CA2010172A1 - Production of low cholesterol animal fat by a short path distillation - Google Patents

Abstract

PRODUCTION OF LOW CHOLESTEROL ANIMAL FAT
BY SHORT PATH DISTILLATION
ABSTRACT OF THE DISCLOSURE
A method for production of low-cholesterol animal fat. Anhy-drous liquid animal fat is subjected to a short path distillation process wherein entrainment-enhancing compositions are used to provide a low-cholesterol animal fat product having composition and organoleptic characteristics substantially similar to those of the natu-ral animal fat.

Description

2~ 72 PRODUCTION OF LOW CHOLESTEROL AND~AL FAT
BY SHORT PATH DISTILLATION
BACKGROUND OF THE INVENN
1. Field or the Invention The sub~ect invention relates to the production of low~
cholesterol animal rat by a short path distillation process in combina-tlon with use o~ entrainment enhancing compositions. The invention also relates to low-cholesterol animal rat products produced by this method.
2. D~icdpnon Or Related Art Products derived rrom animal sources are popular sources of rood products intended ror human consumption. Food products derived~rrom animal sources include products easily identiried as hav~
ing~an animal source, such as eggs and cuts of meat, and other, less-readily identifid~ produots, such as ice cream.
However, some consumers have become hesitant about utilizing pr~cts containing animal Iats. This hesitance is derived in part from~ the knowledge that all animal rats contain cholesterol.
- ~ Re~ently, consun~ption or excessive quantities of cholesterol has been identi ied~as undèsirable and ~cely to be hazardous to human health.
One category oI typically high-cholesterol Ioods, milk fat-con-taining roods, isl~popularilwithlconsumers. Consumers prize the dis-tinctlve organoleptic properties of milk fat. For example, butter is highly prized for~its properties as a condiment. However, milk fat contains cholesterol. The popularity of frozen dessert products which have reduced fat content (lower than that of ice cream), such as tofu, frozen low-fat yogurt, ice milk, and the like, indicate that consumers preferences are changing away from products wherein animal fa~
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provide a significant portion of the nutritive value. No doubt, this change is due, at least in part, to the negative impact ingested cholesterol has on human health.
The desirability of reducing the cholesterol content of animal ~ats, including milk fat, has been recognized. However, known meth-ods have proven to be less than satisfactory becau~e the organoleptic properties of the product typically differ significantly i'rom the prop-erties of the natural product. For example, mouth feel, melting point, or color may be significantly altered by the cholesterol removal technique.
A satisfactory cholesterol removial process preferably would maximize removal of cholesterol while minimizing alterations to the properties of the cholesterol-containing product to yield a low~
cholesterol product indistinguishable from fresh, natural product.
However, known cholestérol-removing processes also make significant changes In products or organoleptic characteristics.
Some known methods for deodorizing and stabilizing oils remove sterols from oil, as noted in U.S. Patent 2,613,215. This pat-ent discloses a method which removes l'unsaponifiable matefials, together with free fatty acids, from oil. After partial hydrogenation, the unsaponifiable materials are removed by high temperature fractionation with a liquified, normally-gaseous hydrocarbon solvent.
This patent also discloses that polar solvents can be utilized to sepa-rate unsaponifiable materials, which are soluble in the solvent, Erom the mapr portion of the oil, which is substantially immiscible in polar solvent. The thus-treated oil isi further ~'deodorized,~ essentially as taught in U.S. Patent 2,351,832, i.e., by injecting steam at a tempera-ture above 250C through the oil at a pressure of ~ess than 20 milli-meters of mercury. Deodorization, æ taught in this patent, is unsat-isfactory for removing cholesterol from animal fat because, under these conditions, very little cholesterol is removed.
Fractionation of fats has been used to obtain separate compo-nent portions, typically so that the portions can be selectively recombined to yield a product having pre-selected characteristics.

For example, the solvent-assisted fractionation disclosed in U.S. Pat-ent 4,005,228 is utilized to separate butter fat into fractions by melt-ing point, i.e., melting point less than 0C, between 0 and 20C, and above 20C. The high- and low-melting rractiOns are combined to yield a dairy spread.
Supercritical extraction has also been utilized to modify vari-ous foodstuffs, including butter, as described in U.S. Patent 4,504,503.
However, one of the drawbacks to this technique is that conditions which maintain the solvent in the supercritical region typically involve extremes of temperature and pressure. Therefore, the equip-ment required is expensive. For example, in this patent, the pr~
ferred temperature range is from 40 to 250C, while the preferred pressure range is from 100 to 400 bar.
British patent specification 1,559,064 discloses the use of molecular dl;stillation to reduce the cholesterol content of a medium containing fats. Af ter degassing, anhydrous ~at is subjected to molec-;~ular distillation at preslsures less than 0.005 Torr to remove the unsaponificable fraction, which contains the sterols. An aqueous medium having a viscosity of from 2000 to 20,000 cp measured at a temperature between 20 and 30C is mixed into the treated fat at a temperature between lS and 45C. The mixing forms a water-in-oil emulsion which represents product of the butter or margarine type.
-~ ~Both U.S. Patent 2,613,215 and EP 0 174 848 A2 teach that cholesterol can be removed from fats by contacting the fat with a solid absorbent or adsorbent material. Silica gel and activated carbon are utilized as examples of appropriate material.
Shishikura, I~Modifications of Butter Oil by Extraction with Supercritical Catbon Dioxidel~, 50 Agric. Biol. Chem. 1209 ~1986), notes that supercritical fluid extraction using carbon dioxide is useful for fractionation of triglycerides in butter oil according to carbon number, but that this technique does not separate cholesterol from the triglycerides. Instead, butter oil was contacted with supercritical carbon dioxide in a silicic acid column. However, this supercritical chromatographic technique not only lowered the cholesterol level, but 2~ i72 ~:

also affected the triglycertde distribution. Thus, the technique is unsatisfactory, because the composition and spreadability are affected.
It is an object of this invention to provide a method for produc-tion of low-cholesterol animal fat by a short path distillation process.
It is a further object of invention to provide a method for pro-ducing low-cholesterol animal fat by a short path dtstillation process in combination with the use of entrainment enhancing compositions.
It is yet another object of this invention to provide a method for production of low-cholesterol animal i'at by a short path distilla-tion process in combination with use of entrainment enhancing com-positions which are components of the animal fat.
It is another object OI this invention to provide the low-cholesterol products of these methods.
SUMMARY OF THE INVENTION
In accordance with these and other ob~ects, this invention relates to a method for production of low-cholesterol animal fats.
Anhydrous liquid animal fat ts subjected to a short path distillation process wherein entrainment-enhancing compositions are used to pro-vide a low-cholesterol animal i'at product having composition and organoleptic charactertstics substanttally similar to those of the natu-ral animal fat. In particular, the invention relates to a method of producing low-cholesterol butter fat.
DETAIL~D DESCRIPlION O~ THE INVENTION
This invention is based on the discovery that cholesterol can be removed rrom animal fat without exposing the fat to high tempera-ture for extended periods and without utilizing solvents. A short path dlstillation process is employed wherein entrainment enhancing com-positions are used to provide a low-cholesterd animal fat which has composition and organoleptic characteristics essentially similar to those of natural animal fat and which retains essentially all of the color pigments originally present. Thus, the color of a low- -cholesterol butter fat product is essentially identical to that of the untreated butter. It has also been discovered that the entrainment -, . . , ";
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ZG10~72 enhancing composition~C may be prepared by partially hydrolyzing a portion of the animal fat being treated.
In the practice of this invention, typically, at least about 50 percent of the cholesterol is extracted. It is preferred to remove at least about 60 percent, more preferably at least about 70 percent, of the cholesterol originally present. However, any removal level can be ~ ;
selected by those who practice the invention. Cholesterol reduction in excess of 90 percent has been achieved by the practice of this invention.
Any anhydrous animal fat which contains cholesterol can be suitably processed by the method of this invention. For convenience, the invention will be described with reference to butter fat. How-ever, the scope of the invention is not limited to butter fat.
Anhydrous butter fat may be obtained from butter by any known method. Butter typically is obtained by churning milk to rup-ture the milk fat globule membranes and obtain an emulsion of fat and aqueous components. Butter can be dehydrated by heating to about 70C (158F) and centrifuging. Other methods of dehydration known to those skilled in the art are acceptable.
Anhydrous butter fat typically will contain less than abaut 0.5 percent, preferably less than about 0.2 percent, and more preferably less than about 0.1 volume percent aqueous components.
In accordance with the method Or the invention, cholesterol is removed rrOm anhydrous butter fat under short path distillation con-ditions. Thase skilled in the art recognize that short path distillation encompasses distillation operated under high vacuum in apparatus wherein the vapor path is unobstructed. As defined herein, short path distillation conditions encompass conditions suitable for molecular distillation, i.e., high vacuum in apparatus wherein the conderLer is separated from the evaporator by a distance less than the mean free path of the evaporating molecules. Additional details may be found in Perry~s Chemical Engineering Handbaok, Fourth Edition, pages 1?-29 to 17-33.

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Any short path distillation equipment conveniently is used in the method of the invention. Known equipment includes falling film and wiped falling film stills, commercially available short-path distil-lation apparatus, and centrifugal rotating disk evaporators. Suitable stills are described in the above-referenced Perry's Chemical Engi-neering Handbook.
In the method of the invention, short path distillation equip-ment is utilized, as described herein, to separate cholesterol from the remainder of the fat. Cholesterol is vaporized while the remainder of the fat is essentially unvaporized. Thus, a cholesterol-rich fraction is separately recovered by condensing molecules which have been vapor-ized and recovering condensate separately from the remainder, i.e., the unvaporized portion, which remains in the evaporator.
Short-path distillation equipment is especially suitable for use in the method of the invention. An example of short-path distillation equipment is the "KD" series ot short-path distillation apparatus sold by Leybold-Heraeus GmbH. The conditions under which short-path distillation is achieved are especially suited for use in this inventlon.
The temperature to which the fat is exposed is relatively low and the duration of the exposure is relatively short. Further, such distillation is carried out under very low pressure. Typically, the pressure is between about 0.001 and 0.1 Torr, preferably between about 0.005 and 0.05 Torr, and more preferably between about 0.01 and 0.03 Torr.
Thus, the operating conditions allow separation to proceed while min-imlzlng exposure of product to deleterious conditions.
It hæ been discovered that the presence of hydrolyzed frac-tions Or fat enhances the cholesterol-removal efficiency of the distil-lation. These hydrolyzed cornponents act as entrainment aids, i.e., they aid the liberation of cholesterol from the desirable fat fraction during the fractional distillation. Typically, entrainment aids are materials which boil at a temperature below the boiling temperature of the material being removed and which interact in some way with that material. Thus, the material to be removed may form a comple.
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with the entrainment aid, may be soluble in the entrainment aid, or may lnteract in other ways with the entrainment aid.
The relationship between the material being removed and the entrainment aid affords the opportunity to separate the material from the other components at conditions more favorable than those requ'red without use of aid, or to obtain a better separation, reflected in reduced loss of desired product, increased removal of the material, or in other ways.
The hydrolyzed fractions of fat which are useful in this capac-ity are mono- and di-glycerides. The source of these components is not critical to the practice of the invention. Thus, the components can be added to the fat prior to distillation, or can be generated L
situ by partial hydrolysis prior to distillation. Conditions under which such partial hydrolysis can be undertaken are known to those scilled in the art.
Hydrolyzed fats can be prepared by hydrolysis of less expensive fractions of fats from a source different from the fat being treated herein. If a fat source other than the fat being treated is utilized to obtain these hydrolyzed components, care should be taken to ensure that no foreign or objectionable odors or flavors are added by these components. Use of the hydrolyzed portion of the fat being treated eliminates ~he possibility of introducing objectionable odors or flavors.
The quantity of monoglyceride or diglyceride entrainment aids, or oi' hydrolyzed fat fraction containing at least one of these aids, utllized in the method of the invention is limited, inter alia, by con-siderations such as cost, effect of entrainment aid on organoleptic characteristics, identity of the entrainment aid, and concentration of entrainment aid in the hydrolyzed fat fraction utilized. Up to about 20 wt. percent, preferably between about l and 15 wt. percent, and more preferably between about 2 and 10 wt. percent, of entrainment aid is added to the fat being treated.
Monoglycerides are preferred entrainment aids. Both saturated and unsaturated monoglycerides having between about 12 and 20 ; .

2~10~7 carbon atoms are preferred when the animal fat being treated is but-ter fat. Monostearin, an 18-carbon saturated fatty acid monoglyceride, is an especially preferred entrainment aid for treat-ment of butter fat.
A portion of the fat being treated can be separately hydrolyzed to produce a component containing monoglycerides, diglycerides, or a mixture thereof. This component then is re-introduced to the fat being treated to provide an ei'fective quantity of entrainment aids.
The hydrolyzed fat component is prepared by introducing a quantity of lipase sufficient to produce the desired concentration of glyceride entrainment aid in the component. Those skilled in the art will be able to determine the quantity of lipase required in accor-dance with the guidance provided herein. Skilled practitioners also recognize that pancreatic lipase is preferred to ca~f gullet lipase because the former yields primarily monoglycerides while the latter yields primarily diglycerides. As noted above, monoglycerides are preferred entrainment aids. Although it is preferred to hydrolyze a portion of the rat being treated in accordance with method of the invention, any fat source may be used. Similarly, any lipase source may be used. For example, fungal, microbial, and animal (e.g., calf gullet) lipases are satisfactory. Of course, care must be taken to avoid contamination by organoleptically foreign characteristics.
The hydrolyzed fat component can be further treated, e.g.
deodorlzed, before it is mixed with the fat to be treated in accordance wlth the method of this invention. Deodorization is a treatment known to skilled practitioners. A small quantity of steam is sparged through the component or the component is subjected to molecular distillation at a temperature of about 150C to remove relatively vol-atile compounds, i.e., those compounds which may impart an unac-ceptable quality to the product.
As described above, the quantity of entrainment aid added typi-cally is up to about 20 wt. percent, preferably between about 1 and 15 wt. percent, and more preferably between about 2 and 10 wt. percent of the fat being treated. Entrainment aid will be present in , 2~
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hydrolyzed fat component in various concentrations. The quantity of hydrolyzed fat component utilized will, therefore, depend not only on the desired quantity of entrainment aid but also on the concentration of entrainment aid in hydrolyzed fat component.
The concentration of entrainment aids, i.e., mono- and diglycerides, in the hydrolyzed fat component can be determined by any known method. For example, any of the methods described in the following documents may be used:
AOAC Method 28.133, ~Official Methods oi Analysis,"
13th Ed., Association of Official Analytical Chemists (1980);
Quinlin, 35 J. Am. Oil Chemists' Society 325 (1958);
Ravin, 34 J. Am. Oil Chemistsl Society 261 (1957); and Riisom, 55 J. Am. Oil Chemistsl Society 649 (1978).
Animal fat is treated in accordance with the method of the invention by mixing fat and entrainment aid, fractionally distilling the mixture under short path distillation conditions and separately recovering a cholesterol-rich fraction and a cholesterol-depleted fraction. The cholesterol-depleted fraction is the desired product.
The cholesterol-rich fraction can be discarded, or can be further pro-cessed to recover cholesterol or the monoglyceride fraction.
In the distillation process, the number of stages and the tem-perature difIerences between the stages is a matter of economic choice. Prei'erably, between about 1-3 stages, more preferably between about 1-2 stages, and temperatures between about 1~0 and 230C, are utilized. At a temperature less than about 1~0C, cholesterol removallis~minimal, while a temperature greater than about 230C results in excessively high fat losses.
Where a plurality of stages is used, the temperature in a later stage can be either higher or lower than the temperature in an earlier stage. However, it is preferred to keep the temperature of the butter oil low for as long as possible to minimize the deleterious effects on the butter fat. Thus, for example, a suitable profile within the 2i~

method of th~s invention is 170C in a first stage, 190C in a second stage, and 210C in a third stage. Examples of suitable two~tage temperature profiles include 190C in the first stage and 210 in the second, 185C in both stages, and 200C in the first stage and 180C
therea$ter.
The degree o~ cholesterol removal is a matter of economic cho1ce. Typically, at least about 50 percent of the cholesterol is removed. Preferably, cholesterol removal exceeds about 60 percent, more preferably exceeds about 70 percent, and most preferably exceeds about 80 percent.
Ad~uvants may be added to the product. Typical additives include colorants, anti-oxidants such as TBHQ and BHA, stabilizing agents such as citric acid, salt, and vitamins. Known adjuvants are incorporated in manners known to those skilled in the art.
The following examples illustrate various aspects of this inven-tion, but are in no way intended to limit the scope of the invention.
The scope of the invention is limited only by the appended claims.

A mixture consisting of 3 parts by weight anhydrous butter oil and 1 part by weight lipolyzed (calf pre-gastric lipase) butter oil hav-ing an acid number of 25 were treated in accordance with the method of the invention on a Model KDL-l single stage short-path distillation apparatus (0.018 m2 active evaporator area) manufactured by Leybold-Heraeus GmbH. Between about 1 and 2 grams of mixture were fractionally distilled per minute in a one stage molecular distil-lation process. The pressure was maintained at 0.1 Torr, and the tem-perature was maintained in the range described in Table 1 below. The condenser temperature~was maintained at 65C.

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Cholesterol Reduction ~y Short-Path s~ation Percent Cholesterol TestTemPerature DC Reduction Feed-Anhydrous butter oil without entrainment aid ~Prior Art) Feed-Anhydrous butter oil (3 parts) and deodorized, lipolyzed butter oil (1 part) (Invention) This example indicates clearly the superiority of the method of the invention in producing significant cholesterol reduction.
EXAMPLES 2 ~ND 3 In Examples 2 and 3, various butter oil-containing streams were separately treated in a KD-6 single stage short-path dlstillation appara~
tus (0.06 m2 active evaporator area) manufactured by Leybold-Heraeus 1 - -Gm~bH. The feed rate was about 1100 ml/hr and the pressure was main-talned at about 0.003 Torr.
In eaoh example, the following streams were treated in accor- -dancewith the methodof the invention.
STRE~M ENTIFICATION
L Anhydrous butter oil without entrainment aid M Anhydrous butter oil plus 4 wt. percent (based on weight of butter oil) monostearin as entrainment aid N Three parts anhydrous butter oil plus 1 part deodor~
ized, lipolyzed butter oil (acid number of 25) as entrainment aid : ::

~:GiO~1~72 E~CAMPLE 2 The above-described streams were treated in single-step distilla-tion to reduce the cholesterol concentration in accordance with the method of the invention. The temperature at which each stream was treated is shown in Table 2 below.

Percent Cholesterol Feed Temperature C Reduction N 220 ~2 This example clearly indicates the superiority of the method of the invention for cholesterol removal.
EX~MPLE 3 Feedstreams L and M, described above, were treated in accor-dance with the method of the invention by twice passing the streams through the single stage short path distillation apparatus described in Example 1. The temperatures at which each stream was treated are shown in Table 3 below:

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Z~10~72 _ --Temperatures, C-- Percent Cholesterol Feed StreamFirst StaeeSecond StaeeReduction L 190 200 7g This example clearly illustrates the superiority ot the method of ~-the ir.vention for cholesterol removal. ~ - -:~: * * * *
Although preferred embodiments of this invention have been discussed herein, those skilled in the art will appreciate that changes and modifications may be made wlthout departing from the spirit of the ~invention, as defined in and limited only by the scope of the ~ ~;
appi~bdclaims.

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Claims (20)

1. A process for producing low cholesterol animal fat comprising:
a. providing a mixture comprising anhydrous animal fat and an entrainment aid, said entrainment aid selected from the group consisting of monoglycerides, diglycerides, and mixtures thereof;
b. fractionally distilling said mixture under short path distillation conditions to produce a cholesterol-rich fraction and a cholesterol-depleted fraction; and c. separately recovering the cholesterol-depleted fraction.

2. The method of claim 1 wherein the animal fat is butter fat.

3. The method of claim l wherein the quantity of entrain-ment aid is up to about 20 weight percent based on the weight of the anhydrous animal fat.

4. The method of claim 3 wherein the quantity of entrain-ment aid is between about 1 and 15 weight percent.

5. The method of claim 4 wherein the quantity of entrain-ment aid is between about 2 and 10 weight percent.

6. The method of claim 3 wherein the entrainment aid is produced by partially hydrolyzing an organoleptically unobjectionable fat.

7. The method of claim 2 wherein a major portion of the entrainment aid is monoglycerides having between about 12 and 20 car-bon atoms.

8. The method of claim 7 wherein a major portion of the entrainment aid is monostearin.

9. The method of claim 3 wherein the molecular distillation pressure is between about 0.001 and 0.1 Torr.

10. The method of claim 9 wherein the pressure is between about 0.005 and 0.05 Torr.

11. The method of claim 10 wherein the pressure is between about 0.01 and 0.03 Torr.

12. The method of claim 2 wherein the quantity of entrain-ment aid is up to about 20 weight percent based on the weight of the anhydrous animal fat.

13. The method of claim 12 wherein the quantity of entrain-ment aid is between about 1 and 15 weight percent.

14. The method of claim 13 wherein the quantity of entrain-ment aid is between about 2 and 10 weight percent.

15. The method of claim 7 wherein the molecular distillation pressure is between about 0.001 and 0.1 Torr.

16. The method of claim 15 wherein the pressure is between about 0.005 and 0.05 Torr.

17. The method of claim 16 wherein the pressure is between about 0.01 and 0.03 Torr.

18. A cholesterol-depleted animal fat produced by the method of claim 1.

19. A cholesterol-depleted butter fat produced by the method of claim 2.

20. A cholesterol-depleted butter fat produced by the method of claim 16.