Palm oil is subjected to a two-stage fractionation in a solvent free system using controlled heating and cooling to give a mid-fraction of iodine value 48-53 and melting point 32.degree.-38.degree. C. The isolated mid-fraction is then either subjected to partial hydrogenation to reduce its linoleic acid content to not more than 2% or preferably has 0.01-1.5% of a dry edible gum e.g. a mixture of guaranate and carraghenate gums, incorporated therein. This gum treatment converts this particular mid-fraction into a dimensionally stable solid which can be cast or moulded and can be used to extend cocoa butter in amounts up to 30% or more without adversely affecting the Jenson cooling curve.

This invention relates to glycerides and is particularly concerned with a 
method of producing a cocoa butter substitute or extender from palm oil. 
Cocoa butter is a naturally occurring triglyceride which has acquired 
considerable importance in the confectionary industry. World requirements 
for cocoa butter now far exceed the supply of the natural product and 
considerable effort has been devoted over recent years to producing 
synthetic or semi-synthetic substitutes which can be used to replace, or 
more usually, to extend, naturally occurring cocoa butter. 
For many years, palm oil has been recognized as a potential starting 
material for the manufacture of cocoa butter substitutes and various 
processes have been proposed involving, as the major step, a fractionation 
of palm oil to give a so-called mid-fraction. The exact nature of the 
mid-fraction is controlled by the exact fractionation method used and, 
prior to the present invention, as a practical matter, the only 
fractionation methods which have been available for producing a 
mid-fraction from palm oil suitable for use as a cocoa butter substitute 
have been fractionation methods involving the use of an additive such as 
water or a solvent. Various solvents have been proposed for use in this 
process, notably acetone, and by controlling the nature and proportion of 
solvent and by controlling temperatures, it has been possible to separate 
palm oil into various components. 
In order to produce palm oil mid-fraction suitable for use as a cocoa 
butter substitute, it is necessary to remove from the palm oil most of the 
tri-saturated glycerides and most of the di- and tri-unsaturated 
glycerides to leave a product which is essentially a 
1,3-di-saturated-2-mono-unsaturated glyceride where the number of carbon 
atoms in the saturated and unsaturated chains and the nature of the 
unsaturation chain is such that at room temperature, the mid-fraction is 
solid but that the mid-fraction has a relatively narrow melting range in 
the region of human body temperature, about 37.degree. C. 
It is not only necessary to control the exact triglyceride composition of 
the mid-fraction to give the correct melting range, but also to give the 
correct mechanical properties and the correct taste to a chocolate or 
other product in which the cocoa butter substitute is incorporated. In 
order to control the physical properties of the mid-fraction, it is 
necessary to ensure that the unsaturated portion of the glyceride is 
primarily the 2-mono-unsaturate. 
Fractionation methods involving the use of solvent are not altogether 
attractive on a commercial scale because they involve the additional cost 
of providing the solvent, handling the larger volumes of liquid that the 
use of solvent produces and, eventually, removing the solvent. We have now 
found that it is possible to isolate from palm oil a mid-fraction suitable 
for use as a cocoa butter substitute or extender by a fractionation method 
which does not require the use of a solvent or any other added chemical 
and which the fractionation is brought about simply by careful control of 
temperatures. 
The present invention provides a method for producing a cocoa butter 
substitute or extender comprising the steps of: 
1. maintaining a phospholipid-free neutralised pre-bleached palm oil having 
an iodine value (IV) of 50-55 at a temperature of 42.degree.-52.degree. C. 
for a period of at least 6 hours, 
2. increasing the temperature of the palm oil to 70.degree.-75.degree. C. 
over a period not exceeding 2 hours and then immediately cooling the palm 
oil to a temperature of 28.degree.-33.degree. C. over a period of not less 
than 5 hours to produce a first liquid fraction of IV 55-60 and a first 
solid fraction of IV 38-44 and melting point 50.degree.-55.degree. C., 
3. separating the first liquid fraction from the first solid fraction 
within 5 hours of completion of formation of the first solid fraction, 
4. maintaining the first liquid fraction at a temperature of at least 
65.degree. C. for a period of time sufficient to form a fluid homogeneous 
crystal free oil and then maintaining the first liquid fraction at a 
temperature of 38.degree.-48.degree. C. for a period of at least 4 hours. 
5. increasing the temperature of the first liquid fraction to 
60.degree.-65.degree. C. over a period of 1.5-2 hours and then immediately 
cooling the first liquid fraction to a temperature of 
14.degree.-17.degree. C. over a period of not less than 10 hours to 
produce a second liquid fraction of IV 59-64 and cloud point 
3.degree.-7.degree. C. and a palm oil mid-fraction of IV 48-53 and melting 
point 32.degree.-36.degree. C. 
6. separating the second liquid fraction from the mid-fraction at a 
temperature of 14.degree.-17.degree. C. within 3 hours of completion of 
formation of the mid-fraction, and then either 
7A. subjecting the separated mid-fraction to catalytic hydrogenation under 
conditions such that the IV is reduced to 38-45, the linoleic acid content 
is reduced to not more than 2% and the melting point of the hydrogenated 
mid-fraction is 33.degree.-36.degree. C. or 
7B. incorporating into the separated mid-fraction a total of 0.01-1.5% by 
weight of at least one edible structural modifier based on the weight of 
mid-fraction. 
By operating in this way, it is found that it is possible, without adding 
any further chemicals to the palm oil during the fractionation, to produce 
a palm oil mid fraction of excellent properties for use as a cocoa butter 
substitute either directly or after a selective partial hydrogenation. 
In carrying out the fractionation, we have found it convenient to monitor 
the process by determining the iodine value of the various fractions. In 
the specification, iodine value means the iodine value calculated in 
accordance with British Standard 684. Melting points are measured in 
accordance with British Standard 684. 
We find it important to use a neutralised pre-bleached palm oil as starting 
material in our process. The prior removal of phospholipids, acidic 
materials and dark colouring materials is well known in the processing of 
palm oil and facilitates the subsequent fractionation. 
In the first step of the fractionation, the oil is first maintained at a 
temperature of 42.degree.-52.degree. C. for at least 6 hours. During this 
period, crystal formation begins to occur in the hot oil and we find that 
if the bulk of oil is kept at about 47.degree. C., adequate seeding of the 
oil has occurred in about 6 hours. After seeding, the temperature of the 
oil is increased to 70.degree.-75.degree. C., over a period not exceeding 
2 hours to melt any solids present other than the desired crystal seeds 
and is then immediately and carefully cooled. The rate of cooling during 
this and subsequent fractionations is very important and we find it 
necessary to use a period of not less than 5 hours to reduce the 
temperature of 28.degree.-33.degree. C. For example, a cooling rate of 
5.degree. C. per hour can be used, the cooling rate preferably being based 
on a heat transfer control, to reach a final temperature of 
28.degree.-32.degree. C. in a period of 7-8 hours. In this way, it is 
possible to produce a first solid fraction which is separated, 
conveniently by filtration, decantation or centrifugation, a first liquid 
fraction. The separation is preferably carried out immediately the 
formation of the first solid fraction is complete and should be completed 
within 5 and preferably within 3 hours of the completion of formation of 
the first solid fraction. 
This first solid fraction contains the high melting point triglycerides, 
normally the tri-saturated glycerides which are of no interest in the 
production of cocoa butter substitute and this fraction can be utilised 
for processing into other products. The first liquid fraction contains the 
desired di-saturated glycerides and this is subjected to a further 
fractionation step. This second fractionation step is carried out in a 
rather similar way to the first in that the first liquid fraction, is once 
again maintained at a temperature of 38.degree.-48.degree. C. for at least 
4 hours, for example at 44.degree. C. for 6 hours, during which period of 
time, small crystals begin to appear in the liquid phase. When this 
seeding of the first liquid fraction has occurred, the oil is heated to 
60.degree.-65.degree. C., e.g. 63.degree. C., over a period of 1.5-2 
hours, e.g. 1.75 hours, to melt any solids present other than the desired 
crystal seeds and is once again immediately subjected to a carefully 
controlled cooling. In this second fractionation, the temperature of the 
oil is reduced from 60.degree.-65.degree. C. to 14.degree.-17.degree. C. 
over a period of not less than 10 hours and here, a typical cooling rate 
may be about 4.degree.-5.degree. C. per hour, based on a heat transfer 
control, so that a temperature of 15.degree.-16.degree. C. could be 
reached in a period of 11-13 hours. As a result of this controlled 
cooling, a second solid phase crystallizes out. This second solid phase, 
which is the desired mid-fraction, can be separated from the residual oil, 
by conventional methods, e.g. filtration, decantation or centrifugation, 
normally immediately formation of the mid-fraction is complete and, in any 
event, within 3 hours of completion of mid-fraction formation. It is 
important to control the temperature during the separation of the solid 
and liquid phases to within the final temperature range to which the oil 
is cooled after the second fractionation, that is to 14.degree.-17.degree. 
C. 
By operating in this way, it is possible to recover a mid-fraction having 
an IV of 48-53 and melting point 32.degree.-36.degree. C. The residual 
second liquid phase will have an IV of 59-64, preferably 60-62 and a cloud 
point of 3.degree.-7.degree. C., preferably 3.degree.-5.degree. C. 
The separated mid-fraction is found to consist predominately of 
1,3-di-saturated and 1,2-di-unsaturated tri-glycerides. These two 
components comprise approximately 83% by weight of the total mid-fraction, 
the remainder being tri-saturated and tri-unsaturated glycerides, 
1,2-di-saturated and 1,3-di-unsaturated glycerides. 
This mid-fraction is one having a certain proportion of unsaturated 
residues containing more than one site of unsaturation. It is suitable for 
blending with cocoa butter but the incorporation of more than about 10% of 
this mid-fraction in cocoa butter adversely affects the Jenson cooling 
curve. If it is desirable, to extend cocoa butter to a greater extent 
without adversely affecting this cooling curve, we have found that it is 
possible to do this by subjecting the mid-fraction obtained by the 
fractionation method described above, to partial hydrogenation so as to 
remove, to a very large extent or substantially completely, unsaturated 
glycerides containing more than one site of unsaturation. This final 
hydrogenation step can be carried out in a manner known per se by 
catalytic hydrogenation, for example using a nickel containing or a 
platinum or palladium containing catalyst which may be supported or 
unsupported. Hydrogenation can be carried out at a relatively low 
temperature, e.g. not above 300.degree. C. or at temperatures up to about 
250.degree. C. the progress of the hydrogenation being monitored both by 
the amount of hydrogen absorbed and by the IV of the triglyceride. We have 
found that the best results are obtained when linoleic acid content of the 
hydrogenated triglyceride is not more than 3% and preferably not more than 
2% when measured by gas liquid chromatography by the method described in 
AOCS CE1-62 and the iodine value is reduced to 38-45.5 and preferably to 
44-45.5. 
As an alternative to the partial hydrogenation of the separated 
mid-fraction, we have found that by incorporating 0.01-1.5% by weight of 
an edible structural modifier into the mid-fraction, we can produce a 
product of superior physical and taste properties which can be used for 
blending with cocoa butter in an amount of up to 30% by weight or even 
more without adversely affecting the Jenson cooling curve. 
The purpose of the selective hydrogenation in step 7A is to convert the 
polyunsaturated chains in the triglyceride into mono-unsaturated chains, 
but the use of catalytic hydrogenation to produce a cocoa butter 
substitute or extender is not always desirable from the health point of 
view and Government health agencies are beginning to legislate against the 
use of such hydrogenated products. In our alternative procedure of 
incorporating a modifier in the mid-fraction, the polyunsaturated chains 
remain in the final product whose iodine value is substantially identical 
to that of the untreated mid-fraction. However, two or three times the 
amount, or even more, of the modified mid-fraction compared to untreated 
mid-fraction can be introduced into cocoa butter before the adverse effect 
on the Jenson curve begins to become apparent. We find that when the 
modifier is incorporated in the mid-fraction, it undergoes a most 
surprising physical change in that, instead of being an ordinary liquid, 
it increases in plasticity and becomes dimensionally stable holding any 
shape and can be cast or moulded into bars or slabs which can then be 
transported as if it were a solid material. This effect is not 
particularly noticeable on laboratory scale, but occurs quite rapidly on 
pilot plant scale or above. 
As a practical matter, we find it convenient to melt the mid-fraction to a 
temperature of about 65.degree.-75.degree. C., to stir in about 0.5-1% by 
weight of the modifier and then to allow the mass to cool slowly while 
agitation is maintained. For example, if the mid-fraction is heated to 
70.degree. C., the mixture including the modifier can be stirred for 15 
minutes at 70.degree. C. and then allowed to cool to 25.degree.-30.degree. 
C. over a period of at least 24 hours e.g. about 48 hours, the mixture 
being stirred preferably continuously during the cooling period. At the 
end of this period, the product can be cast or moulded and becomes 
dimensionally stable for prolonged storage periods. 
The function of the modifier is uncertain at the moment, but it is believed 
that it provides a continuous phase enclosing small particles of the palm 
oil. Any of the edible, naturally occurring, semisynthetic or synthetic 
gums can be used as a modifier in accordance with this invention and 
legislation of many countries lists those gums permitted in foodstuffs. 
"Gum" in this Patent Specification means any material which can be 
dissolved or dispersed in water to give a viscous solution or dispersion. 
We find that a mixture of a guaranate and carraghenate gum, permitted in 
most countries, is quite suitable. Other vegetable gums, such as 
alginates, carob gum, gum arabic or gum tragacanth can also be used. These 
gums are normally available as dry pulverulant solids and can be blended 
in that form into the mid-fraction. 
A particularly convenient way of carrying out the fractionation stages of 
the present invention involves the use of the fractionator and 
fractionation procedure described in Belgian Pat. No. 713,430. This 
fractionator is essentially a fractionating tank provided with inlet and 
outlet conduits, internal mechanical agitating means and baffles and an 
encircling heat exchange jacket. A heat exchange liquid is circulated 
through the heat exchange jacket so that the contents of the tank can be 
heated or cooled. Temperature sensing means are provided for both the 
contents of the tank and the contents of the heating jacket and signals 
from these two temperature sensing means are analysed and utilised in an 
automatic control system which can control the heat transferred from the 
oil to the heat exchange fluid. In this way, it is possible, during the 
cooling phase of the fractionation, to maintain a very carefully 
controlled delta T, the rate at which the contents of the fractionating 
vessel are cooled. 
It is, of course, also possible to carry out the heating phases of the oil 
in the fractionating vessel, utilising a heat exchanger on the cooling 
circuit and then to cool the oil, at the controlled rate, to the desired 
temperature, by injecting a cold or chilled fluid into the same circuit 
under the control of the automatic system. 
When the formation of a solid phase in the oil is completed, the solid and 
liquid phases are separated from one another, e.g. by filtration. We have 
found that it is advantageous to filter the material on a stainless steel 
filter of the type described in Belgian Specification No. 713330 which 
permits careful temperature control during the separation of the solid and 
liquid phases from one another.

The following Examples are given to illustrate the invention. 
EXAMPLE 1 
A phospholipid-free, neutralized, pre-bleached, Malaysian Palm oil was 
fractionated using a fractionator of the type described in Belgian Pat. 
No. 713430 and the solid stearine fraction separated from the liquid 
fraction on a Florentine filter of the type described in Belgian Pat. No. 
713330. 
18 Kilos of the palm oil was melted and placed inside the fractionator 
where it was maintained at 47.degree. C. for 6 hours. After this period of 
time, the temperature of the oil was elevated to 72.degree. C. over a 
period of 1.75 hrs. 
The oil was then allowed to cool at a rate of 4.degree. C./hr., the cooling 
rate being uniformly maintained until the oil temperature was 30.degree. 
C. The mixture was then filtered on the Florentine filter to give a first 
stearine fraction of 19% yield. The composition and characteristics of 
this stearine fraction are shown in Table 1. 
TABLE 1 
______________________________________ 
Combined Fatty Acids % wt. 
______________________________________ 
C.sub.12 .11 
C.sub.14 1.06 
C.sub.16 56.54 
C.sub.18 4.6 
C.sub.18 29.09 
(mono-unsaturated) 
C.sub.18 8.6 
(di-unsaturated) 
Slip Point .degree.C. 52 
Iodine Value 42.2 
______________________________________ 
The liquid fraction from the first fractionater was maintained in the 
fractionater at 47.degree. C. for 3.5 hrs., and then elevated in 
temperature to 65.degree. C., whereupon the oil was cooled at a rate of 
21/2.degree. C./hr., the cooling rate being uniformly maintained until an 
oil temperature of 15.degree. C. was reached. At this temperature 
crystallisation in the vitreous phase occurs. By this we mean that a 
crystalline layer forms suddenly around existing crystals suspended in the 
liquid phase so that the character of the oil changes from one being 
predominantly liquid in which crystals are suspended to one being 
predominantly solid but still having a liquid phase but now totally 
enclosed inside the solid stearine mass. 
It is however possible to separate the liquid phase from the solid stearine 
phase obtained under these conditions of vitreous phase crystallisation 
using the Florentine filter and carrying out the filtration at 
14.degree.-17.degree. C. The desired stearine or mid-fraction recovered 
gave a 36.5% yield. 
The resulting mid-fraction was then subjected to partial hydrogenation in 
an autoclave at a temperature of 180.degree. C. using a 10 psi pressure of 
hydrogen. A nickel containing catalyst (Unichema PS) was used in a 
proportion of 2 lb/ton equivalent. The hydrogenation was carried out for 
15 minutes until the iodine value was reduced from 52.5 to 46.1. The 
composition and characteristics of the mid-fraction before and after 
hydrogenation are given in Table 2. 
TABLE 2 
______________________________________ 
Hydrogenated 
Mid-fraction 
Mid-fraction 
Combined Fatty Acids % wt. 
Stearine stearine 
______________________________________ 
C.sub.12 .12 trace 
C.sub.14 .79 .81 
C.sub.16 43.8 41.2 
C.sub.18 3.6 4.7 
C.sub.18 -mono-unsaturated 
42.1 51.8 
C.sub.18 -di-unsaturated 
9.59 1.49 
Slip Point 32.degree. C. 
37.2.degree. C. 
Iodine Value 52.5 46.1 
Cooling Curve .degree.C.* 
Max. 25.5 
Min. 20.1 
Rise 5.4 
Time (mins.) 80 
______________________________________ 
*Jenson Cooling Curve method as described by B. W. Manifie in "Chocolate, 
Cocoa and Confectionery Science and Technology" based on 30% addition of 
the hydrogenated midfraction stearine to cocoa butter. 
The liquid fraction from the vitreous phase crystallisation was recovered 
in a yield of 44.5%. Its composition and characteristics are shown in 
Table 3: 
TABLE 3 
______________________________________ 
Fatty Acids % wt. 
______________________________________ 
C.sub.12 .13 
C.sub.14 1.28 
C.sub.16 36.9 
C.sub.18 3.42 
C.sub.18 43.6 
(mono-unsaturated) 
C.sub.18 14.67 
(di-unsaturated) 
Cloud Point .degree.C. 4 
Iodine Value 61.2 
______________________________________ 
EXAMPLE 2 
A phospholipid-free neutralised pre-earth bleached Malaysian palm oil was 
fractionated by the procedure similar to that described in Example 1 to 
give two 200 Kg samples of mid-fraction recovered in a 20% yield. 
In the first stage of the fractionation, temperature control was identical 
to that in the first stage of fractionation in Example 1. The temperature 
of the liquid fraction from the first fractionater was then adjusted to 
16.degree. C. over a period of 12 hours, held at 16.degree. C. for a 
further 21/2 hours, cooled rapidly to 15.degree. C. and then rapidly 
filtered at 15.degree. C. so that a solid mid-fraction was recovered in 
20% yield. The composition and characteristics of this mid-fraction was as 
follows: 
______________________________________ 
Combined fatty acids weight % 
______________________________________ 
C.sub.12 trace 
C.sub.14 1.3 
C.sub.16 47.27 
C.sub.18 3.65 
C.sub.18 mono-unsaturated 
40.67 
C.sub.18 di-unsaturated 
7.29 
Slip point 33.5.degree. C. 
IV 48.17 
______________________________________ 
These fractions were then heat bleached and deodorized. The deodorized 
mid-fraction was then heated to a temperature of 70.degree. C. and 
homogenised and 0.12% w/w of gums added. The gum used was a mixture of 
0.04% carraghenate of 40 micron particle size, 0.04% of carraghenate of 
ungraded particle size and 0.04 guaranate of 40 micron particle size. 
This mixture was then slowly cooled to between 25.degree.-30.degree. C. 
over a period of 2.5 hours. The product was then cast into 20 kilo blocks 
and allowed to cool naturally to room temperature. The product so formed 
was the vitreous phase and at a temperature of 18.degree. C. had physical 
properties similar to cocoa butter. 
The addition of the gum did not alter the melting point or crystallization 
temperature but increased homogenity and plasticity. The untreated 
mid-fraction and gum-treated mid-fraction were blended into chocolate, of 
the following composition: 
Chocolate liquor: 45 g 
Untreated or gum-treated mid-fraction: 5 g 
Sugar: 49.05 g 
Lecithin: 0.05 g 
The chocolate so prepared was compared against a similar chocolate 
containing total cocoa products, i.e. 50 g chocolate liquor and no 
mid-fraction, for its `snap` characteristics. Taking the total cocoa 
product as the ideal 100% snap at the temperature of test of 18.degree. C. 
the following were recorded: 
______________________________________ 
UNTREATED GUM-TREATED 
SNAP AT MID-FRACTION MID-FRACTION 
______________________________________ 
24 Hr. 80.5% 94.4% 
48 Hr. 77.7% 88.9% 
6 days 77.7% 94.4% 
______________________________________