Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Mid-fraction production by fractional crystallization with
stearin and olein fraction recycling to interesterification
The present invention relates to a method for the produc-
tion of mid-fraction by fractional crystallization of fatty
substances, including fats and glyceride oils. In particular,
the invention relates to the production of mid-fraction by
tapping fractional crystallization and bottoming fractional
10 crystallization, in which the stearin topping fraction and
olein bottoming fraction ~ormed as byproducts are mixed and
interesterified, and the interesterified mixture is recycled as
additional feedstock.
Natural glyceride oils and fats comprise a great many dif-
15 ferent triglycerides, the physical prop~rties of which to alarge extent are determined by the chain lengths and the de-
grees of unsaturation of the fatty acid moieties. To make natu-
ral glyceride oils or fats more suitable for particular appli-
cations it is often required to separate them into fractions
20 characterized by fatty acid glyceride distributions which are
homogeneous with respect to the melting behavioux.
The fractional ~rystalliization may be carried out on the
oils and ~ats as such (dry fractionation) or after mixing with
~ a solvent (solvent fractionation~. In the fractional crystalli-
25 zation treatment the oil is cooled to a temperature at whichonly a higher melting triglyceride fraction crystallizes, fol-
lowed by separation of the crystallized solids (stearin fracti-
on) from the liguid fraction (olein fraction) e.g. by filtrati-
on or ce~trifugation.
In the production of mid-fraction the oil or fat is first
sub~ected to a topping fractional crystallization treatment
providing a stearin topping fraction and an olein topping frac-
tion. This olein topping fraction is subjected to a bottoming
fractional crystalliza~ion treatment at a lower crystallization
35 temperature, providing the aimed mid-fraction and an olein
bottoming fraction.
It is understood that the topping fractional crystalliza-
tion treatment and the bottoming fractional crystallization
treatment may comprise more than one consecutive fractional
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crystallizations in which the olein fraction and/or stearin
fraction are passed to the next or former fractional crystalli-
zation.
Mid-fraction is a desired starting oil or ~at blend for
5 producing margerines. Mid-fraction possesses a good consistency
and a good melting performance imparting the margerines obtai-
ned good organoleptic properties and a suitable consistency at
a temperature within the range of 15-~5C. However, the produc-
tion o~ mid-fraction inevitably results in the formation of two
10 byproducts, namely a stearin topping fraction and an olein
bottoming fraction. These fractions are generally less valua-
ble, ~io that the method for the production of mid-fraction is
not optimal from an economic point of view.
The invention is based on the ~inding, that when the feed-
15 stock comprising fatty substances, used for the production ofmid-fraction has a fatty acid composition of the triglycerides
which is similar to that o~ the mid-fraction produced, and the
stearin topping fraction and the olein bottoming fraction are
mixed and this mixture is randomly interesterified, this inter-
20 esterified mixture should have a fatty acid composition similarto that of the ~eedstock and may be recycled, substantially
avoiding the formation of byproducts.
- Accordingly, tha present invention provides a method for
the production of mid-fraction by fractional crystallization of
25 ~atty substances, in which:
i) a fatty substances comprising feedstock is subjected
to a topping fractional crystallization treatment pro-
viding a stearin topping fraction and an olein topping
fraction;
ii) the olein topping fraction is subjected to a ~ottoming
fractional crystallization treakment providing the mid-
fraction and an olein bottoming ~raction:
iii)the stearin topping fraction and the olein bottoming
fraction are combined and subjected to interesterifi-
cation, and the interesterified mixture of fatty sub-
stances is recycled to the topping fractional crystal
lization treatment.
A requisite ~or the method according to the invention
is, that the stearin topping ~raction and the olein bottoming
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fraction are subjected to a random interesterificati~n. There-
fore, the method according to the invention is not suitable for
the production of mid-fraction comprising specific symmetrical
or asymmetrical triglycerides.
As feedstocks any fatty substance may be used, such as
semi-solid glyceride oils and fats of vegetable, animal or
marine origin, such as fully or substantially hydrogenated palm
oil, palm kernel oil, tallow, butter fats, fish oils, sunflower
oil and their solvent or dry fractionated stearin or olein
10 fractions. Preferred ~eedstock components comprise hydrogenated
palm oil, hydrogenated palm kernel oil, fractionated palm oil
stearin, sunflower oil, such as palm oil hardened to a melting
point of 58C (Cl6 40-50%;Cl8 60-50%), hardened palm oil stea-
rin (C76 50-85%;Cl8 50-15~), hydrogenated palm kernel oil har-
15 dened to a melting point of 39C (Cl2 45-55%; Cl4 12-18%; Cl6
5-10~; Cl8 12 25%), hydrogenated palm kernel oil stearin har-
dened to a melting point of 41C ~Cl2 50-60%; Cl4 15-25%; Cl6
5-10~; Cl8 5-12%~ and sunflower oil hardened to a melting
point of 69C (Cl~ 5-10%;Cl8 95-90%). Using these feedstock
20 components any practical distribution of fatty acids in trigly-
cerides of mid-fraction may be formulal:ed.
Using these hardened feedstock components, for mid-fracti-
on obtained by solvent fractionation,
preferably the mid-fraction obtained has a H3 (>C50 ) of less
25 than 13, prefera~l~ less than 11, and a H2 M value (C44 ~ C46 ~
C48 ) which is as large as possible, generally higher than 60,
pref~rably higher than 64, and a H3 ~H2 M value which is as
large as possible, generally larger than 70.
For mid-fraction obtained by dry fractionation the H3 value
30 is generally less than 16, preferably less than 15. The H2 M
value i~ generally larger than 45, preferably larger than 50.
The H3 +H2 M value is generally larger than 65.
The interesterification used in the method according to
the invention comprises any suitable interesterification pro-
35 cess, by which the fatty acids o~ the triglycerides are random-
ly ex~hanged. Any prior art interesterification process might
be used, such as the proces disclosed in EP-A-76,682. Preferred
is a catalyst comprising an alkaline metal or hydroxide. Prefe-
rably the catalyst system comprises sodium or sodium hydroxide,
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glyceride and water in a weight ratio of 1/2/3 to 1/2/7. The
catalyst is generally added in a concentration of at least
9.03% by weight sodium hydroxide based on the oil. The informa-
tion of the European patent application EP-A-76,682 is included
5 by re~erence.
For an optimal distribution of the fatty acids over the
triglycerides, used in the feedstock, it is preferred that the
feedstock as well as the stearin topping fraction and olein
topping fracti~n are subjected to the interesterification.
Depending on the separation efficiency, the solid particle
content, the crystallization temperature and the cooling rate
used in the fractional crystallization of the topping fractio-
nal crystallization treatment and bottoming fractional crystal-
lization treatment, these treatments may comprise more than
15 one, such as two consecutive fractional crystallizations.
When the topping fraction of crystallization treatm~nt
comprises two or more consecutive fractional crystallizations,
a higher midfraction yield may be obtained when, according to a
preferred embodiment the stearin topping fraction originates
20 from the second consecutive topping fractional crystallization,
and the olein topping fraction originates from the first conse-
cutive topping fractional crystallization.
When the bottoming fractional crystallization treatment
comprises two consecutive fractional crystallizations, it may
25 be preferred for obtaining better midfraction quality when the
olein bottoming fraction originates from the first consecutive
bottoming fractional crystallization, and the mid-fraction
originates ~rom the second consecutive bottoming fractional
crystallization~
I~ the olein topping or bottoming fraction comprises a
relatively high solid content, it is preferred that this frac~
tion is partly recycled to the topping or bottoming ~ractional
crystallization treatment whereby the fraction is diluted.
Preferably the recycling ratio of the recycled olein fraction
35 is about 10-60%, more preferably 25-50%.
The consecutive topping and bottoming fractional crystal-
lizations may be carried out as countercurrent ~ractional crys-
talllzations, such as disclosed in the earlier European patent
application to be included.
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Impurities present in the feedstock or formed during the
production of mid-fraction, such as partly saturated triglyce-
rides or diglycerides, may accumulate in the recycled stearin
topping or olein bottoming fractions. Therefor~, it is prefer-
5 red that intermittantly or continuously a minor part of thestearin topping fraction and/or olein bottoming fraction is not
recycled but disposed. The disposed fraction may comprise up to
about 5% by weight of the recycled olein topping or bottoming
~raction. Alternatively these impurities may be removed inter-
10 mittantly or continuously from the recycled fractions, forinstance by adsorption.
The method accordin~ to the invention for the production
of mid~fraction will be illustrated hereafter by way of non li-
miting examples. The two processes used are shown in the an
15 nexed single drawing in which each box refers to a fractional
crystallization and the subsequent separation of the stearin
fra~tion from the olein fraction.
In a batchwise process it is possible to use only one
crystallizer and various storage tanks in which the olein and
20 stearin fractions obtained in the topping fractional crystalli-
zation treatment and bottoming fractional crystallization tre-
ament are temporarily stored.
EXAMPLE I
Mid-fraction was produced according to method A. Feedstock
(F) comprising 47% fully hydrogenated palm oil and 53% fully
hydrogenated palm kernel oil was subjeoted to interesterifica-
tion ~I) using 0.02% by weight metallic sodium.
In the two consecutive countercurrent fractional crystal-
30 lizations 1 and 2 (crystallization temperature 44C and 40C,respectively) of the topping fractional crystallization treat-
ment the solid particle content (SPC) was 11~. In the two con-
secutive fractional crystallizations 3 and 4 (crystallization
temperature 35C and 31C, respectively) of the bottoming frac-
35 tional crytallization treatment the SPC was 17%. The stearintopping fraction and the olein bottoming ~raction were recycled
to the interestification and mixed with the feedstock in a
ra~io of 60/40. Initially the mid-fraction had a H3/H~M value
of 12/55 and after steady state of 12/54.
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For comparison purposes in each fractional crystallization
the separation efficiency was kept at 0.5.
Table 1 shows the fatty acid composition (%) of the mid- ¦
fraction and of the feedstock. l~
1 :
Table 1
1, .
Fatty acid composition (%) of the midfraction and the feed
after 10 cycles of intPresterification and fractionation.
Chain length Feed Mid
in carbon ~'
numbers
: 8 2.2 2.1
15 10 2.0 2.2
12 26.2 26.0
14 8.9 9.0
1~ ~5.5 25.7
18 34.5 34.7
20 20 0.3 0.3
EX~MPL~
Feedstock comprising 7~ fully hydrogenated, dry fractiona-
ted palm oil stearin, 33% fully hydrogenated palm oil and 60%
25 fully hydrogenated palm kernel oil was used for the production : :-
of mid-fraction using method ~
In the fractional crystallization of the topping fractio- -
nal crystallization treatment SP~ was 8%, and in the fractional : - .:
cry~tallization of the bottoming fractional crystallization :
30 trea~ment SPC was 18~. The topping ætearin fraction 1 and the
bottoming olein fraction 2 were recycled to the esterification ; :
and mixed with the feedstock in a ratio of 71/29.
At a separation efficiency of 0.5 the mid~fraction had a ..
H3/H2M value of 15/45.
The ~atty acid composition (%) of the mid-fraction obtai~
ned and of the feedstock is shown in Table 2. ; ~
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Table 2
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Fatty acid composition (%) of the mid-fraction and the feed
after 10 cycles of interesterification and fractionation. ~ :
Chain length Feed Mid
in carbon 1.-
numbers
~ 2.9 2.7
10 10 2.3 2.2
1~ 29.3 29.4
1~ 9.6 9.1
16 24.6 25.0
18 31.3 31.6
EXAMPLE III
The same process as used in Example II was used, but the
olein fractions were recycled at a recycling ratio of 50% on ~ :
the f2ed. In the topping fractional crystallization treatment
20 SPC was 5.4% and in the bottoming fractional crystallization ~.
treatment SPC was 12%. The mid-fraction obtained had a H3/H2M
value of 15/45.
EXAMPLE IV
Feedstock, ~omprising 1,5~ fully hydrogenated sunflower -.
oiI, 46,5% fully hydrogenated palm oil, 26% fully hydrogenated
palm kernel oil and 26% fully hydrogenated palm kernel stearin
was processed according to method A. In the topping fractional
crystallization treatment the SPC in the crystallizations 1 and
30 2 was 8%. In the bottoming fractional crystallization treatment
the SPC of ~he fractional crystallizations 3 and 4 was 16%. The
stearin topping fraction and olein bottoming fraction were
recycled and mixed with the feedstock in ratio of 62/38. At a
separation eff.iciency of 0.5, the H3/H2M value of the mid-frac- :
35 tion was 12/49.
Table 3 shows the fatty acid composition (%) o~ the mid-
fraction and of the feedstock. -
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Table 3
Fatty acid composition (%) of the mid-fraction and the feed
after 15 cycles of interesterification and fractionation.
1.
Chain length Feed Mid
in carbon ',
numbers
8 1.8 1.8
10 10 1.7 1.8
12 27.5 27.4
14 10.3 10.4
16 25.6 25.3
18 33.1 33.3
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EXAMPLE V
A feedstock comprising 42% hydrogenated palm kernel stea-
rin, 53% hydrogenated palm oil and 5% hydrogenated sunflower
oil, was subjected to sol~ent fractionation in acetone in a
20 r~tio o~ 1/5 wt/wt. In the topping fractional crystallization :.
treatment SPC was 29% and the crystallization temperature about
30C. In the bottoming fractional crystallization treatment SPC
was 33% ~on present fat) and the crystallization temperature : :
was about 20C. The stearin topping fraction 1 and the olein
25 bottoming ~raction 2 were recycled and after removal of the :
acetone, mixed with the feedstock in a ratio of 47.5/52.5,
andthereafter interesterified. The fatty acid composition o~ :
the mid ~raction resembles closely the composition o~ the ~eed-
stockj see Table 4.
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Table 4 .
The fatty acid compositio~ (%) of the mid-fraction and thP
feedstock after 10 cycles of interesterification and fractiona-
tion.
~
Chain lengthFeedstock Mid :
in carbon :
numbers
8 l.l 1.3
10 10 1.2 1.3 `
12 23.8 23.8
14 10.0 9.4
16 28.0 28.5
18 35.5 35.7
The H3/H2M value of the mid-fraction was 14/59. From time
to time it was:necessery to remove diacylglycerols by adsorp-
tion on silica. The time period between the removal procedures
of these impurities was depending on th~ composition of the
fePdstock. , '
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EXAMPLE VI . -
A feedstock romprising 85% palm oil and 15~ solvent frac- :
tionated palm oil stearin was used in method B. The mid-fracti-
on obtained had a constant composit:ion of 1.2%S3 , 67%S2 0,
25 6.3%S2 Li and 25,5~ others.
EXAMPLE V~II
Midfraction was produced according to method C. Feedstock
comprising 43% fully hydrogenated palm kernel oil was subjected
30 to interesterification (I) using O.OZ% metallic sodium. In the
two consecutive countercurrent fractional crystallizations 1
and 2 (crystallization temperatures of 44 and 48C, respective-
ly) of the topping fractional crystallization treatment the ~:
solid particle content (SPC) was 18.5%. In the bottoming frac-
35 tional crystallization 3 (crystallization temperature of 38~
of the bottoming fractional crystallization treatment the SPC
was 30%. The stearin topping fraction and the olein bottoming
fraction were recyaled to the interesterification and mixed
with the feedstock in a ratio of 50/50. In the steady state the
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H3/H2M ratio was 12/52. For comparison purposes the separation !J
efficiency was kept at 0.5. Table 5 shows the fatty acid compo-
sition (%) of the midfraction and of the feedstock. Usually,
method C may be used in systems in which the SE is still high ?~
5 at a high SPC.
Table 5
Fatty acid composition t%) of the feed and of the midfrac-
tion after 10 -cycles of interesterification and fractionation
10 (method C~. :
Chain lengthFeedstock Mid
in carbon l~ .
numbers I ::
8 2.2 2.1 : -
2.1 2.0 ;~
12 27.1 27.4 - .
14 8.g 9.2 . ~
16 25.5 26.1 : .
18 33.5 33.3
0.3 0.3 ,
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