point in the range of about 96-105~F.
A primary use for these products is confectionery coatings. The
present invention has also been advantageously used with a
hydrogenated rearranged coconut or palm kernel oil having a Melting
Point in the range of about 93-104F. Primary uses for these
products are confectionery coatings and vegetable dairy systems.
The present invention can also be used advantageously with a lauric
stearine.
All of the above applications are food uses. It should be
understood that the present invention also has applicability in
oosmetic and pharmaceutical applications where both oxidative and
hydrolytic rancidity must be avoided.
Citric acid has a decQmposition temperature of about 150C, so that
29
7 73390-3
it is necessarily added, as mentioned, subsequen-t to final
deodorization. It can be anhydrous or dissolved in water or
another carrier. For ease oE dispersibility, a solution is
preferred. For food applications the citric acid must be food
grade. The amount added is a sequestering amount. The exact
amount added will depend upon use, type of fat or oil, type of
storage, and other parameters well Xnown in the industry, and is
not a part of the present inventionO In the examples of the
present application, it is added at a level of 20 ppm based on the
weight of fat. This is a conventional sequestering amount. Also
in the examples of this application, it is added as a solution.
The carrier used was propylene glycol, with the concentration of
citric acid in the carrier being about 10%; o-ther carriers such as
water or ethyl alcohol could be used.
The lecithin can be added either prior to or subsequent
to final deodorization. Any commercially available lecithin
product can be used. Most commercially available lecithins are
soybean derived; however, lecithins derived from other oils such
as canola oil could be used. An hydroxylated lecithin can also be
used.
The lecithin can be in liquid or granular form. All
lecithins derived from soybean oil, even granular lecithins, have
a characteristic flavor and odor, although in the case of granular
lecithin the flavor is a relatively non-objectionable, nutty
flavor. If the lecithin is added to the fat or oil prior to final
deodorization, the flavor and odor can be improved by removal of
volatiles.
~ X
8 73390-3
It is known, however, that lecithin is subject to de-
gradation from high -temperatures, causing darkening of the fat or
oil to which it is added. Deodoriæation is conven-tionally carried
out at 430-450F and will cause oil darkening if the lecithin is
added prior to deodorization. This darkening can be prevented or
minimized in several ways, one being by treatment of the lecithin
with a s-trong base such as sodium hydroxide, magnesium hydroxide
or potassium hydroxide, following the teachings of patent No.
4,528,201. Another is pretreatment of the lecithin dissolved in a
small amoun-t of fat by the addition of water followed by heating
and filtration, as disclosed in U.S. patent No. 4,524,085, issued
18 June 1985 to Procter & Gamble CoO
The pretreatment process of patent No. 4,524,085 invol-
ves adding water to lecithin previously mixed with a small amount
of fat. The lecithin is diluted with fat such that the lecithin
is from about 5% to about 85%, preferably from about 5% to about
25%, by weight of the lecithin/fat mixture. Water is added in an
amount such that it constitutes from about 5% to about Z5% by
weight of the lecithin, preferably from about 5~ to about 50% by
weight of the lecithin. The mixture is heated to a temperature of
from about 130F. (54C) to about 170F (77C) with mixing. The
mixture is fil-tered hot.
The treatment process of 4,528,201 involves adding the
base as a water solution, either directly to the fat or as a pre-
treatment of the lecithin. The amount of basic solution added
will depend upon the concentration of the basic solution.
:
;2~
8a 73390-3
Solutions of about 5% to about 50% base by weight are preferred.
For weaker bases, solutions of from about 20% by weigh-t base to
saturated solutions can be employed. Addition as a solid often
results in incomplete disso]ution and dispersal in the fat result-
ing in uneven color development. To retard fat discoloration upon
heating, a minimum base concentration of at least about 0.00005%
by weight of the fat is required. Preferably, for the composi-
tions of the present invention, the base concentration comprises
at least about 0.0003% by weight of the fat. Most preferably, the
base concentration comprises a minimum of about 0.0015% by weight
of the fat.
Further details on the amount of base required can be
found in the '201 patent.
~2~
Any of several stabilization technigues for treatment of the
lecithin or fat with a strong base can be employed. Each method is
effective to prevent discoloration of the fat. One method to
retard discoloration by base stabilization of the lecithin is to
add the base directly to the fat either prior to or after addition
of the lecithin. No pretreatment of the lecithin is required.
~n a pretreatment stabilization process for the lecithin, a strong
base is added to lecithin optionally mixed with a small amount of
fat, heated and mixed, and added to the lauric fat.
In a third alternative, the base can be added to lecithin
optionally mixed with a small amount of fat, heated and filtered,
and mixed with the lauric fat. Filtration of the lecithin in
combination with the base treatment reduces color development more
than the base treatment alone. Much of the lecithin is rem~ved by
the filtration, thereby additionally reducing color development. A
final pretreatment stabilization process for the lecithin
comprises: ~1) addition of a strong base to lecithin; (2) optional
neutralization of the resulting solution; (3) extraction of the
lecithin with a nonpolar solvent, and (4) addition of the lecithin
to a lauric fat. The neutralization is usually accomplished by
addition of an acid such as phosphoric acid. Hexane, or other
similar nonpolar solvents are employed for the extraction step. The
extracted lecithin can be heated to aid in its dispersion in the
lauric fat. An equivalent procedure is to dissolve crude lecithin
in a nonpolar solvent such as hexane with the strong base,
neutralize with an acid/base titration, extract the lecithin, wash
it with a solvent such as acetone, and add it to the desired fat.
.
In a paper entitled "A Process for the Separation of Phosphatide
Mixtures: The Preparation o Phosphatidyl Ethanolamine-Free
Phosphatides from Soya Lecithin", R. Aneja et al~ it is disclosed
that phosphatidyl choline tPC~, phosphatidyl ethanolamine (PE) and
73390-3
phosphatidyl inositol (PI) are the three major phosphatide con-
s-tituents of soya lecithin. This paper discloses a process for
separation of phosphatidyl choline and phosphatidyl inositol from
commercial soya lecithin, to give a product which is free of phos-
phatidyl ethanolamine. The three chief phosphatides, PC, PE and
PI, are yenerally present in approximately equal amounts in soy-
bean lecithin. In this paper, it is disclosed that PE has a dele-
terious affect on the anti-spattering properties of PC and would
best be removed completely from the mixture. There is no
reference in this paper to the processing of fats, particularly
lauric fats and oils, or to the use of lecithin prior to
deodorization.
The present invention, in part, resides in the discovery
that removal of PE from lecithin is also effective in minimizing
thermal darkening of lauric fats and oils during deodorization.
In the following Examples, parts expressed are parts by
weight, and percentages are percentages by weigh-t.
EXAMPLE 1
This Example illustrates the effect of treating a hydro-
genated and rearranged lauric fat with both citric acid and leci-
thin. The citric acid was added in a sequestering amount. ~oth
the lecithin and citric acid were added subsequent to final
deodorization.
The particular fat treated was Paramount B (trademark
SCM Corporation), a partially hydrogenated rearranged palm kernel
oil having a Wiley Melting Point of about 93-96F, an IV of about
3 maximum, a free fatty acid content of about 0.05 maximum and an
SFI profile as follows:
~Z~916~
11 73390-3
Temperature Solids
50F 64 min.
70F 51 min.
80F 35 min.
92F 6 min.
100F 1 max.
Th0 fat is conventionally used in confectioner's coat-
ings, vegetable dairy systems, candy centers, icings, cosmetics
and pharmaceutical products.
The lecithin treatment was carried out in one series of
runs with a typical natural, fluid, soybean lecithin marketed
under the trademark Actiflo 68-SB by Central Soya. This lecithin
is in solution form comprising about 66-68% active phospholipids
(about 23~ PC, 30% PE and 14% PI). It is marketed as an amber
fluid.
; In a second series of runs, the lecithin treatment was
; carried out with a hydroxylated soybean lecithin marketed by Cen-
tral Soya under the trademark Centrolene A. This product has been
58% active phospholipids and is marketed as a heavy bodied fluid.
In the treatment process, the citric acid was added as a
10% propylene glycoL solution. It was added in an amount necess-
ary to give the oils a citric acid concentration of 20 ppm. There
is no criticality with regard to order of addition.
Water also was added to all samples, except control
samples, to apply a simulated stress to the lauric fat. The water
was added at percent levels of 0.05 and 0.10. The lecithin was
added in the amounts of zero and 250 ppm. No advantage was seen
~ in exceeding a concentration of 250 ppm.
: ~ :
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"
6~
The procedure followed was adding warm distilled water directly to
the oil, which was heated to about 50C. A nitrogen atmosphere was
maintained over the oil while it was mixed for 15 minutes with a
mechanical stirrer (3000 RPM). The samples requiring no added
water were still subjected to the 15 minute mixing under nitrogen
at 50C. The results obtained are given in the following Table 1
(for the addition of Actiflo lecithin) and Table 2 (for the
addition of hydroxylated lecithin). Storage results in terms of
free fatty acid and flavor develo~nent were obtained at intervals
of two months, four months, and six rnonths.
SE2 FOLLOWING P~OES FOR TABLES
3L2~ 2~
-:L3-
o Ul U~ o ~ C~l oo
U~ ~;; ~ ~o u~ ~o u~ `D
I I I I In o
~ ';t ~O
~ ~ O ~ O U~
O O O O O O
O 00 0 5~ 0 C~l
U'~ O O O
~ ~ O ~ O
ii~ O C~ O O O O
~ ~ O 1~ 0 O
E-l i~ u~ O O O O O
~1 ~ u~, ;~ U`) ) ~ U~ ',
. ~ ~ ~ O O O ~ O
3 ~ ~ u~ o o
~ ~ ~ o o o ~
V ~ ~ o o~ o o ~o o~ i
æ ~ o 0~ o o o o
~q
o~ooo
; ~ 3~o o o o o o
U~
o
U3
.... .
.
-14-
~'d ~ C~
o ~ ,1 o ~ o U~ o
~ o o o o o o
~ o ul o
æ~l o o o o o o
~o ~ ~ ~ ~ o ~7 o ~ o
~ ~ o o o o o o
C~l
~
H ~ I ~ C`l O O
~i ~ O O O O O O
~: ~: ~
3 ~ I o , o o ~ ~
~ o o o o
,, ~ ~1 o c~ o o o o
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The data of Table 1 shows that in a hydrogenated rearranged lauric
fat the free fatty acid content, with no lecithin added tsamPles 1,
3 and 5) increased substantially even with no water present. In
sample 1, with no water added, the increase was from 0.02 to 0.15%
over the storage period. In s~mple 3, having 0.05~ added water,
the increase was to 0.38%~ and in sample S, the increase was to
0.56~.
All samples showed corresponding decreases in flavor. A lower
flavor value indicates poorer flavor, with optimum being about B,
plus or minus, wi~h an acceptible flavor rated about a 7. The
flavor score is a subjective panel evaluation only and is subject
to substantial error or deviation. However, the data does show a
flavor deterioration for the lecithin-free samples from a mean of
about 6.8 to a mean of about 5.
By contrast, samples 2, 4 and 5 containing 250 ppm lecithin were
koth free fatty acid and flavor stable, showing virtually no
hydrolysis even with water levels of 0.05~ and 0.10% (samples 4 and
6). The flavor scores of the lecithin oontaining samples decreased
slightly during storage from a mean soore of about 7.2 initially to
a mean score of 6.4 at six months.
A~ain, there appeared to be no advantage in adding lecithin at a
level m~re than 250 ppm, for instance 500 or 1000 ppm, although
nothing precludes such higher addition, other than economics.
Similar data is given in Table 2, with those samples having
hydroxylated lecithin showing little free fatty acid build-up,
those without lecithin having substantial build-up, e.g., up to
~ .53%.
No flavor data is given since the hydroxylated lecithin itself
tended to impart to the samples a "sour" off-flavor.
EXAMPLE 2
In this Example, the starting oil was fractionated palm kernel oil
deodorized to a free fatty acid content of less than 0.01%. The
oil had a Mettler Drop Point of about 33.3C, a calculated rv of
about 5, and fatty acid and SFI data as follows:
Approximate
FAC Va1ue
12:0 58
14:0 21
16:0 8.~
Others Remainder
SFI
50F 68-75
70F 62-71
8QF 48-60
92F 4 max
The procedure used was the same as in ~xample 1. The following
data was obtained.
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.,
e~l O O O
D ~ o o o
~1 o o o
ol o - -
~ ~ ~ ~31 0 o
o r~
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18
In Table 3, sample 1 was a control s~nple and shows that this oil
inherently is very stable. With no water added, even with citric
acid present, the sample showed little free fatty acid build-up.
However, with the addition of 0.10% waterl there was substantial
free fatty acid build up, to about 0.21%. In the presence of
lecithin, this build-up was held to about 0.02%.
Similar data was obtained with the use of hydroxylated lecithin.
With 0.05~ added water and no lecithin, the free fatty acid
build-up after six months was about 0.27%. In the presence oE 250
ppm hydroxylated lecithin, the free fatty acid build-up was held at
about 0.02%, from an initial value of about 0.02%.
EXAMPLE 3
In this example, the lecithin added was a granulated lecithin
marketed by Riceland Foods under the trademark Lecigran F. An
advantage in using a granulated lecithin is that it is generally
free of the characteristic soybean odor. The lecithin was 97~
active phopholipids (about 23.5% PC, 20% PE, 14% PI and 39.5% other
phospholipids).
The procedure used was the same as in Example 1. The data obtained
in Table 4 shows that with as little as 50 ppm granulated lecithin
the free fatty acid build-up is negligible.
~L~9~i2~
19
TABLE 4
Granulated Citric Initial 1 month 2 months 3 nths
Lecithin Acid Water %FFA %FFA %FFA _ ~FFA
200 ppm 20 ppm .1% .02 .02 .03 .03
100 ppm 20 ppm .1% .02 .02 .02 .02
50 ppm 20 pEm .1% .02 .02 .02 .02
O ppm 20 ppm .1% .03 .11 .16 .17
With up to 250 ppm granulated lecithin added, the same is non-detectable
in tenms of odor and flavor.
