WO 2021/058647 _PR0 CESS FOR THE PRODUCTION OF STEROLS ANDK£T ^{/EP2020/076723} TOCOPHEROLS WITH RECOVERY OF BY-PRODUCTS

Field of invention

The presently claimed invention relates to a method of obtaining phytosterols and/or tocopherols from residues of a distillation of the esters of vegetable oils, preferably from oil distillation residues from a transesterification of vegetable oils and also to a method of purification of a sterol-containing phase, in particular sterol crystals.

Background of the invention

Phytosterols and their esters possess hypocholesterolaemic properties, i.e. these substances are capable of lowering the cholesterol level in the blood. Accordingly, they are used as food additives, for example for the production of margarine, frying oils, sausages, ice creams and the like. The production of sterols and other unsaponifiable constituents, such as tocopherols for example, from distillates obtained in the deacidification of vegetable oils has already been variously described in the patent literature, cf. EP-A20610742 (Hoffmann-LaRoche), GB-A1 2,145,079 (Nisshin Oil Mills Japan) and EP-A1 0333472 (Palm Oil Research and Development Board).

The main sources of phytosterols are residues from tall oil processing and distillates from vegetable oil refining. There are a several prior arts which disclose the processes for production of phytosterol based on these raw materials. Furthermore, fatty acid methyl ester (FME) as a source for obtaining phytosterols and tocopherols which consists of distillation residues from the vegetable oil methyl ester production for the field of use of biodiesel hereinafter "fatty acid methyl ester" as "FME"; in the art also known sometimes named "FAME") is rarely used . Only few methods are known for obtaining phytosterols and tocopherols from FME.

While using distillation residues from the vegetable oil methyl ester production, care should be taken to ensure that the matrix of concomitant components and contaminants, which can have a disruptive effect on the process for obtaining sterols and tocopherols with regard to achievable yields and purities, is different from the one in steam distillates. Besides the useful products, the distillation residue contains for example phosphatides, coloring components, enriched long-chain FMEs and polymerization products from the distillation. Thus, the processing of the distillation residues needs to be done differently from the processing of the steam distillates.

Accordingly, several attempts have been made to produce phytosterol and/ or tocopherol by various methods, but there still is a need to produce sterols in high yields and high purity by an economical process that would avoid high pressure reactions and, at the same time, to utilize residues from the distillation of transesterified oils more economically.

EP 0656894 B1 (Henkel) describes a process for the production of sterols in which a residue from the distillation of methyl esters consisting essentially of glycerides, sterols, sterol esters and tocopherols is transesterified with methanol in the presence of alkaline catalysts. After neutralization of the catalyst, removal of the excess methanol by distillation and, optionally, removal of the catalyst by washing, the sterols are crystallized by lowering the reaction temperature from about 65 to 20 °C. The thus obtained crystals are washed with methanol and water. Unfortunately, the yield of sterols is unsatisfactory.

EP 2635592 B1 (Verbio) discloses a method for obtaining phytosterols and tocopherols using multi-phase separation systems to isolate the sterol and/or tocopherol.

EP1179535 B1 and EP1179536 B1 (both: BASF) disclose processes for the production of sterols using a two-step-transesterification to obtain sterols from vegetable oil distillates. Crystallization of the obtained sterols and washing with methanol and FME is disclosed as subsequent process steps in dependent claims. Although in EP1179536 B1 "methyl ester" is disclosed as employed solvent in the examples, the "methyl ester" actually used in the examples and disclosed in the description is the FME from the transesterifications of the vegetable oil. EP1179535 B1 discloses in its examples the use of "FME"; in [0036] and [0042] EP1179535 B1 also discloses that the crystals obtained in examples a) and b) "are washed with suitable solvents". However, which solvents those actually might be is not disclosed.

EP1169335 B1 (BASF) discloses a process for the crystallization of sterols from a specific mixture of methanol and FME in certain ratios and washing of the obtained crystals. Objective of this disclosure is to provide sterols in high yields and "good color quality". Key is according to this disclosure the optimum amount and ratio of methanol during crystallization and thus the crystallization temperature which is said to lead to the desired improvement. The obtained crystals are then washed with FME, which step is said to further improve the color quality of the sterol crystals obtained. It is to be noted that the "methyl ester" disclosed by EP1169335 B1 clearly is the "fatty acid ethyl ester", as both descriptions/ terms are used inter-changingly as can be seen from e.g. [0008], which mentions twice the washing of the crystals but uses "methyl ester" at the first occasion and "FME " on the second occasion. Claim 1 in the binding German version thus correctly uses the term "FME" (whereas claim 1 in the English translation using incorrectly the term "fatty acid ester").

However, it is still a challenge to perform a process with improved yield of sterol without the use of toxicologicahy and ecologically unsafe solvents. Further, improving the color of the sterol with high purity also remains a challenge.

Summary of the Invention

It has surprisingly been found that the yield, color and purity of the phytosterol is significantly influenced by the process used for the downstream processing of the vegetable oil distillate and the solvent used for purification. Thus, the conditions of the process and the choice of solvent used for the purification process each play - independently - a significant role in improving the color of the phytosterol and reducing the amount of impurities without compromising on the yield of the final product.

Hence, in one aspect, the presently claimed invention relates generally to the production of phytosterols and more particularly to a process for the production of phytosterols from residues of the distillation of transesterified oils. In order to be able to obtain sterols in pure form, they have to be converted from the esterified to the free state. Otherwise, they are very difficult to separate from the components accompanying them. The conversion into free sterols may be carried out, for example, by hydrolysis, saponification or transesterification. The presently claimed invention is directed to the use of a transesterification mechanisms.

In an aspect, the presently claimed invention relates to a method of obtaining phytosterols and/ or tocopherols from residues of a distillation of the esters of vegetable oils, preferably from distillation residues from a transesterification of vegetable oils, in particular from the vegetable oil-based FME production for the biodiesel field of application, wherein the method comprises at least the steps of: a) a first basic transesterification stage, wherein a reaction of partial glycerides contained in the distillation residues is carried out in the presence of a basic catalyst and methanol, whereby two phases are formed, wherein one phase comprises to a large extent glycerin and the second phase comprises the basic catalyst and unreacted methanol, and FME, with thereafter the further optional steps i), ii) and/ or iii) of i) optionally separating methanol ii) optionally separating FME, iii) optionally separating the basic catalyst, b) separating the phase comprising glycerin, c) a second basic transesterification stage, wherein a reaction of sterol esters is carried out, d) after the second transesterification stage, adding water to a reaction mixture to form a multiphase system to crystallize sterols from this mixture, preferably with the water being added in an amount ranging from 15% to 25%, based on the mass of a total batch in order to set a mass ratio of sterol: FMEs: methanol: water of substantially l:2.5-3:2.2-2.5:0.8-1.2; during and/or after the addition of water homogenizing the reaction mixture to an emulsion/ suspension by mixing, whereby a multi-phase system is produced, e) crystallizing the sterols from the multi-phase system comprising a methyl ester phase, an aqueous phase, and the sterols, to form sterol crystals, wherein the crystallization is affected by cooling down the mixture to a temperature of below the temperature of the second transesterification, in particular to a temperature in the range from 5°C to 35°C, preferably in the range from 10°C to 30°C, and particularly preferred in the range from 15°C to 25°C; f) separating the multi-phase system into a substantially sterol (crystals)-containing phase, a substantially glycerin-containing and a methanol-containing aqueous phase, and a tocopherol-containing FME phase, g) optionally further crystallizing the remaining sterols from the liquid phase; h) optionally - but preferably being implemented - purifying the sterol crystals from the sterol-containing phase using a mixture or an azeotrope of a protic polar solvent and an aprotic polar solvent, i) optionally further drying the sterols, j) optionally further purifying the sterols by melt-drying to remove trace amounts of solvents within the sterols k) optionally further subjecting the sterols to a particle-forming process to obtain sterol particles, l) optionally purifying the tocopherol from the tocopherol-containing phase; m) optionally purifying the glycerin; and/ or n) optionally purifying the FME.

In an aspect of the presently claimed invention, a two-stage basic catalyzed transesterification of a FME distillation residue from the biodiesel production or other oil transesterification process, preferably from the biodiesel production, with an intermediate separation of a glycerin phase produced in the transesterification is accumulated for completion of the glyceride reaction is carried out in the second reaction stage without methanol- or catalyst- removal such removal by e.g. flashing, distillation or washing.

In yet another aspect of the presently claimed invention, the glycerin phase produced after the first transesterification stage can advantageously be fed directly to a process, preferably a distillation process, for obtaining glycerin of desired grade and purity, such as being suitable for use in cosmetics and/ or pharmaceutical applications.

In another aspect, the presently claimed invention relates to a purification process, wherein the color of the final phytosterol product is significantly improved and/ or, preferably and, the amount of phytosterol ester as an impurity is significantly reduced.

In yet another aspect, the presently claimed invention relates to a significantly reduced solvent content in the final phytosterol product.

Detailed description of the invention

Although the presently claimed invention will be described with respect to particular embodiments, this description is not to be construed in a limiting sense.

Before describing in detail exemplary embodiments of the presently claimed invention, definitions important for understanding the presently claimed invention are given. As used in this specification and in the appended claims, the singular forms of "a" and "an" also include the respective plurals unless the context clearly dictates otherwise. In the context of the presently claimed invention, the terms "about" and "approximately" denote an interval of accuracy that a person skilled in the art will understand to still ensure the technical effect of the feature in question. The term typically indicates a deviation from the indicated numerical value of ±20 %, preferably ±15 %, more preferably ±10 %, and even more preferably ±5 %. It is to be understood that the term "comprising" is not limiting. For the purposes of the presently claimed invention the term "consisting of" is considered to be a preferred embodiment of the term "comprising of". If hereinafter a group is defined to comprise at least a certain number of embodiments, this is meant to also encompass a group which preferably consists of these embodiments only.

In case the terms "first", "second", "third" or "(a)", "(b)", "(c)", "(d)", "i", "ii" etc. relate to steps of a method or use or assay there is no time or time interval coherence between the steps, i.e. the steps may be carried out simultaneously or there may be time intervals of seconds, minutes, hours, days, weeks, months or even years between such steps, unless otherwise indicated in the application as set forth herein above or below. Preferably, however, the steps are performed in the numerical or hierarchical order implied by it, i.e. at first a, then b, then c etc., first i), then ii), then iii) etc. It is to be under-stood that this invention is not limited to the particular methodology, protocols, reagents etc. described herein as these may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the presently claimed invention that will be limited only by the appended claims. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.

Unless otherwise indicated, the following definitions are set forth to illustrate and define the meaning and scope of the various terms used to describe the invention herein and the appended claims. These definitions should not be interpreted in the literal sense as they are not intended to be general definitions and are relevant only for this application.

The term "final sterol product" signifies the phytosterol which is obtained after the purification steps.

The term "(oil) distillate" encompasses edible vegetable oil distillates (VODs) which are even preferred.

The term "(oil) distillation residue" encompasses transesterified oil distillation residues which are even preferred. Said transesterified oil distillation residues are preferably fatty acid alkyl ester distillation residues, more preferably fatty acid methyl ester distillation residues in particular from the production of biodiesel.

The term "partial glycerides" encompasses all combinations of mono-, di- and/or triglycerides. In case of oil distillates as starting material, there are only or nearly only triglycerides and no mono- and diglycerides, whereas, in case of typical oil distillation residues, there are mainly triglycerides and diglycerides and only a few monoglycerides.

Meaning of the terms that are not defined herein are generally known to a person skilled in the art or in the literature.

It is also intended that of course the various embodiments and preferred options of the various process steps disclosed herein are to be combined within the actual complete process, so that for a specific performance of this overall process for one process step the general outline is selected, for another process step within this overall process the preferred embodiment and for the again another process step the most preferred option etc. In an embodiment, the presently claimed invention relates to a method of obtaining phytosterols and/ or tocopherols from residues of a distillation of the esters of vegetable oils, preferably from distillation residues from a transesterification of vegetable oils, in particular from the vegetable oil-based FME production, specifically for the biodiesel field of application, with the following embodiments 1 to 4 defining the general invention, and the further description below those embodiments disclosing further features and more details of the process steps, preferred options and alternatives still encompassed by the present invention:

Embodiment 1 of the present invention

Method of obtaining phytosterols and/or tocopherols from residues of a distillation of the esters of vegetable oils, preferably from distillation residues from a transesterification of vegetable oils, in particular from the vegetable oil-based FME (FAME) production, more preferably from the production of biodiesel, wherein the method comprises at least the steps of: a) providing a starting material containing unsaponified matter which is a residue from the work-up of vegetable oils, such residue containing sterols and usually also tocopherols, wherein the starting material which contains at least 5, preferably at least 10, more preferably at least 15, even more preferably at least 20 weight % of sterols, b) optionally subjecting the starting material to a concentration step to increase the content of sterols compared to the initial content, preferably to a content of at least 25, more preferably at least 30, even more preferably at least 40 and most preferably to at least 50 wt.% of sterols in the concentrated residue, by subjecting the residue to a transesterification reaction using methanol as solvent and reactant and sodium methylate as catalyst, subsequently removing at least part of the formed glycerine, optionally repeating once or twice said steps of transesterification and said removal of glycerine, then optionally followed by removal of at least part of the excessive methanol, and then optionally removing further at least part of the remaining glycerine, then followed by removing the methyl ester; c) optionally subjecting the residue of step a) or the concentrated residue of step b) to a purification step using adsorbents such as clays, earths and oxides, to improve the color, lowering the content of soaps, and/or absorbing trace metals and/or metal ions, preferably all of those improvements, such purification step being performed at ambient or elevated temperature, preferably at elevated temperature, of ambient temperature to about 100 degree Celsius, preferably 60 to 90 °C, at suitable treatment duration in the range from 10 minutes to several hours, preferably 1 to 10 hours, more preferably 1 to 3 hours, even more preferable about 2 hours at 75 to 90°C; d) a first basic transesterification stage, wherein a reaction of partial glycerides contained in the distillation residues is carried out in the presence of a basic catalyst and methanol, whereby two phases are formed, wherein one phase comprises to a large extent glycerin and the second phase comprises the basic catalyst and unreacted methanol, and FME, with thereafter the further optional steps i), ii) and/ or iii) of i) optionally separating and removing methanol from the reaction mixture obtained from the transesterification step; ii) optionally separating and removing FME from the reaction mixture obtained from the previous step, iii) optionally separating and removing the basic catalyst from the reaction mixture obtained from the previous step, e) separating and removing at least partially the phase comprising glycerin from the reaction mixture obtained from the previous step, f) a second basic transesterification stage, wherein a reaction of sterol esters to free sterols is carried out, and i) optionally separating and removing methanol from the reaction mixture obtained from the transesterification step; ii) optionally separating and removing FME from the reaction mixture obtained from the previous step, iii) optionally separating and removing the basic catalyst from the reaction mixture obtained from the previous step, iv) optionally separating and removing the phase comprising glycerin from the reaction mixture obtained from the previous step, g) after the second transesterification stage, adding water to a reaction mixture to form a multiphase system to crystallize sterols from this mixture, preferably with the water being added in an amount ranging from 15% to 25%, based on the mass of a total batch in order to set a mass ratio of sterol: FMEs: methanol: water of substantially l:2.5-3:2.2-2.5:0.8-1.2; during and/or after the addition of water homogenizing the reaction mixture to an emulsion/ suspension by mixing, whereby a multi-phase system is produced, h) crystallizing the sterols from the multi-phase system comprising a methyl ester phase, an aqueous phase, and the sterols, to form sterol crystals, wherein the crystallization is affected by cooling down the mixture to a temperature of below the temperature of the second transesterification, in particular to a temperature in the range from 5°C to 35°C, preferably in the range from 10°C to 30°C, and particularly preferred in the range from 15°C to 25°C; i) separating the multi-phase system into a substantially sterol (crystals)-containing phase, a substantially glycerin-containing and a methanol-containing aqueous phase, and a tocopherol-containing FME phase, j) optionally further crystallizing the remaining sterols from the liquid phase following the same measures of step g) before, followed by separation of the crystals following the same measures of step i) before; k) optionally purifying the sterol crystals obtained in step h) and - if performed - step j), either in a separate process step or a combined process step, using a an organic solvent, solvent mixture of more than one organic solvents, or an azeotropic solvent mixture of at least one protic polar solvent and an at least one aprotic polar solvent, l) optionally further drying the sterols; m) optionally further purifying the sterols by melt-drying to remove trace amounts of solvents within the sterol's solids; n) optionally further subjecting the sterols to a particle-forming process to obtain sterol particles, o) optionally purifying the tocopherol from the tocopherol-containing phase; p) optionally purifying the glycerin; and/ or q) optionally purifying the FME.

Embodiment 2 of the present invention

A method of obtaining phytosterols and/ or tocopherols from residues of a distillation of the esters of vegetable oils according to embodiment 1, wherein the method consists of the following steps: a) providing a starting material containing unsaponified matter which is a residue from the work-up of vegetable oils, such residue containing sterols and usually also tocopherols, wherein the starting material which contains at least 5, preferably at least 10, more preferably at least 15, even more preferably at least 20 weight % of sterols, wherein the residue preferably stems from the production of bio-diesel such as the work-up of rapeseed oil being transesterified and worked-up to produce rapeseed methyl fatty acid ester (RME) and a distillation residue, b) (step b) of embodiment 1 omitted); c) (step c) of embodiment 1 being omitted); d) a first basic transesterification stage, wherein a reaction of partial glycerides contained in the distillation residues is carried out in the presence of a basic catalyst and methanol, whereby two phases are formed, wherein one phase comprises to a large extent glycerin and the second phase comprises the basic catalyst and unreacted methanol, and FME, with thereafter the further optional steps i), ii) and/ or iii) of i) optionally separating methanol ii) optionally separating FME, iii) optionally separating the basic catalyst, preferably being the steps i), ii) and iii) being omitted; e) separating and removing the phase comprising glycerin at least partially, f) a second basic transesterification stage, wherein a reaction of sterol esters is carried out, g) after the second transesterification stage, adding water to a reaction mixture to form a multiphase system to crystallize sterols from this mixture, preferably with the water being added in an amount ranging from 15% to 25%, based on the mass of a total batch in order to set a mass ratio of sterol: FMEs: methanol: water of substantially l:2.5-3:2.2-2.5:0.8-1.2; during and/or after the addition of water homogenizing the reaction mixture to an emulsion/ suspension by mixing, whereby a multi-phase system is produced, h) crystallizing the sterols from the multi-phase system comprising a methyl ester phase, an aqueous phase, and the sterols, to form sterol crystals, wherein the crystallization is affected by cooling down the mixture to a temperature of below the temperature of the second transesterification, in particular to a temperature in the range from 5°C to 35°C, preferably in the range from 10°C to 30°C, and particularly preferred in the range from 15°C to 25°C; i) separating the multi-phase system into a substantially sterol (crystals)-containing phase, a substantially glycerin-containing and a methanol-containing aqueous phase, and a tocopherol-containing FME phase, j) optionally further crystallizing the remaining sterols from the liquid phase obtained in step h) and/ or step i); k) purifying the sterol crystals obtained in step h) and - if performed - step j), either in a separate process step or a combined process step, using a an organic solvent, solvent mixture of more than one organic solvents, or an azeotropic solvent mixture of at least one protic polar solvent and an at least one aprotic polar solvent, l) further drying the sterol crystals, m) optionally further purifying the sterols by melt-drying to remove trace amounts of solvents within the sterols, preferably by stream stripping at a temperature of 130 to 200, preferably 150°C- 170°C, for 1- 3 hours to remove the solvent, preferably performing this step, n) optionally further subjecting the sterols to a particle-forming process to obtain sterol particles, preferably subjecting to prilling under liquid nitrogen, this step preferably being performed; o) optionally purifying the tocopherol from the tocopherol-containing phase; p) optionally purifying the glycerin; and q) optionally purifying the FME.

Embodiment 3 of the present invention

The process according to embodiment 1 or 2, wherein the residues of a distillation of the esters of vegetable oils comprises a residue derived from an oil selected from the group consisting of soybean oil, sunflower oil, rapeseed oil, coconut oil, palm oil, palm kernel oil, and mixtures thereof.

Embodiment 4 of the present invention

The process according to embodiment 3, wherein the oil distillation residue comprises a residue derived from rapeseed oil such as high eruic acid rapeseed oil or CANOLA oil.

Description of the individual process steps

In the following the further features and more details of the process steps, preferred options and alternatives as generally described above in embodiments 1 to 4 are disclosed and explained in in more detail in the following:

Step a) - Starting material The starting material for the presently claimed process may be obtained using known processes as outlined herein above using the known prior art processes.

The starting material thus is a residue from the work-up of vegetable oils, such residue containing sterols and usually also tocopherols. Such residue is obtained by several esterification and transesterifications, treatment with acid etc., all of which is known in the art. One such process is the known process to produce biodiesel, i.e. fatty acid methyl ester. In the following this residue resulting from such vegetable oil processing and work-up including that from the bio-diesel process is meant with the term "residue".

Such residue as a starting material for the present process contains "unsaponified matter", such unsaponified matter containing sterols and usually also tocopherols, with the content in the starting material being at least 5, preferably at least 10, more preferably at least 15, even more preferably at least 20 weight % of sterols, however usually at the lower end with about 5 to 15wt% sterols.

Such residues may be obtained as outlined herein above, using the known prior art processes. Especially suitable residues are such from the work-up of vegetable oils containing sterols and usually also tocopherols. These residues are obtained by several esterification and transesterifications, treatment with acid etc., all of which is known in the art. One such known process is the process to produce biodiesel, i.e. fatty acid methyl ester.

Preferably, the oil distillation residue comprises a residue derived from an oil selected from the group consisting of soybean oil, sunflower oil, rapeseed oil, high erucic acid rapeseed oil (HEAR), low eruric acid rapeseed oil (CANOLA; CANadian Oil Low eruic Acid), coconut oil, palm oil, palm kernel oil, and mixtures thereof, more preferably, the oil distillation residue comprises a residue derived from soybean oil, sunflower oil, rapeseed oil such as HEAR or CANOLA, even more preferably, the oil distillation residue comprises a residue derived from sunflower oil, rapeseed oil, preferably HEAR.

These residues are preferably residues from coconut oil, from palm kernel oil, from palm oil, from soybean oil, from sunflower oil, from rapeseed oil such as from HEAR and/ or CANOLA, more preferably from soybean oil, sunflower oil, rapeseed oil such as HEAR, even more preferably from sunflower oil and/or rapeseed oil, and especially HEAR, with acid values of 0 to 10, preferably from 0 to 6 and contain mixtures of di- and triglycerides, FMEs, sterol esters, wax esters and free sterols, preferably 1 to 7 % by weight triglycerides, 3 to 15 % by weight diglycerides, 15 to 40 % by weight FMEs, 40 to 50 % by weight, in particular 42 to 47 % by weight sterol esters, 3 to 4 % by weight wax esters and 3 to 15 % by weight free sterols and small quantities of mono glycerides.

In another embodiment of the presently claimed invention, oil distillates are used as raw materials for the production of sterols. These distillates are preferably such of coconut oil, of palm kernel oil, of palm oil, of soybean oil, of sunflower oil, of rapeseed oil such as from HEAR and/ or CANOLA, more preferably of soybean oil, sunflower oil, rapeseed oil such as from HEAR, even more preferably of sunflower oil and/or rapeseed oil from HEAR, containing 45 to 65 % by weight triglycerides and 35 to 55 % by weight sterol esters summing up to 100 %.

Step b) - Concentration of residue

To improve the process of the present invention, such residue may be further concentrated. The residue as outlined before can be concentrated to a content of "unsaponified matter" of about more than 20 such as 35 to 60, preferably 40 to 55 and more preferably 45 to 50 weight percent of unsaponified matter relative to the total weight of concentrated residue (hereinafter "concentrated residue"). Such concentration can be achieved by submitting the residue as obtained to a transesterification reaction using methanol as solvent and reactant and sodium methylate as catalyst. The aim is to convert remaining glycerides in the residue to methyl esters. Following that transesterification, the formed glycerin is to be removed by standard means, e.g. decanting. This process of transesterification with following glycerin removal can be repeated once or twice or more, but one repetition usually is enough and thus a preferred embodiment. Excess methanol is then to be removed, followed by optional further removal of remaining glycerin which can form again as separate phase during or after the removal of methanol. Then, the formed methyl ester can be removed, by e.g. distillation. This thus also increases the yield of the fatty acid methyl ester, i.e. biodiesel.

This process of concentration is an optional process step which can be employed prior to the "first transesterification" which then follows to convert the sterols present in the "unsaponified matter" in the residue or concentrated residue to purified sterols which can then be crystallized and further purified.

Step c) Initial purification step by adsorption

As a further optional process step the residue or - in case the optional step of concentration the residue is performed - concentrated residue can be subjected to the purification using adsorbents such as clays, earths and oxides. Suitable adsorbents are well-known, e.g. the Trisyl-grades (e.g. from the company Grace). This treatment allows for an improvement of the color, lowering the content of soaps, and/ or absorbing trace metals and/ or metal ions, preferably all of those improvements, by choosing suitable adsorbents. This treatment may be performed at ambient or elevated temperature. In view of the high viscosity of the residue or concentrated residue, treatment at elevated temperature is preferable. Suitable temperatures are ambient to about 100 degree Celsius, with temperatures of around 60 to 90 °C being preferred mainly to a good combination of viscosity and energy cost needed. Suitable treatment duration may be anything from 10 minutes to several hours, e.g. even 5 to 10 hours. Duration mainly depends on the degree of removal desired and the amount of contaminants present in the residue or concentrated residue. Preferably durations are about 1 to 10 hours, more preferably 1 to 5 hours, even more preferable 1 to 3 hour, most preferably about 2 hours at 75 to 90°C.

This process of initial purification by adsorption is an optional process step which can be employed prior to the "first transesterification" which then follows to convert the sterols present in the "unsaponified matter" in the residue or concentrated residue to purified sterols which can then be crystallized and further purified.

Step (d) - First transesterification

In an embodiment of the presently claimed invention, the first transesterification stage is carried out with a content of basic catalyst, preferably sodium methylate, but for example also sodium hydroxide (NaOH) or potassium hydroxide (KOH) could be used instead or together, in the range from 0.1 % to 0.3 %, preferably in the range from 0.18 % to 0.22 % and with a methanol content in the range from 12 % to 18 %, preferably in the range from 14 % to 16 % and the second transesterification stage with a content of catalyst in the range from 0.5 % to 1 %, preferably in the range from 0.6% to 0.8%, and with a methanol content in the range from 20% to 38%, preferably in the range from 34% to 36%, wherein the added quantity of basic catalyst is standardized to an addition of sodium methylate and, if appropriate, should be adapted to the use of other basic catalysts. On the basis of these necessary additions of catalyst and methanol, which were very low with regard to known methods, to the individual transesterification stages, the method according to the presently claimed invention can be operated in a particularly cost-effective and recycling-friendly manner, because for example only small quantities of methanol must be supplied for methanol recovery. According to a further embodiment of the presently claimed invention, during the first transesterification stage, after mixing in of methanol and catalyst, glycerin is added in an amount in the range from 0.2% to 7.2%, preferably in the range from 0.5% to 6.0%, and particularly preferably in the range from 1.0% to 5.5%, in each case based on the mass of the total batch. By this addition of glycerin to the total batch the later phase separation is improved, and contaminants are better discharged in an advantageous manner into the heavy glycerin phase.

In an embodiment of the presently claimed invention, the second transesterification reaction is carried out at a temperature range of 25 °C to 150 °C depending on the pressure and time conditions.

In an embodiment of the presently claimed invention, the first transesterification stage is carried out at a temperature in the range from room temperature (e.g. 25 °C) to 100 °C, preferably to 95, more preferably to 90 and even more preferably to 88°C, preferably in the range from 40 °C to 75 °C and particularly preferably in the range from 55 °C to 70 °C, such as at a temperature of 60 to 65 °C, and furthermore in particular at normal pressure. The reaction may be performed depending on the temperature and pressure chosen under reflux or without reflux. When methanol is chosen which is the most favorable alcohol to be employed, this means that the reaction is performed at the boiling temperature of methanol or slightly below when operating at ambient pressure. By this a good temperature control can be implemented. This embodiment of the invention enables an energy-saving and cost- efficient performance of the method, because high heating costs are avoided and the respective transesterification reactions can be preferably carried out inter alia at normal pressure, so that expensive pressurized reactors and complex and expensive generation and maintenance of the temperatures and pressures, such as are necessary in the prior art, can be omitted. Thus, this embodiment is preferred over the following two embodiments for this process step.

However, of course, depending on the duration employed for the transesterifications, at lower temperatures the duration of the reaction has to be prolonged compared to high temperatures, as otherwise no satisfying yields are obtainable. Hence, the net benefit in terms of energy saving depends on the complete outline of the process, the equipment employed and the temperature and duration of the reactions, as a simply reduction in time leads to higher reaction temperature (if the yield should stay the same) or lower yields (if the duration stays the same).

In an alternative embodiment of the presently claimed invention, the transesterification reaction of the partial glycerides is preferably carried out over a period of 5 to 20 minutes and more particularly 8 to 15 minutes at a temperature of 110 to 160, more preferably at 115 to 145° C. and more particularly at a temperature of 120 to 130° C at a pressure of 2 to 10 bar.

Steps i), ii) and iii) of step d) are described in the following section.

Steps i), ii) and iii) of step d) and step e) - Separating the phase containing glycerin, methanol, FME and catalyst.

In an embodiment of the presently claimed invention, the glycerin phase may be preferably be removed without previous separation of FME, methanol and/ or catalyst, more preferably the glycerin phase may be removed without previous separation of FME, methanol and catalyst.

In one embodiment the glycerin phase is removed from the reaction mixture of the transesterification reaction without prior removal of methanol, fatty acid ester and catalyst.

In an embodiment of the presently claimed invention, the basic catalyst used according to the presently claimed invention can be used and recycled without any environmental or food- related problems, wherein in an advantageous manner, unlike for example in the aforesaid U.S. Pat. No. 5,424,457, there should be no fear of heavy metal contamination in the produced products, in this case phytosterols and/ or tocopherols.

In yet another embodiment of the presently claimed invention, the basic catalyst is optionally separated from the reaction mixture resulting from the first transesterification process.

In yet another or economic reasons being preferred embodiment the reaction mixture resulting from the first transesterification reaction is submitted to the following additional process steps: i) depletion of methanol by e.g. flashing and/ or distillation, ii) depletion of FME by e.g. flashing and/ or distillation, with the steps i) and ii) being performed either first step i) and then step ii) or both steps i) and ii) being performed together or with some overlap, i.e. that step ii) starts before step i) is finished, and iii) removal of the catalyst by e.g. absorption on suitable absorbents such as suitable Trisyl-grades (e.g. from Grace) and the like, optionally by adding suitable acids during or before adding the adsorbent.

In step 3) as part of the presently claimed invention, the glycerin phase, preferably the glycerin phase resulting from the reaction mixture after having performed the further process steps i), ii) and iii) of previous step d) and only then having separated the glycerin-phase, from the first transesterification stage can advantageously be fed directly to a process for obtaining glycerin of any desired grade and purity, such process preferably being a multi stage distillation process using typically, known equipment and conditions.

Step (f) Second transesterification

In an embodiment of the presently claimed invention, the second transesterification reaction is carried out at a temperature range of 25 °C to 150 °C depending on the pressure and time conditions.

In an embodiment of the presently claimed invention, the second transesterification stage is carried out at a temperature in the range from room temperature (e.g. 25 °C) to 100 °C, preferably to 95°C, more preferably to 90°C and even more preferably to 88°C, preferably in the range from 40 °C to 75 °C and particularly preferably in the range from 55 °C to 70 °C, such as e.g. 60 or 65 °C, and furthermore in particular at normal pressure. The reaction may be performed depending on the temperature and pressure chosen under reflux or without reflux. When methanol is chosen - which is the most favorable alcohol to be employed - this means that the reaction is performed at the boiling temperature of methanol or slightly below when operating at ambient pressure. By this a good temperature control can be implemented. This embodiment of the invention enables an energy-saving and cost-efficient performance of the method, because high heating costs are avoided and the respective transesterification reactions can be - preferably - carried out inter alia at normal pressure, so that expensive pressurized reactors and complex and expensive generation and maintenance of the temperatures and pressures, such as are necessary in the prior art, can be omitted. Hence this embodiment is preferred over the other embodiments for the second transesterification step requiring other temperatures and pressures and thus durations.

Furthermore, the low reaction temperature during the first and/or the second transesterification stage contributes to a reduction in the operating costs relative to known methods and thus also improves the economy of the method relative to previously customary methods. However, of course, depending on the duration employed for the transesterifications, at lower temperatures the duration of the reaction has to be prolonged compared to high temperatures, as otherwise no satisfying yields are obtainable. Hence, the net benefit in terms of energy saving depends on the complete outline of the process, the equipment employed and the temperature and duration of the reactions, as a simply reduction in time leads to higher reaction temperature (if the yield should stay the same) or lower yields (if the duration stays the same). A further advantage of the transesterification which can be carried out according to the presently claimed invention without pressure also resides in the fact that costly safety measures, which are necessary in the event of the use of pressure vessels, can be omitted, when the method is applied, since all operations are carried out at normal or atmospheric pressure, and, due to the low reaction temperatures, in an energy-efficient manner and quickly. Especially performing the reaction at around the boiling temperature of the solvent/ reactant employed for the transesterification (i.e. the alcohol such as methanol, ethanol etc.) permits a good temperature control, as excessive temperatures can be avoided as then the alcohol component will boil and thus cool down the reaction mixture again to the desired temperature. Hence, the obvious advantage of performing at ambient pressure and lower temperatures is the omittance of (more expensive) pressurized equipment but with the drawback of usually longer reaction times needed to obtain the same yield of conversion.

In an alternative embodiment of the presently claimed invention, the second transesterification reaction takes place over a period of about 2 to 10, preferably over a period of 4 to 10 hours and more particularly 5 to 8 hours at temperatures of 90 to 145° C. and more particularly 120 to 130°C and under a pressure of 2 to 10 bar. The obvious advantage of this embodiment is the very high conversion to be achieved at relatively short times.

Further optional steps following the transesterification are: i) optionally separating and removing methanol from the reaction mixture obtained from the transesterification step; ii) optionally separating and removing FME from the reaction mixture obtained from the previous step, iii) optionally separating and removing the basic catalyst from the reaction mixture obtained from the previous step, and/ or iv) separating and removing the phase comprising glycerin from the reaction mixture obtained from the previous step.

The same rationales, measures etc., are applied as already described above in the paragraph on the first transesterification, to obtain the in principle same results and/ or achieve the same advantages as described there and thus to further purify the mixture prior to the next process step.

Step (g) - Addition of water

In an embodiment of the presently claimed invention, when water is added in step (g), it is added in an amount in the range from 15% to 25%, preferably from 18% to 22%, and particularly preferably in the range from 19.5% to 20.5%, in each case based on the mass of a total batch, in order in particular to set a mass ratio of sterol: FMEs: methanol: water of substantially 1 : 2.5-3 : 2.2-2.5 : 0.8-1.2.

In an embodiment of the presently claimed invention, the steps of optionally separating and removing methanol from the mixture obtained from the step of adding water; optionally separating and removing FME from the mixture obtained from the previous step, optionally separating and removing the basic catalyst from the mixture obtained from the previous step, and/ or separating and removing the phase comprising glycerin from the mixture obtained from the previous step, as described for the previous step f) could be applied again after the end of step g). The same rationales, measures etc. are applied as already described above for such measures within the paragraph on the first transesterification, to obtain the same results as described there and thus to further purify the mixture prior to the next process step.

The addition of water to the reaction mixture, which takes place after the second transesterification stage, makes it possible in a particularly simple manner for substances which would impede crystallization of the sterols to be removed in particular from a sterol- containing phase of the transesterified batch. Thus, by the addition of water, glycerin present in the reaction mixture, catalyst and contaminants are separated off from the distillation residue, wherein the said substances pass into the water phase. Furthermore, the added water largely extracts the methanol, which is still present in the reaction mixture, so that the solubility of the sterols in the methyl ester phase decreases considerably and they crystallize out or at least start to crystallize.

Furthermore, during the addition of water to the reaction mixture, it was surprisingly ascertained that when a specific water concentration is reached, a spontaneous, very complete crystallization out of the sterols can already be observed at the reaction temperature, wherein a 3-phase system, consisting of a FME phase, a water phase and sterol crystals forms simultaneously, wherein the respective density of the three phases increases in the aforesaid sequence. Thus it has been shown that in particular the addition in the aforesaid quantitative ratio of sterol: FMEs: methanol: water of substantially l:2.5-3:2.2- 2.5:0.9-1.1 is particularly effective in order to achieve a clear separation of the three phases, whereby further processing of the reaction mixture is greatly simplified, which in turn has an extremely positive effect on the economy of the procedure, in particular with regard to an energy-saving and time-saving reaction of the starting products and obtaining the desired phytosterols and tocopherols.

Furthermore, it has proved advantageous to cool the homogenized emulsion or suspension to a temperature in the range from 5° C. to 35° C, preferably in the range from 10° C. to 30° C. and particularly preferably in the range from 15° C. to 25° C., so that a subsequent phase separation is simplified considerably. Furthermore, the crystal structure of the required phytosterol crystals can be significantly improved by compliance with a maturation period, which in turn has a perceptible positive effect on improved filtration properties of the crystals and also yields of crystals. According to the invention the maturation period is in particular in the range from 1 hour to 48 hours, preferably in the range from 2 hours to 36 hours and particularly preferably in the range from 4 hours to 12 hours.

Step (h) - Crystallization of the sterols

Successful crystallization typically requires a free sterol concentration of at least 20 to 25%. Sterol concentrations of > 40% can be achieved by the process according to the presently claimed invention. Should the concentration still be below a value which does not allow reasonable crystallization, it is increased by distilling off the fatty acid esters produced in the "transesterification of the sterol esters" process step. The procedure involved corresponds to the "fatty acid ester distillation" step. If the transesterification of the sterol esters was carried out under pressure and the metal soaps precipitated were removed by adsorption, FME is added as solvent. In this case, the quantity of FME is again 30 to 200% by weight and preferably 50 to 100% by weight, based on the amount of product used in the transesterification of the sterol esters.

In an embodiment, the presently claimed invention relates to the purification of the sterol fractions which, apart from the lower alcohol, mainly contain methyl esters, takes place in a known manner, i.e. the hot mixtures (ca 50- 70 °C.) are slowly cooled to form the phytosterol crystals, which are formed at a temperature of from 15 °C to 50 °C, preferably 20 °C to 45 °C, more preferably 25 °C to 35 °C, even more preferably 20 °C to 30 °C, in a crystallizer. If necessary, alkaline catalyst from the transesterification present in the mixture can be neutralized beforehand, for example by addition of citric acid or other suitable organic or inorganic acids that are also suitable or acceptable for the intended use of the sterols later on; preferably, such neutralization is omitted if the feed for the crystallization allows for.

In an embodiment of the presently claimed invention, the lower alcohol is selected from the group consisting of methanol, ethanol and isopropyl alcohol. Preferably the lower alcohol is methanol. The alcohol may contain small amounts of water, but preferably is essentially water-free.

In an embodiment of the presently claimed invention, only those mixtures which already have a ratio by weight of sterol to methanol of 100:25 to 100:75 from their production should be used. Otherwise methanol has to be added or distilled off. Under these conditions, the crystallization begins at temperatures of 60 - 65 °C, but could be also done at higher temperatures, if the crystallization is done at elevated pressures and/ or if the solvent mixture employed has a high boiling point than the one disclosed as preferred herein.

In an embodiment of the presently claimed invention, the ratio of sterol: methanol is in the range of 1: 0.1 to 1: 5, preferably 1: 0.5 to 1:3, more preferably 1:0.5 to 1:2.5.

In an embodiment of the presently claimed invention, the sterol containing phase, which primarily contains sterol crystals, may subsequently be washed with methanol, wherein the quantity of methanol is in the range from 20% to 800 %, preferably in the range from 125% to 600%, more preferably in the range from 200% to 400% in each case based on the mass of the sterol crystal phase.

In an embodiment of the presently claimed invention, the sterol containing phase, which primarily contains sterol crystals ,may subsequently be washed with methanol, wherein the quantity of methanol is in the range from 50% to 800%, preferably in the range from 125% to 700%, more preferably in the range from 200% to 550% in each case based on the mass of the sterol crystal phase, wherein this methanol washing is optionally preceded by a displacement washing of the sterol crystals with methyl ester, in particular vegetable oil methyl ester such as, for instance, methyl ester of rapeseed oil and/ or soya oil and/ or sunflower oil and/ or coconut oil and/ or palm oil and/ or cottonseed oil and/ or corn germ oil, at a proportion in the range from 50% to 500%, preferably in the range from 75% to 400%, and particularly preferred in the range from 100% to 350%, in each case relative to the mass of the sterol crystal phase.

In an embodiment of the presently claimed invention, the phytosterol crystals are formed at a temperature of from 15°C to 50 °C, preferably 20°C to 45°C, more preferably 25 °C to35 °C even more preferably 20 °C to 30 °C, such as 20 °C, 21 °C, 22 °C, 23 °C, 24 °C, 25 °C, 26 °C, 27 °C, 28 °C, 29 °C, 30 °C, 31 °C, 32 °C, 33 °C, 34 °C or 35 °C.

In an embodiment of the presently claimed invention, the phytosterol crystals are formed at a temperature of from 15 °C to 50 °C, and more preferably at every temperature in between 15 to 50°C.

In an embodiment of the presently claimed invention, in order to increase the sterol yield, part of the mother liquor is recycled, for example to the crystallization process, after filtration of the crystal suspension. The return stream is fed to the system together with the fatty acid esters in the "catalyst removal (II)" process step. Another way of recycling the mother liquor is to introduce it into the first (a) or second (c) transesterification step.

The recycle ratio of the mother liquor depends to a very large extent on the starting material and hence on the composition of the mother liquor. It may be in the range from 0.1 to 5.0. A recycle ratio of 0.2 to 3.0 is preferably established.

Step (i) - Separation of phases In an embodiment of the presently claimed invention, the separation of the phases is carried out by means of a filter, a screen or a decanter centrifuge or the like apparatus suitable for separating liquid/ solid (or solid-containing) phase-mixtures, wherein a filter centrifuge or a decanter is preferably used, with a filter centrifuge being more preferred. By the use of a filter or a decanter centrifuge in practice a filter cake can be obtained with a significantly lower residual moisture ("moisture" meaning the content of solvent(s) employed) than would be possible for example with differential pressure filtration or other filtration techniques.

Furthermore, a 3-phase decanter is also very suitable for separating the multi-phase system consisting of a sterol-containing phase, a glycerin-containing and a methanol-containing phase and a tocopherol-containing phase, wherein the phase containing sterol crystals or the sterol crystals themselves form the heaviest phase and can be separated off or pre-thickened well by means of the 3-phase decanter, whilst simultaneously the FME phase and the water phase containing glycerin and methanol can be obtained separately.

In this case the separation of the sterol crystals by means of a discontinuously operating filter centrifuge also offers the possibility of carrying out cake washing immediately after the filtration.

Step (j) Optional crystallization of the Sterols

In an embodiment of the presently claimed invention, the free sterols obtained from crystallization (in step (h)) and phase separation in step i) may be further (re-) crystallized to obtain sterol crystals of higher purity, by re-dissolution in the same solvent/ solvent mixture used for the first crystallization. Then, again, the obtained crystals have to be separated as disclosed before for step i).

Step (k) - Purification of the sterol

In an embodiment of the presently claimed invention, the separated sterol crystals are subjected to further purification.

In an embodiment of the presently claimed invention, the sterol crystals are further purified using a solvent or solvent system. The sterol crystals obtained in step h) and - if performed - step j), either in a separate process step or a combined process step - are purified using an organic solvent, a solvent mixture of more than one organic solvents and optionally but not preferred also containing water, or - more preferred - an azeotropic solvent mixture of at least one protic polar solvent and an at least one aprotic polar solvent.

In an embodiment of the presently claimed invention, the purification of the sterol fraction occurs in the presence of a solvent system which comprises at least one polar aprotic solvent.

In an embodiment of the presently claimed invention, the step k) of the purification of the sterol fraction occurs in the presence of at least one polar aprotic solvent which is ethyl acetate, methyl ethyl ketone and methyl acetate, dichloromethane, N- methyl pyrrolidone, tetrahydrofuran, acetone, dimethylformamide, acetonitrile, dimethyl sulfoxide, heptane and/ or hexane, with ethyl acetate, methyl ethyl ketone, methyl acetate, acetone, heptane and/ or hexane being preferred, and with ethyl acetate, methyl ethyl ketone and/ or methyl acetate being even more preferred, with methyl acetate being most preferred.

In an embodiment of the presently claimed invention, the purification of the sterol fraction occurs in the presence of at least one polar aprotic solvent which is ethyl acetate, acetone, methyl ethyl ketone and/ or methyl acetate. In a particularly preferred embodiment, methyl acetate is used as the sole polar aprotic solvent.

In an embodiment of the presently claimed invention, the purification of the sterol fraction occurs in the presence of at least one polar aprotic solvent and at least one polar protic solvent which are mixed together and/ or form an azeotrope in the solvent system.

In an embodiment of the presently claimed invention, the polar protic solvent is water, ethanol, methanol, isopropyl alcohol, butanol and/ or acetic acid.

In an embodiment of the presently claimed invention, the polar protic solvent is water, ethanol, methanol and/ or isopropyl alcohol.

In a particularly preferred embodiment methanol is used as the sole polar protic solvent.

In an embodiment of the presently claimed invention, the polar aprotic solvent is present in the range of 25 to 75% by weight, based on the amount of phytosterol, preferably in the range of 30 % to 50 % by weight, based on the amount of phytosterol, and every value in between 30 % to 50 %, based on the amount of phytosterol, with ethyl acetate, acetone, methyl ethyl ketone and/ or methyl acetate being the preferred polar aprotic solvent (s), and methyl acetate being more preferred as the sole polar aprotic solvent.

In an embodiment of the presently claimed invention, the polar protic solvent is present in the range of 5 to 50 % by weight, based on the amount of phytosterol, preferably in the range of 10 to 30 % by weight, based on the amount of phytosterol, and every value in between 10 % to 30 %, based on the amount of phytosterol, with methanol being the preferred polar protic solvent.

In an embodiment of the presently claimed invention, for measurement of the Gardner color number, the phytosterol is provided in the form of a 10% by weight solution in pyridine,

In an embodiment of the presently claimed invention, the final sterol product has a Gardner color number of less than 4.0, when measured for a 10 wt.% of sterol in pyridine.

In an embodiment of the presently claimed invention, the final sterol product has a Gardner color number of less than 3.0, preferably less than 2.0, more preferably less than 1.5, when measured for a 10 wt.% of the sterol in pyridine.

In an embodiment of the presently claimed invention, the solvent content in the purified phytosterol is less thanlOO ppm, preferably less than 50 ppm, more preferably less than 20 ppm, and even more preferably less than 10 ppm such as 5 or 1 ppm, and every value in between 100 and 1 ppm, based on the total weight of the purified phytosterol.

In an embodiment of the presently claimed invention, the sterol ester content in the purified phytosterol is less than 10 % by weight, preferably less than 5 % by weight, more preferably less than 2 % by weight, even more preferably less than 1 % by weight, and most preferably less than 0.5 % by weight, such as 0.1, 0.05 % by weight and every value in between 5 and 0.05 % by weight, based on the total weight of the purified phytosterol.

Step 1) - optional further drying the sterols

The washed sterol crystals can be dried using conventional dryers of all kinds, to remove remaining solvents. Application of reduced pressure helps to increase the removal of solvent traces. This step serves as drying or "pre-drying", depending on the method employed and the desired content of residual solvent in the final sterol product to be obtained. The latter of course mainly depends on the intended use of the sterols. Thus, in an embodiment the sterols obtained as sterol crystals may be further dried by e.g. stream stripping at a temperature of 130 to 200, preferably 150 °C to 170 °C, for 1 to 3 hours, to remove the solvent.

Step m) - optional further purifying the sterols by melt-drying to remove trace amounts of solvents within the sterols

Following the "conventional" drying of the previous step 1), the (pre-)dried crystals can be melted preferably under reduced pressure to remove solvent traces enclosed within the crystals. By this, the residual content of solvents can be lowered even more so as to achieve certain higher product qualities being usable also for critical applications, e.g. direct applications to human beings in nutritional or pharmaceutical products.

Step n) - optional subjecting the sterols to a particle-forming process to obtain sterol particles

The melted sterols from previous step m) need to be solidified. That could be done either by simple cooling with stirring of any kind, e.g. in an extruder, a paddle dryer and the like. Other known methods for solidification of melts are prilling, in apparatuses such as prillers including jet-prillers, which can form droplets close to spherical shapes, or simply in dripping towers, in which molten material is dropped into colder air or gases, all such methods to finally obtained solid, particulate sterols, which are preferably in forms that do not show dusting but good fiowability and preferably a high density, to obtain sterols particulates with easy handling properties.

Thus, in a further embodiment, the sterols obtained - and preferably (pre-) dried - are subjected to a particle forming process, such as prilling, preferably jet-prilling, which is preferably done under liquid nitrogen, to obtain solid, close to spherical, low to non-dusting sterol particles of very low organic solvent-content, which are suitable for direct use including oral intake by humans.

Step (o) - Tocopherol separation and purification

In an embodiment of the presently claimed invention a further stage of obtaining tocopherols from the tocopherol-containing phase the FME phase of the multi-phase system, which contains the tocopherol in dissolved form, is preferably subjected to a distillation for separation off of the methyl ester, whereby it is possible to concentrate the tocopherol content in the FME phase to over 10 wt.% based on the amount of FME, in order to enable a simple further preparation of the tocopherols in a known manner.

In an embodiment of the presently claimed invention, the tocopherol is separated by known processes.

In a further embodiment of the presently claimed invention, the tocopherol is purified by known methods.

Steps (p) and (q)

In an embodiment of the presently claimed invention, the steps (p) and (q) could be optionally performed by known process steps, to obtain the substances in pure forms of the desired purity.

Advantages

The presently claimed invention is associated with at least one of the following advantages:

1. The method according to the presently claimed invention, which - as its core -is a two- stage basic-catalyzed transesterification with a glycerin phase precipitation after the first transesterification stage and then sterol crystallization out of the reaction mixture with the addition of water, wherein interposed method steps such as neutralization, distillation off of reagents or solvents and washing out of catalyst are preferably omitted, and in which furthermore by means of a combination of methyl ester displacement washing followed by washing of the sterol crystallizate filter cake with an azeotrope as disclosed in the specification whilst adhering to specific aforesaid process parameters, it is possible to obtain phytosterols and tocopherols from distillation residues from a transesterification of vegetable oils, in particular from the vegetable oil-based FME production for the field of use of biodiesel with levels of purity and yield which have not been attained hitherto.

2. Furthermore the previously described method according to the presently claimed invention can be fully implemented in a plant for FAME (biodiesel) production or as a down-stream processing unit to such plant, wherein in an advantageous manner the substances which are usual in FAME plants can be used in an optimal manner as reagents, which is why the method is particularly effective and economical both from the economical point of view and also from the logistical aspects.

3. The process is suitable for various starting mixtures and does not involve the use of toxicologically and ecologically unsafe solvents.

4. The better utilization of the distillation residues leads to an economic, ecologically safe process that is easy to carry out on an industrial scale.

5. The phytosterols are obtained with a Gardner color number of less than 4.

6. The phytosterols are obtained in a high yield with a very low content of sterol ester (i.e. less than 10%) by using the above described purification process.

7. The solvent content of the final product is low (less than lOOppm).

Examples

The presently claimed invention is illustrated in detail by non-restrictive working examples which follow. More particularly, the test methods specified hereinafter are part of the general disclosure of the application and are not restricted to the specific working examples.

Examples 1 and 2 are as disclosed in EP 2635592B1

Example 1

3850 g of a residue from the distillation of rapeseed methyl ester ("RME") are mixed according to the presently claimed invention with 1782 g RME. The analysis of the batch gives contents of 21.73% sterol ester, 6.21% free sterols, 1.68% tocopherols, 9.8% glycerides and 44.17% methyl ester.

The batch is temperature-controlled at 65 °C. and in a first transesterification stage 37.5 g Na methylate (30% solution in methanol) and 818 g methanol are added and mixed in. After 50 minutes settling time 301.2 g glycerin-containing bottom phase are drawn off. The reaction in the partial glycerides is over 95%.

For the second transesterification stage for conversion of the sterol esters into free sterols 150.2 g Na methylate (30% solution in methanol) and 1865.6 g methanol are added. The reaction takes place at 65 °C. over 90 minutes.

1126 g water are added to the batch whilst being stirred, and sterol crystals formed. The suspension is cooled to 20 °C. whilst being stirred and then subjected to maturation at this temperature.

Then the suspension is filtered by means of a filter centrifuge, and the cake formed is subjected while still in the centrifuge to a first washing with 3.5 liters RME distillate and a second washing with 10.4 liters methanol. After drying of the filter cake moistened with methanol the result is 908 g of white sterol powder with a sterol content of over 98%, which corresponds to a yield (based on the total sterol content of the distillation residue) of over 82%.

The filtrate from the filtration of the suspension separates by itself into a light phase containing FMEs, sterols and tocopherols and into an aqueous phase containing methanol and catalyst. Sterols and tocopherols are also dissolved in the washing RME phase, whilst no tocopherols are detectable in the washing methanol phase.

In the combined FME phases there are 87% of the tocopherols originally detected in the RME distillation residue. After distillation of the methyl ester phases a residue with a tocopherol content of 11% can be obtained which is suitable for further working up of the tocopherols.

Example 2

3119 g of a residue from the distillation of rapeseed methyl ester are mixed according to the presently claimed invention with 2324 g RME. The analysis of the batch gives contents of 27.2% sterol ester, 5.17% free sterols, 1.12% tocopherols, 8.14% glycerides and 42.74% FME.

The batch is temperature-controlled at 65 °C. and in a first transesterification stage 36.3 g Na methylate (30% solution in methanol) and 873.5 g methanol are added and mixed in. After 50 minutes settling time 319.2 g glycerin-containing bottom phase is drawn off. The reaction in the partial glycerides is over 95%.

For the second transesterification stage for conversion of the sterol esters into free sterols 145.1 g Na methylate (30% solution in methanol) and 1995.7 g methanol are added. The reaction takes place at 65 °C. over 90 minutes.

1208 g water are added to the batch whilst being stirred, and sterol crystals formed. The suspension is cooled to 20 °C. whilst being stirred and then subjected to maturation at this temperature.

Then the suspension is filtered by means of a filter centrifuge, and the cake formed is subjected while still in the centrifuge to a first washing with 2.4 liters RME and a second washing with 10.4 liters methanol. After drying of the filter cake moistened with methanol the result is 956 g of white sterol powder with a sterol content of over 98%, which corresponds to a yield (based on the total sterol content of the distillation residue) of 80%. Example 3 - Purification of the sterol crystals

Example 3:

The sterols crystals obtained by a process as described and disclosed in the previous examples (example 1 and 2) was submitted to the following purification step:

On completion of the crystallization, the crystals were filtered off, washed free from FME with pure methanol and further subjected to washings with the following solvents.

- ethyl acetate and its azeotrope with methanol, or

- methyl ethyl ketone and its azeotrope with methanol, or

- methyl acetate and its azeotrope with methanol with subsequent pure methanol washing.

Further the crystals were melt- dried to constant weight and subjected to particle forming by prilling.

The results obtained were compared with the experiments where the crystals were washed with FME with subsequent pure methanol washing. The results obtained are summarized in Tables l-3(laboratory scale) as well as in Tables la- 3a (commercial scale, e.g. plant level). In each table, example Cl and T1 refer to the same sterol batch originating from the same rapeseed methyl ester distillation residue. The same applies to C2 and T2, C3 and T3 as well as C4 and T4 (if applicable). Thus, example Cl has to be compared with example T1 and so on.

Table 1- Solvent used is azeotrope of ethyl acetate with methanol (laboratory scale) Table la- Solvent used is azeotrope of ethyl acetate with methanol (commercial scale) n.d. = not determined

Table 2- Solvent used is azeotrope of methyl ethyl ketone with methanol (laboratory scale)

Table 2a- Solvent used is azeotrope of methyl ethyl ketone with methanol (commercial scale) n.d. = not determined Table 3: Solvent used is azeotrope of methyl acetate with methanol (laboratory scale)

Table 3a - Solvent used is azeotrope of methyl acetate with methanol (commercial scale) n.d. = not determined

Conclusions:

According to Table 1 (laboratory scale), the color of the final sterol product is remarkedly better in case of T1 to T4 than in case of Cl to C4. In comparison to the latter, the purity is at least slightly better, whereas, the yield is at least the same or even better for T1 to T4. As can be taken from Table la (plant level), the color is strongly improved for T1 compared to Cl, whereas, the yield more or less stays the same.

According to Table 2 (laboratory scale), the color and especially the yield of the final sterol product is remarkedly better in case of T1 to T3 than in case of Cl to C3. In comparison to the latter, the purity is slightly better for T1 to T3. As can be taken from Table 2a (plant level), color and yield are improved for T1 compared to Cl.

According to Table 3 (laboratory scale), the yield and especially the color of the final sterol product is remarkedly better in case of T1 to T4 than in case of Cl to C4. In comparison to the latter, the purity is at least the same or even slightly better for T1 to T4. As can be taken from Table 3a (plant level), color and yield are improved for T1 compared to Cl.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the presently claimed invention as defined by the appended claims.