CA1130988A

CA1130988A - Process for extractive treatment of vegetable and animal substances

Info

Publication number: CA1130988A
Application number: CA337,471A
Authority: CA
Inventors: Hans-Albert Kurzhals; Peter Hubert
Original assignee: Hag AG
Current assignee: Hag AG
Priority date: 1978-10-13
Filing date: 1979-10-12
Publication date: 1982-09-07
Also published as: EP0010665B1; EP0010665A1; DE2844781A1; JPS5554003A; ATE413T1

Abstract

PROCESS FOR EXTRACTIVE TREATMENT OF VEGETABLE
AND ANIMAL SUBSTANCES
ABSTRACT OF THE DISCLOSURE
A process for extractive treatment of vegetable and animal material with a non-reactive solvent mixture having two components, the first of which is gaseous and the second of which has physical properties such that, at the employed temperature, it forms a liquid when mixed with the first component.

Description

1~3~9~3 BE~IEF SUM~ARY OF THE INVENTIOI~

The invention relates to a process for the careful extracti~e treatmen~ of vegetable ~nd animal~
material with a non-reactive, liquid solvent mixture with adjustable solvent properties without residue problems, either the plant or animal carrier substance or the extracted substances being able to b~ recovered in a simple manner.

BACKGROUND OF THE INVENTION

Most prior ar~ processes for the extractive treatment o~ ma~erials of vegetable or animal origin work with solvents consistlng of pure substances or mixtures of substances whose components are liquid under normal conditions. Normally, in addition to water, organic solvents are predominantly used, e.g., hydrocarbons, alcohols, acids, esters, ketones, etc., their halogena~ed derivatives are also frequently being used~ In most cases, it is necessary to remove the solvents ~rom ~he treated materials and/or extracts.

The principal drawback o these sol~ents is the relatively large intermolecular forces whic~ make it necessary to use large amounts vf energy or complicated and extravagent processes for the removal of the solvents.
Apart from the economic disadvantage~ this often results in changes in the treated material and~or in the extract ,. '~ .

1~3~ 8 having their cause in (chemical~ adduct formations, e.g., with the solvent, or in thermal denaturations~ This generally renders a complete residue-free removal of the solvent from material and/or extract impossible. 5uch residues are undesirable.

,~
Many of the solvents used for ~he extraction of ~egetable and animal materlals are combustible and thus cause problems in industrial use.

In order to avoid the above-described disadvantages resulting from the use of solvents which are li~uid under normal conditions, it has recen~ly been proposed to use processes involving the use of supercritical or li~uid gases at high pressures. The adaptation of the solvent properties is mainly by selection of pressure and t mpera-ture in the case of supercritical gases and mainly by pressure in the case of liquid gases. Examples of such processes are the reco~ery of spice extrac-ts (German Patent No. 21 27 611), production of hop extracts ~German Patent No. 21 27 618), denicotinization o~ tobacco (Germa~ Patent No. 21 42 205) and production oE cocoa bu~tex (German Patent No. 21 27 643).

These processes all require relatively high pressures, generally in excess of 150 bar, for the attainment of sufficiently high degrees of extraction.

~L36~9#1~3 BRIEF INTRODUCTIO~ TO THE_D~WINGS

Figures 1 and 2 are schematic diagrams of apparatus suitable for carying out ~he pro~ess according to the present in~ention.

DESCRIPTION OF PREFERRED EMBODIMENT

It is an object of the present invention to overcome the a~ove-mentioned disadvantages of the prior art processes. This object i5 attained by use of a solvent mixture comprising two components, a) the ~irst o~ which is gaseous p~r se under the employed condi,tions, and b) the second of which in itself has physical properties such that ~he mixture of (a) and ~b) is liquid at the employed temperature.

It has been determined that, optimal adjustment of the solvent properties tselectivity~ solubility and yield) is possible by suitable selection of ~he components of the mixture to be used according to the invention without the above-mentioned disadvantages occurring.

For the first component~ whi~h i~ gaseous per se under the employed çonditions, gases are suita~le which are not injurious to health, especially non-combustible g~ses.
Gases which occur naturally in the material tv be ~3091~

treated are preferred, and these can be used alone or - :
in mixtures.

The f~llowing gases are among those suitable for the first component: C02, N20, ~here the decom-position ranges must be considered), SF6, Xe, CF4t methane, ethylene, acetylene, cyclopropane~

For the second component, which in itself has physical properties such that its mixture with the component which is gaseous per se under the employed con-ditions is liquid at the employed temperature, substances are suitable whlch are not injurious to health, partlcu-larly component substances of the materials to be extract~d~
This use o component substances as the second co.mponent has the advantage that they do not raise food-related legal problems since they are not considered substances in the sense of regulations relating to additives. The following groups of compounds, which are also naturally contained in the starting materials mentioned by way of example, are among those suitable as the second component: hydrocarbons, alcohols, ketones, keto alcohols, acetals, eth~rs, esters, carboxylic acids, amines, lip~ds.

Examples of uses for which the process according to the invention is suitable include recovery of:

aroma oil from roast coffee tea aroma from black tea .

~3~9~8 hop extractsspice extracts having a natural ~omposition tobacco with no or reduced nicotine, also having reducecl condensate conte~t vegetable Eats and oils fat-free enzymes odorous and odoriferous substances ~rom vegetable and animal materials drug extracts aglycones from glycosides, if appropriate a~ter prior cleavage extracts from ci~rus fruiks dyestuffs rom vegatable materials vegetable insecticides meat aromas animal fats or fat-reduced meat In many applications of the process of the invention to the starting materials ~oted above by way o~ example, all those components are to be completely extracted which in their entirety con~titute the valuable substance, and are free of ballast material to ~he major extent. The selection of the second component must hence be made from the aspect of the separation of a generally complex mixture, in many cases not only one of the a~ove-noted compounds but a mixture of several compounds ,~ , .

~13(~

being advantageous as the second component. Its selection and concentration in the solvent according to the invention depends (given the criterion of the highest possible solu-hility for the extract to be recovered) on ~he nature of the material to be extracted, the selected operating conditions, and the properties of the first component with which a liquid solution is to be obtained.

The temperature of the extra~tion according to the invention is preferably in the range of about 260 to 400 K, and, if C02 is used as the first component, preferably between room temperature and about 340 K. The ~xtraction pressure is to be at least high enough so tha~ ~he solution to be selec~ed according to the invention is liquid at the selected composition and adjusted temperature, the upper limit of the extraction pressure to be employed depending merely on commercial considerations.

Surprisingly, in many systems, isothermal pressure lncreases are accompanied by increases in the velocity of extraction, even though the increase in density of the }iquid solution is relati~ely slight. Conversely, the use of lower pressures makes it possible to xeduce the apparatus expenditure.

The quantitive ratio of liquid solution to the material to be extracted should be sufficientl~ high for .

~13~

the duration of extraction to be as short as possible, while on the other hand commercially excessive amounts of solvent should be avoided.

Extraction proceeds in the conventional manner, and can be carried out according to all known processes of solid-liquid extraction, both continuous and batch processes being employable.

Separation of the ex-tract from the solvent is preferably by distillation, by utili~ing a misclbility gap of the solvent consistiny o the two components, or by shifting the solvent characteristics of the solvent in the single-phase s~stem (e.g., precipitation). In all cases, a pressure and/or temperature change i5 required. Where a miscibility gap is used, it is particularly ad~antageous for one of the segregated components ~ have a s~gnificantly better solvent capacity for the extract than the other compo~ent. This phase is then discharge~ from ~he system, separated by separation processes known per se, ana the pure component reintroduced into the system.

Further alternatives for separation of the extract consist of removing the extract by adsorption ~bonding to solid substances) or by liquid-liquid extractio~ from the sol~ent mixture to be us~d according to the inve~tion. This type of separation is par~icularly advan~ageous where the 13~3~9~8 extract is to be utilized further bonded to a solid or liquid carrier material rather than in its pure form~

After extraction is completedr the liguid solution is separated from the material which has been extracted.
If this separation occurs while the pressure is simul-taneously lowered, substantially only a small portion of the second component remains in the system, and hence in the extracted material, and can if necessary be removecl by evacuation, heating, steaming or rinsing with the first com- -ponent or other inert gases.

Surprisingl~, it has been found that, when treating extraction material having a solid matrix, the residues o the two components after separation of the solution are located almost exclusively on the surface of the extraction material, and can thus be removed simply and completely.

In the case of isobaric separation of the solution, the volume it occupiss in the extracting system can be replaced by lnert gases ox by the pure first component. If use is made of inert gases or of first components which are incompustiblP and which do not support com-bustion, this method of separation offers the advantage that combustible second components are present ~n such low concentration during the subsequent evacuation of the apparatus that theix mixture with air --8~

., , 9~38 is not ignitable. The described manner of isobaric separation of the solution normally requires no supple-mental treatment for the removal of soLvent residuesO

EXAMP~E I

2.5 kg of air-dry Hallertau hops were extracted in apparatus accordin~ to Figure 1 under the following conditions with a liquid mixture of 94 moles ~ C02 ~from supply container ~I) and 6 Mol % n-butane (from supply con~ainer V2) having ~ critical temperature of 310.~ R
and a critical pressure of 71.9 bar:
extxaction pressure: 82.7 bar extraction temperature: 308.2 X

The solvent was conveyed with the aid of pump Pl and was brought to tempera~ure by heat exchanger W1, cir-culated through extraction container A and ~nriched with extract. The pressure of a secondary stream was reduced to 50 bar in separation container B. A butane-rich, liquid phase resulted, containing both dissolveA and undissolved extract components, as well as a C02-rich, gaseous phase, which was almost free of dissolved hop constituents. The latter was withdrawn upwardly out of the sepaxation con- -tainer. The liquid phase was clarified in separator S, the u~dissolved extract portion I being obtained. The clari~ied liquid pha~e was freed in the distillation apparatus D o~

~3~

the dissolved hop substances which were ohtained as extract portion IIJ The C02-rich gaseous phase from B
was repressurized by compressor P2 anal the distillate from D was conveyed by pump P3, ~nd the two material streams were brought together. The resulting mixture, which at this point again had the same composition as the pure solvent, was brought to temperature ex~raction con-ditions in heat exchanger W2 and then returned to the main stream in liquid form.

The appaxatus according to Figure 1 was opexated for four hours. ~ yield of 355g light green extract wa~
obtained. It was found that extract portlon II was particularly rich in such components which are attributable to hop oil, while extract portion I contained relatively few hop oils, but more soft resin proportions.

The ~ollowing table shows the analytical da~a for the hops used as starting material, the extract, l.e., the sum o~ portions I and II, as well as the da~a for t~e spent hop grains:

Results of Hop Analysis Spent Determination of Untreated Ho~s Residue Extract I ~ II

_ % Water 10.5 12.3 3.4 Total resin 23.0 4.1 91.9 So4t resin 20.8 ~.0 89-4 .

~os~ .

Results of Hop Analysis (Cont'd) SpQnt Provision of Untreated HoPs ~esidue Extract I and II
% o~-acids 10.1~ 0.~ 46.3 ~ B~acids 10.7 1.9 41.5 % hard resins 2.2 2.3 2.t % hop oils 1.0< 0.1 4.9 ~ tanning materials 4.3 5.3 o EXAMPL~ II

5 kg of ground black pepper with a piperine content o~ 9.8% wexe e~tracted in the apparatus accordin~ to Figure 1 with a mixture of 58.8 mole ~ C02 and 4t.2 mole % propane at 325 K and 78 bar. The mode of operation was the same as described in Example I. However, separator S was ~ot needed.
Rather was the liquid phase which appeared in s~paration container B after pressure reduction to 45 bar conveyed directly to distillation apparatus D together with the pre-cipitated extract components.

The apparatus was operated for two hours. 936 g of a yellow pepper extract having an intensive odor were obtained containing 51.3% piperine. This corresponds to a yield of 18.7%. The degree of extraction, with respect to piperine, i5 thus 98~.

, The following examples relate ~ the treatmen~ of tobacco, the aim being the recovery of the vegetable

3~9~

:

matrix, and such treatment can proceed in one or more steps.

EXA~LE III
.

5 kg of Burley cut tobacco containin~ 3~7~
nicotine in the dry material, were moistened ~o a water content of 20% and then denicotinized for 2.5 hours in the apparatus shown in Figure 2. The solvent was a liquid mixture consisting o~ 93 mole ~ C0z ~rom supply container VI) as the first component and 7 mole ~ ethanol (rom supply container V2, supplied by pump P2) as the second component, '~he solvent was circulated by means of pump P1 through the tobacco-containing extraction container A and the adsorber C. The latter contained an ion exchange resin as a selectively-acting adSorbent for nicotine. Heat exchanger W served for setting the 316 K extraction temperature. The circulation pressure was 100 bar.

- After ~reatment, the tobacco was re-dried to its in~tial moisture content o~ about 10%. The nicotine content in the dry material was 0.03%. Its bulk density had diminished from 170 to 136 kg/m3. Otherwise the typical appearance of the cut tobacco was ~nchanged. The material also had excellent smoking properties with resp~ct to aroma.
The condensate content of the treated vis-a-vis the untreated tobacco was reduced by 43~.

EX~PLE V

The ~ollowing multi step process was used ~or a more aroma-sensitive Virginia tobacco:

First step The aroma was re~oved rom S kg of dr~ Virginia tobacco having a mois~ure content of 8% in an apparatus according to Figure 1 and the tobacco conveyed to a previously nicotine-reduced tobacco charge. The starting material was located in extraction container A, and the tobacco to be aromatized in separation container B. The solvent was a liquid mixture consisting of 94 mole % C02 and 6 mole ~ n-butane. The extractlon press~re was 88 bar, and the extraction tempexa~ure 30~ K. The pressure o~ the aroma-containing solven stream was reduced in container B
with a pressure of 28 bar being set. This resulted in a butane-rich liquid phase and a C02-rich vapor phase, which was withdrawn from B. The liquid phase percolated through the tobacco and thereby gave up most of the aroma substances to the tobacco. It was then withdra~-n with ~he aid of pump P3, but without use of separator S and distillation app~ratus D; combined with the C02-rich phase, which had been re-pressurized by pump P2, and recycled to the extraction via heat exchanger W2, Second Step: The de-aromatized tobacco was ~hen moistened to a water content of 22% an~ its nicotine content reduced as described in ~xample III. After )98~

re-drying to about 10~, it was subjected to an aroma transfer from a fresh tobacco charge in container B, as described in the first step. The resulting product had the same appear-ance as the starting material and very good smoking proper-ties.

Analysis Data Starting - Nicotine tobacco De-aromatized reduced Re-aromatized % nicotine in dry substance 1.85 1.83 0.04 0.05 bulk density not de- not de-(Kg/m ) 170 terminedtermined 128 EXAMPLE V
25 kg of ground soybeans were extracted in an apparatus according to Figure 1. A solvent consis-ting of a liquid mixture of 92 mole % CO2 and 8 mole ~ pentane was used, with an extraction pressure of 100 bar and an extraction temperature of 339 K. After reducing the pressure to 42 bar, the resulting CO2-rich, extract-free gas phase B was repressurized by pump P2. The pentane-rich, extract-~ontaining liquid phase was withdrawn from separation container B and freed of pentane and C2 in distillation apparatus D without use of the sepa~
rator. The distillate was recycled as described in the preceding examples. ~.6 kg of light yellow soy oil was - 1~

~L~3~91~

obtained. The starting material had a fat content of 18.5% while the residual fat content of the extracted material was C0.1%.

EX~PLE Y

500 kg ground, naturally moist orange peels were extracted for the recovery of the inherent colvring matter (carotin) in an apparatus according to Figure 1 with a liquid mixture consisting of 92 mole ~ C02 ~nd 8 mole acetone, at an extraction pressure of 90 bar and an extraction temperature o~ 310 K for 0.5 hours. The separation pressure in con~ainer B was 25 bar. The gaseous, extract-free C02-rich phase was repressurized by pump P2, w~ile the liquid phase was freed of acetone and C02 in distillation apparatus D without use of separator S. The distillate was reclycled ~see preceding examples). A dark-red oil with a total carotin content of 150 g carotin was obtained.

The caro-tin content of the startiny material was about 320 mg/kg dry material. The yield was thus 93~8~.
A residual acetone content of<10 ppm was foun~ in the extract.

Claims

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. Process for the extractive treatment of vegetable and animal matter with a liquid solvent solution which is not injurious to health, and which comprises using a two-component solvent solution a) the first component of which is gaseous per se under the employed conditions, and b) the second component of which has in itself physical properties such that the mixture of the two components is liquid at the employed temperature.

2. Process according to claim 1, wherein the first component is selected from the group comprising CO2 alone, and gases and gas mixture not injurious to health.

3. Process according to claim 1 or 2, wherein said second component is selected from the group comprising con-stituents of vegetable or animal matter, and food substances.

4. Process according to claim 1, wherein the operative temperature range is 260 to 400 K.

5. Process according to claim 1, wherein the preferred operating temperature range is room temperature to 340 K.

6. Process according to claim 1, wherein the solvent is circulated and the extract is separated by lowering the pressure and/or raising the temperature, thereby producing phase separation of the solvent into a gaseous and liquid phase.

7. Process according to claim 6, wherein the extract is removed from the system with the liquid phase, and is then separated from the liquid phase, the latter being recycled.

8. Process according to claim 7 r wherein the extract is fractionated by separating a constituent of the extract which is insoluble in the liquid phase prior to recovery of the entire extract from the liquid phase.

9. Process according to claim 8, wherein the extract is separated into more than two fractions by separating the phases in several pressure and/or temperature stages and separately removing the respective undissolved portion of the extract from the particular stage.

10. Process according to claim 1, wherein the extract is bonded to solid adsorbents by adsorption from the solvent.

11. Process according to claim 1, wherein the extract is removed from the solvent by liquid-liquid extraction.

12. Process according to claim 1, wherein the solvent is after the extraction separated from the vegetable or or animal matter with simultaneous lowering of pressure, and the residual solvent is removed by evacuation, heating, steaming or rinsing with said first, gaseous component or other inert gases.

13. Process according to claim 1, wherein the solvent is removed isobarically from the extraction system after extraction, and that the volume it occupied is replaced by inert gases or by the pure liquid first component in the case of simultaneous lowering of the temperature.

14. Process according to claim 1, wherein the solvent used for extraction contains combustible constituents, and the mixing proportions are such that the mixture is not ignitable in air.