CA1333671C - Process suitable for the decaffeination of raw coffee - Google Patents
Process suitable for the decaffeination of raw coffeeInfo
- Publication number
- CA1333671C CA1333671C CA000583041A CA583041A CA1333671C CA 1333671 C CA1333671 C CA 1333671C CA 000583041 A CA000583041 A CA 000583041A CA 583041 A CA583041 A CA 583041A CA 1333671 C CA1333671 C CA 1333671C
- Authority
- CA
- Canada
- Prior art keywords
- carbon dioxide
- process according
- extraction
- caffeine
- raw coffee
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23F—COFFEE; TEA; THEIR SUBSTITUTES; MANUFACTURE, PREPARATION, OR INFUSION THEREOF
- A23F5/00—Coffee; Coffee substitutes; Preparations thereof
- A23F5/20—Reducing or removing alkaloid content; Preparations produced thereby; Extracts or infusions thereof
- A23F5/206—Reducing or removing alkaloid content; Preparations produced thereby; Extracts or infusions thereof by extraction of the beans with selective solvents other than water or aqueous bean extracts, including supercritical gases
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Polymers & Plastics (AREA)
- Tea And Coffee (AREA)
- Fats And Perfumes (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- General Preparation And Processing Of Foods (AREA)
Abstract
A process for the decaffeination of raw coffee. The process involves increasing the moisture content of the raw coffee and selectively extracting caffeine from the raw coffee by using hydrous liquefied carbon dioxide as an extractant at a pressure below the critical pressure of carbon dioxide. The process differs from conventional processes which use liquefied carbon dioxide at pressures above the critical pressure but it is surprisingly found that the process of the invention does not result in the co-extraction of aroma components of the coffee. The use of lower pressures means that the process of the invention is more economical than conventional processes.
Description
~ 33~671 Process suitable for the decaffeination of raw coffee The present invention relates to a process suitable for the decaffeination of raw coffee.
West German published patent application DE-AS 22 12 281 describes a process wherein the extraction of caffeine is carried out by employing carbon dioxide as the extractant at a pressure above the critical pressure of carbon dioxide.
The employment of a supercritical extraction pressures is considered to be necessary, since it is believed that extraction at lower pressures causes the removal of essential substances and a concomittant reduction in the aroma and taste of the coffee.
The pressures used bear considerably-upon the economy of the conventional process. In this particular case, which includes the recovery of extracted caffeine by the vaporization of carbon dioxide, substantial energy losses are occasioned by large pressure differences existing between the extraction and caffeine separation steps. Despite the use of high pressures of 380 atm., the known process in which caffeine is recovered by means of CO2 vaporization requires long extraction times, which can be up to 18 hours According to West German published patent application DE-OS 23 57 590, raw coffee is first extracted with water, whereafter the caffeine is removed from the extract solution by liquid-liquid extraction with CO2 at a temperature slightly below the critical temperature and at an equilibrium pressure of carbon dioxide corresponding to such temperature.
This process too is quite uneconomical since a water extraction step is required prior to the liquid-liquid extraction step, and the latter step is followed by the reimpregnation of the extracted raw coffee with the decaffeinated extract solution.
The object of the present invention is therefore the development of a similar type of process suitable for ~' t 33367 1 decaffeinating raw coffee, such a process being more economical than known processes and enabling an uncomplicated separation and recovery of caffeine without impairing the aroma of the coffee.
According to the invention there is provided a process for the decaffeination of raw coffee, which comprises increasing the water content of raw coffee and selectively extracting caffeine from the raw coffee with the aid of hydrous liquefied carbon dioxide at a pressure below the critical pressure of carbon dioxide.
The present invention is based upon the surprising discovery that decaffeination of raw coffee having a high water content can be accomplished, in contrast to the generally held assumption, without any loss of aroma, i.e.
the decaffeination process can be carried out selectively at extraction pressures below the critical C02 pressure. By enabling the maintenance of minimal pressure differences between the extraction and caffeine separation steps, this treatment precludes, to the greatest extent possible, energy losses through pressure gradients. The caffeine separated in this manner does not differ, according to analytical criteria, from caffeine extracted at pressures above the critical pressure of carbon dioxide. The coextraction of aroma-related and constituent substances was not observed, as feared by experts.
The above-mentioned result was unexpected in view of the powerful dissolving effect of liquefied subcritical carbon dioxide on such materials, especially since its strong dissolving power has always been used in prior art processes for fully extracting the constituent substances of plant products (see, for example, Food Technology 1969, Vol. 23, 1382 and ibid., June 1986, 66-69). It is this very rôle of subcritical carbon dioxide as described in the above-mentioned publication that has incited prejudice against the use of liquefied subcritical C02 for selective removal purposes.
In an advantageous embodiment of the proposed process, a water content of between 10 and 60%, preferably between 45 and 50% is suggested. The carbon dioxide should, ideally, be virtually saturated with water when introduced at the extraction stage so that the water content of the raw coffee cannot, during extraction, decrease as a result of the continuous removal of water by the carbon dioxide.
The extraction pressures can lie slightly below the critical pressure of the carbon dioxide; as the extraction pressure approaches the critical pressure, the density and consequently the dissolving power of C02 increase. The extraction pressure lies most preferably between 65 and 70 bar.
The ideal extraction temperature lies preferably between 20 and 25C; the lower limit of the proposed temperature range is however, determined by the permissible time span and the amount of C02 available for this process, while the upper limit of the range is determined on the one hand by the vaporization point of C02 and on the other hand by the possibility, which rises with every increase in extraction temperature, of quality damage to the coffee.
The advantages conferred by the proposed process are most effectively realized when the carbon dioxide is cycled through extraction and caffeine separation steps. The devices required for decreasing or increasing the pressure as well as for heating the carbon dioxide are complemented by a moisture regulating step, which precedes the extraction step in the cycle and ensures that the C02 is vaporized in the caffeine separation step so as to facilitate the simple and economical~recovery of caffeine. This procedure furthermore enables the maintenance of the smallest possible pressure differences between the extraction and caffeine separation steps and thus allows only minimal energy loss.
;y The invention is described in further detail with reference to the accompanying drawing which is a schematic representation of a preferred apparatus suitable for carrying out the process of the invention.
The device illustrated in the drawing comprises an extraction vessel 1 containing raw coffee of a preset water content.
Liquefied C02 is introduced into the device initially from a supply 7, flows (upwards as in the diagram) through the extraction vessel 1 to be enriched with caffeine, which it extracts from the moist raw coffee. The C02 has, in this embodiment, a pressure of approximately 70 bar and a temperature of approximately 22 to 23C.
The liquefied C02, which is loaded with caffeine together with a small quantity of water, flows from extraction vessel 1 through a release valve 9 into a separator vessel 2, where it expands to about 60 bar. The temperature drop resulting from C02 expansion is counteracted by the supply of an equivalent amount of heat to the system.
The caffeine, caffeine-saturated water and C02 separate in separator vessel 2. The gaseous C02, relieved of caffeine, is, together with water, released at the top of separator vessel 2 and enters a condenser 3, in which the C02 is re-liquefied. The re-liquefied C02 flows through a collector vessel 4 (this step may be omitted if required) to a pump 5, which recirculates the C02 through a heat exchanger 6 and a water container 8 to the bottom of extraction vessel 1. Heat exchanger 6 raises the temperature of the liquefied C2 again to the extraction temperature of approximately 22 to 23C. The C02 is saturated with water in the water container 8.
The C02, thus loaded with water, flows again through extraction vessel 1 to extract more caffeine from the raw coffee.
1 33~6~ 1 The raw coffee is decaffeinated to the extent required, removed from the extraction vessel 1 and replaced with fresh raw coffee.
The caffeine deposited in the separator vessel 2 as a S result of C02 vaporization can be discharged at purity of over 99% from the base of separator vessel 2.
West German published patent application DE-AS 22 12 281 describes a process wherein the extraction of caffeine is carried out by employing carbon dioxide as the extractant at a pressure above the critical pressure of carbon dioxide.
The employment of a supercritical extraction pressures is considered to be necessary, since it is believed that extraction at lower pressures causes the removal of essential substances and a concomittant reduction in the aroma and taste of the coffee.
The pressures used bear considerably-upon the economy of the conventional process. In this particular case, which includes the recovery of extracted caffeine by the vaporization of carbon dioxide, substantial energy losses are occasioned by large pressure differences existing between the extraction and caffeine separation steps. Despite the use of high pressures of 380 atm., the known process in which caffeine is recovered by means of CO2 vaporization requires long extraction times, which can be up to 18 hours According to West German published patent application DE-OS 23 57 590, raw coffee is first extracted with water, whereafter the caffeine is removed from the extract solution by liquid-liquid extraction with CO2 at a temperature slightly below the critical temperature and at an equilibrium pressure of carbon dioxide corresponding to such temperature.
This process too is quite uneconomical since a water extraction step is required prior to the liquid-liquid extraction step, and the latter step is followed by the reimpregnation of the extracted raw coffee with the decaffeinated extract solution.
The object of the present invention is therefore the development of a similar type of process suitable for ~' t 33367 1 decaffeinating raw coffee, such a process being more economical than known processes and enabling an uncomplicated separation and recovery of caffeine without impairing the aroma of the coffee.
According to the invention there is provided a process for the decaffeination of raw coffee, which comprises increasing the water content of raw coffee and selectively extracting caffeine from the raw coffee with the aid of hydrous liquefied carbon dioxide at a pressure below the critical pressure of carbon dioxide.
The present invention is based upon the surprising discovery that decaffeination of raw coffee having a high water content can be accomplished, in contrast to the generally held assumption, without any loss of aroma, i.e.
the decaffeination process can be carried out selectively at extraction pressures below the critical C02 pressure. By enabling the maintenance of minimal pressure differences between the extraction and caffeine separation steps, this treatment precludes, to the greatest extent possible, energy losses through pressure gradients. The caffeine separated in this manner does not differ, according to analytical criteria, from caffeine extracted at pressures above the critical pressure of carbon dioxide. The coextraction of aroma-related and constituent substances was not observed, as feared by experts.
The above-mentioned result was unexpected in view of the powerful dissolving effect of liquefied subcritical carbon dioxide on such materials, especially since its strong dissolving power has always been used in prior art processes for fully extracting the constituent substances of plant products (see, for example, Food Technology 1969, Vol. 23, 1382 and ibid., June 1986, 66-69). It is this very rôle of subcritical carbon dioxide as described in the above-mentioned publication that has incited prejudice against the use of liquefied subcritical C02 for selective removal purposes.
In an advantageous embodiment of the proposed process, a water content of between 10 and 60%, preferably between 45 and 50% is suggested. The carbon dioxide should, ideally, be virtually saturated with water when introduced at the extraction stage so that the water content of the raw coffee cannot, during extraction, decrease as a result of the continuous removal of water by the carbon dioxide.
The extraction pressures can lie slightly below the critical pressure of the carbon dioxide; as the extraction pressure approaches the critical pressure, the density and consequently the dissolving power of C02 increase. The extraction pressure lies most preferably between 65 and 70 bar.
The ideal extraction temperature lies preferably between 20 and 25C; the lower limit of the proposed temperature range is however, determined by the permissible time span and the amount of C02 available for this process, while the upper limit of the range is determined on the one hand by the vaporization point of C02 and on the other hand by the possibility, which rises with every increase in extraction temperature, of quality damage to the coffee.
The advantages conferred by the proposed process are most effectively realized when the carbon dioxide is cycled through extraction and caffeine separation steps. The devices required for decreasing or increasing the pressure as well as for heating the carbon dioxide are complemented by a moisture regulating step, which precedes the extraction step in the cycle and ensures that the C02 is vaporized in the caffeine separation step so as to facilitate the simple and economical~recovery of caffeine. This procedure furthermore enables the maintenance of the smallest possible pressure differences between the extraction and caffeine separation steps and thus allows only minimal energy loss.
;y The invention is described in further detail with reference to the accompanying drawing which is a schematic representation of a preferred apparatus suitable for carrying out the process of the invention.
The device illustrated in the drawing comprises an extraction vessel 1 containing raw coffee of a preset water content.
Liquefied C02 is introduced into the device initially from a supply 7, flows (upwards as in the diagram) through the extraction vessel 1 to be enriched with caffeine, which it extracts from the moist raw coffee. The C02 has, in this embodiment, a pressure of approximately 70 bar and a temperature of approximately 22 to 23C.
The liquefied C02, which is loaded with caffeine together with a small quantity of water, flows from extraction vessel 1 through a release valve 9 into a separator vessel 2, where it expands to about 60 bar. The temperature drop resulting from C02 expansion is counteracted by the supply of an equivalent amount of heat to the system.
The caffeine, caffeine-saturated water and C02 separate in separator vessel 2. The gaseous C02, relieved of caffeine, is, together with water, released at the top of separator vessel 2 and enters a condenser 3, in which the C02 is re-liquefied. The re-liquefied C02 flows through a collector vessel 4 (this step may be omitted if required) to a pump 5, which recirculates the C02 through a heat exchanger 6 and a water container 8 to the bottom of extraction vessel 1. Heat exchanger 6 raises the temperature of the liquefied C2 again to the extraction temperature of approximately 22 to 23C. The C02 is saturated with water in the water container 8.
The C02, thus loaded with water, flows again through extraction vessel 1 to extract more caffeine from the raw coffee.
1 33~6~ 1 The raw coffee is decaffeinated to the extent required, removed from the extraction vessel 1 and replaced with fresh raw coffee.
The caffeine deposited in the separator vessel 2 as a S result of C02 vaporization can be discharged at purity of over 99% from the base of separator vessel 2.
Claims (15)
1. A process for the decaffeination of raw coffee, which comprises increasing the water content of raw coffee and selectively extracting caffeine from the raw coffee with the aid of hydrous liquefied carbon dioxide at a pressure below the critical pressure of carbon dioxide.
2. A process according to Claim 1 wherein the water content of the raw coffee is increased to 10 to 60%.
3. A process according to Claim 1 wherein the water content of the raw coffee is increased to 45 to 55%.
4. A process according to Claim 1 wherein the carbon dioxide is substantially saturated with water immediately prior to the extraction step.
5. A process according to any one of Claims 1 to 3 wherein the extraction pressure of the carbon dioxide lies slightly below the critical pressure in the range of 65 to 70 bar.
6. A process according to any one of Claims 1 to 3 wherein the extraction is carried out at a temperature below the critical temperature of carbon dioxide.
7. A process according to any one of Claims 1 to 3 wherein the extraction is carried out at a temperature in the range of 20 - 25°C.
8. A process according to Claim 1 wherein caffeine is separated from the carbon dioxide following the extraction step.
9. A process according to Claim 2 wherein caffeine is separated from the carbon dioxide following the extraction step.
10. A process according to Claim 3 wherein caffeine is separated from the carbon dioxide following the extraction step.
11. A process according to Claim 8, wherein the carbon dioxide is vaporized during the caffeine separation step.
12. A process according to Claim 9, wherein the carbon dioxide is vaporized during the caffeine separation step.
13. A process according to Claim 10, wherein the carbon dioxide is vaporized during the caffeine separation step.
14. A process according to Claim 8, Claim 9, Claim 10, Claim 11, Claim 12 or Claim 13, wherein the variation of carbon dioxide pressure between the extraction and caffeine separation steps is smaller than 30 bar.
15. A process according to Claim 8, Claim 9, Claim 10, Claim 11, Claim 12 or Claim 13, wherein the variation of carbon dioxide pressure between the extraction and caffeine separation steps is smaller than 10 bar.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19873738783 DE3738783A1 (en) | 1987-11-14 | 1987-11-14 | PROCESS FOR RAW COFFEE DECOFFINATION |
| DEP3738783.9-41 | 1987-11-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1333671C true CA1333671C (en) | 1994-12-27 |
Family
ID=6340543
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000583041A Expired - Lifetime CA1333671C (en) | 1987-11-14 | 1988-11-14 | Process suitable for the decaffeination of raw coffee |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0316694B1 (en) |
| JP (1) | JP2728132B2 (en) |
| AT (1) | ATE72620T1 (en) |
| BR (1) | BR8805920A (en) |
| CA (1) | CA1333671C (en) |
| DE (2) | DE3738783A1 (en) |
| ES (1) | ES2032518T3 (en) |
| MX (1) | MX171464B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4003483A1 (en) * | 1989-02-09 | 1990-08-16 | Schoeller Bleckmann Stahlwerke | Caffeine removal from raw coffee - by extn. with supercritical carbon di:oxide super-satd. with water |
| DE4335321C2 (en) * | 1993-10-15 | 1996-08-01 | Joachim Brimmer Ingenieurbuero | Process for extracting coffee oil containing aroma components |
| JP5106843B2 (en) * | 2005-12-28 | 2012-12-26 | 豊和株式会社 | Method for extracting purple root extract and method for producing skin external preparation |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1692284A1 (en) * | 1966-07-25 | 1971-11-11 | Weiss Geb Schotte Irmgard | Process for the refinement of raw coffee beans, without the addition of chemicals using CO2 with or without H2O |
| CH535543A (en) * | 1970-02-05 | 1973-04-15 | Studiengesellschaft Kohle Mbh | Process for decaffeinating green coffee |
| DE2212281C3 (en) * | 1972-03-14 | 1978-11-18 | Hag Ag | PROCESS FOR DECOFFEINATING RAW COFFEE |
| DE2357590C3 (en) * | 1973-11-19 | 1983-02-03 | Hag Ag, 2800 Bremen | Process for decaffeinating green coffee |
| DE2638383A1 (en) * | 1975-08-27 | 1977-03-03 | D E J Int Research | Caffeine removal from coffee - by extraction with water, stripping with liq. or supercritical and renewed extraction |
| DE2737793A1 (en) * | 1977-08-22 | 1979-03-08 | Peter Siegfried | Decaffeination of raw coffee - by selective extraction of caffeine with extractant and compressed gas at elevated temp. and pressure |
| US4472442A (en) * | 1980-09-26 | 1984-09-18 | General Foods Corporation | Decaffeination process |
-
1987
- 1987-11-14 DE DE19873738783 patent/DE3738783A1/en active Granted
-
1988
- 1988-11-05 EP EP88118484A patent/EP0316694B1/en not_active Expired - Lifetime
- 1988-11-05 ES ES198888118484T patent/ES2032518T3/en not_active Expired - Lifetime
- 1988-11-05 AT AT88118484T patent/ATE72620T1/en not_active IP Right Cessation
- 1988-11-05 DE DE8888118484T patent/DE3868486D1/en not_active Expired - Lifetime
- 1988-11-11 MX MX013767A patent/MX171464B/en unknown
- 1988-11-11 BR BR888805920A patent/BR8805920A/en unknown
- 1988-11-14 CA CA000583041A patent/CA1333671C/en not_active Expired - Lifetime
- 1988-11-14 JP JP63288688A patent/JP2728132B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE3868486D1 (en) | 1992-03-26 |
| ES2032518T3 (en) | 1993-02-16 |
| EP0316694A3 (en) | 1989-08-30 |
| DE3738783C2 (en) | 1990-02-08 |
| MX171464B (en) | 1993-10-28 |
| JPH01240146A (en) | 1989-09-25 |
| ATE72620T1 (en) | 1992-03-15 |
| JP2728132B2 (en) | 1998-03-18 |
| BR8805920A (en) | 1989-08-01 |
| EP0316694B1 (en) | 1992-02-19 |
| DE3738783A1 (en) | 1989-05-24 |
| EP0316694A2 (en) | 1989-05-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |