AU657233B2 - Separation of sterols from lipids - Google Patents

Description

-1Ir/moii Rcgilation 3.2

AUSTRALIA

Patents Act 1990 6)57 23 3 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

U

t *0 4

I

9 9.

0 Name of Applicant: CORRAN NORMAN STUART MCLACIILAN Actual Inventors: Corran Normnan Stuart McLachlan, Owen John Catchpole and Bruce Henry Hamilton.

Address for service in Australia: CARTER SMITH BEADLE 2 Railway Parade Camnberwell Victoria 3124 Australia Invention Title: SEPARATION OF STEROLS FROM LIPIDS The following statement is a full description of this invention, including the best method of performiing it known to us la SEPARATION OF STEROLS FROM LIPIDS

FIELD

This invention relates to the separation of sterols (and in particular cholesterol) from lipids, i.e. from naturally occurring fats or oils.

It has particular though not sole application to the preparation of a low cholesterol or cholesterol free butter or tallow.

0.

*o

BACKGROUND

0* Attempts have been made to modify butter in an attempt to fractionate the triglycerides, in order to produce a more spreadable butter, 10 and/or to remove the cholesterol present in the butter. However, none of these prior art techniques has proved to be satisfactory, as they have either not satisfactorily removed the cholesterol, or in removing the cholesterol have modified the flavouring of the butter or otherwise degraded the butter by altering its physical properties, as 15 well as its keeping properties.

Concern is being increasingly expressed at the level of cholesterol in foodstuffs. In addition to concern over the presence of saturated fats in our diet, it is likely that legislation will be enacted 'in some countries which will require cholesterol content to be shown 20 along with other nutritional values when the foodstuff is sold.

The primary source of cholesterol in foodstuffs is lipid-containing food such as meat, either red or white, shell-fish, and dairy products such as butter or cheese.

The lipid components of interest are those known as neutral lipids.

This class of lipids contains: mono-, di- and tri-acylglycerides, collectively known as fat; free and esterified cholesterol, and other sterols; free fatty acids, fatty alcohols and wax esters. Of most interest are the fat and cholesterol components, and in the case of butter, it is desirable to remove cholesterol from the butter without 2 in any way degrading the fat component.

PRIOR ART EP 0174848 (A2) in the name of New Zealand Dairy Research Institute, teaches a method of removing cholesterol from anhydrous milk fat at a temperature of 700 900 C, with the addition of active pulverised carbon, which is stirred into the heated fat for one hour, removed by filtration, and then the heated fat is treated again with pulverised carbon a number of times until the milk fat is cholesterol free or at least substantially free of cholesterol. However, such a treatment 10 degrades the milk fat by heating, results in oxidation and unpleasant

C.

odours, requiring the subsequent use of a deodoriser and antioxidants, and degrades or removes the flavouring and colouring components of the milk fat. The milk fat thus requires additional treatment and addition of additives in order to endeavour to simulate its original colour and flavour.

Another approach is mentioned in US Patent 4,504,503 assigned to Lever Brothers Company. In this patent, there is disclosed a process for producing a mixture of triglycerides displaying butter-like properties by fractionating fats with a liquified gas or gas under supercritical 20 conditions. The preferred gas is supercritical CO 2 which is used to treat butter fat or hardened butter fat at a temperature of 600 1000 C and subsequently separated by fractional condensation by varying the pressure or temperature of the CO 2 in order to preferentially separate out the different triglycerides. This results in the preferential separation of a mixture of triglycerides having a carbon number of 24 42, suitable for use in the manufacture of margarine. No mention is made in this patent of the removal of cholesterol.

In Japanese Patent 134042 by Shishikura et al., and in their related paper entitled "Modification of Butter Oil by Extraction with Supercritical CO2" Agric. Biol. Chem., 50(5), 1209-1215, 1986, A.

Shishikura, et al. concluded that the preparation of a low cholesterol butter oil by simple extraction with supercritical r0 2 is impractical.

In that paper, there is described an attempt at modifying butter oil by dissolving the butter oil in the supercritical CO 2 at 40°C and 300 -3to 350 bar, and passing the supercritical fluid through a column of Silicic Acid.

A. Shishikura, et al. reported they could achieve significant (over 90%) reduction of cholesterol but only at the expense of very high yield losses (up to Under conditions where yield loss was reasonable (15-20%) cholesterol yields fell to 70-80%. Experiments were also undertaken with mixtures of activated carbon and silicic acid. This resulted in cholesterol removal of above 75% but both flavour and colour constituents were almost entirely removed.

OBJECT

It is an objection of the present invention to provide an improved process for separating sterols from lipids, and in particular an improved process for separating cholesterol from butter.

SUMMARY OF THE INVENTION Surprisingly, we have found that it is possible to separate sterols, and in particular cholesterol, from fats by dissolving the cholesterol/fat mixture in a high pressure liquid or 15 sub or supercritical gas such as CO2, and to selectively adsorb the cholesterol from the S* dissolved fat mixture by contacting the high pressure fluid mixture with an adsorbent which is made up from or includes basic oxygen containing salts of metals such as the oxides, hydroxides, carbonates, and sulphates.

We prefer to pass the high pressure fluid mixture through a bed or column of the basic 20 adsorbent material to allow the cholesterol to be selectively adsorbed by the material, so that the high pressure fluid leaving the bed contains a fat product which is substantially free of cholesterol.

Accordingly, in one aspect, the invention provides a method of separating sterols from lipids, including: dissolving the sterol/lipid mixture in a high pressure physiologically BM H l«4183 2 D, bw. 1g 4 -4icceptable fluid (either as a high pressure liquid or as a high pressure sub or supercritical gas), and contacting the high pressure fluid mixture with an adsorbent selected from the group consisting of the minerals calcium hydroxide, calcium carbonate, calcium phosphate, magnesium carbonate and magnesium hydroxide to remove the sterols, removing the substantially sterol free lipids from the high pressure fluid and recovering the sterols from the adsorbent by displacement with a solvent.

Preferably, the cholesterol or other sterols can be selectively removed from the adsorbent material by stripping the adsorbent material using the same, or another high pressure fluid, or by using organic solvents, such a propan-2-ol, and chloroform/methanol mixtures for example. By this means, it is possible to selectively refine cholesterol or other sterols for pharmaceutical or other purposes.

DRAWINGS

The above gives a broad description of the present invention, a preferred form of which will now be described by way of example only with reference to the accompanying drawings in which: FIGURE 1 is a flow chart showing the extraction of fat and cholesterol from a S• cholesterol containing feed material such as meat, egg powder, or milk .00. to* powder using a high pressure fluid and separating the cholesterol from the o. cholesterol/fat mixture by selective adsorption of the cholesterol on an adsorbent material.

FIGURE 2 is a flow chart showing a similar process where the feed material is a fat or oil such as butter, plant oil, or fish oil, which is dissolved in the high pressure fluid, and the cholesterol is selectively removed therefrom by adsorption on an adsorbent material, and the substantially cholesterol free fat or oil is S 25 condensed from the high pressure fluid.

1 ~2 OC obr, 1954 In these two processes, a high pressure fluid is used either to dissolve the fat or oil, where the feed stock is butter, or an animal or plant oil; or where the feed stock is a matrix containing fats and cholesterol, e.g. meat, cheese, milk fats, egg powder, or the like, the fat and cholesterol can be extracted using the high pressure fluid.

Suitable extraction fluids include:

CO

2 NO, CF 3 C1, CF 2 C1 2

CH

2

CF

2 SF, CHF 3

CHF

2 CI, CF3CI, CF 2

CH

2 C3F,, ethane, propane, ethylene, or mixtures thereof, and other gases unobjectionable from a health point of view for treating foodstuffs, and which will be sub or supercritical in temperature and pressure ranges suitable for the processing of footstuffs. Entrainers (as discussed below) can also be used in conjunction with the high pressure fluid. The high pressure fluid can be a liquid, or can be a sub or supercritical gas.

In a high pressure fluid extraction process, pressure and temperature are the controlling parameters. A substance is in the supercritical state when it is above its critical temperature, Tc, and pressure, Pc. In this state, it can no longer be compressed into a liquid, for any pressure. A subcritical fluid is a fluid whose pressure P or temperature T are both less than To or Pc or where one or the other is greater than its critical value, in this instance, preferably where T is less than Tc and P is greater than Pc.

For CO2, Tc 31.3°C, and Pc 72.8 Bar. Both sub and supercritical fluids can be used for extraction purposes.

Suitable extraction Pressures for CO2: 50 400 Bar (preferably 200-250 Bar).

Suitable extraction Temperatures for CO2: 30 60°C (preferably Of the options available, the preferred extraction pressures are in the range 200-300 bar, and temperatures in the range 30-50°C, using CO 2 as the extracting agent. Temperatures above 60C preferably should not be used where the cholesterol is extracted from a protein containing source so as to avoid protein denaturisation. CO, was chosen as our preferred Q eJtl01419 a 1904

I

/4 -6extractant because it is physiologically inert, it has bacteriostatic/bacteriocidal properties, has relatively low critical temperature and pressure requirements, is particularly suited to treating food products, and is compatible with our preferred adsorbant materials.

Our preferred processes are concerned with the application of adsorption techniques to cholesterol and other sterols when dissolved in a high pressure fluid. Cholesterol or other sterols are separated by selective adsorption from a mixture of neutral lipids (mainly triacylglycerides) of natural origin, i.e. from animals, plants, yeasts or the like. The feed mixture can be obtained in the following ways: By extraction from a solid matrix such as meat, egg powders, milk powders, and other animal products containing a certain amount of cholesterol containing fats.

By extraction of liquid or solid purified animal fats, such as lard, butter, fish oils, wool grease, plant oils, or the like.

The lipid mixture is extracted or dissolved into a high pressure (liquid or sub or supercritical) fluid.

15 Separation of cholesterol or other sterols (as discussed below) from the dissolved lipid mixture, is achieved by contacting the high pressure fluid mixture with an adsorbant which is made from or contains basic oxygen containing salts of metals such as the oxides, hydroxides, carbonates, sulphates, or the like. The oxygen containing salts may include (but are not limited to): oxides, hydroxides, carbonates, sulphates, phosphates, acetates, 20 or carboxylates. A wide range of basic metal oxides, hydroxides, carbonates, sulphates and other oxygen containing salts can be used and these include magnesium oxide, calcium oxide, strontium oxide, barium oxide, cadmium" oxide, cobalt 1 oxide, manganese oxide, nickel oxide, zinc oxide, and the hydroxides, carbonates, sulphates and other oxygen containing salts of these metals.

2*o Our preferred adsorbants preferentially adsorb cholesterol and other sterols, with minimal "N i2 Dww, 1*04 J1 148 -7adsorption of the other lipids. Consequently a substantial cholesterol free lipid mixture can be obtained from the high pressure fluid as it leaves or is otherwise separated from the adsorbant.

In most cases, this will involve passing the high pressure fluid through a column or bed of the adsorbant material, although it is possible to add the adsorbant material in the form of a fine powder to the high pressure fluid, e.g. stirred into a tank and then separating the powder from the fluid by filtration, by a hydro-cyclone, a centrifuge, or other solid/fluid separation technique.

The degree of separation will depend upon the quantity of high pressure fluid used. For example, where a bed or column of the adsorbant material is used, the bed or column of adsorbant can be regenerated by contacting it with a greater quantity of the same high pressure fluid. Alternatively a different fluid which strips off the cholesterol or other sterols more quickly may be used for regeneration. The final stage of the process involves the separation of the purified lipid mixture from the high pressure fluid. Options for achieving this include: Redeposition in and on a solid matrix, e.g. meat, milk powders or egg powders.

Redeposition on and mixing with the insoluble residues of for example, butter.

Collection as is, e.g. in the case of lard or butter.

Process 1 (Figure 1) Removal of Cholesterol from a Solid Matrix 20 Lipids are extracted from a feed material such as finely sliced and at least partly dried meat, by extracting the lipids with a high pressure fluid. The preferred fluid is sub or supercritical carbon dioxide in a preferred pressure range of 150 300 bar, maintained at a temperature within a preferred range of 30° 60* C.

The extract lipids, mainly fat and cholesterol, dissolved in the high pressure fluid are then passed over a closely packed column of adsorbant material, which is preferably granulated C BCJKI1143 2teceb, 1W04 -8or pelletized with a particle size chosen in order to provide a good flow path through the column, whilst at the same time maximising the surface area of the adsorbant material.

As will be seen from the examples, different basic oxides, hydroxides, carbonates and other oxygen containing salts can be used as the adsorbant material. It is preferred that the column has multiple entry and exit points so that different portions of the bed can be used at different times to adsorb the cholesterol. By suitably separating the different portions of the bed, it is possible to use one portion of the bed whilst another portion is being stripped of its cholesterol, The flow rate of the high pressure fluid, and the quantity of fat/cholesterol mixture dissolved in the fluid is preferably controlled so that substantially all of the cholesterol is selectively adsorbed on the bed (with minimal adsorption of the fat except where controlled separation of the triglycerides is required) so that the high pressure fluid leaving the bed in most cases consists of substantially all of the fat with complete or almost complete removal of the cholesterol present.

The high pressure fluid leaving the bed, is then processed to separate the fat from the high pressure fluid, and this can be achieved in a variety of ways, e.g. by a increase ir temperature, or a decrease in pressure, or a combination of both.

•9 The preferred method involves stripping of the fat from the high pressure fluid by an increase in temperature to a level at which the solubility of the fat in the high pressure fluid t.o: is reduced, or becomes negligible. This ranges from 10-30°C greater than the extraction 0:9"temperature for CO2. The fluid remains at high pressure and is recycled.

Alternatively, the fat can be stripped from the fluid by reducing its pressure. This can if S desired be combined with a change in temperature. The pressure can be reduced to atmospheric, with no recycling of the fluid; or the high pressure fluid can have its pressure 9 reduced to the range 50 100 bar and then recycled. In some instances a combination of both processes may be most economical.

X, ~,cM t418 2 D{ mbor, 1904 :1.t 4~t -9- As the fat in this case has been removed from a meat product, e.g. beef, the resulting beef tallow can be added back to the meat, during reconstitution of the meat product. Some or all of the fat can be added back in this way, depending upon the fat level required for the resulting meat product. For example, it may be desirable to produce a low fat (cholesterol free) meat product, in which case some of the beef tallow can be removed, and the rest of it redeposited on the meat product.

Process 2 (Figure 2) Cholesterol Free Butter This process if similar to that of Figure 1, except that the feed material is butter fat, and is dissolved in a high pressure fluid such as sub or supercritical carbon dioxide. This is then passed over a column of adsorbant material as previously described, so that the cholesterol is selectively adsorbed on the material, and the high pressure fluid leaving the column contains the bulk of the fat, and substantially no ciholesterol.

This cholesterol free fat can be separated from the high pressure fluid, preferably by an increase in temperature as previously described, although it is equally possible to separate it by a decrease in pressure. The high pressure fluid is preferably recycled, and used to dissolve further butter fat, which then passes over the adsorbant material and the process continues as shown in the flow chart.

The cholesterol is preferably stripped from the adsorbant material, as described above, to provide a substantially pure form of cholesterol.

In the process described with reference to Figures 1 and 2, it will be appreciated that the adsorbant material is chosen in order to ensure that substantially all of the cholesterol is adsorbed on the bed and the resulting cholesterol free fat is suitable for use as a food product. In order to achieve this, it is preferred that the adsorbant material is physiologically acceptable, and is of relatively low cost, and does not preferentially bind the triacylglycerides, fatty acids, or other naturally occurring food sensitive products: e.g.

flavourings, olfactory agents, colouring agents, or the like.

B AJ 14103 ZDo bw., 1084 L 10 Of the basic oxides, hydroxides, carbonates and other oxygen containing salts tested, we prefer to use tha oxides, hydroxides, and carbonates of magnesium and calcium. Although where the high pressure fluid is other than carbon dioxide we prefer to use the corresponding carbonate.

Indeed, the preferred material is calcium carbonate for use with high pressure carbon dioxide, as we have found that by using basic oxides or hydroxides with supercritical carbon dioxide they are converted in the adsorption column into the corresponding carbonate. As calcium c'-.bonate is an inert, low cost, naturally occurring mineral, it is the preferred material for use in this cholesterol/sterol adsorption process.

There are many variations possible for use with the process of this invention, and come of these are described below.

PROCESS OPTIONS Adsorbants: Basic metal oxides, as well as their hydroxides, carbonates, sulphates, and other oxygen containing salts, are the preferred adsorbant materials. Calcium carbonate, calcium oxide, magnesium carbonate, magnesium oxide and magnesium hydroxide are the most preferred of the naturally occurring adsorbant materials, although other appropriate 9 adsorbants include (but are not limited to) the oxides, hydroxides, carbonates, sulphates, and other oxygen containing salts of magnesium, calcium, strontium, barium, cadmium, cobalt, manganese, nickel, and zinc. They may be used alone or in mixtures, and preferably are used in their naturally occurring form.

Some of these are not suited to a food grade product, although in the separation of sterols, the resulting sterol free fat may not be intended as a food grade product so some or all of these materials could be used.

The properties of the adsorbant materials depend on the crystalline structure (and thus the surface structure), and polar nature (acidic or basic). The choice of adsorbant material, will SBCJH: l14183 20 cmlbW. 19G4 t .9 -11 depend upon the design of the plant, the strength of adsorption of the material, and the particle size and strength of the material (in the case of a bed or column) is important to avola channeling allowing the high pressure fluid to pass through the column without adsorption and it is also desirable to avoid the breakdown of the material into a fine powder which would have the opposite effect of clogging the column. Thus the adsorbants could be provided in pelletized or granular form, or as naturally occurring minerals, or deposited onto suitable substrates such as glass beads or rings.

As we have found that the most suitable materials are the basic oxides, hydroxides, carbonates, sulphates, and other oxygen containing salts of metals, the adsorbant material can be chosen in terms of its relative strength of adsorption. We have found that for a given anion the strongest adsorption of sterols by the basic oxygen containing salts of the metals is shown by magnesium and this decreases through nickel, cadmium, cobalt, zinc, calcium, strontium to barium which shows the least adsorption of this group.

We have found that acidic oxides are not suitable for use with high pressure fluids, as they cause too strong an adsorption of all of the lipid material so that separation is difficult without overloading the adsorbant. Such acidic oxides include Silicic Acid, Florlsil, and Alumina, and as such are to be excluded form the process of this invention.

S. Any fluid which at high pressure (either as a liquid or as a sub or supercritical gas exh'its solvent properties can be used with this invention.

The following gases have critical properties in the correct range and are unobjectionable from the health point of view for treating foodstuffs. Carbon dioxide, ethane, propane, ethylene, NO 2 SF, CF3C1, CF 2

CL

2

CH

2

CF

2

C

3

F

8

CHF

3 and miy'ures thereof, and other gazes unobjectionable from a health point of view, and which will be sub or supercritical in temperature and pressure ranges suitable for the processing of foodstuffs.

25 Other solvents: Subcritical additives which have been shown to enhance the solubility of lipids or cholesterol, include: Propan-2-ol, ethanol, acetone, methanol, chloroform, ether, S" ~uJK 14183 l Dfbonbr. 1r04 t .t m eaue a d p e s r a g ss ia l o h r c sig o o d tfs -12ethylene dichloride and ethyl acetate and mb tures thereof, or othe, liquids known In the art may be used to enhance the solubility of the lipids, v- especially the solubility of cholesterol or other sterols in the high pressure fluid.

Process conditions (for the preferred solvent CO and the preferred adsorbants MgCO,, MgO, CaCo 3 CaO): Pressure: Pressure is in the range 100 -400 bar car be used with a preferred range being 150 300 bar.

Temperature: Temperature is in the range 20" 80°C can be used, with a preferred range being 30" Fat/Adsorbant Ratio: 0.001g fat/g adsorbant to 0.11g fat/g adsorbant.

Moisture Content of the Adsorbant material: 0.2% w/w 5.0% w/w, with the preferred moisture content being as low as possible. Similarly, the high pressure carbon dioxide Is kept as dry as possible.

at" Methods of contacting the fluid and the adsorbant: Any suitable method of contacting the two phases can be used, and this is not necessarily limited to the passage of the high 15 pressure fluid through a static column or bed of adsorbant material. For example, the high pressure fluid can pass through a Jet through which finely ground adsorbant also passes, or a finely powdered adsorbant material can be introduced into the high pressure fluid and stirred in a reaction vessel, or could be introduced Into the fluid and pumped along with the Sfluid to be collected at the solvent/solute separation stage whereby the -sulting 'sludge" 20 of adsorbant material on which the cholesterol ,s adsorbed can then be removed by appropriate physical *e 0 13 processes such as filtration, by using a hydro-cyclone, or possibly by centrifugin7. Nevertheless, it is preferred that a fixed bed of prciculate or granular adsorbant material is used, in order to avoid abrasive reaction of fine particulate material passing through the S plane with the high pressure carbon dioxide.

EXAMPLES

The invention will now be described with reference to experimental 00 examples. In example A cholesterol is separated from butter using a calcium hydroxide adsorbant, and within the limits of experimental 00 10 error, 100% of the cholesterol was retained in the bed of adsorbant material, and 80% of the triglyrerides were recavered. There was no change of colcur, and no change to the iodine value of the butter (this is a test traditionally used to check the degree of unsaturation of the butter).

15 Examples B and C show the separation of cholesterol from spiked lard samples, i.e. samples of lard in which the cholesterol level was artificially increased. In Example D, the separation of cholesterol *O from butter is combined with the partial fractionation of the triglycerides in order to show that is possible to use this invention to both remove the cholesterol from the butter fat and enhance the concentration of lower molecular weight triglycerides to provide a more spreadable cholesterol free butter without changing any of its 0 other food related characteristics.

In examples A, B and D, magnesium and calcium hydroxides were used as the adsorbant material whereas in example C, calcium carbonate was used. In other examples we have used oxides of calcium and magnesium, as well as the oxide hydroxides, carbonates, sulphates, and other oxygen containing salts of the various basic metals referred to above.

EXAMPLE A Seoaration of cholesterol from butter usino a raliiim hydroKxide adsorbant.

14 Run N~o. 197.1 Adsorbant details: mass particle size distribution 45 125 microns type Calcium hydroxide Experimental conditions: Pressure =220 Bar Temperature -459C Animal fat sample: 10 sample type unsalted butter sample weight 0.50g composition 242 mg/1b0g cholesterol (wiet basis) 16% moisture 0 0060 00 06 0 0* 0 00 00 *0 0 6.00 0000

S

0060 Lipid Triacyl.glycerides Cholesterol Bed Retention 20.0% 100.0% Recovery 80.0% 0.0% 00 00 00 S 0 0000 00 *0 0 0000 00 00 b Comparisons Colour 20 iodine value Feed Yellow 33.0 Recovered Fat yellow 32. 1 0.00 0 0000 0 00000.

0 X-ray analysis of the calcium hydroxide as used in example A end of a test run revealed that a significant proportion of had been converted to calcite, and subsequent tests with carLcnate (Example C) showed that it is a suitable, and preferred, adsorbant material for use with carbon dioxide.

at the the bed calcium indeed, EXAMPLE B Separation of cholesterol from a spiked lard sample Using Calcium Hydroxide as an adsorbant.

Run No. 193-1 Adsorbant details: Mass Particle size distribution 45 125 mn 15 type= Experimental conditions: Pressure Temperature Animal fat sample: Sample size= Sample type Composition= 10 Lipid Triacylglycerides Cholesterol calcium hydroxide 220 bar 35 0

C

S

S.

S6 0@

S

OOSS

S 5.0

S

0. lard (beef fat) for cooking 990.7mg/1b0g 10x normal level) balance triglycerides.

Bed Retention 2.3% 100 .0% Recovery 97.7% 0.0% 3* 05

S

0 S *5 S 0s OS S *5*5

S

EXAM4PLE C Separation of cholesterol from a spiked lard sample, using calcium 15 carbonate as an adsorbant.

Run No. 204.1 Adsorbant details: M~ass= Particle size distribution= 20 Type Experimental Conditions Pressure= Temperature Animal fat sample: As in run 193.1 (Example B) 45 125mm Calcium Carbonate 220 bar 450 C Lipid 'rriacylglycerides Cholesterol Bed Retention 0.0% 99.7% Recovery 100% 0.3% 16 EXAMIPLE 0: Separation of cholesterol from butter, and partial fractionation of the triglycerides (by molecular weight) using a magnesium hydroxide adsorbant.

*0@S 0O 0e 0 C 0 0#

S*

Run no. 189.1 Adsorbant details mass particle size distribution type= 10 Experimental conditions: Pressure Temperature animal fat sample: sample type 15 sample weight composition 45 125mm Magnesium oxide 220 bar 35 0

C

unsalted butter 2.04 g 242 mg/1b0g cholesterol 16% moisture (wet basis) Lipid Bed Retention Recovery Triglycerides 20 Cholesterol 40.3% 100% 59.7% 0

S

C

CeSC 0e S The following conceatrations by mass of triglycerides were obtained.

(The carbon number,, C, excludes carbons in the glycerin chain).

Triglyceride Composition.

Carbon No.

Triglycerides C34 C36 C38 C4 0 C44 C4 6 Feed Triglycerides 3.96 11.60 17.46 11.87 8.93 9.09 Bed Triglycerides Recovered 2.90 4.46 6.71 4.13 5.74 10.03 4.64 16.22 24.35 16.83 10.96 8.49 17 C48 12.71 16.69 10.17 11.45 21.08 5.29 C52 12.89 28.24 3.06 The recovered butter fat was considerably enhanced in concentration of lower molecular weight triglycerides, reduced in higher molecular weight triglycerides, and completely cholesterol free. The recovered butter oil also had a lower melting point, thus making it more spreadable at low storage temperatures.

ft.

The butter fat obtained was yellow and the ratios of saturated to 9 10 unsaturated fats was unchanged.

VARIATIONS

Although the above examples concentrated on the separation of cholesterol from butter or lard, it will be appreciated that the invention can be used to separate a wide range of other sterols from 15 lipid rich source material, so that the process of this invention could be used to preferentially concentrate sterols suitable for pharmaceutical use, e.g. the production of hormones, steroids, and the vitamin D series.

The following are examples of other sterols which can be extracted by 20 the process of this invention: Stigmasterol, Beta Sitosterol, Brassicasterol, Campesterol, Spinasterol, Zymosterol, Sterols of different varieties found in marine algae, and marine invertebrates, Autoxidation products of sterols, especially the autoxidation products of cholesterol.

Lanosterol, Ergosterol, 18 Vitamin D 2 (Calciferol) Vitamin D 3 (Cholecalciferol) Related steroids and hormones could also be purified and concentrated using the process of this invention, and for this purpose it is to be understood that the general description "separation of sterols from lipids" is intended to encompass the separation also of steroids and hormones of related structure.

Finally, it will be appreciated that various alterations and modifications may be made to the foregoing without departing from the 10 spirit or the scope of this invention.

C.

m *C* **so

C

e gee EeoC

C

Claims (6)

1. A method of separating a sterol from a lipid, including: dissolving the sterol/lipid mixture in a high pressure physiologically acceptable, fluid (either as a high pressure liquid or as a high pressure sub or supercritical gas) to form a high pressure fluid mixture, contacting the high pressure fluid mixture with an adsorbent material selected from I;ie group consisting of the minerals calcium hydroxide, calcium carbonate, calcium phosphate, magnesium carbonate and magnesium hydroxide, to remove the sterols, removing the substantially sterol free lipid from the high pressure fluid, and recovering the sterol from one adsorbent by displacement with a solvent.

2. A method as claimed in claim 1 wherein the sterol is selectively removed from the adsorbent material by contacting the adsorbent material with a stripping agent chosen from the group comprising: the same high pressure physiologically acceptable fluid as in claim 1, (ii) another high pressure fluid, or (iii) an organic solvent.

3. A method as claimed in claim 1 or claim 2 wherein the high pressure physiologically :acceptable fluid is sub or supercritical carbon dioxide at a pressure in the range 50-400 Bar, and at a temperature in the range 30-60°C.

4. A method as claimed in any one of claims 1-3, in which the solvent is selected from 20 the group consisting of propan-2-ol, ethanol, acetone, methanol, chloroform, ether, ethylene dichloride, hexane, benzene, methyl pentane and ethyl acetate or mixtures thereof.

5. A method of separating cholesterol from butter fat, including: dissolving the butter fat in a high pressure physiologically acceptable fluid (either as a high pressure liquid or as a high pressure Sub or Supercritical gas) to form a high pressure fluid mixture, contacting the high pressure fluid mixture with an adsorbent material selected from the group consisting of calcium hydroxide, calcium oxide, calcium BC|41, 2D3mtb 194 20 carbonate, magnesium carbonate, and magnesium hydroxide, to selectively adsorb cholesterol on the adsorbent material, and recovering the substantially cholesterol free butter fat from the high pressure fluid.

6. A method of separating cholesterol from butter fat as claimed in claim 5 wherein the substantially cholesterol free butter fat is recovered by increasing the temperature or reducing the pressure of the high pressure fluid, or a combination of both of the above. oo* j tr^- 1 C:Hr4 Z m tr -Y ABSTRACT A process for separating sterols from lipids, (eg cholesterol from butter fat) using sub or supercritical fluids (such as CO2) by dissolving the sterol/lipid mixture in a high pressure physiologically acceptable fluid (either as a high pressure liquid or as a high pressure sub or supercritical gas) to form a high pressure fluid mixtL.., then contacting the high pressure fluid mixture with an adsorbent material chosen from the group comprising calcium hydroxide, calcium oxide, calcium carbonate, magnesium carbonate, and magnesium hydroxide, to selectively adsorb sterols on the adsorbent material, and removing the substantially sterol free lipids from the high pressure fluid. e i A i- -0 ;CJt 4B 0 ntt B