WO2019139533A1

WO2019139533A1 - Physical refining process for palm oil

Info

Publication number: WO2019139533A1
Application number: PCT/SE2019/050012
Authority: WO
Inventors: Tore Kiilerich JOHANSEN
Original assignee: Aak Ab
Priority date: 2018-01-09
Filing date: 2019-01-09
Publication date: 2019-07-18

Abstract

A distillation process for removing free fatty acids (FFAR) from a palm oil (PO), the process comprising:- providing a palm oil (PO), - adding base (BS) to the palm oil (PO) and - heating the palm oil (PO) in the presence of a base (BS) to a temperature of at least 180 degrees Celsius, to obtain a FFA-reduced palm oil (FFARPO),wherein the base is present in an amount of between 0.0001 wt% and 0.1 wt% of the palm oil, and the palm oil and base are heated at a temperature of at least 180 degrees Celsius for less than one hour; wherein the degree of interesterification of the FFA-reduced palm oil (FFARPO) is kept below 50%.

Description

PHYSICAL REFINING PROCESS FOR PALM OIL

FIELD OF INVENTION

The present invention relates to the field of refining palm oil. More particularly, the invention relates to a process for removing free fatty acids by physical refining of palm oil.

BACKGROUND OF THE INVENTION

It is known that 3-monochloropropane-l,2-diol (3-MCPD) and 2- monochloropropane-l,3-diol (2-MCPD) are formed in processes for removing free fatty acids (FFA) in physical refining of a palm oil for foodstuff.

Typically, these compounds are found as esters of fatty acids in palm oil and fractions thereof at various concentrations, depending on the palm oil source, refining steps and other factors. Also, glycidol and fatty acid esters thereof may be present in refined triglyceride fats and oils.

2- and 3-MCPD and esters thereof are not desirable in foodstuff due to potential hazards related to their intake. Knowledge about the exact mechanisms of the formation of these compounds during the processing of edible oils is limited. There remains a need to obtain palm oil having lower levels of 2- and 3-MCPD and esters thereof, as attempts so far have been with little success, or are economically unviable. The present invention addresses such needs and interests in a simple and effective way.

SUMMARY

Palm oil is a vegetable oil extracted from the fruit of oil palms. In order to be rendered edible, extracted palm oil must undergo a series of refining steps to remove unwanted components. Extracted palm oil comprises mono-, di- and tri-glycerides, carotenes, sterols, as well as free fatty acids (FFA), which are not esterified with glycerol. FFA lead to degradated quality of the oil and an increase in rancidity and is thus one of a number of components that the refining process seeks to remove from the extracted palm oil. The refining of palm oil requires a series of purification steps, with one of them being to decrease the free fatty acid level of the (crude) palm oil. This step is very important for the quality of the final product and has a major impact on the economic feasibility of the whole process. Several techniques, alternative to conventional caustic neutralisation or steam distillation methods, are suggested in the literature, such as supercritical extraction, membrane technology and solvent extraction. The solvent extraction of free fatty acids may be achieved using short chain alcohols. Its technical feasibility is due to the differences in solubility of free fatty acids and neutral oil in different solvents. All of the above mentioned techniques usually have the drawback of high cost and / or significant investments compared to physical refining.

The origin of 2- and 3-MCPD and esters thereof in palm oil is not entirely clear, but possible health issues relate to their presence. It is believed that most 2- and 3-MCPD and esters thereof are formed at elevated temperatures during refining steps, such as steps removing free fatty acids, from substances naturally present in the palm oil. However, when the free fatty acid removing step comprises adding base to the palm oil and heating the palm oil to at least 180 degrees Celsius surprisingly low or almost non-existent amounts of 2- and 3-MCPD or esters thereof are found in the obtained FFA-reduced palm oil, without randomizing the triglyceride structure of the palm oil to a too high extent. The invention relates to a process for removing free fatty acids (FFA) in physical refining of a palm oil, the process comprising:

providing a palm oil,

adding base to the palm oil and

- heating the palm oil to at least 180 degrees Celsius,

to obtain a FFA-reduced palm oil,

wherein the degree of interesterification of the FFA-reduced palm oil is kept below 50 %. According to an advantageous embodiment of the invention, the process is performed for less than 1 hour.

The invention relates in a further aspect to a refining process for physical refining of a palm oil, the refining process comprising a free fatty acid removal step according to the invention or any of its embodiments.

The invention relates in an even further aspect to a use of the process according to the invention or any of its embodiments or a refining process according to the invention or any of its embodiments in the manufacture of a physical refined palm oil.

The invention relates in an still even further aspect to physical refined palm oil treated according to the process of the invention or any of its embodiments or obtained by the process of the invention or any of its embodiments.

DETAILED DESCRIPTION

Definitions

As used herein,“%” or“percentage” all relates to weight percentage i.e. wt% or wt- % if nothing else is indicated.

As used herein, the singular forms“a”,“an” and“the” include plural referents unless the context clearly dictates otherwise. As used herein,“at least one” is intended to mean one or more, i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

As used herein, the term“fatty acid” encompasses fatty acid residues in triglycerides. As used herein, the term“free fatty acid” is intended to mean fatty acids which are present in their acid or carboxylate form and not part of mono-, di- or triglycerides.

As used herein, the term“triglycerides” may be used interchangeably with the term ‘triacylglycerides’ and should be understood as an ester derived from glycerol and three fatty acids.“Triglycerides” may be abbreviated TG or TAG.

As used herein,“edible” is something that is suitable for use as food or as part of a food product. An edible fat is thus suitable for use as fat in food or food product and an edible composition is a composition suitable for use in food or a food product.

As used herein,“interesterification” should be understood as replacing one or more of the fatty acid moieties of a triglyceride with another fatty acid moiety or exchanging one or more fatty acid moieties from one triglyceride molecule to another or exchanging the position of a fatty acid within one triglyceride to another position in the same triglyceride. A fatty acid moiety may be understood as a free fatty acid, a fatty acid ester, a fatty acid anhydride, an activated fatty acid and/or the fatty acyl part of a fatty acid. The interesterification process may be an enzymatic interesterification or chemical interesterification. Both chemical interesterification and enzymatic interesterification is described well in the art. Both chemical and enzymatic interesterification may be done by standard procedures.

As used herein “Physical refining” is intended to mean a process of removing free fatty acids from a vegetable oil by means of physical mechanisms, as for example destilation.

As used herein“stripping” is intended to mean a a physical separation process where one or more components are removed from a liquid stream by a vapor or gas stream.

As used herein“pre-stripping” is intended to mean a stripping process performed prior to the final deodorization process.

As used herein“reduced pressure” means pressure lower than atmospheric pressure.

As used herein“crude palm oil” means a palm oil which has not previously been subject to a process of removing free fatty acids.

As used herein“distillation” is intended to mean a process in which the component of the oil are separated by heating it to a certain temperature and condensing the resulting vapors. Palm oil has components that vaporize at different temperatures and thus may be separated by condensing their vapors in turn. Distillation is also used as a purification process in which non-volatile components are separated from volatile components.

The degree of interesterification is calculated by determining sum of PPO (1,2- dipalmitate-3-oleateglycerol) and POP (l,3-dipalmitate-2-oleateglycerol) content of the crude palm oil (CPO) and the FFA-reduced palm oil (FFARPO). The PPO+POP level can be determined by HPLC (AOCS Ce 5b-89 or AOCS Ce 5c-93 method). Additionally the sum of PPO and POP content of a fully randomised oil can be calculated from the fatty acid content of the crude oil (IUPAC 2.301 (methylation), IUPAC 2.304 (GC-method)). The degree of interesterfication can then be calculated from the following equation, where

POP(CPO) is the POP / PPO content of crude palm oil

POP(FFARPO) is the POP / PPO content of FFA reduced palm oil

POP(RPO) is the POP / PPO content of randomised palm oil as calculated from the fatyy acids composition.

Interesterfication = 100

The free fatty acid removing process may also be called FFA-removing process or be considered a free fatty acid removal step.

Abbreviations

3-MCPD = 3-monochloropropane-l,2-diol

2-MCPD = 2-monochloropropane-l,3-diol

FFA = Free fatty acids

P = palmitic acid/palmitate

POP = l,3-dipalmitate-2-oleateglycerol

The invention relates to a process for removing free fatty acids (FFA) in physical refining of a palm oil, the process comprising:

providing a palm oil,

adding base to the palm oil and

- heating the palm oil to at least 180 degrees Celsius,

to obtain a FFA-reduced palm oil,

wherein the degree of interesterification of the FFA-reduced palm oil is kept below 50 %. One significant advantage of the invention is that this provides a FFA-reduced palm oil having a very low content of 2- and 3-MCPD and esters thereof. This in turn enables obtaining a physically refined palm oil with very low content of 2- and 3- MCPD and esters thereof, while allowing the use of crude palm oil, which in a conventional physical refining process would be prone to formation of 2- and 3- MCPD and esters thereof.

The base may be added prior to heating the palm oil, or the base may also be added after the palm oil is heated to at least 180 degrees Celsius. The base may also be added at a temperature lower than 180 degrees Celsius, as long as the temperature is subsequently then raised to above 180 degrees Celsius.

Usually, during the removal of free fatty acids in the physical refinement of a palm oil, 2- and 3-MCPD and esters thereof are formed, which is highly undesired. This may especially be the case, when the provided palm oil is a crude palm oil for example in the cases, where the palm oil is not freshly obtained. However, by adding a base during the process of removing free fatty acids from a palm oil according to the present invention while heating to a temperature above 180 degrees Celsius, the amount of 2- and 3-MCPD and esters thereof in the resulting FFA-reduced palm oil is drastically lowered or even not detectable compared to a FFA-reduced palm oi from a conventional physical refining process, which makes the palm oil especially suitable for human consumption. In addition, the degree of interesterification is kept below 50% or even much lower, such as lower than 10% or 5%, thus the triglyceride composition of the original oil is retained to a large extent and thereby preserving the original properties of the palm oil, with respect to for example melting point. Hence, the overall properties and value of the FFA-reduced palm oil may be significantly improved, while, importantly, not altering the triglyceride composition in any significant way. The authenticity of the palm oil is therefore largely or fully preserved.

The process for free fatty acid removal in physical refinement of a palm oil may be performed in a pre-stripping process prior to a bleaching and a deodorization step.

The process may easily be implemented in an already established process for physical refining palm oil. According to an advantageous embodiment of the invention, the process is performed for less than 1 hour. According to a further embodiment of the invention, the process is performed for less than 30 minutes, alternatively between 2 to 60 minutes such as between 2 to 30 minutes or between 5 to 30 minutes.

It has surprisingly been found that only short process time, such as less than 1 hour or less than 30 minutes, is necessary to achieve substantial reductions in the amount of free fatty acids while obtaining very low amount of 2- and 3-MCPD and esters thereof in the resulting FFA-reduced palm oil as well as keeping the degree of interesterification very low, such as lower than 10% or 5%. Presumably because, the time during which the palm oil is heated can be minimized.

It may be especially advantageous that the process according to the invention is performed for less than 1 hour or even less than 30 minutes, such as between 2 to 30 minutes. The degree of interesterification may be minimized by shortening the time the process is performed. By performing the process for a short period of time, such as between 2 minutes and 1 hour, an advantageous optimum of both obtaining a low amount of 2- and 3-MCPD and esters thereof as well as a surprisingly low degree of interestification may be obtained.

According to an advantageous embodiment of the invention, the base is a weak base.

All types of bases may be added, however weak bases have the advantage that the process may be easier to control, so that both the amount of 2- and 3-MCPD and esters thereof and the degree of interesterification is kept low, and the results are predictable and reproducible. According to a further advantageous embodiment of the invention, the base is a metal carbonate or metal bicarbonate.

According to an embodiment of the invention the base is potassium carbonate, sodium carbonate, potassium hydrogen carbonate, sodium hydrogencarbonate or any combination thereof.

It has surprisingly been found that when the added base is a metal carbonate or metal bicarbonate the amounts of 3-MCPD in the obtained FFA-reduced palm oil may be extremely low, such as lower than 0.5 or 0.1 ppm, while also keeping the degree of interesterification very low, such as below 5%.

In an embodiment of the invention the base is provided as an aqueous solution. In order to achieve the desired results, small amounts of water may be needed to assist in the base-catalyzed reactions taking place in the palm oil. Most palm oils comprise small amounts of water and the base may be added as a solid and still efficiently act as a hydrous base, when contacting the water in the oil. Water may also be present in the form of steam which is passed through the oil. Nevertheless, it may be convenient to add the base as an aqueous solution in some embodiments.

According to an even further advantageous embodiment of the invention, the corresponding acid of the added base has a pKa value of between 8 to 12.

According to a still further advantageous embodiment of the invention, the concentration of the base when mixed into the palm oil is 0.0001 - 0.1% of base by weight of said palm oil, more preferable 0.001 - 0.01% of base by weight of said palm oil.

In an embodiment of the present invention, the base concentration is kept within certain limits, for example 0.0001 to 0.1% or 0.001 to 0.01% of base by weight of the palm oil. This may help in controlling the degree of interesterification while still effectively avoid creation of 2- and 3-MCPD and esters thereof.

The concentration of base is important for both the desired removal of 2- and 3- MCPD and esters thereof and the undesired interesterification since both are catalysed by base.

It is advantageous to keep the concentration of base comparatively low in order to preserve the original triglyceride composition as much as possible. Interesterification may lead to an oil with for example melting properties considerably different from the original oil. On the other hand, if base concentration is too low, the creation of 2- and 3-MCPD and esters thereof may not be avoided. The choice of concentration of base is thus based on a trade-off between desired and undesired reactions, and, for example, the choice of process temperature and time.

According to an advantageous embodiment of the invention, the crude palm oil is not freshly extracted. .

It may for example be a crude palm oil which has been transported away from the place it was extracted. It appears, without being bound to any specific theory, that a crude palm oil may in some way be altered, for example during storage and / or transportation, so that when subjecting the crude palm oil to physical refinement, especially when involving heating, 2-and 3-MCPD and esters thereof will arise to an undesirable extent. Thus, the process according to embodiments of the present invention may be especially useful for removing free fatty acids in physical refining of a crude palm oil not freshly extracted, since a crude palm oil may in this way be refined without leading to undesirable amounts of 2-and 3-MCPD and esters thereof.

When a palm oil is not freshly extracted, and for example transported or stored for a period of time, the content of free fatty acids may rise to more than 0.5% by weight of the palm oil. For example, the content of free fatty acids in the crude palm oil is between 0.5 to 10%. According to a further advantageous embodiment of the invention, the crude palm oil contains more than 0.5% by weight of free fatty acids..

According to an even further advantageous embodiment of the invention, the content of free fatty acids in the FFA-reduced palm oil is below 1% by weight of the FFA- reduced palm oil. It should be understood, that the content of free fatty acids in the FFA-reduced palm oil will always be less than the content of free fatty acids in the palm oil that entered the process.

According to an embodiment of the invention, the content of free fatty acids in the FFA-reduced palm oil is less than 0.5% by weight of the FFA-reduced palm oil, such as less than 0.1% by weight of the FFA-reduced palm oil, such as less than 0.05% by weight of the FFA-reduced palm oil. Alternatively the content of free fatty acids in the FFA-reduced palm oil is between 0.01 to 1% by weight of the FFA- reduced palm oil.

According to a still further advantageous embodiment of the invention, the content of free fatty acids is reduced by at least 70%.

Meaning the reduction of the content of free fatty acids in the FFA-reduced palm oil relative to content of free fatty acids in the palm oil entering the process.

According to an embodiment of the invention, the content of free fatty acids is reduced by at least 90%, such as at least 95% or between 70 to 99%. Alternatively, the FFA content in the FFA-reduced palm oil is below 30% by weight of the FFA content in the palm oil entering the process. 2- and 3-MCPD and esters thereof are believed to be formed in palm oil during standard refining processes from components present in the palm oil. As such, the present process is particularly relevant in refining palm oil. Suitable methods for measuring 2-MCPD esters, 3-MCPD esters and glycidyl esters is the AOCS method Cd 29a-l3, alternatively AOCS Cd 29b-l3 or AOCS Cd 29c-l3 or any other validated indirect or direct analytical methods. These methods are performed by for example SGS Germany GmbH Laboratory Services (Hamburg, Weidenbaumweg 137, DE-21035 Hamburg, Germany).

According to an advantageous embodiment of the invention, the FFA-reduced palm oil has a content of 2- and 3-MCPD and esters thereof below 6 ppm.

According to an embodiment of the invention the FFA-reduced palm oil has a content of 2- and 3-MCPD and esters thereof below 4 ppm, such as below 3 ppm, such as below 1 ppm. Alternatively, the FFA-reduced palm oil has a content of 2- and 3-MCPD and esters thereof between 0.01 to 6 ppm, such as between 0.01 to 4 ppm or such as between 0.01 to 1 ppm. Thus, the FFA-removal step of the present process will result in a FFA-reduced palm oil with very low amounts of 2- and 3- MCPD and esters thereof and may obviate optimization of preceding or even subsequent process steps.

According to a further advantageous embodiment of the invention, the FFA-reduced palm oil has a content of 3-MCPD and esters thereof below 4 ppm. According to an embodiment of the invention, the FFA-reduced palm oil has a content of 3-MCPD and esters thereof below 3 ppm, such as below 2 ppm or such as below 0.5 ppm. Alternatively, the FFA-reduced palm oil has a content of 3-MCPD and esters thereof between 0.01 to 4 ppm, such as between 0.01 to 2 ppm or such as between 0.01 to 0.5 ppm. In an embodiment of the invention the concentration of glycidyl esters in the FFA reduced palm oil is less than 2 ppm such as below 1 ppm. Glycidyl esters are, like 2- and 3-MCPD and esters thereof, not desirable in palm oil. The inventive process may thus, in certain embodiments, help diminishing the amount of glycidyl esters in the FFA reduced palm oil

According to an advantageous embodiment of the invention, the process comprises heating the palm oil to at least 200 degrees Celsius.

According to an embodiment of the invention, the process comprises heating the palm oil to at least 220 degrees Celsius. Alternatively, the process comprises heating the palm oil to between 220 to 280 degrees Celsius, such as between 220 to 250 degrees Celsius.

The heating is advantageously carried out at temperatures not too high, such as below 280 degrees Celcius or below 250 degrees Celius. By keeping the temperature not too high, a more selective process may be achieved, wherein the formation of 2- and 3-MCPD and esters thereof in the oil is avoided without causing too much interesterification.

Excessive interesterification of a palm oil may lead to a less valuable oil due to alteration of the physical and/or nutritional properties of the original oil. Therefore, the inventive process is particularly useful, when preservation of the original triglyceride composition of the palm oil is desirable, such as for example in physical refined palm oil for food products.

According to an advantageous embodiment of the invention, the degree of interesterification of the FFA-reduced palm oil is below 30%. For example, the degree of interesterification of the FFA-reduced palm oil is between 1 to 29%. It may also be between 1 to 49%. Since base is known to catalyze interesterification of triglycerides, it is quite surprising that the process according to the invention comprising blending palm oil with base at temperatures above 180 degrees Celsius succeeds in providing a FFA- reduced palm oil with very low or almost non-existing amounts of 2- and 3-MCPD and esters thereof without causing excessive interesterification.

According to embodiments of the present invention, the degree of interesterification in the triglyceride oil is preferably kept as low as possible. In certain embodiments of the present invention, surprisingly low degrees of interesterification may be achieved, and thereby obtaining an FFA-reduced palm oil, where the physical properties such as for example melting point are retained. For example, the degree of interesterification of the FFA-reduced palm oil may be below 10%, such as below 5% or 3%. The degree of interesterification may thus be between 0.1 to 10% or 0.1 to 5%.

According to an advantageous embodiment of the invention, the process is performed at reduced pressure.

One advantage of this may be to avoid oxidative decomposition during the process and another may be that undesired volatile, such as for example free fatty acids are evaporated and thus removed from the blend at a lower temperature , whereby a more effective process may be achieved.

Thus, according to an embodiment of the invention, the process is performed at a pressure between 1 to 900 mbar.

According to a further advantageous embodiment of the invention, the process is performed at a pressure of between 0.001 to 100 mbar. According to another embodiment of the invention, the process is performed at a pressure of between 0.1 to 10 mbar. At lower pressures, for example below 3 mbar, a lower temperature may be used, as long as the temperature is still at least 180 degrees Celsius. At a higher pressure a higher temperature may be preferred to obtain the same result, other things being equal.

Free fatty acids may be removed from a palm oil by different methods, such as for example caustic or steam distillation methods, supercritical extraction, membrane technology or solvent extraction.

According to an advantageous embodiment of the invention, the process further comprises a separation of free fatty acids from the palm oil by subjecting the palm oil to a counter flow of an inert gas. The inert gas may for example be nitrogen and the separation may for example be distillation.

According to a further embodiment of the invention, the palm oil is atomized, for example by spraying the oil, and subjected to a counter flow of inert gas. This may for example be the case in a stripping process.

Alternatively, instead of subjecting the palm oil to a counter flow of inert gas, it may be subjected to a counter flow of steam (water vapor).

According to an embodiment of the invention, the process further comprises contacting the palm oil with irregular surfaced metal plates. This may induce turbulent flow of the palm oil and easier removal of free fatty acids.

According to a further embodiment of the invention, the process comprises

providing a palm oil, and

adding base to the palm oil, and

heating the palm oil to at least 180 degrees Celsius,

to obtain a FFA-reduced palm oil,

wherein the degree of interesterification of the FFA-reduced palm oil is kept below 50 %, wherein the process is performed for less than 1 hour and wherein the process further comprises a separation of free fatty acids from the palm oil by subjecting the palm oil to atomization and a counter flow of an inert gas or steam.

According to a further advantageous embodiment of the invention, the process is a pre-strippping process. A pre-stripping process is a distillation process performed prior to the final deodorization process and as such not essential for obtaining a refined palm oil intended for human consumption, and thus not part of the standard physical refinement steps, such as degumming, bleaching and deodorization.

The process according to the invention or any of its embodiments may however also advantageously be part of the standard steps of physical refinement of palm oil, such as comprised in the deodorization step, especially when an independent free fatty acid removing step (which sole purpose is to remove free fatty acids) is not part of the physical refining process of a palm oil.

Physical refinement of palm oil may normally comprise several process steps such as degumming, bleaching, and deodorization, which usually are performed in that order, however other refining steps may occur in between.

The invention relates in a further aspect to a refining process for physical refining of a palm oil, the refining process comprising a free fatty acid removal step according to the process of the invention or any of its embodiments.

The process for removing free fatty acids according to the invention or any of its embodiments may be a free fatty acid removing step as such, where the main purpose is free fatty acid removal, or it may be part of a process, which comprises other purposes than removing free fatty acids.

According to an advantageous embodiment of the invention, the refining process further comprises a degumming step prior to the free fatty acid removal step. The purpose of degumming is to remove phospholipids or gums from the crude oil. It is usually performed by the addition of diluted phosphoric acid (for example 0.1- 3%), whereby most of the phospholipids are hydrated and are insoluble in the oil. The hydrated compounds may thus be efficiently separated by filtration or centrifugation. Degumming is mandatory for physical refining and the content of phosphorus after degumming should not exceed a certain level.

According to a further advantageous embodiment of the invention, the process further comprises a bleaching step before the free fatty acid removal step and after the degumming step.

The main purpose of bleaching (or decolorizing) is to reduce the levels of pigments such as carotenoids and chlorophyll, but it also further removes residues of phosphatides, soaps, traces of metals, oxidation products, and proteins. These trace components interfere with the further processing. They reduce the quality of the final product and are usually removed by adsorption with activated clay and silica.

According to a still further advantageous embodiment of the invention, the process further comprises a bleaching step after the free fatty acid removal step.

According to a still further advantageous embodiment of the invention, the process further comprises a deodorization step after the free fatty acid removal step.

The main purpose of deodorization is to remove odours, off-flavours and other volatile components such as pesticides and light polycyclic aromatic hydrocarbons. The deodorization process is usually carried out under vacuum and at high temperatures using a stripping media.

However, also free fatty acids in the case of physical refining may be removed in deodorization and also unwanted color pigments may be degraded. The process according to the invention may thus advantageously be performed prior to a deodorization step, in which case the process according to the invention may for example be comprised in or called a pre-stripping step, or the process according to the invention may also be comprised in a deodorization step.

The invention relates in a still even further aspect to a physical refined palm oil treated according to the process of the invention or any of its embodiments, or obtained by the process of the invention or any of its embodiments.

The invention relates in an even further aspect to a use of the physical refined palm oil of the invention or any of its embodiments or the palm oil treated by the process of the invention or any of its embodiments, in an edible food product.

EXAMPLES

Example 1: Avoiding formation of 3-MCPD in physical refined palm oil

A crude palm oil transported to Europe by ship was obtained. The crude palm oil (CPO) contained no 3-MCPD and had a POP+PPO level of 28.8%, see Table 1. By calculation the POP+PPO level of a fully randomized (chemically interesterfied) fraction of the oil would contain 22.6% POP+PPO, see Table 1. Hence at 100% interesterfication 22.6% POP+PPO is present. Four different trials were carried out (column 4 to 7 of Table 1). Conventional physical refining of the crude palm oil (column 4) which resulted in 4.0 ppm 3-MCPD and 1.6% interesterfication. Trial 1 was carried out with a Free fatty acid removing process (FFAR) with 0.001% K2CO3 and resulted in 2.4 ppm 3-MCPD and 1.6% interesterfication. Trial 2 was carried out with a FFAR with 0.05% K2CO3 and resulted in 0.8 ppm 3-MCPD and 0% interesterfication. Trial 3 was carried out with a FFAR with 0.01% K2CO3 and resulted in 0.1 ppm 3-MCPD and 6.4% interesterfication.

To conclude on the results, all of the trials 1 to 3 showed an ability to hinder the formation of 3-MCPD compared to the conventional physical refining procedure. Furthermore, in all the cases the interesterfication was kept well below 10% which is considered very satisfying. In fact the degree of interesterfication is in trial 1 and 2 comparable to or below the interesterfication obtained by conventionally refining palm oil, while keeping the amount of 3-MCPD much lower. The modified procedure demonstrate a new method for hindering the formation of 3-MCPD in palm oil and at the same time avoid interesterfication.

Table 1

FIGURE REFERENCES PO - Palm oil

CPO - Crude palm oil

DG - Degumming

BL - Bleaching

PS - Prestripping

DEO - Deodorisation

RPO - Refined palm oil

FFAR - Free fatty acid removing process

FFARPO - Free fatty acid reduced palm oil

BS - Base MIX - Mixing

HEAT - Heating

Referring to figure la, a FFA-removing process (FFAR) according to an embodiment of the invention is illustrated. A palm oil (PO) is provided and a base (BS) is added.

The palm oil (PO) now comprising base (BS) may typically be mixed (MIX) and then subsequently heated (HEAT) to a temperature of at least 180 degrees Celsius to obtain a FFA-reduced palm oil (FFARPO). Various amounts of base can be used, e.g. 0.0001 to 0.1% w/w. Also, different types of base can be used, such as strong bases like KOH or weak bases such as sodium carbonate. By means of this process, a FFA-reduced palm oil (FFARPO) can be obtained having very low content of MCPD-compounds, even in some embodiments down to less than 0.3 ppm or less than 0.1 ppm. This example of a FFA removal step is usable wihtin the embodiment illustrated on figure 2 or 3.

Referring now to figure lb, a FFA-removing process (FFAR) according to another embodiment of the invention is illustrated. In this case the palm oil (PO) is heated (HEAT) before the base is added. The heated palm oil (PO) comprising base (BS) may be mixed (MIX) after the addition of base or during the addition of base (BS) or both. The palm oil (PO) may be heated (HEAT) to any temperature between ambient and at least 180 degrees Celsius before the base (BS) is added. It may also be heated (HEAT) to a temperature above 180 degrees Celsius prior to the addition of base (BS). It is however crucial that the palm oil (PO) at least during some time, such as at least a couple of minutes, comprises base (BS) and has temperature of above 180 degrees Celsius to obtain a FFA-reduced palm oil (FFARPO). This example of a FFA removal step is usable wihtin the embodiment illustrated on figure 2 or 3.

Referring to figure 2a, a refining process according to an embodiment of the invention is illustrated. The FFA-removing process (FFAR) according to figure la or lb may be used within this embodiment. The FFA-removing process (FFAR) comprising adding base (BS) to the palm oil (PO) and heating (HEAT) the palm oil (PO) to at least 180 degrees Celsius, wherein the degree of interesterification of the FFA-reduced palm oil (FFARPO) is kept below 50%, may advantageously be performed after a degumming step (DG) and followed by a bleaching step (BL) and then a deodorization step (DEO) to give a refined palm oil (RPO). Other steps may be performed in between. The palm (PO) oil may for example be subjected to a further bleaching step (BL) after degumming (DG) and prior to the FFA-removing process (FFAR).

Referring to figure 2b, a refining process according to an embodiment of the invention is illustrated. The FFA-removing process (FFAR) according to figure la or lb may be used within this embodiment. A palm oil (PO) is subjected to the FFA- removing process (FFAR) prior to a degumming step (DG), and is then subsequently subjected to a bleaching step (BL) and afterwards a deodorization step (DEO) to give refined palm oil (RPO).

Referring to figure 2c, a refining process according to an embodiment of the invention is illustrated. The FFA-removing process (FFAR) according to figure la or lb may be used within this embodiment. Palm oil (PO) is subjected to a degumming step (DG) and then subsequently subjected to a bleaching step (BL) and afterwards the FFA-removing process (FFAR) prior to a deodorization step (DEO) to give refined palm oil (RPO).

Referring to figure 3, a refining process according to yet another embodiment of the invention is illustrated. The FFA-removing step (FFAR) according to figure la, lb, 2a, 2b or 2c may be used within this embodiment. Palm oil (PO) may typically be subjected to a degumming step (DG) followed by a bleaching step (BL) and subsequently may be followed by a prestripping step (PS). In the prestripping step (PS) free fatty acids may typically be removed at least to some extent. Thus, the FFA removal step according to figure la or 2a may be used in the prestripping step (PS). The palm (PO) oil is then further subjected to a bleaching step (BL) and then followed by a deodorization step (DEO). The prestripping step (PS) may advantageously comprise the steps of adding base (BS) and heating (HEAT) the palm oil (PO) to at least 180 degrees Celsius, whereby the amounts of 2- and 3- MCPD and esters thereof as well as the degree of interesterification may be kept exceptionally low. However, the steps of adding base (BS) and heating (HEAT) the palm oil (PO) to at least 180 degrees Celsius may be comprised in other steps such as for example the deodorization step (DEO).

Claims

1. A distillation process for removing free fatty acids (FFAR) from a palm oil (PO), the process comprising:

- providing a palm oil (PO),

- adding base (BS) to the palm oil (PO) and

- heating the palm oil (PO) in the presence of a base (BS) to a temperature of at least 180 degrees Celsius, to obtain a FFA-reduced palm oil (FFARPO),

wherein the base is present in an amount of between 0.0001 wt% and 0.1 wt% of the palm oil, and the palm oil and base are heated at a temperature of at least 180 degrees Celsius for less than one hour;

wherein the degree of interesterification of the FFA-reduced palm oil (FFARPO) is kept below 50 %.

2. A distillation process according to Claim 1, wherein the base (BS) is a weak base.

3. A distillation process according to Claim 2, wherein the corresponding acid of the base (BS) has a pKa of between 8 and 12.

4. A distillation process according to any of the preceding claims, wherein the base (BS) is a metal carbonate or metal bicarbonate.

5. A distillation process according to Claim 4, wherein the base (BS) is selected from potassium carbonate, sodium carbonate, potassium hydrogen carbonate, sodium hydrogencarbonate, or any combination thereof.

6. A distillation process according to any preceding claim, wherein the base (BS) is present in an amount of between 0.001 wt% and 0.01 wt% of the palm oil.

7. A distillation process according to any preceding claim, wherein the base (BS) is added as an aqueous solution.

8. A distillation process according to any preceding claim, wherein the palm oil (PO) and base (BS) are heated at a temperature of at least 180 degrees Celsius for 30 minutes or less.

9. A distillation process according to any preceding claim, wherein the palm oil (PO) and base (BS) are heated at a temperature of at least 180 degrees Celsius for between 2 minutes and 30 minutes.

10. A distillation process according to any preceding claim, wherein the palm oil (PO) and base (BS) are heated at a temperature of up to 280 degrees Celsius.

11. A distillation process according to any preceding claim, wherein the palm oil (PO) and base (BS) are heated at a temperature of at least 200 degrees Celsius, preferably 220 degrees Celsius.

12. A distillation process according to any preceding claim, wherein the palm oil (PO) and base (BS) are heated at a temperature between 220 and 280 degrees Celsius.

13. A process according to any preceding claim, further comprising the step of heating the palm oil (PO) temperature above room temperature but below 180 degrees Celsius before adding the base (BS) to the palm oil.

14. A distillation process according to any of the preceding claims, wherein the process is performed at reduced pressure.

15. A distillation process according to Claim 14, wherein the process is performed at a pressure of between 0.001 and 900 mbar.

16. A distillation process according to Claim 14 or 15, wherein the process is performed at a pressure of between 0.001 to 100 mbar, preferably between 0.1 and 10 mbar.

17. A distillation process according to any of the preceding claims, wherein the process further comprises a separation of free fatty acids from the palm oil (PO) by subjecting the palm oil (PO) to a counter flow of an inert gas.

18. A distillation process according to Claim 17, wherein the inert gas is nitrogen.

19. A distillation process according to any of Claims 1 to 16, wherein the process further comprises a separation of free fatty acids from the palm oil (PO) by subjecting the palm oil (PO) to a counter flow of steam (water vapour).

20. A distillation process according to any preceding claim, wherein the palm oil and base are contacted with irregular surfaced metal plates.

21. A distillation process according to any of the preceding claims, wherein the palm oil (PO) is a crude palm oil (CPO).

22. A physical refining process for removing free fatty acids (FFAR) from palm oil (PO), wherein the physical refining process comprises a distillation process according to any one of Claims 1 to 21.

23. A physical refining process according to Claim 22, wherein the distillation process is a pre-stripping process.

24. A physical refining process according to Claim 22 or 23, wherein the FFA- reduced palm oil (PO) is subjected to further refining steps selected from one or more of a bleaching step (BL), a deodorization step (DEO) and a degumming step (DG).

25. A physically refined palm oil (RPO) treated according to the process of any of Claims 1 to 21 or obtained by the process of any of Claims 22 to 24.

26. A physically refined palm oil (RPO) according to Claim 25, wherein the palm oil comprises less than 1% by weight of free fatty acids by weight of the FFA-reduced palm oil; preferably less than 0.5% by weight; more preferably less than 0.1% by weight , such as less than 0.05% by weight.

27. A physically refined palm oil (RPO) according to Claim 25 or 26, wherein the degree of interesterification of the FFA-reduced palm oil is less than 10%; preferably less than 5%.

28. A physically refined palm oil (RPO) according to any one of Claims 25 to 27, wherein the palm oil has a 2- and 3-MCPD content, including esters thereof of below 6ppm; preferably below 4 ppm, more preferably below 3 ppm, such as below 1 ppm.

29. A free fatty acid reduced palm oil produced using a physical refining process according to any one of Claims 22 to 24.

30. Use of a distillation process according to any one of Claims 1 to 21 in a physical refining process of palm oil.