Abstract:
Fatty acid esters, particularly those suitable for use in foods and cosmetics, are decolored by passing a solution of a fatty acid ester dissolved in an apolar solvent through particulate montmorillonite which is in admixture with particulate silica gel and/or active carbon. The solution passed through the column is obtained and the solvent is eliminated from the ester.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a process for decoloring a fatty acid ester, more particularly a special oil, intended for inclusion in the composition of food or cosmetic products. 
     In the majority of cases, the crude oils extracted by pressing or with solvents cannot be used as such in food or cosmetic products. They contain impurities which have to be eliminated by preliminary refining. The refining process generally comprises four successive steps, namely, acid degumming, alkaline neutralization, decolorization and, finally, deodorization. In certain particular cases of strongly colored oils which are intended for specific applications, for example in cosmetics, which require intensive decolorization, the conventional refining process, which comprises contacting with bentonite or acid-activated montmorillonite in vacuo in the presence of heat, followed by filtration, does not enable the level of decolorization required for the application envisaged to be achieved. 
     An improved decolorization process known as &#34;chromatographic&#34; decolorization comprises diluting the oil in an apolar solvent and adsorbing the impurities by contacting the solution with a solid adsorbent in a column. One such process is described, for example, in European patent application Publication No. 0 108 571, which relates in particular to the stabilization and decolorization of fish oils. In this process, a fish oil rich in polyunsaturated fatty acids is hydrogenated in the presence of a catalyst and is then decolorized in solution using a solid adsorbent, such as silica gel, activated alumina, aluminium silicate or activated clay, by successive passages of the solution through a column containing the adsorbent. 
     SUMMARY OF THE INVENTION 
     It has now surprisingly been found that the use of an adsorbent mixture of montmorillonite clay and silica gel or active carbon in a decolorization process by passage through a column of adsorbent material leads to the almost complete decolorization of oils hitherto impossible to decolorize to a satisfactory degree by the conventional decolorization processes mentioned above. 
     The process according to the invention, in which a fatty acid ester dissolved in an apolar solvent is passed through a column filled with adsorbent and the solvent is subsequently eliminated, is characterized in that a mixture based on montmorillonite containing silica gel and/or active carbon as adsorbent is used. 
     In a preferred embodiment, the adsorbent is a mixture containing from 10 to 60% by weight montmorillonite and up to 80% by weight silica gel. It may consist solely of these two constituents, for example approximately 50% by weight of silica gel and approximately 50% by weight of montmorillonite. 
     In one particularly preferred variant, the adsorbent additionally contains 30 to 60% by weight active carbon. In another particularly advantageous embodiment, the adsorbent mixture contains 30 to 80% by weight active carbon and 20 to 70% by weight montmorillonite. The present invention also relates to a food or cosmetic composition containing a compound decolored by the process according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In accordance with the invention, the montmorillonite may be in the form of a powder having a particle size of, for example, 5 to 60 microns or in the form of granules, for example from 60 to 250 microns in diameter. The silica gel may be in the form of granules, for example from 60 to 500 microns in diameter. The active carbon may consist of granules, for example 100 to 500 microns in diameter, with pores, for example a few microns in size, forming cells at the surface of the granules, and the mixture may contain the active carbon in the form of granules and the montmorillonite in powder form. 
     The montmorillonite may be in the form of a powder or granules or in the form of a mixture preferably containing 40 to 60% by weight powder and 60 to 40% by weight granules, including when the absorbent mixture contains from 10% to 60% by weight montmorillonite and up to 80% by weight silica gel and when that mixture is approximately 50% by weight of each. 
     The adsorbent mixture may additionally contain a filler as filtration additive, for example a diatomaceous earth, for example diatomite or perlite, in a quantity of up to 30% by weight. 
     The compounds to be decolorized by the process according to the invention may be animal oils, for example fish oil, or vegetable oils, for example oil from cumin seeds, Lesquerella, Hevea brasiliensis, elder, calendula, kiwi, bilberry, coffee, or oils of biosynthetic origin, for example from envelopes of yeast, or even of synthetic origin, for example a fatty acid butanediol diester. 
     To carry out the process, the compound to be treated, which has been conventionally refined by degumming, neutralization and decolorization as described above, is dissolved in an apolar solvent, for example an aliphatic hydrocarbon of food quality, preferably n-hexane, in a ratio by weight of compound to solvent of 1:2 to 1:16 and preferably of the order of 1:9. For dissolution, the compound may have to be liquefied by heating, and the solution should be clear. The ratio of compound to solvent is determined by the nature of the compound to be treated and is the result of a compromise between a minimum quantity of solvent, which then has to be eliminated, and sufficient dilution of the compound for the solution to be substantially apolar. 
     The solution is then passed through a column filled with the adsorbent mixture by gravimetry, preferably using a ratio by weight of fat to adsorbent of 0.5:1 to 5:1, for example 2:1, under a low or medium pressure, for example up to 1.5 bar, depending on the type of column and the particle size distribution of the adsorbent used. 
     The columns used may be inter alia columns from 27 to 225 mm in diameter and from 10 to 100 cm in height, short columns of relatively large diameter being preferred. Columns of which the diameter-to-height ratio is less than 1:2, enabling a fine-particle adsorbent to be used and low operating pressures, for example below about 0.2 bar, preferably are employed. The time taken by the solution to pass through the column is, for example, 15 to 60 minutes per liter of solution for approximately 50 g of adsorbent. 
     After percolation, the column is rinsed with solvent, preferably with a volume of solvent corresponding to approximately 25% of that of the solution. After the liquids have been combined, the solvent is eliminated, for example by evaporation in vacuo. 
     A cosmetic composition according to the invention will contain, for example, decolorized oils of cumin, calendula, bilberry, elder, coffee, kiwi, Hevea brasiliensis or a butanediol diester in a cream and oil of Lesquerella in a lipstick for their interesting cosmetic properties. 
     A dietetic food composition according to the invention will contain, for example, decolorized oils of bilberry, elder, kiwi or fish as fatty acid source of the omega 3 series. A dietetic composition according to the invention suitable for use in human or animal dietetics may contain, for example, a decolorized butanediol diester, as a substitute for fats, non-assimilable by the organism. 
     EXAMPLES 
     The invention is illustrated by the following Examples. In the Examples: 
     Parts and percentages are by weight, unless otherwise indicated. 
     The analyses conducted to determine the quality of the products and the level of decolorization are as follows: 
     FFA: free fatty acids expressed in % oleic acid; 
     POV: peroxide index in milliequivalent g oxygen/kg Y(yellow), R(red), N(neutral): colorimetric units measured on the Lovibond scale (optical path of cell 12.7; 25.4 or 133.35 mm). 
     The experimental conditions for all the Examples are as follows: 
     The adsorbent is prepared by dry mixing its constituents in a container, optionally in vacuo, until a homogeneous mixture is obtained. The solvent is added and the whole is vigorously mixed for 2 to 3 minutes in a vacuum, for example a water jet vacuum, of 15 to 30 bar to degas the adsorbent which has an apparent density of approximately 0.4 to 0.5 kg/dm 3 . 
     To prepare the column, which is provided with a filter plate at its base, n-hexane is initially introduced to purge the column, after which the column is filled with the adsorbent suspended in n-hexane. 
     The oil or fat, if necessary melted beforehand, is diluted in the n-hexane to form a perfectly clear solution. The solution is then percolated through the column over a period of 15 to 60 minutes, if necessary under a pressure of 0.2 to 1.5 bar (relative to the ambient pressure), using 1 liter of solution to 50 g adsorbent, depending on the type of column, after which, the column is rinsed with a volume of n-hexane corresponding to 1/4 of the volume of the solution to be decolorized. After the liquids have been combined, the n-hexane is removed by evaporation in vacuo in a rotary evaporator. The n-hexane may be recycled and used to dissolve more of the fat. 
     The following adsorbents are used: 
     a: silica gel having a particle size distribution of 200 to 500μ 
     b: powder-form montmorillonite, 5-50μ 
     c: granulated montmorillonite, 150-250μ 
     d: granulated silica gel, 63-200μ 
     e: granulated silica gel, 100-400μ 
     f: granulated active carbon, 100-500μ with cells a few μ in size at its surface 
     g: diatomaceous earth, 10-100μ. 
     Decoloration in the case of conventional refining comprises contacting the solution with 0.5-3% by weight activated montmorillonite in a vacuum of 1 to 2 mbar at a temperature of 80° to 100° C., followed by filtration in a filter press. 
     Examples 1-2 
     The parameters of the process and the results are set out in Table 1 below for cumin seed oil which has the following fatty acid composition: 
     
         ______________________________________Fatty acids           %______________________________________C16:0                 4.3C18:0                 1.1C18:1, Δ6 (petroselenic) and Δ9                 59.9C18:2                 33.4Others                1.3______________________________________ 
    
     
                       TABLE 1______________________________________      Compar-    Compar-Example    ison 1     ison 2   1     2______________________________________Sample (g) After      150      150   150n-Hexane (ml)      conventional                 450      450   450Adsorbent (type)      decolor-   a        a + b a + b + cProportions (%)      ization    100      a:80  a.:50of the compo-                  b:20  b:20nents of the                         c:30adsorbentQuantity (g)          75       75    75Type of column        Glass    Glass GlassDiameter (mm)         27       27    27Height (cm)           25       25    25Pressure (bar)        Ambient  0.2   0.2FFA (% oleic      0.1        0.05     0.05  0.04acid)POV (meqO.sub.2 kg)      0.86       0.75     0.26  0.33Color Y    68         39       3.7   3.6(25.4 mm cell) R      8.8        3.4      1     0.8______________________________________ 
    
     It can be seen that the treatment with an adsorbent mixture of silica gel and montmorillonite provides for better elimination of the peroxides and produces a significant improvement in decolorization by comparison with the starting product, which has been conventionally decolored (Comparison 1), and by comparison with the use of silica gel on its own (Comparison 2). 
     In addition, conventional decolorization is extremely slow which is due to solidification of the montmorillonite in the presence of solvent. 
     Examples 3-7 
     The parameters of the process and the results are set out in Table 2 below for Lesquerella seed oil which has the following fatty acid composition: 
     
         ______________________________________Fatty acids         %______________________________________C16:0               2.1C16:1               1.5C18:0               3.2C18:1               23.2C18:2               9.7C18:3α        15.1C20:1               1.5C20:1 (14-OH), lesquerolic               43.3Others              0.4______________________________________ 
    
     This oil is characterized by the fact that it continues a large quantity of hydroxylated lesqueolic acid which makes it difficult to decolor by the conventional method. 
     
                       TABLE 2______________________________________    Compari- Compari-Example  son 3    son 4    3       4______________________________________Sample (g)    After    After    50      50n-Hexane 1        2        500     800(ml)     con-     con-Adsorbent    ven-     ven-     a + b + c                              a + b + c + d(type)   tional   tionalProportions    de-      de-      a:50    a:25(%)      coloriz- coloriz- b:20    b:25of the   ation    ations   c:30    c:25components                         d:25of theadsorbentQuantity (g)               50      50of adsorbentType of                    Glass   GlasscolumnDiameter                   27      27(mm)Height (cm)                25      25Pressure                   0.2     0.2(bar)Color   Y    68       69       35.5    17.4(12.7 mm R    12.6     11.9     1.4     1.1cell)   N    2.5      2.6      0.2     0.7______________________________________Example      5             6        7______________________________________Sample (g)   50            50       515Hexane (ml)  500           500      5000Adsorbent (type)        a + b + c + d e + b    d + bProportions  a:25          e:50     d:50of the components        b:25          b:50     b:50of the adsorbent        c:25        d:25Quantity (g) 50            50       600of adsorbentType of column        Glass         Glass    SteelDiameter (mm)        50            50       125Height (cm)  10            10       15Pressure (bar)        Ambient       Ambient  0.3Color Y      13            9.9      8.6(12.7 mm cell) R        1.0           0.9      0.6N            0.3           0        0.2______________________________________ 
    
     It can be seen that conventional decolorization does not improve the degree of decolorization despite two successive treatments (Comparisons 3 and 4). In Examples 3 to 7, the starting material used is an oil which had undergone two successive conventional decolorizations and is decolorized to a considerable extent by a single passage. 
     Examples 8-11 
     These Examples relates to the decolorization of Hevea brasiliensis oil which has the following fatty acid composition: 
     
         ______________________________________  Fatty acids          %______________________________________  C16:0   8.8  C18:0   8.7  C18:1   24.9  C18:2   38.6  C18:3α          16.7  Others  2.3______________________________________ 
    
     The working conditions and results obtained are set out in Tables 3 and 4 below. 
     
                       TABLE 3______________________________________        Compari- Compari-Example      son 5    son 6    8     9______________________________________Sample (g)   After    150      150   150n-Hexane (ml)        1        450      450   450Adsorbent (type)        con-     a        a + b a + b + cProportions (%)        ven-     100      a:80  a:50of the components        tional            b:20  b:20of the adsorbent        de-                     c:30Quantity (g) coloriz- 75       75    75of adsorbent ationType of column        Glass    Glass GlassDiameter (mm)         27       27    27Height (cm)           25       25    25Pressure (bar)        Ambient  0.2   0.2POV (meqO.sub.2 /kg)        0.66     1.05     0.64  0.96Color Y      68       24.5     2.2   2.2(25.4 mm cell) R        13.3     3.9      0.6   0.5______________________________________ 
    
     
                       TABLE 4______________________________________      Compari- Compari-Example    son 7    son 8    10      11______________________________________Sample (g) 100      100      100     100n-Hexane (ml)      900      900      900     900Adsorbent (type)      b        f        a + b + c                                d + b + fProportions (%)      100      100      a:50    d:33.3of the components            b:20    b:33.3of the adsorbent             c:30    f:33.3Quantity (g)      50       50       50      50Type of column      Glass    Glass    Glass   GlassDiameter (mm)      50       50       50      50Height (cm)      10       10       10      10Pressure (bar)      0.2      Ambient  Ambient AmbientColor Y    6.1      3.1      2.4     0.5(25.4 mm cell) R      1.5      0.9      0.7     0______________________________________ 
    
     It can be seen that the decolorization process according to the invention using a mixture of adsorbents gives distinctly better results (Examples 8 and 9 in conjunction with Comparison 6; Example 10 in conjunction with Comparison 7; Example 11 in conjunction with comparisons 7 and 8) than those obtained where only one of the adsorbents is used under the same working conditions. In addition, the mixtures of adsorbents provide for intensive decolorization which cannot be achieved by conventional decolorization (Comparison 5). 
     Examples 12-15 
     The parameters of the process and the results relating to the decolorization of kiwi seed oil are set out in Table 5 below. 
     The oil used has the following fatty acid composition: 
     
         ______________________________________  Fatty acids          %______________________________________  C16:0   4.9  C18:0   2.6  C18:1   11.2  C18:2   14.9  C18:3α          63.8  Others  2.6______________________________________ 
    
     
                       TABLE 5______________________________________      Compari-Example    son 9     12      13    14    15______________________________________Sample (g) After     200     200   200   15000n-Hexane (ml)      1         1800    1800  1800  135000Adsorbent  con-b (%)      ven-      50      25    60    55f (%)      tional    50      75    40    45Quantity (g)      de-       50      50    50    5000of adsorbent      coloriz-Type of column      ation     Glass   Glass Glass GlassDiameter (mm)        50      50    50    225Height (cm)          10      10    10    80Pressure (bar)       Am-     Am-   Am-   Am-                bient   bient bient bientColor Y    68        9.6     11.2  7.3   5.4(133.35 mm R      8.1       1.2     1.3   1.0   0.8cell) N    1.7       0.2     0.6   0.2   0.2______________________________________ 
    
     It can be seen that the adsorbent mixture of montmorillonite and active carbon achieves substantial decolorization of a strongly colored kiwi seed oil which cannot be achieved to the same extent by the conventional method (Comparison 9). 
     Examples 16-19 
     Bilberry oil (16), elder oil (17), calendula oil (18) and fish oil (19) are decolorized under the conditions and with the results set out in Table 6 below. 
     These oils have the following fatty acid compositions: 
     
         ______________________________________      %Fatty acids  16     17         18   19______________________________________C16:0        4.1    7.4        3.2  17.6C16:1        --     --         --   4.7C18:0        1.1    2          2.1  4.5C18:1        23.2   14         4.9  21.8C18:2        35.9   41         31.3 1.4C18:3α 34.3   30.1       0.6  0.4C18:3Δ8, 10, 12        --     --         48   --C20:1        --     --         --   2.5C20:5        --     --         --   6.2C22:6        --     --         --   23.9Others       1.3    5.5        9.9  17______________________________________ 
    
     
                       TABLE 6______________________________________Example  16        17        18      19______________________________________Sample 100    650       650       1000    100n-Hexane 2600      2600      3000    400(ml)Adsorbent    a + b + g a + b + c a + b + c                                a + b + g(type)Proportions    a:70      a:60      a:60    a:60(%)of the   b:20      b:20      b:20    b:20componentsof the   g:10      c:20      c:20    g:20adsorbentQuantity (g)    330       330       660     50of adsorbentType of  Glass     Glass     Glass   GlasscolumnDiameter 27        35        50      27(mm)Height (cm)    25        55        100     25Pressure 0.2       0.8       1.5     0.2(bar)Color Y  0.3       0.5       12.5    0.8(25.4 Rmm cell) 0.1       0.05      0.6     0.1Comparison10,Color after Y    31        7         &gt;40     241 con-ventionaldecoloriz-R    5.3       1         6.8     2.4ation(25.4 mmcell)______________________________________ 
    
     It can be seen that the process according to the invention using a mixture of adsorbents produces a distinct improvement in decolorization by comparison with conventional decolorization. 
     Example 20 
     The parameters of the process and the results of the decolorization of butane-2,3-diol diester prepared in accordance with Example 1 of European patent application Publication No. 0 465 698 are set out in Table 7 below: 
     
                       TABLE 7______________________________________Example         Comparison 11                       20______________________________________Sample (kg)     1           21n-Hexane (l)    con-        84Adsorbent (type)           ven-        f + bProportions (%) tional      f:55of the components           de-         b:45of the adsorbent           coloriz-Quantity (kg)   ation       8.4of adsorbentType of column              GlassDiameter (mm)               225Height (cm)                 80Throughput (l/h)            23Color(25.4 mm  Y         23.3        --cell)     R         4.9         --     B         0.5         --(133.4 mm Y         37.8        0.8cell)     R         52.8        0.1     B         32          0______________________________________ 
    
     It can be seen that the process according to the invention achieves substantially complete decolorization. By contrast, the same result is not achieved by conventional decolorization. 
     Examples 21-22 
     The nomenclature used in these Examples is that of the &#34;Cosmetic, Toiletry and Fragrance Association, Inc. Washington D.C.&#34; (CFTA) in its French translation. 21. To produce a cosmetic cream in the form of an oil-in-water emulsion, the components of the lipidic phases A and B are separately mixed and heated to 70° C., after which phase B is incorporated in phase A. The aqueous phase C is prepared by mixing these components and heating to 70° C. The lipidic phases A and B are added to the aqueous phase C at 70° C. while stirring at average speed. The mixture of the two phases is homogenized, stirred at approximately 100 r.p.m. and then left to cool to 35°-40° C. 
     The additives are incorporated at that temperature, after which the mixture is left to cool to ambient temperature with slow stirring, the stirrer being switched off when the product is semifluid (at approx. 25° C.). 
     The cream has the following composition: 
     
         ______________________________________                 %______________________________________Phase A (lididic)              12.1PEG-10 isocetyl ether monostearate                   4.5Steareth-21             1.5Glycerol stearate       2.6Cetoaryl alcohol        1.5Isodecyl laurate        2Phase B (lipidic)              6.3Decolored cumin oil of Example 1                   6Carbomer 934 (crosslinked acrylic                   0.3acid polymer)Phase C (aqueous)              79.8Water                   74.7Glycerol                5Ethylenediamine tetraacetate (EDTA)                   0.1Additives                      1.8Phenoxyparabene         0.6Silmethicone            0.1Trimethamine (30% aqueous solution)                   0.8Perfume                 0.3                          100______________________________________ 22. Decolored Lesquerella oil is used as a substitute for castor oil in an anhydrous lipstick. 
    
     The product is obtained in the same way as in Example 21, but without homogenization, by hot mixing (approx. 70° C.) and gradual cooling with slow stirring. 
     It has the following composition: 
     
         ______________________________________                  %______________________________________Lesquerella oil decoloured in accordance                    27.45with Example 7Castor oil               30.5Beeswax                  10.5Candelilla wax           7.5Ozocerite                5.5Isopropyl lanolate       5Colourants               13.55______________________________________ 
    
     Example 23 
     A milk product for infants to be reconstituted by addition of water is prepared in powder form by mixing the aqueous and lipidic phases, concentration by evaporation and spray drying in a tower under controlled conditions. 
     The composition of the dry matter is as follows: 
     
         ______________________________________Ingredients           %______________________________________Mixture of fats containing lecithin                 26Fish oil decoloured in accordance                 0.6with Example 19Lactose and maltodextrin                 60Lactic proteins       11Mineral salts         1.6Vitamins and oligoelements                 0.8                 100______________________________________