DE102017220041A1 - Process for the extraction of chloride from triglyceride oils - Google Patents

Abstract

The invention relates to an improved process for the extraction of chloride from triglyceride oils. The extraction of the triglyceride oil is carried out with an aqueous solution of potassium lactate and / or potassium tartrate. The inventive method is characterized by a particularly efficient removal of chloride from triglyceride oils.

Description

The invention relates to an improved process for the extraction of chloride from triglyceride oils. The extraction of the triglyceride oil is carried out with an aqueous solution of potassium lactate and / or potassium tartrate. The inventive method is characterized by a particularly efficient removal of chloride from triglyceride oils.

Background of the invention

Natural fats and oils have various undesirable components such as metals, free fatty acids and phospholipids and therefore must be refined. The refining of natural fats and oils distinguishes between physical and chemical refining.

In chemical refining, which is mainly used for triglyceride oils with a low content of free fatty acids, the free fatty acids are separated by reaction with a base. This produces Soapstocks, an aqueous mixture of base, free fatty acids, the salts of free fatty acids and oil. These soapstocks are an undesirable by-product of chemical refining of low value and limited use.

In the physical refining, which is mainly used for triglyceride oils with a higher proportion of free fatty acids, the free fatty acids, however, are thermally separated. In this way, the formation of Soapstocks can be avoided, but at the same time high temperatures (up to 260 ° C) must be applied in order to remove the free fatty acids by distillation from the oil can.

In addition to chemical and physical refining, other processes are described in the prior art with which free fatty acids can be separated off or soapstocks can be worked up. For example, liquid-liquid extraction techniques are used (C.E.C. Rodrigues, C.B. Gonçalves, E. Batista, J. A. Meirelles, Recent Patents on Engineering 2007, 1, 95-102).

A problem encountered in the refining of triglyceride oils is that treatment at elevated temperatures produces undesirable components. These undesirable components include chlorinated derivatives of propanol (hereinafter "MCPD") such as 2-chloro-1,3-propanediol ("2-MCPD"), 3-chloro-1,2-propanediol ("3-MCPD"). ), 2,3-dichloropropan-1-ol ("2,3-DCP") and 1,3-dichloropropan-2-ol ("1,3-DCP"). It is described in the prior art that the formation of these carcinogenic components is favored by an increased content of chloride in the triglyceride oil ( WO 2016/189114 A1 ). This document describes a process in which quaternary ammonium salts are used to treat triglyceride oils. The WO 2012/031176 A1 , the WO 2016/189115 A1 and the WO 2016/189328 A1 also describe the treatment of triglyceride oils with quaternary ammonium salts and their solutions for removing free fatty acids, metals and other undesirable components.

The CN 106281672 A describes the treatment of triglyceride oils with antioxidants (eg tocopherol, lactate, sorbate) and their alkali metal salts to remove trichloropropanol and its derivatives.

The object of the present invention was to provide an efficient method by which the proportion of MCPDs in triglyceride oils can be further lowered.

Detailed description of the invention

The invention has realized that an efficient way to lower the levels of MCPDs in the refined triglyceride oil is to lower the chloride load in the triglyceride oil. By contrast, the prior art documents only begin with the treatment of triglyceride oils in which MCPDs have already formed by reaction with chloride.

At the same time it was surprisingly found that certain salts are particularly suitable for the extraction of chlorides from triglyceride oils.

• (a) Kontaktieren eines Triglyceridöls T₁ umfassend Chloridionen mit einer wässrigen Lösung W₁ umfassend mindestens ein Salz ausgewählt aus Kaliumlactat, Kaliumtartrat, wodurch eine Triglyceridölphase T₂ und eine wässrige Phase W₂ erhalten werden, wobei T₂ einen gegenüber T₁ verringerten Gehalt an Chlorid aufweist und W₂ einen gegenüber W₁ erhöhten Gehalt an Chlorid aufweist.

The present invention accordingly relates to a process for the extraction of chlorides from triglyceride oils, comprising the step (a) with

• (a) contacting a triglyceride oil T ₁ comprising chloride ions with an aqueous solution W ₁ comprising at least one salt selected from potassium lactate, potassium tartrate to give a triglyceride oil phase T ₂ and an aqueous phase W ₂ , wherein T _{2 has} a reduced T ₁ content Has chloride and W _{2 has} a relation to W ₁ increased content of chloride.

• (b) Abtrennen der Triglyceridölphase T₂ von der wässrigen Phase W₂.

In a preferred embodiment of the process according to the invention, step (a) is followed by step (b):

• (b) separating the triglyceride oil phase T ₂ from the aqueous phase W ₂ .

In a further preferred embodiment, step (b) is followed by step (c), wherein a treatment of the triglyceride oil phase T _{2 is carried out} at a temperature of 160 to 280 ° C.

Although the treatment of triglyceride oils with antioxidants has been described ( CN 106281672 A ), the observation is surprising that with potassium tartrate and potassium lactate a particularly good removal of chloride from triglyceride oils is possible, better than with other structurally similar compounds mentioned in the prior art, such as ascorbates.

The term "triglyceride oil" according to the invention comprises any oil or fat whose main constituent is> 50% by weight of triglycerides. In addition to the major constituent of the triglycerides, the oil or fat may also include mono- and diglycerides.

The triglyceride oil is preferably of natural origin and more preferably of animal or vegetable origin. More preferably, the triglyceride oil is a fat or oil of vegetable origin.

As fats and oils of plant origin and containing flavoring substances are particularly considered (where appropriate in parentheses Latin terms indicate the plant species from which the oil is obtained): algae oil, apricot kernel oil (Prunus armeniaca), argan oil (Argania spinosa), avocado oil ( Persea americana), babassu (Attalea speciosa), cottonseed oil (Gossypium), borage oil (Moringa oleifera), borage oil (Borago officinalis), nettle seed oil (Urtica pilulifera or Urtica dioica), beech oil (Fagus), cashew nut oil (Anacardium occidentale), oil from plants of the genus Citrus (for example lemon, orange, grapefruit, lime), cupuaçu butter (Theobroma grandiflorum), thistle oil (Carthamus), peanut oil (Arachis hypogaea), rosehip seed oil (Rosa), hemp oil (cannabis), hazelnut oil (Corylus avellana ), Jatropha oil (Jatropha curcas), jojoba oil (Simmondsia chinensis), coffee bean oil (Coffea), cocoa butter (Theobroma cacao), camellia oil (Camell ia), cabbage palm (Euterpe oleracea), coconut oil (Cocos nucifera), pumpkin seed oil (Cucurbita), camelina oil (Camelina sativa), linseed oil (Linum), corn oil (Zea mays), macadamia oil (Macadamia integrifolia, Macadamia tetraphylla), almond oil (Prunus dulcis ), Mango butter (Mangifera indica), corn oil (Zea mays), poppy seed oil (Papaver), evening primrose oil (Oenothera biennis), olive oil (Olea europaea), palm oil (oil obtainable from a plant of the genus Elaeis, in particular Elaeis guineensis, Elaeis oleifera), Papaya seed oil (Carica papaya), pecan nut oil (Carya illinoinensis), perilla oil (Perilla frutescens), pine nut oil (plants of the genus Pinus), pistachio nut oil (Pistacia vera), rapeseed oil (Brassica napus), rice oil (Oryza sativa), castor oil (Ricinus communis), Sea buckthorn seed kernel (kernels of Hippophae rhamnoides), sea buckthorn oil (pulp of Hippophae rhamnoides), black cumin oil (Nigella sativa), mustard oil (Brassica nigra), sesame oil (Sesamum indicum), shea butter (Vitellaria paradoxa), soybean oil (Glycine max), Sunflower oil (Helianthus annuus), grape seed oil (Vitis vinifera), tung oil (Vernicia, Aleurites), walnut oil (Juglans regia), watermelon seed oil (Citrullus lanatus), wheat germ oil (Triticum). Preferably, the fats and oils of vegetable origin are selected from coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, rice oil, soybean oil, sunflower oil, rapeseed oil, castor oil, thistle oil. Most preferably, the fat and oil of plant origin is palm oil.

Suitable fats and oils of animal origin and containing flavoring substances are, in particular: marmot fat, butter fat, fish oil, oil obtainable from crustaceans (for example krill), cod liver oil, milk fat, lard, duck lard, goose fat, beef tallow, wool wax.

"Fatty acids" within the meaning of the invention comprises saturated and monounsaturated or polyunsaturated fatty acids. Furthermore, this term according to the invention (unless otherwise specified in the specific case) always includes the protonated as well as the deprotonated form of the respective fatty acid.

Examples of unsaturated fatty acids are myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linolelaidic acid, α-linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid and docosahexaenoic acid. Examples of saturated fatty acids are caprylic acid, capric acid, Undecanoic, lauric, tridecanoic, myristic, palmitic, margaric, stearic, nonadecanoic, arachidic, heneicosanoic, behenic, lignoceric and cerotic acids.

"Palm oil" means an oil obtainable from a plant of the genus Elaeis (part of the family of the palm-like or palm trees Arecaceae or Palmae), in particular Elaeis guineensis, Elaeis oleifera or hybrids thereof. The palm oil may e.g. be available from the pulp or the core of the plant.

The triglyceride oil, in particular the palm oil used in step (a), may be unrefined or at least partially refined. This also includes fractionated triglyceride oil, for example fractionated palm oil, in particular stearic acid fractions or oleic acid fractions of palm oil.

"Unrefined" triglyceride oil according to the invention means triglyceride oil which has not been subjected to a refining step. For example, unrefined triglyceride oil has not undergone any of the following refining steps: degumming, deacidification, bleaching, depigmentation, deodorization, winterization.

"Refined" triglyceride oil has undergone at least one refining step, for example at least one selected from degumming, deacidification, bleaching, depigmenting, deodorization, winterization.

In step (a) of the process according to the invention, a triglyceride oil T ₁ comprising chloride ions is contacted with an aqueous solution W ₁ comprising at least one salt selected from potassium lactate, potassium tartrate.

As a result, a triglyceride oil phase T ₂ and an aqueous phase W ₂ are obtained, where T _{2 has} a reduced content of chloride compared to T ₁ and W _{2 has} a content of chloride which is increased compared to W ₁ .

The temperature in step (a) of the process according to the invention is not limited further. In particular, step (a) of the process according to the invention is carried out at a temperature <100 ° C, preferably at a temperature of 25 ° C to 90 ° C, more preferably at 40 ° C to 80 ° C, even more preferably at 50 ° C.

The pressure in step (a) of the process according to the invention is likewise not limited further. In particular, step (a) of the process according to the invention is carried out at a pressure of 1 bar to 100 bar, in particular at atmospheric pressure of 1 bar.

The contacting of the triglyceride oil T ₁ comprising chloride ions with an aqueous solution W ₁ comprising at least one salt selected from potassium lactate, potassium tartrate can take place by methods known to the person skilled in the art. The contacting can take place in a vessel in which T ₁ and W ₁ are mixed together. It goes without saying that the contacting should take place so that as many chloride ions as possible pass from the triglyceride oil T ₁ into the aqueous phase W ₁ . For this purpose, for example, a mechanical mixer (such as a stirred tank, which can be operated non-continuously or continuously), an ultrasonic mixer or an electromagnetic mixer used. During contacting, an inert gas can be blown through the resulting mixture. Alternatively, T ₁ and W _{1 can} also be mixed in a static mixer such as a Sulzer mixer or Kenics mixer.

It is also possible to mix T ₁ and W ₁ continuously in countercurrent, for example in a column or in cocurrent. The column may be a sieve tray column, a packed column or a stirred column, such as a Kühni column or a Scheibel column.

In the continuous process in direct current, for example, T ₁ and W ₁ can also be guided through a pipe before contacting them with the aid of a pump, at the end of which they meet and mix, and then pass through a flow pipe R.

In the continuous countercurrent process in a column, for example, the triglyceride oil T _{1 is introduced} at or near the bottom of the column and the aqueous solution W ₁ comprising at least one salt selected from potassium lactate, potassium tartrate is introduced at or near the top of the column.

The aqueous phase W ₂ , which has a higher chloride content than W ₁ , is then removed at or near the bottom of the column, and a triglyceride oil phase T ₂ having a reduced chloride level compared to T ₁ is then at or near discharged at the top of the column.

Preferably, the column also has a sump region in which a secondary stream can be collected, and more preferably the triglyceride oil T _{1 is} then fed directly above this sump region.

Of course, several such countercurrent column can be used, for example 2 to 6, or 3 to 5 or 4.

It is preferred that the column also has a packing, for example a pack of Raschig rings or "trays".

Other equipment options for mixing in DC provide mixer settler, which can be arranged in a countercurrent cascade. In addition, as described below, there are centrifugal extractors in which steps (a) and (b) of the process according to the invention can be carried out at once. This is important for the embodiments of the method according to the invention, in which step (b) is carried out.

Preferably, step (a) is carried out in which T ₁ and W ₁ are mixed in cocurrent, more preferably in at least one mixer-settler, in at least one centrifugal extractor and / or at least one stirred tank with centrifuge.

The volume ratio of T ₁ and W ₁ in step (a) of the method is likewise not limited further. The ratio of the volume of the triglyceride oil T ₁ to the volume of the aqueous phase W ₁ is in particular in the range from 10: 1 to 1: 200, preferably 1: 1 to 1: 100, more preferably 1: 2 to 1:20, even more preferably 1: 2.3 to 1:10.

The mixing, such as, for example, the contacting in the column in the case of continuous contacting, can be adapted by the person skilled in the art such that as much of the chloride ions as possible are transferred from the triglyceride oil phase T ₁ into the aqueous phase W ₁ . Accordingly, the contacting is carried out, for example, for 1 second to 2 hours, in particular 30 seconds to 1 hour, preferably 1 to 50 minutes, more preferably 5 to 40 minutes, most preferably 10 to 30 minutes.

In particular, the total molar amount of the potassium tartrate and potassium lactate comprised of the aqueous phase W _{1 is} at least equal to the molar amount of all chlorides included in the triglyceride oil T ₁ . Preferably, the ratio of the total molar amount of potassium hydrate and potassium lactate comprised of aqueous phase W ₁ to the molar amount of all chlorides included in triglyceride oil T _{1 is} in the range 1: 1 to 100,000: 1, more preferably 100: 1 to 50,000: 1, more preferably 1000: 1 to 30,000: 1.

The proportion of chloride ions in the triglyceride oil can be determined by methods known to the person skilled in the art, for example by ion chromatography or inductively coupled plasma mass spectrometry. After determination of the proportions of chloride ions in the triglyceride oil T ₁ , the expert then also knows how large the desired molar amount of potassium tartrate and / or potassium lactate comprised of the aqueous phase W ₁ must be, which he can then adjust accordingly.

In step (a), an aqueous phase W ₁ comprising potassium tartrate and / or potassium lactate is used. In addition to water, the aqueous phase W ₁ may also comprise further solvents, for example acetone, ethyl acetate, alcohols, preferably methanol or ethanol. However, in addition to water, the aqueous phase W ₁ preferably comprises no further solvents, which means according to the invention that the weight fraction of the sum of potassium tartrate and potassium lactate and water in W _{1 is} at least 95% by weight, preferably at least 99% by weight, more preferably at least 99.9 wt .-%, and the rest of W ₁ thereof comprises various chemical substances such as organic solvents.

The concentration of potassium tartrate in the aqueous phase W ₁ is not further limited and is preferably in the range of 0.1 mol / L to 5.0 mol / L, more preferably 0.5 mol / L to 2 mol / L.

The concentration of the potassium lactate in the aqueous phase W ₁ is not further limited and is preferably in the range of 0.1 mol / L to 5.0 mol / L, more preferably 0.5 mol / L to 2 mol / L.

When contacting a triglyceride oil T ₁ comprising chloride ions with an aqueous solution comprising potassium tartrate and / or potassium lactate W ₁ , the chloride ions from the triglyceride oil T ₁ at least partially pass into the aqueous phase W ₁ . Therefore, when carrying out step (a), a triglyceride oil phase T ₂ and an aqueous phase W ₂ are obtained, wherein T _{2 has} a reduced chloride ion content compared to T ₁ and W _{2 has} an increased chloride ion content compared to W ₁ .

In optional step (b) of the process according to the invention, the triglyceride oil phase T ₂ is then separated from the aqueous phase W ₂ .

This separation can likewise be carried out by methods known to the person skilled in the art, for example by means of gravity in a settler unit. In general, the triglyceride oil phase T _{2 is} the upper phase, while the aqueous phase W _{2 is} the lower phase. The separation of the triglyceride oil phase T ₂ from the aqueous phase W ₂ can alternatively also be carried out in a decanter, a hydrocyclone, an electrostatic coalescer, a centrifuge or a membrane filter press. Preferably, in step (b) of the process according to the invention, the triglyceride oil phase T _{2 is separated} from the aqueous phase W ₂ in a centrifuge.

Should during the contacting in step (a) at least partially precipitate a salt (for example, potassium chloride) and in the triglyceride oil phase T ₂ as a solid, it can also be separated by centrifugation or filtration. Solvent or water may also be added to the triglyceride oil phase T ₂ containing the solid to solubilize the solid and separate the aqueous solution comprising the appropriate salt as described above.

In a preferred embodiment of the present invention, the step (a) and the step (b) of the method according to the invention, ie the contacting and separation in a centrifugal separator, such as in US 4,959,158 . US 5,571,070 . US 5,591,340 . US 5,762,800 . WO 99/12650 and WO 00/29120 is described. In particular, T ₁ and W _{1 are} first supplied as separate streams into the separator and mixed in an annular mixing zone. The mixture is then passed to the deposition zone, where the phases are then separated by means of a centrifuge.

More preferably, one uses a series of centrifugal separators, for example 2 to 6, 3 to 5 or 4, and introduces the triglyceride oil T ₁ into the first separator of the series, and the aqueous phase W ₁ into the last separator in the series, so that triglyceride oil As the content of chloride decreases, it passes through the first to last separators in the series, while the aqueous phase passes through the separators in the opposite direction as the content of chloride increases. The aqueous phase W ₂ is then taken from the first separator in the series, the triglyceride oil phase T ₂ is taken from the last separator in the series.

In any case, the triglyceride oil phase T _{2 can} also be fed to a coalescing filter in order to remove the last drop of aqueous solution from the fat or oil phase. Such a coalescing filter is known to those skilled in the art and may comprise a filter material which is wetted by the aqueous phase rather than by the oil phase, for example a glass or cellulose filter material.

After separation of the triglyceride oil phase T ₂ from the aqueous phase W ₂ in step (b), the triglyceride oil phase T _{2 can} then be fed to a further work-up or processing. Such a step may be one or more selected from degumming, deacidification, winterization, bleaching, depigmentation, deodorization. These steps are known in the art and, for example, in the WO 2016/189114 A1 described.

It goes without saying that the triglyceride oil phase T ₂ after the separation in step (b) can be fed once more or several times, for example twice to ten times, to a contacting step (a) in which the triglyceride oil phase T _{2 is used} as triglyceride oil T ₁ is contacted and in each step with a new batch of aqueous phase W ₁ comprising potassium tartrate and / or potassium lactate, in order to further reduce the proportion of chloride ions in the triglyceride oil phase T ₂ .

The following examples are intended to illustrate the invention without limiting it.

Examples

Inventive Examples E1, E2, Comparative Examples V1-V3

150 g of crude palm oil (chloride content 8 ppm, determined by digestion by Wickbold combustion and subsequent ion chromatography) are mixed with 150 mL of a 0.10 M solution of the following salts:
Potassium sorbate (V1); Sodium ascorbate (V2); Demineralised water (V3); Potassium tartrate (E1); Potassium lactate (E2).

The resulting solutions are then stirred at 50 ° C for two hours. The solution is then transferred to a heated separatory funnel and the aqueous phase separated from the triglyceride phase. In the case of potassium sorbate and demineralized water separation in a separating funnel is not possible.

The total chlorine content of the triglyceride phase is determined by digestion by Wickbold combustion and subsequent ion chromatography with toluene-THF mixture. Table 1. attempt saline solution Total chlorine [mg / kg] separation V1 potassium sorbate - No separation Formation of an emulsion V2 sodium ascorbate 6 30 min E1 potassium tartrate <5.0 40 min E2 potassium lactate <5.0 40 min V3 VE water - No separation Formation of an emulsion

The experiments show surprisingly that only with sodium ascorbate, potassium tartrate and potassium lactate, a separation of the two phases is possible. However, only with potassium tartrate and potassium lactate a significant reduction of the chloride content in the oil to be extracted is observed: Thus, the chloride ion content in the extracted triglyceride in the case of tartrate and lactate below the detection limit, in the case of ascorbate at 6 ppm.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2016/189114 A1 [0006, 0053]
• WO 2012/031176 A1 [0006]
• WO 2016/189115 A1 [0006]
• WO 2016/189328 A1 [0006]
• CN 106281672A [0007, 0014]
• US 4959158 [0050]
• US 5571070 [0050]
• US 5591340 [0050]
• US 5762800 [0050]
• WO 99/65050
• WO 0029120 [0050]

Claims (8)

A process for the extraction of chloride from triglyceride oils, comprising the step of (a) contacting (a) a triglyceride oil T ₁ comprising chloride ions with an aqueous solution W ₁ comprising at least one salt selected from potassium lactate, potassium tartrate, whereby a triglyceride oil phase T ₂ and an aqueous phase W ₂ are obtained, wherein T _{2 has} a relation to T ₁ reduced content of chloride and W _{2 has} a relation to W ₁ increased content of chloride. Method according to Claim 1 wherein step (a) is followed by step (b): (b) separating the triglyceride oil phase T ₂ from the aqueous phase W ₂ . Method according to one of Claims 1 or 2 wherein step (a) is carried out at a temperature <100 ° C. Method according to one of Claims 1 to 3 , wherein the ratio of the volume of the triglyceride oil T ₁ to the volume of the aqueous phase W _{1 is} in the range from 10: 1 to 1: 200. Method according to one of Claims 1 to 4 , wherein the aqueous phase W _{1 in} addition to water also includes other solvents. Method according to one of Claims 1 to 4 , wherein the aqueous phase W ₁ does not comprise any other solvents besides water. Method according to one of Claims 1 to 6 where W ₁ comprises potassium lactate. Method according to one of Claims 1 to 6 where W ₁ comprises potassium tartrate.