IE41949B1 - Decaffeination process - Google Patents

Abstract

1516208 Decaffeination processes SOC DES PRODUITS NESTLE SA 7 Nov 1975 [27 Nov 1974 18 Aug 1975] 46175/75 Heading A2B Vegetable materials, especially tea and coffee, are decaffeinated by contacting the materials, themselves or aqueous extracts thereof, with a liquid, water-immiscible fatty material. When an aqueous extract of tea or roast coffee beans is treated, volatiles may be removed before contacting with the fatty material and recombined with the extract after removal of caffeine. When an extract of green coffee beans is treated, it may be recycled for further contact with the beans after contact with the fatty material. The aqueous extract may have a solids content of 2-60% and the contacting temperature may be 0-50‹C. When coffee beans are contacted directly they may have a moisture content of 20-60% and contacting is at 30-150‹C. The fatty material should contain an equilibrium moisture content, e.g. 0.9-1.2%. Contacting may be performed in a multistage counter-current process. The fatty material may be sunflower, soy bean, corn, peanut or coffee oil, triolein or lard.

Description

This invention is concerned with the decaffeination of vegetable materials.

There has long been a recognized demand for decaffeinated vegetable materials, particularly beverages such as cof5 fee and tea. The customary prior art techniques for decaffeination generally involve the use of organic solvents such as trichlorethylene or chloroform, which solvents are contacted either with the vegetable material or with an aqueous extract thereof. When sufficient caffeine has been transferred to the solvent, the resultant solution of caffeine is separated so as to allow further processing of the decaffeinated material or extract.

These organic solvent-based decaffeination techniques have several disadvantages. Of particular concern to the ul15 timate consumer, the utilization of prior art decaffeination solvents often results in substantial loss, or denaturization, of valuable flavour and aroma constituents of the eventual beverage. Thus, decaffeination has frequently been responsible for products lacking in high quality characteristics.

Further, because the prior art solvents themselves are often detrimental, concern has been evidenced respecting contacting them with vegetable materials from which comestibles are to be produced. This cbncern has resulted in the development of complex and stringent processing techniques in order to insure complete solvent separation from the finished products.

In accordance with the present invention, there is provided a process for producing a decaffeinated vegetable material comprising contacting a liquid, water-immiscible fatty material with a caffeine-containing vegetable material, main5 taining said fatty material and vegetable material in contact for a period of time sufficient to transfer caffeine from said vegetable material into said fatty material, and separating the resultant, caffeine-laden fatty material from the decaffeinated vegetable material.

By fatty material as the term is utilized herein, is meant any of the animal or vegetable fats or oils or admixtures or fractions thereof which assume a liquid form within the temperature range — discussed hereinafter — useful for the removal of caffeine from a caffeine-containing composi15 tion. These fatty materials are customarily composed essentially of esters of fatty acids — usually glycerol esters — and may be utilized in either their native form or in those resultant from conventional treatments as are known in the art. Moreover, the fatty materials used should desirably be non-solvents for constituents of the vegetable material other than caffeine.

Thus, for example, the present fatty materials may be in either unsaturated or saturated fats or oils. Similarly, unrefined or conventionally refined oils as well as oils with or without such normal additives as anti-oxidants and preservatives are all useful within the scope of the present invention. - 3 41949 It is preferred, however, that the fatty material be essentially exempt of surfactants, either naturally - present or added. These materials may stabilize emulsions which form upon agitation of liquid compositions utilized in accordance with the present invention and therefore increase the difficulty of such processing steps as centrifugal separation as may be required.

The fatty materials of the present invention include commercial oils and fats and thus numerous examples are rea10 dily available. Of these fatty materials, however, those which are edible are highly preferred because their utilization reduces the need for special care in separation from vegetable materials which will be further processed as comestibles.

These fatty materials are useful for effecting virtually any desired degree of decaffeination of a vegetable material. Thus, although essentially complete caffeine removal is ordinarily preferred, a lesser degree can also be provided upon consumer demand. In either event, however, a corresponding amount of caffeine will become available as a valuable, commercial by-product.

The fatty materials are utilized to extract caffeine from various vegetable materials, most commonly from coffee or tea. In order, however, for decaffeination to proceed rea25 dily, it is desirable that there be water present. It ls believed that this requirement is due to the desirability of - 4 41949 providing the caffeine in an initially water-solubilized or partially water-solubilized form, so as to facilitate its availability to the fatty material decaffeination solvent.

This belief as to a mechanism by which the present invention may operate is not, however, intended to limit the scope of the present invention but rather is set forth merely as an attempt at explanation of what may be occurring incident thereto.

Caffeine-containing vegetable materials which may-be de10 caffeinated in accordance with the present invention are most suitably provided in either aqueous liquid or solid form.

Where a solid form is employed, water should still be present, although it may be bound within the solid. Accordingly, aqueous solutions of vegetable material and vegetable materials having a substantial moisture content are preferred compositions for decaffeination in accordance with the present invention.

Aqueous extracts of tea or roast ground coffee are wellknown and may be produced by means conventional in the art. Because these extracts are themselves eventually converted into beverage products, however, they should ordinarily be treated in a manner so as to minimize exposure to conditions which might result in loss and/or degradation of valuable flavour constituents. One particular class of constituents of these brews — the so-called volatiles or aromatics — is particularly sensitive in this regard.

Accordingly, they are preferably removed early during - 5 41949 processing and recombined with the more stable constituents only at or near the end of the beverage production cycle.

This removal and preservation of the volatile or aromatic constituents of vegetable materials may be accomplished by means well-known in the art. Thus, for example, it is conventional to subject aqueous extraots to stripping with steam, through which technique an aqueous condensate containing the aromatic and volatile constituents is readily obtained. Such isolates are then preserved under conditions of low tempera10 ture until such time as they may be recombined with the processed vegetable material constituents, for example, by admixture therewith immediately preparatory to drying or through application to the dried material itself followed by a short, secondary drying sequence. Accordingly, where aqueous extracts are decaffeinated with the fatty materials, the aqueous solution of vegetable material is preferably free of its customary volatile constituents.

Another liquid vegetable material which may be decaffeinated in accordance with the present invention comprises an aqueous extract of the vegetable material, which has been formed specifically for the purpose of decaffeination and will not constitute any portion of the eventual beverage product. This embodiment of the present invention is most suitable for vegetable materials such as coffee which normally require roasting or some other treatment to form many-of their desired beverage constituents. - 6 j Exemplary of this embodiment of the present invention is an aqueous extract of green coffee beans. Such beans may be extracted with water so as to remove their caffeine content.

The resultant extract, however, contains relatively few of 5 the normal coffee, beverage constituents inasmuch as these water-soluble constituents are largely produced only upon subsequent roasting of the beans.

The formation of this extract is fairly simple. All that Is required is that the green beans be contacted with a weight of water sufficient for dissolving their caffeine content, the beans normally containing about 2 to 3 weight percent caffeine depending on their origin. Ordinarily, dissolution is accomplished by counter-current flow of beans and water; however, this step can be effected simply by slurrying the beans in water or any equivalent contact therebetween for a period of time — usually 10 to 60 minutes — sufficient to allow the desired degree of decaffeination.

Even where green beans are extracted with water, however, some valuable beverage constituents may also be removed to the aqueous phase. One technique by which the avoidance of any substantial loss of these desired constituents has been insured is through closed, cyclic circulation of the aqueous extraction medium. Pursuant to this technique, the aqueous medium rapidly obtains its maximum concentration of the various water-soluble constituents, including caffeine, of green beans. Upon subsequent selective removal of the caffeine from the medium, there is obtained a recyclable aqueous extraction medium which rapidly approaches dynamic equilibrium with respect to those water-soluble constituents of green beans which are not removed by decaffeination of the medium.

With such a dynamic equilibrium in effect, the recycled caffeine-free extraction medium will — upon recontact with green coffee beans — remove essentially only caffeine therefrom. Thus, within a short time, a system may be obtained whereby essentially only caffeine is removed from the green beans.

Both, the recirculating extraction medium and the aqueous extract discussed more completely above are essentially aqueous solutions which contain both caffeine and various water-soluble vegetable material constituents. Accordingly, the present tech15 nique of treating liquid vegetable materials with fatty material to remove caffeine therefrom may be applied to each ih much the same manner. Thus, a liquid vegetable material is admixed with a suitable volume of a liquid water-immiscible fatty material, maintained in admixture therewith until caffeine has migrated into the fatty material, and then separated with a corresponding decrease in its caffeine content. These steps may be accomplished quite simply, because the fact that both phases are liquid permits easy and thorough admixture under agitation, while the immiscibility of the two phases — aqueous and fatty — -allows substantially complete separation by many known techniques, including decantation.

Of major importance for the efficiency of decaffeination are the caffeine solubility characteristics of the fatty material. These properties are dependent upon the particular material selected and the temperature during admixture with the liquid vegetable material. This effect may be discussed in terms of the distribution coefficient for caffeine between equal volumes of the fatty and aqueous phases during admixture and at equilibrium. More particularly, the affinity of the fatty material for caffeine is defined by the relation10 ship: Distribution coefficient = .....Phase caffeine concentration in aqueous phase for any given temperature. Clearly then, higher distribution coefficients evidence a superior ability to effect decaffeination.

In Table I which follows, exemplary data for various fatty 15 materials at different temperatures are provided. The data reflect the equilibrium achieved by single admixtures of volumes of fatty material and aqueous caffeine solutions. It should be understood that the fatty materials actually utilized are only representative commercial products. Thus, depending on the par20 ticular history of a given material, some variation in the distribution coefficient would be expected. With this data and the additional description provided herein, however, the characteristics and optimum conditions of use for other fatty materials within the scope of the present invention may easily be deter25 mined. 419 49 TABLE I SOLUBILITY CHARACTERISTICS OF FATTY MATERIALS Fatty Material Temperature Caffeine Distribution Coefficient for Equal Volumes of Aqueous and Fatty Phases Safflower Oil 20 °C .064 10 °C .067 Soy Bean Oil 20 °C .064 10 °C .059 10 Corn Oil 20 °C .064 15 °C .064 10 °C .071 5 °C .085 Peanut Oil 10 °C .067 15 Coffee Oil 23 °C .140 Triolein (oleic acid ester of glycerol) 23 °C .085 Olive Oil 23 °C .076 Lard 65 °C .197 The time of contact between fatty and vegetable phases is relatively unimportant. Only a few minutes are required for approaching the equilibrium degree. The optimum temperature for decaffeination with any particular fatty material within the scope of the present invention however should be determined prior to utilization. Exemplary data are reflected in Table I, but additional determinations may be made by wellknown techniques and thus this aspect of the present invention may be ascertained by simple experimentation after selection of the particular fatty material to be utilized.

In determining the optimum temperature, the particular materials involved place limits on the degree of desirable variation. Thus, the freezing point of the aqueous vegetable material and the solidification point of the fatty material define the lower limit for useful temperatures. At the other end of the range, the degradation to flavour which may result upon exposure of flavour and aroma constituents to higher temperature should also be avoided. Normally, however, decaffeination can be effected within the range of from 0° to 50 °C, with from 10° to 30 °C being preferred for aqueous extracts. Where these constituents are essentially absent, still higher temperatures, up to the instability point for the particular vegetable material remain useful.

Once a particular fatty material and temperature for the decaffeination step have been selected, there remains the consideration of the desired degree of decaffeination. This is usually controlled, at least partly through the ratio of vegetable to fatty materials. Ordinarily, a ratio of fatty material to aqueous vegetable material of about 20 : 1 will achieve only partial decaffeination in a single contacting sequence.

Thus, for example, at that ratio, distribution coefficients of .035 and .085 yield about 40 % and 65 % decaffeination respectively. Increases in the ratio of fatty to vegetable material will, of course, increase this degree of decaffeination just as lower ratios decrease it.

Additionally, however, the means through which contacting with fatty material is accomplished affects the degree of decaffeination. Decaffeination can occur as previously described, through a one-step decaffeination sequence including contacting a particular weight of fatty material with a particular weight of aqueous extract, maintaining such materials in contact for a period sufficient to approach or reach the caffeine distribution equilibrium, and then separating the extract. The efficiency of decaffeination may however be increased by increasing the number of steps. Accordingly, in a preferred em10 bodiment of the present invention, decaffeination is performed in a multi-step sequence, wherein the vegetable material is contacted with successive aliquots of the fatty material until the desired degree of decaffeination has been reached.

This preferred embodiment may most simply be followed by successively contacting the caffeine-containing composition with aliquots of a particular fatty material, maintaining the fatty and aqueous phases in contact for a period of time sufficient to effect a substantial transfer of caffeine into the fatty material (such a transfer ordinarily being in an amount greater than about 70 % of the equilibrium distribution therein) , separating the aqueous and fatty phases and then repeating this sequence of steps with additional aliquots of caffeine free fatty material.

Still another form of this preferred embodiment comprises counter-current decaffeination. Therein, an initially caffeinefree fatty material is passed through consecutive volumes of vegetable material which are arrayed in reverse order by caffeine content. Thus, the fresh fatty material first contacts the most decaffeinated vegetable material volumes, and then those of higher caffeine content. During this process 5 embodiment, when the first vegetable material volume reaches the desired degree of decaffeination, it is simply by-passed while a new volume — having the highest caffeine content — is connected down-stream, to maintain a constant number of volumes on stream and a proper order of contact with the fatty material.

It is additionally noted that aqueous solutions or extracts of vegetable material may contain, for example, from 2 to 60 % soluble solids by total weight. Ordinarily, however, it is preferred that the solutions to be decaffeinated have a soluble solids concentration of from 10 to 50 %, preparatory to contacting with the fatty material caffeine solvent. Such concentrations are preferred for the purpose of minimizing the subsequent volumes of liquids whioh may be utilized in the decaffeination sequence, as well as for the purpose of reducing the quantity of water which must eventually be removed from a brew or extract which is to be dried to solid form.

Concentration may be obtained through techniques well known to the prior art. Again, because the aqueous extract will eventually provide the dried beverage product, it is de25 sirable that such concentration be obtained under conditions which will minimize the possibility of adverse effect on fla13 vour. Accordingly, it is preferred that techniques such as low pressure evaporation or freeze concentration, which avoid exposing the brew to higher temperature for any substantial period of time, be utilized.

The present invention also includes utilization of a fatty material for direct decaffeination of solid vegetable materials. Exemplary of such solids are green coffee beans which may be provided in ground, crushed and, most desirably, whole form. Roast coffee beans may also be utilized; however volatiles should first be removed to avoid undue loss of valuable beverage constituents. Consequently, the decaffeination of whole green beans is most preferred and the following discussion of this embodiment is particularly directed thereto, although other vegetable materials may be treated in similar manner.

Use of solid vegetable materials is a particularly preferred embodiment of the present invention inasmuch as it obviates certain disadvantages of dealing with aqueous solutions of vegetable material. Thus, the separation of the fatty mate20 rial from the caffeine-containing composition is facilitated by the fact that, while the fatty material remains liquid, the vegetable material is in solid form. Separation of the beans and fatty material may even conveniently be effected by simple drainage of the beans and, where centrifugal force is utilized . to facilitate this separation, fairly simple machinery is adequate.

Further, in the separation of green coffee beans from a liquid fatty material, the degree of separation may be essentially 100 %. Whereas even the most sophisticated of immiscible liquid separations may result in some retainment of one liquid in the other, no such problem is encountered here. Once most of the fatty material has been separated from the beans, a secondary physical purification step, such as direction of a burst of steam through the beans, permits essentially 100 % separation of retained fatty material. Moreover, even this additional step may be rendered unnecessary. Because of the post-decaffeination roasting and extractive processing of the beans, where a substantially flavourless fatty material is utilized, little if any effect upon the flavour of the eventual beverage product will result even if separation is incomplete.

In order to be in a form readily susceptible to caffeine removal, green coffee beans should contain some moisture. The beans ordinarily naturally contain from 8 to 10 % moisture, although higher amounts, of at least about 20 % by total weight are preferred. The upper limit of moisture content, however, is more variable. Decaffeination of a caffeine-containing composition comprising green beans is desirably performed in the absence of free liquid water, so as to avoid the separation problems incident to an admixture of liquids and the possible loss of valuable vegetable material constituents solubilized in that water. Accordingly, in this embodiment of the present invention it is preferred that the green beans contain between about 20 and 60 %, most preferably between about 40 and 60 %, water by total weight.

The incorporation of water into green beans is easily accomplished. Thus, for example, the beans may simply be immersed in water and there maintained for several hours, until they have absorbed the desired amount of moisture. Thereafter, they may easily be separated from the excess water, for example, by centrifugation. Through the use of heat and/or pressure, this incorporation or swelling of the beans may be accelerated. Thus, for example, where beans are immersed in water at a temperature of about 80 to 90 °C, they achieve the desired moisture content much more quickly. Also, Upon being subjected to steam at about 2 atmospheres, even less time — normally about 1 to 30 minutes — is sufficient to reach the desired moisture content.

Once the beans have been swollen to an appropriate moisture content, they are placed in a bath or stream of fatty material until the desired degree of decaffeination has been achieved. Here, the time of admixture becomes significant : transfer of caffeine from the beans is much slower than from dilute solution. Accordingly, it is desirable that periods of at least 30 minutes, with longer periods for more complete degrees of decaffeination, be permitted for this step.

In processes leading to high degrees of decaffeination, it is also important to ensure that the moisture content of the swollen beans does not significantly decrease during treat16 ment. Contact between swollen beans and fatty material can result in lower moisture contents due to loss of water from the beans to the fatty material. Where this decrease brings the beans to a moisture content below the preferred 40 to 60 % range, there occurs a corresponding decrease in the efficiency of decaffeination.

It is therefore preferred that the fatty material utilized for decaffeination contain a small amount of water.

From 0.9 to 1.2 %, most desirably about 1.0 %, of water by weight of fatty material is ordinarily utilized in this preferred embodiment of this invention. This amount acts to maintain in equilibrium the amount of water present in the beans and the fatty material, so that during contacting there is no net migration of water from the beans to the fatty phase, nor vice-versa. On the other hand, it prevents excessive removal of water from the beans, and on the other it minimizes the total amount of water present during decaffeination, thereby avoiding undue loss of non-caffeine, water-soluble bean constituents.

Again, the use of multi-step as opposed to single-step contact of fatty material with the vegetable material may be practiced in the manner previously described. Thus co-current and, more preferably, counter-current extraction with fatty material are desirable embodiments of the present invention.

One aspect by which the decaffeination of swollen green beans differs substantially from decaffeination of aqueous 41049 caffeine-containing solutions lies in the effect of temperature upon the efficiency of decaffeination. As previously noted, where decaffeination involves the contacting of fatty material with an aqueous caffeine-containing solution, differences in temperature during suoh contacting do not have a large effect upon the efficiency of decaffeination. In treating solid beans, however, increases in the prevailing temperature for decaffeination may dramatically increase the rate of caffeine removal.

Accordingly, to achieve maximum efficiency of caffeine removal, decaffeination of beans is preferably carried out at as high a temperature as is practicable. Degradation of fatty materials customarily occurs at or around a temperature of about 150 °C, and therefore this temperature usually represents a practical maximum limit for decaffeination. Also, prolonged contact times at very high temperatures may produce some degradation of flavour constituents. Accordingly, it is preferred that the decaffeination of green beans be performed within the temperature range of from about 50° to 120 °C.

A further aspect ol the present invention involves regenerating caffeine-containing fatty material so as to permit reuse thereof in the decaffeination process. This is most efficiently achieved by contacting the separated caffeine-containing fatty materia] with water, permitting the transfer of the caffeine into aqueous phase, and then separating the fatty material to permit its recycle for further decaffeination. In large measure, the regeneration sequence reverses the steps already described above with respect to decaffeination. In addition, however, it readily permits isolation of the caffeine from the regenerate aqueous phase.

For regeneration of the fatty material, the efficiency of caffeine removal to aqueous phase is again governed by the same parameters of temperature, the caffeine distribution coefficient of the particular fatty material, and the weight ratio of fatty material to water as discussed above with res10 pect to the separation of caffeine from an aqueous solution of vegetable material.

Because flavour degradation is not a serious problem during regeneration, as constituents of the final product are not present, the temperature during regeneration may be raised to improve the efficiency of caffeine transfer to the aqueous phase. Thus where, with increasing temperature, the solubility of caffeine in water increases more rapidly than in the fatty material, it is advantageous to effect regeneration at a temperature up to 100 °C (and even higher where pressure is uti20 lized to avoid evaporation). If on the other hand, lower temperatures favour this transfer then they should be employed.

Also, because it is here desired to transfer caffeine from the fatty material to an aqueous phase, the relatively greater solubility of caffeine in water permits the utiliza25 tion of low fatty to aqueous phase ratios, even for substan19 419 49 tially Complete transfer. Additionally, where it is desired further to minimize the amounts of water utilized in regeneration of the fatty material, a multi-step regeneration sequence comprising co-current or counter-current extraction of fatty material with water may be utilized in the same manner as has already been described hereinabove so as to facilitate the efficient regeneration of the fatty material.

Incident to regeneration of the fatty material through removal of caffeine with water, it has been discovered that the separated fatty material can contain — even when separation of these immiscible liquids is accomplished through Such normally efficient means as centrifugal separation — about 1 % by weight of water. This water is desirably removed from the fatty material before recontacting vzith vegetable material so as to avoid dilution of liquid vegetable materials. Removal of the entrained water in the fatty material can be accomplished by such means as a flash distillation under vacuum conditions or equivalent known techniques.

As previously described, certain preferred embodiments of this invention relating to decaffeination of solid vegetable materials rely upon utilizing a fatty material containing a small amount of water. In the practice of these embodiments, the dilution factor becomes negligible. Therefore, the regenerated fatty material containing entrained water may be used directly for further decaffeination. Alternatively, its aqueous content may be adjusted — for example, by adding water or by partial stripping — as required to bring it to an optimum water content.

Even where the presence of water in the fatty material is desired, however it is preferred to remove the entrained water and then add the desired amount of water to dry fatty material. This sequence of steps ensures an optimum water content and avoids the difficulties and/or interruptions required for monitoring the entrained water content of regenerated fatty material and then adjusting it, as desired.

The following examples are illustrative of the present invention. Unless otherwise noted, the percentages are on a weight basis.

EXAMPLE 1 An aqueous extract of roast ground coffee beans is stripped with steam to remove volatiles. 10 kilograms of the stripped extract, at a soluble solids concentration of 19 % and a temperature of 22 °C, are then added to 179 kilograms of corn oil at 60 °C. The resultant admixture is agitated for 30 minutes and then passed through a centrifugal separa20 tor at a rate of 3.16 kilograms per minute. The brew, which is separated from the oil in the centrifuge, has a 51 % degree of decaffeination.

By repeating this treatment of the brew with additional corn oil, the degree of decaffeination is successively in25 creased until essentially complete caffeine removal is effected. - 21 419 49 EXAMPLE 2 A tea extract having a soluble solids concentration of 27.6 % and a temperature of 22 °C is mixed with corn oil in a volume ratio of 1 : 20, respectively, and maintained under agitation for 10 minutes. The admixture is then subjected to centrifugal separation to yield a tea extract exhibiting 63 % decaffeination. Again retreatment affords a means for achieving any greater desired degree of decaffeination.

EXAMPLE 3 Green coffee beans are decaffeinated utilizing a recirculating aqueous medium which has reached an equilibrium soluble solids concentration of 29 % and is at a temperature of 22 °C. Decaffeination is performed by passing the aqueous medium in counter-current through a column of green beans, with essentially caffeine-free beans being removed from the column at one end and natural green beans added at the other. Within the circulating aqueous system, and at a point removed from the column, aqueous medium is diverted through a centrifugal extractor to which coffee oil at 50 °C, in a ratio of 21 ί 1 to the medium, is added for removal of caffeine from the aqueous extract. Heat exchangers in the system are used to maintain the temperatures of these two liquids essentially as indicated.

With a single pass of the medium and oil through the centrifuge, over one-third of the caffeine in the medium is removed. A second pass of the medium and a further equal aliquot of oil increases the decaffeination of the medium to over 60 %. After roasting, grinding and extracting separate samples of decaffeinated beans obtained after the single and second passes, it is found that both sample aqueous extracts are essen5 tially caffeine-free.

EXAMPLE 4 Green coffee beans are subjected to steam at 110 °C until they reach a moisture content of 45 % by total weight, and 10 kg aliquots are placed into separate extraction chambers. Each of the aliquots is decaffeinated for four hours at 95 °C with corn oil which is passed through the chambers at a rate of 1.1 kg/minute.

In one Trial, A, oil is passed through only one chamber. Thereafter it is regenerated by extraction with water to remove its caffeine content, the water is removed, and the oil is then recirculated to maintain a continuous flow of caffeine-free corn oil to swollen beans in the chamber.

In a second Trial, B, four chambers are connected in series so that the corn oil flows through each. Regeneration and recirculation of the oil is accomplished only after it has passed through all four chambers. One chamber - the first contacted by oil - is removed each hour and a new chamber is added at the downstream end. In this manner, and after a start-up period of 6 hours a system is achieved wherein the four chambers contain beans of varying caffeine content by virtue of the fact - 23 419 4 9 that they have been subjected to different durations of onstream oil decaffeination.

The caffeine contents of beans from Trial A and from a chamber which has passed through all four stages of Trial 5 B after start-up were analyzed. Despite the fact that each of these beans had been decaffeinated under essentially the same physical conditions, their respective degrees of decaffeination are markedly different. Thus while the beans of Trial A exhibit 52 % decaffeination, those of Trial B ex10 hibit 92 %. Xt is therefore evident that multi-step extraction substantially increases the efficiency of decaffeination.

EXAMPLE 5 An aqueous extract of roast ground coffee beans is stripped with steam to remove volatiles. 200 grams of the stripped brew having a soluble solids concentration of 18.4 % are then admixed -with 2 kg of safflower oil and agitated for 30 minutes at 20 °C. This admixture was then centrifuged to break the emulsion and the brew separated by decantation. The separated brew exhibits a 56 % degree of decaffeination.

EXAMPLE 6 The process of Example 5 is repeated with the change that 2 kg of soy bean oil are substituted for the safflower oil. After separation, the brew exhibits a 56 % degree of decaffeination.

EXAMPLE 7 The process of Example 5 is repeated substituting 2 kg of peanut oil for the safflower oil. Additionally, the brew and oil are maintained at 10 °C - instead of 20 °C - through5 out the process. The separated brew exhibits a 56 % degree of decaffeination.

EXAMPLE 8 Green coffee beans are decaffeinated with coffee oil in a four-chamber countercurrent extraction zone in the manner 10 described for Trial B of Example 4. Each chamber, or cell, contains 6.8 kg of beans by dry weight. The oil is maintained at 105 °C and extraction is performed over a total extraction period of 6 hours (1.5 hours for each cycle). A total oil to bean weight ratio of 120 : 1 is utilized.

After each pass of the recirculating oil through all four chambers of the extraction zone, the oil regenerated by aqueous extraction for caffeine and then is stripped to remove its aqueous content. A predetermined measure of water is admixed with the oil preparatory to its recirculation.

Utilizing the foregoing procedure, five different Trials are made. These Trials differ essentially in the addition of varying amounts of water to stripped, caffeine-free fatty material. Data for steady-state conditions of operation of each Trial are as follows: Trial No. Water Content of Bean Charge Water Content maintained in Oil Percent Decaffein- atian NonCaffeine Solids Loss Type of Coffee Beans 5 1 54 % 0.37 87 % 2.5 % Milds (1.33% caffeine) 2 55 % 1.00 97 % 1.1 % It ' 3 55 % 1.00 97 % 1.1 % tl 10 4 55 % 0.75 69 % 2.4 % Rcbusta ¢2.15 % caffeine) 5 57 % 1.20 97 % 5.2 % It This data indicates that proper moisture contents permit optimum decaffeination with minimal loss of non-caffeine bean constituents. The efficiency of decaffeination decreases where the concentration of water present in the fatty material during decaffeination decreases. It is also shown that, although the efficiency of decaffeination remains high at higher aqueous contents for the fatty material, the high level of water present in the system results in an increase loss of non-caffeine solubles from the beans.

Claims (13)

1. WE CLAIM ;

1. A process for producing a decaffeinated vegetable material comprising contacting a liquid, water-immiscible fatty material with a caffeine-containing vegetable material, main5 tainxng said fatty material and vegetable material in contact for a period of time sufficient to transfer caffeine from said vegetable material into said fatty material, and separating the resultant, caffeine-laden fatty material from the decaffeinated vegetable material. 10

2. The process of Claim 1, wherein the caffeine-containing vegetable material comprises an aqueous extract of a member selected from the group consisting of tea and roast ground coffee.

3. The process of Claim 2, wherein prior to contacting the 15 aqueous extract with the fatty material, volatiles are separated from said extract.

4. The process of Claim 1, wherein the caffeine-containing vegetable material comprises an aqueous extract of green coffee beans. 20 5. The process of Claim 4, wherein the decaffeinated aqueous extract of green coffee beans, following contact with fatty material, is recycled for further contact with green coffee beahs. 6. The process of any one of Claims 2 to 5, wherein the aqueous 25 extract has a soluble solids concentration of 2 to 60 % by total weight. 419 49 7. The process of Claim 6, wherein said aqueous extract has a soluble solids concentration of 10 to 50 % by weight. 8. The process of any one of Claims 2 to 7, wherein the aqueous extract and fatty material are contacted and maintained at a

5. Temperature between 0 °C and 50 °C.

6. 9. The process of Claim 1, wherein the caffeine-containing vegetable material is green or roasted coffee beans.

7. 10. The process of Claim 9, wherein volatiles are separated from said roast coffee beans prior to decaffeination. 10 11. The process of Claim 9 or Claim 10, wherein prior to contact of the beans with fatty material, said beans are swollen with water to a total moisture contact of from 20 to 60 % by weight. 12. The process of any one of Claims 9 to 11, wherein the beans 15 and fatty material are contacted and maintained at a tempe- rature between 30° and 150 °C. 13. The process of any one of Claims 9 to 12, wherein the fatty material utilized to contact the beans has a moisture content which is substantially in equilibrium with the moisture 20 content of the beans.

8. 14. The process of any one of the preceding Claims, wherein the separated caffeine-laden fatty material is contacted with water to transfer substantially all the caffeine contained therein into aqu'.ou:; solution, the caffeine-laden aqueous 25 solution is separated from said fatty material and the caf28 feine-free fatty material is recycled for further contact with caffeine-containing vegetable material.

9. 15. The process of Claim 14, wherein prior to recycle of the caffeine-free fatty material, the moisture content of said 5 fatty material is adjusted to a level which is substantially in equilibrium with the moisture content of the caffeine-containing vegetable material.

10. 16. The process according to any preceding Claim, wherein the fatty material is safflower oil, soy bean oil, com oil, pea10 nut oil, coffee oil, triolein or lard.

11. 17. The decaffeinated vegetable material produced by a process according to any preceding Claim.

12. 18. The process of producing a decaffeinated vegetable material according to Claim 1 substantially as herein described with 15 reference to any one of the Examples.

13. 19. Coffee decaffeinated by a process according to any one of Claims 1 to 16 or Claim 18.