OA10495A - Process for extracting palm oil and extracted oil - Google Patents

Abstract

Process for extraction of oil palm oil comprises a simultaneous single-stage extraction of the oils contained in oil-palm drupe to give a mixture of palm oil and palm kernel oil (chou-palmiste oil) contained in the fruit. The trusses of picked fruit are steam sterilised and the fruits are stripped off the fibrous stalks. The fruit is milled, optionally in the presence of water, under conditions leading to the liberation of most of the oil present in the fruit whilst avoiding any emulsification of the oil, to yield a pulp charged with oil. The paste may be subjected to a heat treatment at \- 50 deg C to inactivate the lipolytic enzymes and to stop development of the cryptogamic flora present in the fruit. The resulting pulp is kneaded, optionally in the presence of a small amount of water, under conditions of sufficient energy to form a continuous oil phase, e.g. in a horizontal kneader. The resulting mixture is separated at > 50 deg C e.g. by mechanical separation or centrifuging and the oil obtained is subjected to a purification or polishing treatment followed by drying.

Description

010495

PROCESS FOR EXTRACTING PALM OIL AND OIL

EXTRAITE

The present invention relates to a new extraction process of palm oil and the oil thus extracted.

It is known that the palm oil regimes consist of a fibrous support, called a stalk, on which are fixed fruits.

These fruits, also called drupes, consist of an egg-shaped walnut surrounded by a pulp rich in oil cells and a smooth skin.

The nuts are made of a shell that contains an almond called palm kernel.

The palm kernel contains a fat called palm kernel oil that can be extracted by trituration, after drying the kernel. Palm oil extracted from the pulp of the fruit has a composition, physical and chemical characteristics as well as applications very different from those of palm kernel oil extracted from almonds.

Thus, freshly made palm oil has a fairly pleasant flavor and odor, and has a lipid moiety consisting essentially of palmitic and oleic acids. This palm oil can be used post-consumer in the food industry, especially in the manufacture of margarines, table oils and other cooking greases. It is often consumed as is by natives in Africa. Palm kernel oil is characterized by a high content of low molecular weight saturated acids, and its properties are very similar to those of coconut oil. After refining, this palm kernel oil is particularly used in the food industry and lipochemistry (detergents, cosmetics, etc ...).

Because of these differences in compositions, properties and applications, pulps and almonds are subjected to clean extraction treatments.

Thus, the industrial methods of treatment of oil palm systems, used until now, generally consist of dissociating progressively into several distinct fractions: stalks, fibers, palm oil, hulls, almonds, by a succession of transformations and phase separations. .

In addition, the techniques and materials used in industrial units have not evolved for many years. 010495

FIG. 1 schematically shows a conventional manufacturing line used in palm oil mills.

As we see, this process aims, initially, to separate the fruit stalks, then in a second time, to extract the palm oil and nuts from them.

To do this, the fruits are subjected to a specific treatment allowing palm oil to be extracted from the pulp while the nuts are subjected to a specific treatment allowing the recovery of the almonds from which the oil can subsequently be extracted. palm kernel. The palm oil is extracted from the fruit pulp by the following successful operations: - sterilization of the diets - destemming of the bunches - mixing of the fruits - extraction by pressure of the fruits - clarification of the oil - finishing of the oil

Sterilization is the treatment of whole diets and loose fruits with water vapor under pressure. This treatment generally comprises several pressurized pressures followed by abrupt detents at atmospheric pressure, the assembly constituting what is generally known as the de-sterilization cycle.

This operation, which involves reheating at a final temperature above 100 ° C. for a period of the order of one hour, is intended to prevent the subsequent development of the acidity of the oil, to facilitate the detachment of the fruits from the stalk, prepare the fruit pulp for subsequent treatments and take off the shell almonds.

This operation requires the implementation of relatively severe temperature and pressure conditions. Stalking essentially consists in separating the sterilized rasp and fruit diets, by applying repeated shocks, with or without tearing the larafle, the fruits being separated by passage through bars or openings of appropriate size. For this purpose, it is most often used for continuous apparatus such as a cage de-stemmer or a stalker.

The mixing consists essentially of brewing the sterilized fruit, still hot, from the destemmer by arms supported by a vertical axis, in order to detach the pulp from the nuts, to burst the cells to release oil they contain, and prepare the subsequent extraction. During this operation, the temperature of the fruits is raised to a value close to 98 ° C. Extraction consists essentially in separating from the mixed fruits the liquid fraction still called crude palm oil or raw juice.

Various means can be used to achieve this objective, and the treatment will be: static pressure, made in hydraulic presses with perforated cages; by continuous pressure, made in so-called continuous presses, generally screw; by spinning, carried out in a basket centrifuge, by washing with hot water and steam.

Clarification separates palm oil from other components of the raw juice extraction.

The clarification is generally carried out in two stages, which are usually designated by first and second decantation, and several processes can be used, among which mention may be made of: static decantation, continuous static decantation and centrifugal decantation.

The finishing of the oil generally comprises the following three stages: - reheating; - polishing, by static or centrifugal decantation; - drying.

This operation makes it possible to perfect the purification of the oil which, leaving the clarification, still contains a few units per thousand of moisture and foreign matter.

During this operation, the moisture content is generally lowered to a value of 0.10 to 0.20% which is of the order of magnitude of the dissolution rate of the water in the oil.

The humidity level may be lowered to still lower values but it is necessary in this case to use a natural dehydrator or intended to operate under average vacuum:

The process just described is now perfectly controlled and ensures very good oil yields.

However, it has two important disadvantages. On the one hand, this process is specifically designed for large production units and therefore requires relatively large investments.

Thus, the industrial units of average capacity (3 to 6 tons of 5 regimes per hour) or small capacity (1.5 to 3 tons of regimes per hour) carried out according to this scheme work correctly, but do not allow to obtain rates of as high as those observed in large units with a capacity greater than 20 tonnes.

In addition, units with a capacity of less than 10 tonnes10 (expressed in palm systems) per hour, can not ensure their energy autonomy, which considerably increases the production costs and the competitiveness of these units. On the other hand, this conventional extraction method requires, for its implementation, large volumes of water (approximately 500 l / ton of regimes) and generates very large quantities of effluents loaded with organic matter (400 to 5001 / ton of regimes at 30000 U BOD).

These pollution problems are even more acute for small units that are generally not adequately equipped for wastewater treatment. Lastly, it should be added that investments weigh very heavily on the operating costs of small units.

It is therefore an object of the present invention to solve the technical problem of providing a new process for extracting oil from the pulpwood, better suited to small capacities, relatively inexpensive in terms of investment and energy, and allowing to limit the problems of pollutioncorrelatives to the classical extraction process.

The solution according to the present invention, to solve this technical problem, consists of a palm oil extraction process characterized in that it comprises a step of simultaneous extraction in a single operation of the oils contained in the fruit of the palm tree. oil, to obtain a mixture of palm and palm kernel oils contained in this fruit.

According to a presently preferred embodiment, this process is further characterized in that it comprises: a) milling, optionally in the presence of water, oil palm fruits under conditions allowing the release of a major part of the oil; oil in these fruits, while practically avoiding the emulsification of this oil, thus leading to a paste loaded with oil; b) optionally, heat treatment of the resulting paste at a temperature of at least 50 ° C for a time sufficient to inactivate the lipolytic enzymes and stop the development of cryptogamic flora present in said fruits; c) mixing the dough thus obtained, possibly in the presence of a small amount of water, under energy conditions sufficient to form a continuous oily phase, for example by means of a horizontal mixer; d) separating the mixture thus obtained mechanically and / or centrifugally, for example by means of a belt press, a two-phase decanter, a screw press, at a temperature above 50 ° C; e) purifying or polishing the oily phase separated in the preceding step and; f) drying the oil obtained.

As is understood, unlike the conventional method used up to now, the method according to the present invention is not intended to separately produce palm and palm kernel oils, but achieves in a single passagel'extraction of most of the fat present in the fruit of the palm tree.

This process is particularly simple, since a single unit operation (separation) makes it possible to replace two steps of the conventional process (extraction and clarification) and that, moreover, the process according to the invention does not require the recovery of the nuts. palm kernel, which corresponds to a simplification of the production units insofar as it is no longer necessary to provide a palm tree.

This relative simplicity results in a strong compaction of the treatment workshop, and therefore in a reduction of the necessary investments.

In addition, the waste generated by the implementation of the process according to the invention are relatively small: in addition to the sterilization condensates and stains already obtained in the conventional process, this process generates less loaded effluents than clarification sludge obtained in oil mills. conventional dehal and solid wastes (pomace) which because of their fineness, their granulometry and their low compaction can be dried very easily and are then an excellent fuel whose heat capacity far exceeds the needs of the process, including drying.

Thus, the energy autonomy of the units using this process is improved regardless of their nominal capacity. 6 010495

Finally, the quantities of manufacturing water and liquid effluents sontrelativement limited and can be further reduced by recycling the water rejected by the polisher at the dilution of the kneaded pulp before separation.

As understood, the oil extracted by the implementation of the method according to the invention consists of a mixture of palm oil and palm kernel oil. In general terms, the main characteristics of the oils that can be obtained by carrying out the process according to the present invention are the following: - general composition * palm oil * palm kernel oil - density - refractive index - unsaponifiable - fatty acid compositions (in%) C6: 0 <0.05 C8: 0 0.1 to 0.6 C10: 0 0.1 to 0.7 C12: 0 1.5 to 6.6 C14: 0 1 to 7.5 Cl6: 0 to 57 C16: 1 <0.6 C18: 0 1.5 to 8 C18: 1 25 to 51 C18: 2 4.5 to 13.5 C18: 3 <1.5 C20 : 0 <1

-DOBI - total carotenoid content - phosphorus content 90 to 96% 4 to 10% 0.890 to 0.9001,450 - 1,460max 12 g / kg> 2,6 to 500 to 2,000 mg / kg <15 ppm

It has been found, quite surprisingly and unexpectedly, that the oil thus obtained has a very low acidity and sensory and nutritional properties quite remarkable.

This can be explained by the fact that the processing times required for carrying out the process according to the invention are considerably reduced compared to the conventional method.

Thus, except sterilization, the conventional method requires about 5 hours on average to extract palm oil.

On the other hand, the process according to the present invention only requires an average time of about 1 hour to achieve the same result.

This results in obtaining an oil with improved quality characteristics (acid number, peroxide index) compared to the procedeclassique. The oil obtained by carrying out the process according to the invention can be used locally for cooking, without having been previously refined.

On the sensory level, this oil has a very pleasant fruity taste. On the nutritional level, this oil is particularly interesting insofar as it does not require refining at high temperature, it remains unscathed from any alteration and contains all its biological principles. active (carotenes, antioxidants, etc ...); it could thus become an oil to taste and get an excellent place in dietetics.

In addition, due to the presence of palm kernel oil in the composition, the oil extracted by the process according to the invention leads to a better yield of olein by fractionation.

This oil can be optionally refined for use as a flat table oil; the losses in refining are less important than in the case of oils obtained by the implementation of the conventional method of extraction, the oil being less acidic at the beginning. The palm fruits used as starting material in the process according to the present invention can be obtained in a manner analogous to that used in the conventional method by sterilization and destemming.

However, and this is an advantageous characteristic of the process according to the present invention, these steps can be carried out under much milder conditions than those required by the conventional procedure.

Thus, the sterilization can be carried out for a less important period of the order of 45 minutes.

In addition, since the process according to the invention does not comprise a step of separating the nuts, the sterilization does not require, contrary to the conventional procedure, a cycle comprising several pressure and pressure rise at 010495 atmospheric pressure. Thus the steam consumption is reduced.

Some tests have shown, quite surprisingly and unexpectedly, that it was possible to carry out the extraction method according to the present invention from fresh fruits obtained by cutting the sliced calming regimes and destemming the pieces thus obtained. The invention will be better understood and other objects, characteristics and advantages thereof will appear more clearly on reading the following explanatory description, with reference to the appended diagrammatic drawings in which: FIG. 1 schematically represents a chain of FIG. conventional manufacturing used in the state of the art; and Figure 2 schematically shows a manufacturing line according to the invention.

In the introductory part of the present application, a conventional manufacturing line used up to now in palm oil mills has been described.

As can be seen in FIG. 2, the process according to the present invention is essentially characterized by the fact that it aims to carry out in a single pass the extraction of the majority of the fatty substances present in the fruits of the palm tree. The oil is extracted simultaneously from the fruit pulp and almond by the following successive operations: - sterilization; - destemming; - grinding ; - mixing; - separation; - purification; and - drying.

As indicated above, the sterilization and stripping operations can be carried out under conditions similar to those of the conventional method described above or possibly under more moderate conditions.

The grinding carried out on the fruits is carried out under conditions allowing the release of a major part of the oil present in the fruits, all while practically avoiding the emulsification of the oil.

By "major part" is meant here at least 85% of the oil present 010495 in the fruit.

The grinding must be carried out under sufficiently moderated energy conditions to avoid the shearing of the fat globules and the emulsification of the oil.

The ratio of palm oil to palm kernel oil in the finished product also depends on the grinding conditions.

The means necessary for the implementation of this step and the operating conditions can be easily determined by the person skilled in the art with regard to the goal to be achieved. For this purpose, it is possible to use a grinder with toothed disks having a capacity of 1,800 kilos per hour.

During this operation which leads to a paste loaded with oil, there is a fragmentation of the nuts and a cut of the fibers and the formation of three phases is observed: an aqueous phase; an oily phase (micro droplets of oil); anda solid phase.

This solid phase consists essentially of fibers and nuts debris whose largest dimension is generally less than 8 mm and average size of the order of 5 mm under normal operating conditions.

When the type of mill used requires it, a small amount of water may be added, for example of the order of 10% by weight expressed relative to the weight of the fruit.

This grinding operation will generally be carried out at a temperature above about 50 ° C., which ensures the inactivation of the lipolytic enzymes and the stopping of the development of the cryptogamic flora present in the fruits.

If the grinding operation is carried out at a temperature below 50 ° C., then a heat treatment operation of the milled pulp will be provided at a temperature of at least 50 ° C. for a time sufficient to control the enzymes and the cryptogamic flora present in the mill. the fruits.

This optional heat treatment operation of the crushed pulp may be performed before or simultaneously with the kneading operation. The kneading operation essentially consists in stirring the paste obtained after grinding and optional heat treatment, to cause the lacoalescence of the micro-droplets of oil present in the paste to form a continuous oily phase.

It is therefore important during this operation to impart sufficient energy to the column to cause coalescence, but sufficiently limited to prevent the division of the oily phase, i.e. the possible emulsification of a portion of it. Those skilled in the art will easily determine the conditions to be met to achieve this objective depending on the temperature of the dough and the diameter of the micro-droplets of oil present therein.

This operation will generally be performed at a temperature above 50 ° C, preferably in the range of 60 to 80 ° C, for a period of about 10 to 20 minutes.

This operation will advantageously be carried out in a horizontal kneader in the presence of a small quantity of water determined to adjust the viscosity as a function of the desired oil flow rate and whose temperature is preferably at least 50.degree.

An amount of water of about 10% by weight relative to the weight of the dough was found to be appropriate. The separation operation is a particularly important step of the process according to the present invention. It can be carried out mechanically, centrifugally or by any combination of these two routes. The term "mechanical" means the use of apparatus such as a belt press or screw press, for example, and by centrifugal means that of decanters with two or three phases for example.

This operation makes it possible to separate the three phases present in the mixer in descending order of density.

Thus, the solids (solid phase) are firstly recovered. In a second step, the heavier liquid phase, ie the aqueous phase, whose density is of the order of 1.0, is recovered. .

Finally, in a third step, the oily phase is recovered whose density is of the order of 0.85 to 0.88.

In a presently preferred embodiment, this separation operation is carried out centrifugally. Advantageously, a three-phase tricantor or decanter will be used for this purpose and in this case this operation may be carried out at a temperature greater than 50.degree. C. and preferably from about 60.degree. To 80.degree. C. The purification or polishing of the oily phase thus separated is carried out conventionally by static decantation or in a plate centrifuge or polisher.

Similarly, the drying of the oil thus obtained can be carried out in conventional conditions allowing the elimination of residual water in the oil. Drying under reduced pressure can be used for this purpose.

Preferably, this drying will be carried out under conditions allowing the humidity level to be lowered to a value of 0.10 to 0.20% or less.

The solid phase obtained during separation and consisting of shell and almond debris and fibers can be incinerated after drying.

It is indeed an excellent fuel for the production of steam used for sterilization and during the process as shown in Figure 2.

An example of implementation of the method according to the present invention will now be described in more detail.

The method which is the subject of the present invention was implemented and tested on a pilot line, comprising the following main equipment: a disk mill or a hammer mill; - A mixing set consisting of four tanks formed inauges equipped with rotary stirring devices with a total capacity of 7,500 liters; the troughs had a double jacket to ensure warming by circulation of hot water, while the tanks were provided in the two lower compartments, ramps for injecting steam at 3 bars of pressure directly into the dough; - Flottweg three-phase decanter type Z4D-3/441; a Veronesi BSGAR 480 separator; as well as all ancillary equipment, pumps, steam exchangers / hot water, transfer screws to ensure the continuous operation of the pilot under satisfactory conditions.

Further tests were also carried out, replacing the three phase decanter with a Flottweg brand belt press; these tests showed the equivalence of these two means of separation.

In addition, other tests have been carried out, completing the separationso performed, either by a three-phase decanter, or by a belt press, by a finishing treatment using a conventional screw press of the type of those that are usually used to squeeze palm fruit.

The pilot line was installed between the two chains of an industrial oil mill and a feed auger was used to take the sterilized fruit directly from the de-stemmer of one of these chains.

The pilot line was thus fed with the same raw material as the traditional installations, thus making it possible to compare the results obtained with the two technologies.

All the analysis and weighing means making it possible to characterize the products obtained and to establish precise material balances have been implemented.

During the various trials, nearly 100 tonnes of palm diets were processed by the pilot unit, thus producing more than 20 tonnes of oil.

Fractionation and refining tests showed the good behavior of the product for these two operations and the tests of use showed the good acceptability of the oil obtained and derived products, particularly olein.

During one of the many tests carried out, 4,160 kg of fresh diets were weighed which were sterilized normally in the factory facilities. On destemming, the diets yielded 2,700 kg of sterilized fruits.

These were milled in the disc mill in which water was introduced in order to improve the grinding and to avoid heating.

The paste thus obtained was kneaded for a period of about 20 to 30 minutes: two of the four mixing tanks making up the apparatus were used to limit the mixing time. The kneaded paste was maintained at a temperature of about 80 ° C. by simply circulating hot water in the double envelopes of the tanks.

The paste was then treated in the three-phase decanter, giving: - 1600 kg of solid phase containing on average 48% of water and 8% of oil, - 2.650 kg of aqueous phase containing approximately 0, 8% oil and less than 3% solids, - 980 kg oil containing 0.5% water and traces of impurities. The oil was then centrifuged and a moisture of less than 0.2% and less than 0.02% of impurities was obtained.

Thus the extraction rate expressed by the ratio of the weight of oil extracted on the weight of machined diets was 23.49% while the extraction rate obtained simultaneously on the mill by the traditional technology was 20.62%. %. 13 010495

The process according to the invention has thus made it possible to obtain an improvement of almost 15% in the extraction rate compared with the conventional procedure.

The solid phase from the decanter was subjected to additional treatment tests by a screw press. With a screw press, the moisture content of the solid phase has been reduced to about 40%, which is comparable to the moisture content of the fibers exiting the presses in the conventional process. The use of a waste boiler is therefore possible.

Moreover, the pressure has made it possible to recover an easily decantable oily juice which can be reinjected into the dough before separation by the three-phase decanter. The analyzes and material balances show that the oil thus recovered represents at least 1% of extraction rate on schemes. The oil obtained in this test has been analyzed and its main characteristics are given below. This oil consisted of about 94 to 95% palm oil and 5 to 6% palm kernel oil.

Its composition of fatty acids and triglycerides is given in Table I below. 14 010495

Fatty acid composition (%) Triglyceride composition (%) C8: 0 0.1 LLO 0.7 00: 0 0.2 PLL 2.4 02: 0 2.5 OLO 1.7 04: 0 1, 5 PLO 10.6 06: 0 40.3 PLP 8.9 06: 1 0.1.000 3.6 08: 0 5.5 OOP 22.3 08: 1 38.7 POP 26.7 08: 2 10, 2 PPP 4.8 08: 3 0.3 soo 2.7 C20: 0.4 POS 5.6 C20: 0.1 PPS 1.1

TABLE I

In the aforementioned Table I, the letters L, O, P and S respectively denote the chains derived from linoleic, oleic, palmitic and stearic acids used in the composition of triglycerides. 010495 15

The following additional characteristics have been determined: - acidity - density - refractive index - saponification number - peroxide value - iodine number - DOBI (bleaching capacity) - unsaponifiable (hexane) content - carotenoid content totals - β-carotene content (HPLC) - tocopherol content - tocotrienol content - phosphorus content 2.5% (expressed as palmitic acid) 0.899 1.455 200.9 1.6 mg C ^ / kg 52.8 2.7 0.43 % 72.3 mg eq β-carotene / 100 g43.6 mg eq β-carotene / 100 g190 ppm 642 ppm 10 ppm

The advantages of the process just described are numerous and the following points are particularly noteworthy: extraction of a good quality oil at a relatively low cost; - low investment; - Implementation relatively simple little sensitive to temperature and dilution conditions; 10 - possible use for a wide variety of installations and sizes (this process is suitable for low capacity plants - on the order of 1.5 to 3 t / h - as for large plants - greater than 20 t / h); simplification of the process which comprises a number of steps lower than that observed in the conventional method; Reducing the volume and the charge of the effluents generated, the process as a whole being less polluting; - the generated waste guarantees a heating autonomy whatever the capacity of the installation.

Claims (9)

16 010495 CLAIMS 1. A process for extracting palm oil, characterized in that it comprises a step of simultaneous extraction in a single operation of the oils contained in the drupe of the oil palm, to obtain a mixture of palm oil and palm kernel contained in the fruit. 2. Method according to claim 1, characterized in that it comprises: a) the grinding, optionally in the presence of water, oil palm fruits under conditions allowing the release of a major part of the oilpresente in these fruits, while practically avoiding the emulsification of this oil, thus leading to a paste loaded with oil; b) optionally, heat treatment of the resulting paste at a temperature of at least 50 ° C for a time sufficient to inactivate the lipolytic enzymes and stop the development of cryptogamic flora present in said fruits; c) mixing the dough thus obtained, possibly in the presence of a small amount of water, under energy conditions sufficient to form a continuous oily phase, for example by means of a horizontal mixer; d) mechanically and / or centrifugally separating the mixture thus obtained at a temperature above 50 ° C; e) purifying or polishing the oily phase separated in the preceding step and; f) drying the oil thus obtained. 3. Method according to claim 2 characterized in that the fruits used as starting material are obtained by the implementation of the following steps: -sterilization of whole diets by steam under pressure; - Stalking of the diets thus sterilized in stalks and fruits. 4. Method according to claim 2, characterized in that the fruits used as starting material are obtained by the implementation of the following steps: - cutting the palm regimes into pieces, - de-stemming the pieces thus obtained. 5. Process according to one of Claims 2 to 4, characterized in that the above-mentioned separation step d) is carried out in a three-phase decanter at a temperature above 50 ° C. 6. Installation for carrying out the method according to one of Claims 1 to 5, characterized in that it comprises: - a grinder, preferably with toothed disks or hammers; 010495 17 - a horizontal mixer; a device for separating mechanically and / or centrifugally; means for purifying or polishing an oily phase such as, for example, a plate centrifuge or a polisher; Means for drying the oil. 7. Installation according to claim 6, characterized in that the aforementioned separation device is a three-phase settler. 8. Oil obtainable by carrying out the process according to one of claims 1 to 5, characterized in that it consists of 90 to 96% by weight of palm oil and 4 to 10% by weight. % by weight of palm kernel oil. 9. Oil according to claim 8, characterized in that it has the following main characteristics: - density: - refractive index: 0.890 to 0.900 1.450 - 1.460 - unsaponifiable: maximum 12 g / kg - fatty acid compositions (in% ): C6: 0 <0.05 C8: 0 0.1 to 0.600: 0 0.1 to 0.720 02: 0 1.5 to 6.604: 0 1 to 7.5 06: 0 30 to 57 06: 1 <0.6 08: 0 1.5 to 8 25 08: 1 25 to 51 08: 2 4.5 to 13.5 08: 3 <1.5 C20: 0 <1 -DOBI 30 - total carotenoid content - phosphorus content> 2.6 between 500 and 2000 mg / kg <15 ppm