IE41884B1 - Process for purifying phosphatides - Google Patents

Abstract

Pure phospholipids are recovered from crude phospholipids, for example from soyabean phospholipid slurry, if the crude phospholipids are treated simultaneously with a water-immiscible, nonpolar, phospholipid-dissolving organic liquid and water. When an aqueous crude phospholipid slurry is used, water does not need to be added or only for further dilution. The mixture can contain less than 75% of organic polar solvent. After treatment, the mixture is centrifuged and pure phospholipid is recovered from the hydrophobic phase by evaporation.

Description

The invention relates to a process for purifying crude phosphatides and the phosphatide product obtained by said process.

Conventionally phosphatides are obtained from beans, in particular soya beans and other phosphatide-containing materials. In the processing of beans the crude phosphatides are, for instance, obtained by pressing or solvent extraction of the beans and by separating the crude phosphatides from the resulting crude oils by a treatment with water or aqueous solutions (i.e. desliming the crude oil).

The aqueous sludge obtained contains phospholipids, a certain proportion of oil, fatty acids, carbohydrates, proteins, mineral salts, sterols, some remainders of the bean shells and occasionally other materials. The sludge may be dried to obtain a yellow to black mass with a wax-like consistency. The crude phosphatides may be subjected to various treatments such as removal of the oil, replacement of the oil by another oil, hydroxylation and hydrolysis, either by enzymatic action or by acidic or alkaline hydrolysis. The term crude phosphatides used herein denotes phosphatide-based products obtained by desliming crude oils as indicated above, optionally after one or more of the additional treatments indicated immediately above. Such products are also often referred to as lecithin.

Until now, however, it has been very difficult to remove from the crude phosphatides some of the materials which render them less suitable for certain applications.

U.S. Patent Specification 2,201,064 describes a purification process in which dried crude phosphatides are dissolved in hexane. Belgian Patent 590,731 describes a purification process in which dried crude phosphatides are treated with e.g. hexane and e.g. acetone which may contain up to 10% of water.

These prior art processes do not yield a transparent phosphatide product.

It has now been found that a purified phosphatide product is obtained when crude phosphatides are subjected to the combined action of a hydrophobic liquid, in which the phosphatides are soluble, and an aqueous liquid. The two liquids are separated and the purified phosphatide product is recovered from the hydrophobic liquid.

According to the process of the invention a transparent phosphatide product can be obtained.

Surprisingly it has been found that the presence of a large amount of a polar organic solvent, dissolved in the aqueous liquid, adversely affects the purification. It is therefore a special feature of the instant invention to carry out the process while 0 to 30¾ by weight, preferably 0 to %, of the aqueous liquid consists of an organic polar solvent.

The process of the invention produces a purified phosphatide product which is transparent. Moreover, much of the disagreeable off-flavour normally associated especially with conventional hydrolysed phosphatides appears to have been removed during the purification treatment.

The hydrophobic liquid to be used in accordance with the present invention may be any hydrophobic liquid in which phosphatides are soluble. Examples are aliphatic, preferably saturated hydrocarbons, preferably alkanes such as heptane, hexane and pentane. Cyclic alkanes such as cyclohexane are also suitable. Aromatic compounds such as benzene may also be used. Hexane is preferred. The aqueous liquid will normally be water which, however, may contain some proportion of another liquid or other liquids dissolved or dispersed therein.

As stated above the aqueous liquid should not contain large amounts of polar organic liquids i.e. should contain less than 30% of such polar organic liquids. The presence of amounts substantially larger than 30% of polar organic liquids tends to make the subsequent separation of hydrophobic liquid and aqueous liquid more difficult. Moreover, it has been found that polar organic liquids cause the recovery of the phosphatide product from the hydrophobic liquid to be more troublesome and affect the quality of the product adversely. Smaller quantities, on the contrary, do not exhibit these undesirable characteristics, and may even facilitate the separation of hydrophobic liquid and aqueous liquid.

Another preference is the presence in the aqueous liquid of a minor amount of a bleaching agent. A suitable agent is - a. 41884 H202· Suitable quantities are 0.5-5%, preferably 0.5-2% by weight, based on the aqueous liquid.

The amount of aqueous liquid to be used in accordance with the process of the invention is preferably between 5 and 150% by volume of the crude phosphatides, more preferably between 50 and 100%.

The amount of hydrophobic liquid to be used in the process of the invention is preferably between 200 and 2000% by volume of the crude phosphatides, more preferably between 400 and 600%.

The process is preferably carried out while the ratio of the volume of the hydrophobic liquid to the total volume of the crude phosphatides plus the aqueous liquid is between 1:1 and 3:1, and is particularly preferably about twice. The sequence in which the two liquids are added to the crude phosphatides is immaterial. In a preferred embodiment the hydrophobic liquid is directly added to the aqueous phosphatide sludge obtained in the desliming of a crude oil as described, optionally after some other treatment like, for instance, hydrolysis of the phospholipids. This procedure has the advantage that the need for an intermediate drying step is obviated.

The manner in which the two liquids are separated is not important. Centrifuging is preferred.

Recovery of the purified phosphatide product from the hydrophobic liquid is preferably by evaporation.

The temperature and pressure at which the process is carried out can vary within wide limits. Atmospheric pressure at ambient temperature is preferred.

The purified phosphatide product obtained is 418 8 4 transparent and superior to the untreated one with respect to odour, taste and oil-solubility. The product can especially usefully be applied, in food preparations like margarine.

Still another advantage of the purified phosphatide product according to the invention is its good oil solubility as compared with conventional products.

The advantages of the process according to the invention are especially pronounced when the process is applied to crude phosphatides which have been hydrolysed by pancreatin.

The invention is illustrated by the following examples.

EXAMPLE I 100 kg crude soybean phosphatide sludge containing 33% of water were homogenized with 200 1 hexane and centrifuged. The transparent hexane phase emerging from the centrifuge was evaporated in two stages, in the first stage in a vertical evaporator, in the second stage in a thin film evaporator. As compared with the phosphatides recovered in the conventional way, i.e. by drying of the sludge, the phosphatides obtained showed the following properties. conventional process process of the invention Acetone-insoluble matter (1) % 63 63 Moisture (2) % 0.5 <0.05 Colour/Gardner (3) 10 10 Colour/Iodine (4) 20 18 Colour/lovibond (5) 35 g+ 3.6 r+ 0.6 b 35+3.2 Sugar (calc, on saccharose) (6) % 3.5 1.5 Transparency (7) % 12.8 84.5 - 6 41884 Acid Value (8) Phosphorus (9) Iron (10) Composition with 20% oil 1.93 ppm 152 2.0 settles does not settle (1) Acetone-insoluble matter determined according to the Official and Tentative Methods of the American Oil Chemist's Society. (2) Modified Karl Fischer Method according to the Official and Tentative Methods of the American Oil Chemist's Society. (3) Official and Tentative Methods of the A.O.C.S. (4) Methods of the Deutsche Gesellschaft fur Fettwissenschaft, Miinster/Westf. (5) Methods of the A.O.C.S. (6) Methods of the A.O.C.S. (7) Transparency was determined as follows: The material is heated to 50°C in a water-bath. It is then dissolved with stirring in equal parts by weight of xylol.

Turbidity of the solution is measured in a turbidity measuring unit sold by B. Lange GmbH, Berlin, Germany.

The transparency of the solution is Tv=100—t wherein t is the measured turbidity The extinction of the solution is Ev=logyv The transparency of the material is then calculated from the formula Ev . 2=log4~ (8) Methods of the A.O.C.S. (9) Methods of the A.O.C.S. (10) Methods of the Deutsche Gesellshaft fur Fettwissenschaft, Munster/Westf.

EXAMPLE II 100 kg of crude soybean phosphatide sludge containing 55% of water were treated as described in Example I. The loss of sludge, calculated on the dry matter, amounted to abt. 9.5%. Analytical results: Acetone-insoluble matter Moisture Colour/Iodine Sugar Transparency Acid Value Phosphorous Iron Composition with 20% oil conventional process process of the invention % 67 67 % 0.6 <0.05 24 22 % 3.2 1.7 % 10 88 18 18 Q. T3 1.96 2.04 ppm 280 135 settles does not settle EXAMPLE III kg of crude soybean phosphatides were homogenised with 10 1 water. The sludge was then homogenised with 40 1 cyclohexane and the mixture was centrifuged. The white - 8 41884 solvent phase was evaporated. The phosphatides thus obtained were transparent. Analysis showed that the sugar content decreased to abt. 40% and the iron content to abt. 55% of the starting value. The P-content had risen by 0.04%. Colour, acetone-insoluble matter and acid value had remained, substantially constant.

EXAMPLE IV kg crude soybean phosphatides were dissolved in 40 1 hexane. Subsequently 10 1 water was stirred into the solution. After 10 min. stirring the solution was allowed to settle. After a resting period of 5 h and separation of the phases the hexane solution was evaporated. The phosphatides thus obtained were transparent. The analytical data corresponded to those of the preceding examples.

EXAMPLE V kg crude phosphatide sludge, which had been hydrolysed enzymatically according to United States Patent 3,652,397, were homogenised with 20 1 hexane and centrifuged. The hydrolysed phosphatides isolated from the hexane phase were transparent. The sugar and iron contents had been reduced to about half the starting values.

The P-value had increased by 0.05%. The other values (colour, acetone-insoluble matter, acid value) had remained constant.

Claims (20)

1. CLAIMS: 1. Process for purifying crude phosphatides, which comprises subjecting the crude phosphatides to the combined action of a hydrophobic liquid, in which the phosphatides are soluble, and an aqueous liquid, containing o to 30 wt.% of an organic polar solvent, separating the hydrophobic and the aqueous liquids and recovering the phosphatide product from the hydrophobic liquid.

2. Process according to claim 1, in which the aqueous liquid contains less than 10 wt.% of the organic polar solvent.

3. Process according to claim 1 or claim 2, in whioh as the hydrophobic liquid, an aliphatic saturated hydrocarbon is used.

4. Process according to claim 3, in which as the hydrophobic liquid hexane is used.

5. Process according to any one of claims 1 to 4, in which the aqueous liquid contains a bleaching agent.

6. Process according to claim 5, in whioh the aqueous liquid contains 0.5 to 5 wt.% of hydrogen peroxide.

7. Process according to claim 6, in which the aqueous liquid contains 0.5 to 2 wt.% of hydrogen peroxide.

8. Process according to any one of claims 1 to 7, in which the amount of aqueous liquid used is between 5 and 150 vol.% calculated on the crude phosphatides.

9. Process according to claim 8, in which the amount of aqueous liquid used is between 50 and 100 vol.%, calculated on the crude phosphatides.

10. Process according to any one of claims 1 to 9, in which the amount of hydrophobic liquid used is between 200 and 2000 vol.%, calculated on the crude phosphatides.

11. Process according to claim 10 in which the amount of hydrophobic liquid used is between 400 and 600 vol.%, calculated on the crude phosphatides.

12. Process according to any one of claims 1 to 11, in which the ratio of the volume of the hydrophobic liquid used to the total volume of the crude phosphatides plus the aqueous liquid is between 1:1 and 3:1.

13. Process according to claim 12 in which the volume of the hydrophobic liquid used is about twice the volume of the crude phosphatides plus the aqueous liquid.

14. Process according to any one of claims 1 to 13, in which the hydrophobic liquid is directly added to the aqueous phosphatide sludge obtained in the desliming of a crude oil.

15. Process according to any one of claims 1 to 14, in which the hydrophobic and the aqueous liquids are separated by centrifuging.

16. Process according to any one of claims 1 to 15, in which the phosphatide product is recovered from the hydrophobic liquid by'evaporation.

17. Process according to any one of claims 1 to 16, in which the process is carried out at ambient temperature and under atmospheric pressure.

18. Process according to any one of claims 1 to 17, in which enzymatically hydrolysed crude phosphatides are purified.

19. Prooess according to claim 1 substantially as hereinbefore described with particular reference to any one of the examples.

20. Transparent phosphatide-product purified by a process according to any one of claims 1 to 19.