Process for the recuperation of pure lecitine which can be used directly for physiological purposes

Method for obtaining pure lecithin directly usable for physiological purposes Procedure for obtaining pure lecithin directly usable for physiological purposes

The invention relates to a process for obtaining directly usable, pure lecithin for physiological purposes by means of a supercritical gas by extraction.

Lecithins refer to a group of compounds belonging to the phosphatide series. These compounds containing the element phosphorus as the phosphate ester can be prepared by treating certain fatty products of plant and animal origin.

For example, soybeans are used as a starting material for the isolation of soy lecithin. After the crude material has been purified, peeled and ground, this material is treated with solvents to give an oily product containing lecithin as a colloidal solution. The lecithin content of the solution is increased by further treatment with water at an elevated temperature, after which the water is again removed to obtain a semi-solid, pasty material, i.e. a so-called raw lecithin. This contains about 60-70% phosphatides and about 30-40% oil components.

For the further processing and technical use of lecithin, the proportion of oil must be kept to a minimum. As lecithin is quite widely used in the manufacture, handling and preservation of nutrients and pharmaceutical and cosmetic products, the highest possible requirements are set for the quality of lecithin, especially with regard to the physiological safety of lecithin.

the oil content has so far been further reduced by applying expensive refining treatments either by boiling and steaming or by further extraction with certain solvents and solvent mixtures. These measures require either additional energy-intensive drying associated with the treatment, or, in the case of extraction methods, the largest excess of solvents used leaves lecithin waste, so that waste of foreign solvents must be removed again. In this case, lecithin is exposed for a long time to stressful conditions, such as elevated temperatures, which increases the risk of ester cleavage or other degradation phenomena.

The invention discloses a new process for the preparation of pure lecithin directly usable for physiological purposes, by treating crude lecithin as a gas extractant using conditions supercritical to pressure and temperature by applying the various steps of the main process claim.

Extraction methods using supercritical gases as the extractant are already known.

Thus, using the method described in DE-PS 2.127.618, hop extract is prepared by extraction with a supercritical gas. In this case, resin components, volatile oils and acid components are non-selectively removed.

As described in DD-PS 41362, polar substances such as silicone oil, paraffin oil and aluminum sec are extracted. butylate simultaneously with non-polar supercritical gases.

Chamomile is extracted with a supercritical gas using the method described in DE-OS 2.709.033. According to this method, in addition to the desired extractants, harmful extraneous substances, e.g. lipoids, dyes, etc., are introduced into the extract to a greater extent, the content of which can be reduced by applying a certain expensive treatment without still substantially reducing the lipid content.

According to DE-A-2 127 596, supercritical gases are used for the extraction of vegetable fats and oils. FI patent publication 56 855 describes a similar method for removing fat from chopped plant parts. In the process of U.S. Patent No. 3,923,847, coconut pulp is separated by extraction with supercritical gases.

Quite surprisingly, and according to the known level of the invention, it is not expected that by means of supercritical extraction, oily by-products can be completely separated from lipoid-containing lecithin.

In principle, all gases which are physiologically harmless and chemically inert to lecithin can be used as extractants, for example the gases listed below: C0₂, CHF3, CF3-CF3, CHCl = CF₂,

CF3-CH3, CHF₂-CH₃, CHF 1, CF 3 Cl, CF₂= CF₂, CF ^ C1₂, CC1₃-CIK1₂, C₃Fg, SFg,

OF₂0, S0₂, ethane, ethylene, propane, propylene, etc., or mixtures thereof. Particularly preferably, carbon dioxide (C0₂).

In the extraction step, the material to be extracted is exposed to the extractant under conditions such that the gas is in a supercritical state with respect to both temperature and pressure. The critical parameters of the above-mentioned garments have long been known.

In the case where carbon dioxide is used as the extractant, the extraction is carried out in a temperature range of 31.3 to 100 ° C, preferably 35 to 80 ° C, in particular 40 to 60 ° C, and pressures in the range of 7.2. .80 MPa, preferably 20 to 50 MPa, especially 30___40 MPa.

In the case where non-carbon dioxide is used as the extractant, the lower and upper limits of the pressure and temperature used in the extraction, resp., Separation are determined by the respective critical numerical values.

To extract the extract from the extractant, the extractable extractant is passed to a separation step from the extraction step. The separation then takes place by changing the temperature and / or the pressure, in which case both parameters are preferably changed.

In the event that the temperature is changed, the temperature is preferably lowered, in which case the temperature is in particular lowered below the critical temperature, e.g. C0₂at 10 to 32 ° C, especially 15 to 25 ° C.

In the event that the pressure is changed, the pressure is preferably reduced, whereby the pressure is lowered below the critical pressure, e.g. C0₂at about 1.0 to 7.2 MPa, preferably 3.0 to 6.0 MPa.

As described above, as the temperature and / or pressure changes, the ability of the extractant to dissolve the extracted oily by-products decreases to such an extent that they separate from the extractant during the separation step and can be removed during extraction, e.g.

Without much labor and energy-intensive cleaning, the extractant can be re-used directly again without any additional emission problems. In order to re-introduce the extractant into the extraction step, the temperature and pressure of the extractant only need to be changed to a critical state, i.e. again changed from the change in temperature and / or pressure that was made for the separation.

Lecithin purified from its additives (pure lecithin) can be removed from the extraction step after the extraction is completed in batches. However, it is also possible to remove pure lecithin - e.g. via a barrier - during the extraction treatment using a continuous process. In both methods of use, extraction times of 1 to 12 hours, preferably 3 to 7 hours, are sufficient to obtain the final product of the desired purity.

Thanks to the method according to the invention, the desired product can thus be obtained in a short time using as little equipment, labor and energy as possible, in addition to which the environment is not burdened in any way. In this case, the circulating use of the extractant makes it possible, in particular, to automate the purification method, whereby the extraction becomes particularly economical. The pure lecithin obtained can be used directly in nutrients, as well as in pharmaceutical or cosmetic products.

The method according to the invention will be explained in more detail below on the basis of the accompanying schematic drawing.

The material to be extracted (crude lecithin) is fed into the extraction vessel (1). The extractant is then fed into the system via the inlet valve 6, so that it is not necessary to remove the air in the system in advance. The extractant is compressed by a compressor 3 and fed to the heat exchangers 4, respectively. 5 through different processing steps and heated to the desired temperature. The extraction step 1 and the separation step 2 are made for adjusting the thermostats into pressure vessels so that the temperature can be precisely controlled in these treatment steps by means of thermostats.

After the desired pressure and temperature have been reached in the various stages, the inlet valve 6 is closed and the extractant is circulated in the system. In the heat exchanger 5 and the compressor 3, the extractant brought to the extraction conditions comes into thorough contact with the material to be treated in the extraction step 1. The extractant-containing extractant leaves this stage through a sieve, the function of which is to prevent solid components from entering the separation stage, as well as clogging of valves, etc. This extractant is passed through a throttle valve 7 and a heat exchanger 4 to a separation stage 2, where the extract and the extractant separate from each other. The extractant is recirculated to the system circuit via the heat exchanger 5 and the compressor 3, while the extract is removed either through the shut-off at the discharge point 8 or at the end of the extraction treatment directly from separation step 2. Pure lecithin is taken from extraction step 1.

In the case where two or more pressure vessels are used instead of a single pressure vessel 1, the method according to the invention can easily be carried out continuously. In a case known per se, in this case pure lecithin can always be taken from the tank and filled into this tank with fresh material to be treated, while the extraction is carried out in the second pressure vessel or other pressure vessels of the extraction step without interruption.

In this case, it is possible to connect different tanks in parallel or in series. In the latter case, it is particularly advantageous to extract in countercurrent, in which case fresh extractant directly from the compressor 3 is fed to the pressure vessel containing the most thoroughly extracted material in each case, i.e. the container containing the freshest material to be treated is

The following examples illustrate the processing of the method in more detail.

<td colspan="3">conditions:</td>

<td>extraction tank:</td><td>Pressure:</td><td>Pi</td>

<td></td><td>Temperature:</td><td> *1</td>

<td>separation tank</td><td>Pressure:</td><td>p₂</td>

<td></td><td>temperature</td><td></td>

Example 1

1000 g of crude lecithin paste was filled into an extraction tank which was sealed and extracted with CCl 4 gas under supercritical conditions.

p ^ = 40 MPa p₂ = 5 MPa t₁ = 60 ° C t₂ = 20 ° C

Extraction time = 4 h

580 g of a pale yellow solid, pure lecithin, were taken from the extraction vessel. 380 g of a yellow clear oil and 30 g of separated aqueous phase were taken from the separation tank.

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Example 2

100 g of crude lecithin paste with an oil content of about 30% was filled into an extraction tank which was sealed and extracted with supercritical carbon dioxide.

= 40 MPa t₁ = 40 ° C p₂ = 4 MPa t₂ = 20 ° C extraction time = 6 h

69 g of pure lecithin remained as a residue in the extraction vessel as a solid, pale yellow non-hygroscopic substance. The separation tank contained 31 g of a yellow, clear oil.

Examination of the products obtained according to both examples by thin layer chromatography revealed that these products did not contain oily components.