CA1038769A

CA1038769A - Extraction

Info

Publication number: CA1038769A
Application number: CA176,848A
Authority: CA
Inventors: Gerald E. Usher; Margaret E. Holmes
Original assignee: BROOKE BOND LIEBIG Ltd
Current assignee: BROOKE BOND LIEBIG Ltd
Priority date: 1972-07-19
Filing date: 1973-07-19
Publication date: 1978-09-19
Also published as: GB1419958A; BR7305367D0; NL7310092A; BE802504A; ES417009A1; ZA734741B; AU5810273A; DE2336637A1; FR2192852B3; FR2192852A1

Abstract

ABSTRACT OF THE DISCLOSURE

Flavours and fragrances are extracted from plant material, in the presence of water, by treatment with a non-polar fluorinated hydrocarbon adapted to selectively extract desired flavours and fragrances and, if desired, with a second solvent of a polar nature and removal of the solvent or solvents by controlled evaporation.

Description

- ` ~03B769 Backqround of_the Invention This invention relates to the extraction of 1avour and fragrance components from plant material, for example fruit, vegetables and 6pices.
One known method of obtaining flavours and fragrances ~, ' from plank material is the extraction o the separated juice u~ing a fluorinated hydrocarbon (well known under the registered Trade MarX "Arcton'~. Fluorinated hydrocarbons are comparatively ~-, . ~
odourless, non~toxic and virtually non-inflammable, and since they are available wi.th a range of different boiling points it is possible to carry out the extraction and 6eparation ~teps at a low temperature producing a product superior to that from conventional high temperature ~team distillation. `

Summarv of the Invention ~ ~
,. ~ - . -,.
It is now found that the u~;e of fluorinated hydro-carbon~ as a solvent for flavours ancl fragrances is greatly enhanced by extracting the whole plant material rather than the separated juice. The advantage in treating the unæeparated material i~ that some water-insoluble flavour or fragrance com-ponents are also extracted giving a fullex and more authenticorganoleptic ~pectrum, particularly w~en multi-solvent extraction techni~ue~ are used as hereinafter described. In addition there is le~s water soluble material left behind in the residue than there would be had the materials to be recovered been expressed in a juice.
The value of ~luorinated hydrocarbon~ applied to whole plant ma~erial may be further enhanced by using them in con-junction with water and, in s4me ca~es, in conjunction with a ~econd ~luorinated hydrocarbon which i8 of a polar nature.

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The effect of the combination of water with non-polar solvents is to o~tain an extract in surprisingly improved yield and with even better organol~ptic properties than when a non-polar fluorinated hydrocarbon is used aloneO
It further has been found that9 while the extraction is preferably carried out using a combination of a non-polar fluorinated hyd rocarbon and a polar 601vent a~ described above, satisfactory re~ults may be obtained in some instances using a single fluorinated hydrocarbon. In such a case the fluorinated -nydrocarbon is one containing two or more car~on : atoms but the plant material to be extracted must contain not le~s than 6.5% by weight of water.
~ ; The reason fox the quoted minimum content of watex : ~is that the mat0rial being extracted muæt contain sufficient ~ : water to have pre~ent a polar phase to act a~ a retention - ~ ~ , - - .
p~ase or barrier to substances which in the absence of a polar ~olvent would tend to pass into the~non-polar extractant. ;~
Wat.er is the ideal polar ~olvent ~or this purpose because unlike an organic polar ~olvent it is immi~cible with a non-polar organic solvent.
- The minimum amount of water needed will vary from mat~rial to material being extracted but must in all circum-~tances be sufficient to ensure that there is present chemically free, if nst physically free, water such that the surface of eve~y particle of material being extracted ha~ a surface layer o~ free water on ik. It has been ound that the above-mentioned amount o~ at least 6.5% by weight satisfies thi~ criterion.
Ihere is no critical upper limit to the amount of . water the material bein~ extracted should contain, for example, ~, rs lS
,~,, .

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~ 3~37~;'9 it is known from William L. stanley et al United Stat~s Patent No. 3,113,031, granted December 3J 1963 that ~ruit juices can be submitted to extraction; but the presence of so much water as to produce a vi6ible aqueous phase is un-neces~ary in the process of the present invention. Thu8 in the presence of an excessive amount of water the extraction process is prolonged because o the longer time necessary for ~;
substances ko pass through thé aqueous phase into ~he non-polar organic phase. Thi~ is well illustrated by Example 1, hereinafter, w~erein when roasted and hence very dry coffee is extracted with a non-polar solvent, the yield of total oil containing polar substances and non-polar volatiles is a maximum in the non-polar extractant phase. As the water con- ' ~ , tent is increasedg the total oil yield falls but the proportion in it of non-polar volatiles increases. Eventually, as the -;
amount of water excessive, the yields of both total oil and volatiles fall becau~e of the limited time of extraction and ~;
slower pa6sage of extractable material through the aqueous , phase. A similar phenomenon is illustrated in Example 6, wherein there is achieved the very surprising result of separating in the presence of a relatively small but very definite amount of water, a quantity of non-polar substantially volatile oil from ixed oil of a polar nature u~ing an organic solvent. The degree of fractionation achieved is unusual in the extra~tion o aromatic materials using organic solvents. Preferably the amount of water used in the process o~ the pre~ent invention ~hould not exceed 96% by weight in total, made up of any water initially pre~ent in the material being extracted and any water ~dded during the process.

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" , , .; , , , 11 ~3~7~9 Detailed DescriPtion of the Invent on In accordance with the preæent invention there i8 provided a p~oce6s or extracting flavours and fragrances fxom a plant material in the presence of at least 6.5% by weight of water~ either presen-t initially in the plant material or added at the start of the proce~s, which compri~e~ treating the plant material with a non-polar fluorinated hydrocarbon containing two or more carbon atoms and adapted to ~electively extract desired flavours and fragrances, separating the non-polar solvent layer~ and removing the ~olvent from the ~eparated solvent layer by controlled evaporation to yield a volatile oil subskantially free from resinou~ material.
. The inYention also p~ovides a proeess a~ descri~ed ~ ~:
.
above, in which, following the said separation o~ the non-polar : ~olvent layer, the residual plant materiaL i~ treated ~lith a , ,, ~ second organic 601vent of a polar nature, the~econd organic ~-: ~ solvent layer is separated from the plant material and the 801Yent i6 removed by controlled evaporation to yield an extract su~tantially ~ree from volatile oil. ~ :
, It is possible for these operations to be carried out in a clo~ed system so that the fluorinated hydrocarbon may be condensed if nece~sary with a refrigerated heat exchanger and re-u~ed.
In carrying out the invention usi~g a non-polar ~luorinated hydrocarbon and water the whole oiL ex~tract i9 separated from the aque~us layer and the fluorinated hydro~ -carbon removed ~y evaporation. `
An advantage of the above process i~ that it may be used ~or plant material~ containing a high percentage of fixed ~ 4 , . . .

~ L~38~6~
oils such as coffee) nutmeg and clovesO Once the ~hole oil extract in the fluorinated hydrocar~on has been separated from the aqueous layer the bulk of the fixed oil may be isolated by a controlled evaporation of the fluorinated hydrocarbon as -~
the fixed oil is the less soluble fraction. The combined effect~ of ~he reduction in solvent temperature caused ~y the controlled evaporation and by the increase in extract concen- ~;
tration lead to a preferential precipitation of fixed oil which may be readily separated. The optimum temperature and concen- ;
tration profiles may be determined experiment~lly to suit each raw material. In addition to obtaining a relatively pure and ~-concentrated volatile oil comparatively free from fixed oils it is possible by the above proce~s to prepare ~pecialist fixed oil extracts~ or example, for use in co~metics. ~-In addition to or as an alternative to the controlled evaporation of solvent it is possible to separate the fixed oil ~;

., from the essential oil after all the fluorinated hydrocar~on has ~èen removed~by the addition to the whole oil extract of a uitable surace active agent or detexgent followed by a further extraction with a fluorinated hydrocarbon. Although both fixed -and es~ential oils are normally very misci~le in the fluorinated hydrocarbon the effect of the detergent is to delay or modify -the equilibrium in favour of the e~ential oil pos~ibly due to migration of the detergent to the oil/fluorinated hydrocarbon in~erace. By carrying out the extraction under suitable con-dition~ which may be determined e~perimentally for each material it i~ po~sible to 6eparate the fluorinated hydrocarbon ~ontaining the e~ential oil from a comparatively pure fixed oil layer.
The 1uorinated hydrocarbons used in the Examples . .
,:;, , , :, , , 31~769 which follow are: 1:2-dichlorotetrafluoro-eth~ne, having the formula CClF2CClF2, which is a non-polax solvent having a boiling point of 3. 55C, and ~ichlorofluoro-methane having the formula CHC12FJ which is a polar solvent having a boiling point of 8.9 C. The boiling point of 1:2-dichlorotetrafluoro-ethane makes it a preferred solvent or use in normal laborato~y apparatus. Non-polar solvents tend to be more volatile than ~ -polar solvents because they do not have any polar or hydrogen bonding to increase their boiling point. For this reason extraction of a plant material, such as pepper, by a non-polar ~ -fluorinated hydrocarbon would give a product similar to a con-ventional essential oil produced by steam distillation but superior to the latter due to the low temperature at which it is extracted. The two-stage system of the present invention is accordingly advantageous for extracting spices since a non-polar -fluorinated hydrocarbon may be used first to extract the volatile ~: ' . ' flavouring and a polar fluorinated hydrocarbon then used to , extract th~ less volatile constituents and the pungency prin-ciples ~uch as piperine. The two extracts are finally blended ;~
once the solvents have been removed.
The invention will now be illustrated by the following Examples. In the Examples only approximate quantities of fluor-inated hydrocarbon added are given. Under laboratory conditions accurate mea~urement is impractical due to the rapid rate of evaporation.
EXAMPL~ 1 ~ .
A serie~ of experiments was carried out heating 200 g.
quantitie~ of ground Kenya coffee (moisture content 2.2%) treated with different quantities of boiling water to give water contents 376~
of the mixture from 2.2% to 75.5% (boiling water was ufied so that the re~ulting oil would have a conventional cooked coffee flavour). In each experiment the coffee or co~fee/water mixture was extracted twice with an excess of 1,2-dichloro- ~
tetrafluoro-ethane The coffee grounds were then sieved off ~ ~ ;
and the fluorinated hydrocarbon separatad from the residual water, if any. In the experiment with a 1:1 coffee:water ratio a clear solution was o~tained. In the other experiments a cloudy solution was obtained which was dried with magnesium sulphate and filteredO rrhe ~olutions were then allowed to evaporate and the yield of oil recorded. A 4 ~1 ~ample of .
;~ each oil was analysed by vapour phase chromatography (VPC)~

: ~ , . _ ,, , -;
Weight ~olume Yield Total peak Yield of ~olatile oil of of of area count (Yield of whole oil x `~
coffee boiling whole of the major total major peak area -~
water oil peaks count~
g~ ml. mi.
200 o 8.0 7,544 ~0,352 '`~
200 100 5.634,983 195,904 -200 200 4.851,271 246,100 200 300 4.236,703 154,152 - 200 400 4.036,083 144,332 200 600 2.033J852 67J704 ~' It may be seerl that the extraction involving a ~, coffee:waker ratio of 1:1 gave the highest concentration of volatiles per unit o~ fixed oil and the highest yield of volatile oil. ;.
XAMPLE 2(a) 200 g. of ground Kenya coffee was mixed with 200 ml.
o boiLin~ water and the mixture extracted with 1~2-dichloro-~b~ 4 .. .

3137~ -tetrafluoro ethane as described in Example 1. A~ter evapor-ation of the 1uorinated hydrocarbon, the whole oil was ~haken with 1% o~ its volume of detergent and then an exce~s (approx.
20 ml.) of fluorinated hydrocarbon was added. l~/o of the whole oil was extracted by the 1uorinated hydrocarbon and ~-the residue was virtually odourless indicating ~hat substan-tially all o~ the ess~ntial oil had passed into the fluorinated hydrocarbon phase. The fluorinated hydrocarbon was then evaporated and the extraction repeated. In this second extrac-tion, 25% o the enriched oil was ~xtracted ~iving a total concentration of essential oil with respect to fixed oil of EXAMP~ 2~bl 22~ g. cofee was mixed with 200 ml. boiling water as in ~xample 1. The fluorinated hydrocarbon was then eva- ;
: : :
porated under vacuum while the temperature fell from 3 to -~

-25 C. 3 ml. of odourless frozen fixed oil were removed and 0.2S ml. concentrated essential oil recovered.
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A series of experiments was carried out treating 600 g. sample~ of a blend of Indian, ceylon and East African tea3 with quantities of cold or boiling water varying from 0 to 2,400 ml. In each experiment after approximately 30 minute~ the tea or tea/water mixture was extracted with an exces~ of l,2-dichlorotetrafluoro-ethane. After a short contact time the fluorinated hydrocarbon layer was separated, dried with magnesium ~ulphate, filtered and allowed to evaporate. The ~mall quantity of oil obt~ined and the presence o ~olid~ ln ~hi~ oil made an accura~e a~fiessment of yield ,~ ~'s t -:, A ; , ~3876~
difficult but 4 ~1 of each sample was analysed ~y VPC and ~ -~
the results, i.e., peak counts, which are given in the following table give an indication of the concentration o volatile material in each sample. It may be eeen in the cold water expeximents that the optimum concentxation occur~
at a water:tea ratio of 2:1. In the hot water experiments ~ :
the optimum is at a ratio of 3.5:1.
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Thi~ ~xample iJlustrates the application of the method to a natural product which already contains the optimum amount of water.
Orange peel with a moisture content of approxima~ely 72% by weight was carefully removed from the ~ruit and homo~
geni~ed with 1~2-dichlorotetrafluoro-ethane in an atomix.
The fluorinated hydrocarbon was then separated from the peal ;
and the lattex was re-extracted with fresh ~luorinated ~ydro-carbon. The two extracts were bulked and allowed to evapor~
; , ate. A yield of approximately 2~o high quality oil was obtained.
Similar experiments were carried out using lemon, ~
clementineJ grapefruit, and lime peels~ ~ -.:, EXAMP~E 5 ~round cinnamon lea~es with a moisture content of 6.5% by weight were extracted with 1,2-dichlorotetrafluoro~
.: . .
ethane. The fluorinated hydrocarbon layer was separated and allowed to evaporate.
~ The moisture content of the ~econd sample of cinnamon `~
~ 20 leave~ was adju~ted to 68.8% by the addition of two parts by weight of boiling water. The leaf wa~ then extracted with 1,2-dichlorotetrafluoro-ethane and the fluorinated hydrocarbon layer fieparated and dried with magnesium sulphate. Finally, it waM filtexed and allowed to evaporate.
Hal~ micxolitre samples o~ each oil wexe analysed by ~PC. The areas o the two maior peak~ are given below:
6.5% moi~ture - 522~771 66~/o moi~ture 1,676,701 ,.:
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This Example illustrates the use of a non-polar fluorlnated hydrocarbon to produce an unconventional product, viz a clear mobile oil from a spice and the efect of moisture content on yield.
1 Kg. ~ample~ of old ground Malabar pepper were adjusted to different moisture levels and then extracted over 10 minutes with 2 litxes of 1,2-dichlorotetrafluoro-ethane at the solution's boiling point. The li~uor was removed and ~ :
the pepper re-extracted twice, each time for 5 minutes with

2 litres of ~olvent. ~le combined extractx at each moisture level were evaporated to give a yellow/orange.mobile oil.
MQi~ture Content % Yield % .

3 2.94 ~ -8.~5 . . -~ 3.29 . lS 3.65 ~: - , : : 19.75 3.42 :~

: 32 ~.25 :: -73 1.25 .`
, 20 ~ EXAMPLEI
Thi~ Example illu~trates a t~o-stage process to give a high quality pepper oleoresin.
Ground Malabar pepper was extracted with 1,2- ..
dichlorotetra~luoro-ethane as in Example 6 giving product I .~;
in 6.6% yield. The pepper re~idue wa3 then further ex- ~- :
tracted in a ~imilar way with dichlorofluoro-methane giving a dar~ green paGte procluct II in 6~/o yield. This paste wa~ treated with 400/O o it~ weight petroleum ether (boiling o o point 60 to ~0 C) plu~ acet~ne in a l:l ratio and the _ 12 ,.. .
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~ 1387~9 yellow soli.d residue removed by ~iltration. The residue was further extracted in the same way with a 2:l petroleum ether:
acetone mixture yielding a pale yellow powder product III at a yield of l.3%, based on the weight of the original pepper.
A high quality pepper oleoresin was produced by blending products I and III.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for extracting flavours and fragrances from a solid plant material in the presence of at least 6.5% by weight of water, either present initially in the plant material or added at the start of the process, which comprises the steps of:
a) treating the plant material with a non-polar fluorinated hydrocarbon containing two or more carbon atoms and adapted to selectively extract desired flavours and fragrances, separating the non-polar solvent layer, and removing the solvent from the separated solvent layer by controlled evaporation to yield a volatile oil substantially free from resinous material, and b) treating the residual plant material with a second organic solvent of a polar nature, the second organic solvent layer being separated from the plant material and the solvent being removed by controlled evaporation to yield an extract substantially free from volatile oil.

2. A process according to claim 1, in which the fluorinated hydrocarbon is 1:2-dichlorotetrafluoro-ethane.

3. A process according to claim 1 in which the second organic solvent is dichlorofluoro-methane.

4. A process according to claim 1, wherein the extracts obtained by the evaporation of the non-polar solvent and the polar solvent are blended in any desired proportion to produce an extract of controlled composition.

5. A process according to claim 1 for extracting flavours and fragrances from coffee, which comprises treating a coffee/water mixture with an excess of 1,2-dichlorotetrafluoro-ethane and removing the solvent by controlled evaporation from the extract containing the desired flavours and fragrances dissolved therein.