CA1203111A

CA1203111A - Process for restoring virtually caffeine-free coffee bean extract substances into coffee beans which have been extracted with an aqueous liquid and have thereby been decaffeinated

Info

Publication number: CA1203111A
Application number: CA000438055A
Authority: CA
Inventors: Daniel Baumann; Erich Brandenberger; Stefan Gal
Original assignee: Haco AG
Current assignee: Haco AG
Priority date: 1982-10-01
Filing date: 1983-09-30
Publication date: 1986-04-15
Also published as: JPS59130136A; EP0108038A1; ES526098A0; ES8405596A1; CH661409A5

Abstract

Abstract Virtually caffeine-free coffee bean extract sub-stances are restored into coffee beans which have been extracted with an aqueous liquid and thereby decaffeinated.
The swollen extracted beans are brought directly into contact, without intermediate drying, with a concentrated, decaffeinated aqueous coffee extract. The amount of this coffee extract is greater than the amount which the extracted beans are capable of absorbing. The extract content of the beans is thereby brought almost to the extract content of non-extracted coffee beans, virtually without its caffeine content being increased. The excess coffee extract is removed from the coffee beans. It can be recycled to the process again.

Description

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Process for restoring virtually caffeine-free coffee bean extract substances into coffee beans which have been extracted with an aqueous liquid and have thereby been decaffe;nated The decaffeination of coffee beans with water or an aqueous extract of green coffee has been known for a long t;me (compare French Patent Spec;f;cation No. 779~451, published on 5th Apr;l 1935, and U.S~ Patent Spec;ficat;on No. 2,309,09Z, patented on 26th January 1943). Neverthe-less, extract;on of the caffein ~;th organic solvents, ;n part;cular methylene chloride has ga;ned acceptance in recent decades. However~ decaffeination with aqueous liquids has recently again ach;eved importance because toxicolog;cal and ecological objections have lately ar;sen to the use of organic solvents. For this reason, improve-ments have been made to the process for decaffe;nation w;th aqueous liqu;ds (compare European Patent A1-O,OOA,398 of Coffex AG, published on 5th March 1980, and European Patent A1-0,040,712 of Societe des Produits Nestle S.Au~
zn published on Znd December 1981), which relate to the re-duct;on ;n extract;on losses by ;ncreas;ng the selectiv;ty of the active charcoal used for adsorpt;on of the caffeine.
~ wo processes for the decaffe;nation of coffee beans w;th aqueous l;qu;ds have essentially gained accep-tance, and are briefly described below:
The process of the GeneraL Foods Corporation(U.S. Patent Specification No. 2,309,092) uses as the ex-traction solution an aqueous extract from green coffee beans wh;ch is unsaturated in respect of caffeine but quasi-saturated in respect of the extract substances from coffee beans other than caffe;ne. Th;s extract ;s passed over fresh coffee beans, essentially only caffeine be;ng dissolved out of the coffee beans as a result of the g;ven sa~urat;on cond;tions. The caffeine can be removed from the resulting aqueous solution, in which ;t is enr;ched, w;th the aid of processes which have been known for a long time, such as by adsorption on active charcoal or adsorption resins or by liquid/liqu;d extrac--" ~2~3~

tion by means of an organic solvent and the l;ker A dis-advantage of this process is that the aqueous extraction solution must be kept continuously at a high temperature, in particular~ on the one hand, so that it does not cool per;odically and have to be warrned again to the extra-ction temperature, and, on the other hand, so that no micro-organisms can develop~ After the aqueous extraction solution has been ~sed several times, both color and fLavor changes thel~eby occur. As a result, the cof~ee beans decaffeinated with the aid of such solutions wh;ch have been used several times have certain flavor and color de~iciencies.
The other process uses pure water for the extrac-tion of the caffeine. However, besides the caffeine, other extract substances are also thereby dissolved out of the coffee beans and must then be restored to the coffee beans again. This is necessary ;n Sw;tzerland, merely in view of the Swiss regulations on the treatment of foodstuffs and commodities, list of permitted solvents for the decaffeinat;on of coffee of 1st July 1981, para graph II, line 3. For this purpose, the beans are partly dried after the extract;on; the extraction solut;on is decaffeinated ir the abovementioned manner and then con-centrated, and is subsequently brought together with the ~5 extracted, partly dried coffee beans. However, the coffee beans are additionally exposed to heat by the intermed;ate drying, which leads to an impairment in their flavor. In addition, the extract substances are enr;ched at the surface of the coffee beans ~hen the relatively concentrated extract solut;on is adsorbed, and th;s impedes roasting and also impairs the cup quali~y.
The invention relates to a process for restoring virtually caffeine-free bean coffee extract substances into coffee beans which have been extracted with an aqueous liquid and thereby decaffeinated, which does not have the disadvantages of the two processes described above but, because of a technically novel process procedure, combines their advantages~ In particular, it has been found, surprisingly, that rediffusion of the extract substances

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into the extracted cofeee beans is possible under quite specif;c circumstances, even ~ithout predrying of the beans, as long as the aqueous extract is present in an excess in relation to the amount which the extracted beans are capable o~ absorbing. Under these circumstances, an equilibrium is established in the course of the pro-cess between the extract substance content of the coffee beans and the extract substance content of the caffeine-free extract surrounding the beans. It is thereby possible almost to re-establish the natural extract content of the`
coffee beans after decaffeination~ and as a result it is also possible to achieve optimum cup quality by normal roasting of the treated coffee beans.
The process according to the ;nvention thus com-prises bringing the swollen extracted beans, without intermediate drying, directly into contact with an amount of a concentrated, decaffeinated aqueous coffee extract which is gre~ter than the amount the extracted beans are capable of absorbing, whereupon the extract content of the beans is brought almost to the extract content of non-extracted coffee beans, virtually ~ithout their caffeine content being increased, and removing the excess coffee extract from the coffee beans.
Another surprising fact is that even when the excess coffee extract is used again in this process, no reduction in qual;ty of the coffee beans occurs because the extract substances are continuously renewed by mixing the excess coffee extract of relatively low extract sub~
stance content with the fresh decaffeinated coffee extract obtained in the extraction of the subsequent batch of coffee beans with water. In particular, equilibrium con-ditions are established between the extract substances in the fresh decaffeinated coffee extract, the extract substances in the circulating excess coffee extract and the extract substances in the decaffeinated coffee beans~
so that the residence time of the extract substances in the aqueous phase is shortened. This circumstance leads to an addit;onal improvement in the cup quality in com-par;son with the previously kno~n processes.

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Another advantage of the process according to the invention is that an excess of decaffeinated coffee ex-tract in relation to the amount which can be absorbed by the extracted coffee beans is always used, so that the beans in all cases conta;n sufficient extract substances and fulfill the regulations in this respect in Switzerland t22X by weight of extract substances)A In the simple restoration process described above as the second known process, this is no~ necessarily ensured, because the losses of extract substances other than caffeine ~hich unavoidably occur during decaffeination of the aqueous extraction soiution are not compensated, so that these extract substances are absent from the treated coffee beans. Adsorbents which are charged with cof-fee extract substances other than caffeine or with substitutes of corresponding molecular structure and size are therefore used for decaffeination of the aqueous extract in the process according to European Patent A1-0,~08,398. An active charcoal charged with sucrose and formic acid is used in the example of this document. An act;ve charcoal ~hich is pretreated w;th hydrochlor;c acid for the purpose ~f neutral;zation is used ;n the known process accord;ng to uropean Patent A1-0,040,712. These measures are unnecessary ;n the present process.
In the process according to the ;nvention, the excess coffee extract is preferably recycled to the pro-cess by mix;ng with the fresh decaffe;nated coffee extract obta;ned during extract;on of the subsequent batch of coffee beans and concentrating the mixture.
The weight rat;o of extracted coffee beans to concentrated coffee extract ;s as a rule in the range from 1:1 to 1:10, preferably ;n the range from 1:1 to 1:3, and is~ in part;cular, about 1:2.
The decaffe;nated coffee extract usually has a dry 35 substance content of 15 to 50X by weight, preferably of 20 to 40% by we;ght, and in particular of about 30% by weight~
It is aLso poss;ble to follow a procedure in wh;ch the deca-ffeinated cof-fee extract is circulated over the swollen beans, which have been extracted but not 12~3~

inter~ediateLy dried, and through a vacuum evaporator so that the concentration of the extract increases con-tinuously, until the desired end value is reached.
The extracted beans and the decaffeinated coffee extract can be brought into contact with one another at temperatures of 40 to 90C. At 80 ~5C, the dif-fus;on equilibrium is established after 3 to 4 hours, and at 40C this period is correspondingly longer. The process is preferably carr;ed out under normal pressure, but pressures of 2 to 3 bar can also be applied~

Example 1 A) 60 kg of raw coffee ~ith a water content of 8X
by weight, a caffeine content of 1.0X by weight and an extract content of 28% by weight, and 21û liters of pro-cess water are introduced into an extractor of 250 liters capacity. The beans are s~ollen at a temperature of 80C
for about 30 ninutes. The extraction solution is then conveyed, via a pump and a filter~ alternately through Z0 adsorption columns containing untreated ac~ive charcoal and through ~he extractor. After 9 hours, the coffee beans contain only 0.025% by ~eight or less of caffeine and the aqueous extract contains only 0.010Z by weight or less of caffeinea The extraction is ended and the de-caffeinated extract, which has an extract content of 4.5to 5.0% by we;ght (refractometer value 5.5X) is pumped off from the coffee beans and combined with the excess extract from a preceding batch t100 liters, refractometer value 25%).
B) The combined solutions~ includi,ng the water from the lines, the adsorption columns and the like, are con-centrated in vacuo to an extract content of about 30X by weight (refractometer value 35%)~ The solution thus con-centrated (about 125 liters) is conveyed to an ;nter-mediate storage vessel, which is d~signed such that pro-longed storage of the concentrated solut;on is possibleu 100 to 120 liters of this concentrated extract are now added to the decaffeinated coffee beans, which have not been intermed;ately dried, and are mixed therewith at 80C for 4 hours. When diffusîon equ;libr;um has been reached, the excess extract (100 liters, refractometer value 25X) is pumped off again and stored in a tank at 70 to 80C for further use. The coffee beans are freed from the adherin~ extract ~ith a little water and are dried with hot air in the conventional manner. They have a water content of 7X by weight, a caffeine content of 0.06X by weight an~ an ex~ract content of 23X by we;ght.

Example 2 A) The procedure followed is as described in Example 1, under A).
8) The combined solutions are brought toge~her with the water from the lines, the adsorption columns and the like in a vessel and are mixed throughiy, 420 to 450 l;ters of a solution ~;th an extract content of about 15% by weight (refraction value 12 to 15X) being obtained.
This solution is passed in circulat;on over the decaf-feinated beans, which have not been intermediately dried, and through a vacuum evaporator, so that absorption of the extract substançe by the beans takes place simul-taneously with concentration of the extractO After about

3 hours~ the beans have uniformly taken up the desired amount of extract substance and the extract content of the extract has been increased to about 30X by weight.
The process ;s now ended, and the excess extract (100 liters with a refractometer value of about 25Z) is pumped off and stored in a tank at 70 to 80C for further use.
The coffee beans are freed from the adhering extract with a little water and dried with hot air in the conven-t;onal manner. They have a ~ater content of 7X by weight, a caffeine content of 0.05% by weight and an ex- -tract content of Z4Z by weight~
Ins~ead of active charcoal, adsorption resins which are known per se can also be used in the Examples with similar results.

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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 restoring virtually caffeine-free coffee bean extract substances into coffee beans which have been extracted with an aqueous liquid and thereby decaffeinated, which comprises bringing the swollen extracted beans, without intermediate drying, directly into contact with an amount of a concentrated, decaffeinated aqueous coffee extract which is greater than the amount the extracted beans are capable of absorbing, whereupon the extract content of the beans is brought almost to the extract content of non-extracted coffee beans, virtually without their caffeine content being increased, and removing the excess coffee extract from the coffee beans.

2. A process as claimed in claim 1, wherein the excess coffee extract is recycled again to the process.

3. A process as claimed in claim 1 wherein the weight ratio of extracted coffee beans to concentrated coffee extract is in the range from 1:1 to 1:10.

4. A process as claimed in claim 3 wherein the weight ratio of extracted coffee beans to concentrated coffee extract is in the range from 1:1 to 1:3.

5. A process as claimed in claim 3 wherein the weight ratio of extracted coffee beans to concentrated coffee extract is about 1:2.

6. A process as claimed in claim 1 wherein a decaffeinated coffee extract with a dry substance content of 15 to 50% by weight is used.

7. A process as claimed in claim 6 wherein a decaffeinated coffee extract with a dry substance content of 20 to 40% by weight is used.

8. A process as claimed in claim 7 wherein a decaffeinated coffee extract with a dry substance content of about 30% by weight is used.

9. A process according to claim 1, wherein the decaffeinated coffee extract is passed in circulation over the swollen extracted beans, which have not been intermediately dried, and through a vacuum evaporator, so that the concentration of the extract is increased continuously, until the desired end value is reached.

10. A process as claimed in claim 1, wherein the extracted beans and the decaffeinated coffee extract are brought into con-tact at a temperature of 40 to 90°C.

11. A process as claimed in claim 10, wherein the tempera-ture is 80° ? 5°C.

12. A process as claimed in claim 1, wherein the extracted beans and the decaffeinated coffee extract are brought into con-tact under normal pressure.

13. A process as claimed in claim 1, wherein the extracted beans and the decaffeinated coffee extract are brought into con-tact under a pressure of 2 to 3 bar.