CA1057565A - Continuous production of aromatic distillates under vacuum - Google Patents
Continuous production of aromatic distillates under vacuumInfo
- Publication number
- CA1057565A CA1057565A CA232,829A CA232829A CA1057565A CA 1057565 A CA1057565 A CA 1057565A CA 232829 A CA232829 A CA 232829A CA 1057565 A CA1057565 A CA 1057565A
- Authority
- CA
- Canada
- Prior art keywords
- steam
- coffee
- ground coffee
- vessel
- roast
- 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
Links
Landscapes
- Tea And Coffee (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Aromatic distillates from roast and ground coffee are continuously generated by passing steam through a moving bed of the coffee in counter-current fashion under vacuum
Aromatic distillates from roast and ground coffee are continuously generated by passing steam through a moving bed of the coffee in counter-current fashion under vacuum
Description
~(357S65 This invention reIates to a process and apparatus for the production of aromatic distillates from roast and ground coffee, and other aroma bearing substances. More particularly, the invention is concerned with a process for continuously gener-ating aromatic distillates by passing steam through a moving bed of coffee in a counter-current manner under vacuum.
Many methods have been developed for generating aromas from roast and ground coffee by passing steam therethrough, and condensing externally the resultant aroma - steam mixture to a liquid. Occasionally, it has been proposed to fractionate such mixtures to reduce the amount of water together with the more undesirable acid components by taking off a 'bottoms' fraction, and retaining the 'top' fraction containing a higher proportion of the more desirable coffee aromatics. Such distillates or fractionates are then added to instant coffee in different ways or at different stages of the manufacture to obtain more flavor-ful products than might otherwise be produced without this pre-process. In particular such distillates may be added to soluble coffee extracts immediately before freeze-drying.
As, however, the steamed roast and ground coffee has subsequently to be extracted by hot water to obtain the water soluble substances for which the well-known system of percolation column battery is widely-used in practice, it has been found convenient to carry out this preliminary steaming with the roast and ground coffee already filled into percolation columns.
Nearly all prior methods for the steaming of roast and ground coffee for aroma production are based upon an in-column and batch system of operation. The variables in such methods are steam pressure applied, and therefore its temperature, the time of passage of the steam, and the amount of condensate collectedr expressed conveniently as millilitres per lb. of roast and ground coffee steamed. The prior art is now replete with such in-column methods of steaming. - 1 - ~F
~7S65 However, it has been found that the prior methods suffer in that the conditions necessary for steaming result in the pro-duction of water-soluble extracts which are degraded, primarily on account of an excessively high acidity, while the re-addition of aromatic distillate only partially restores acceptable quality.
When it is considered that steaming conditions may be severe in respect of time and temperature, and are determined to a large extent by the pressure of the steam that must be applied to pass steam through a static and deep bed of coffee in a conventional percolation column, this degrading effect may not be surprising.
A further objection to an in-column system of steaming roast and ground coffee is that such a batch system does not lend itself conveniently to subsequent uniform condensation and fractionation of the distillate. It has been proposed to discard the roast and ground coffee after steaming, and add the distillate to the extract obtalned from fresh unsteamed roast and ground coffee, but clearly this is an expensive expedient.
Accordingly, it has been further considered to steam roast and ground coffee under such conditions that the degrading effect already described is minimized or eliminated. One method which has been proposed is by contacting the particles o roast and ground coffee in a separate, moving agitated bed with steam under pressure. However, this method still proposes the use of elevated temperatures in the steaming process from which the degrading effects upon the roast and ground coffee will still be evident.
It has now been found that good quality aromatic distillates without impairment of the subsequent water-soluble extract can be obtained by steaming roast and ground coffee in a continuous counter-current manner under vacuum conditions, viz.
where the pressure of the steam applied is less than atmospheric, that is 14.7 lbs. per sq. in.
In accordance with the present invention, there is pro-vided a process for the production of volatile aqueous aromatic distillates, especially from roast and ground coffee, which comprises passing steam through a moving and agitated bed con-tained in a closed cylindrical vessel, fitted with a helical screw conveyor. The steam is passed through the bed counter-currently to the passage of the roast and ground coffee, with arrangements for the introduction of the coffee and its exit from the chamber under vacuum. The resultant water-aroma vapours are withdrawn under vacuum and subsequently condensed or fractionated. The steam is introduced at a temperature less than 100C, that is vacuum steam is used.
The precise temperature of the steam at the entrance and exit, together with the feed rate of roast and ground coffee, determined in part by the speed of the screw, may be variedj according to the particular conditions and type of coffee, and the aroma quality desired. By having the steam temperature always less than 100C, and having the residence time of the roast and ground coffee less than about 5 minutes, the degrading effect, observed on subsequent examination of the water-soluble extract, with or without the added aromatics, is avoided.
The steamed coffee as it emerges from the continuous vacuum steaming apparatus is in a reasonably flowable condition, and may be conveyed with weighing to a fresh column awaiting filling of a conventional percolation bettery for the extraction of its water soluble coffee substances in the usual or desired manner. The grind of roast and ground coffee used should be that desired in the water extraction.
The aroma-water vapour mixture after condensing in a suitable manner, as for example, by a condenser with surfaces at 0C or lower, should normally constitute 10 ml or less of liquid per lb. of roast and ground coffee used. It may be subsequently added to the aqueous water extract, either dilute as extracted or to a concentrated evaporated extract as desired. In all cases, it is desirable to homogenize the extract with a small quantity of expressed coffee oil, that is about 0.5~ based on the weight of soluble solids. Such aroma-enriched extracts may be subse-quently freeze-dried or processed in other ways as desired to retain these aromatic volatile substances in a finished powder or granular product.
The process of the present invention may be carried out in an apparatus such as that illustrated in the accompanying drawing. The apparatus comprises a continuous counter-current contactor consisting of a chamber of cylindrical cross-section, about 5 feet long and 6 inches diameter. The chamber contains an open scroll-type helical screw conveyor 2 driven by a motor 3 to cause movement of roast and ground coffee from one end to the other; at one end fresh roast and ground coffee is continuously fed into the chamber through a rotary valve device 4, and the steamed grounds removed through another rotary valve 5 at the other end. The feed of roast and ground coffee and the speed of the screw is adjusted accord ng to the residence time of the coffee required, which may be about 1 minute or more. A feed rate of about 300 lbs/hr of coffee would provide a residence time of about 5 minutes ln substantially full bore flow. Steam is intro-duced through an opening 6 into the chamber, where the de-aromatized or steamed coffee is being discharged, and exits at the other end through another opening 7, and piping 8 connected to a condenser 9 and fractionater 10 to a vacuum pump 11 maintain-ing a flow of steam under vacuum, and therefore a temperature of less than 100C. The pressure differential across the chamber is monitored by pressure gauges 12 and 13. The flow of steam and its temperature may be adjusted according to the aromatic quality and quantity desired in the distillate. For example, some 6 lbs/
hr. distillate may be found desirable, with a vacuum at the steam exit point of 20 inches.
1~57565 The accompanying drawing illustrates but one embodiment of the present invention, and is for the purposes of illustration only. Various changes may be made from the illustrated embodi-ment although an essential feature of the invention is that the steam within the contacting vessel should be under vacuum to pro-vide the particular advantages desired. This vacuum measured at the exit point for the steam will normally be between 15 inches and 25 inches of mercury, a higher vacuum may not provide a suf-ficiently high temperature of the steam to cause rapid wetting of the coffee, and thus generate the steam aromas required. In addition, a very high vacuum results in very large volumes of steam-vapour-aromatics to be condensed, which results in the need for large heat transfer surfaces. It is also desirable for optimum quality of aromatic distillate that the roast and ground coffee used should be freshly ground and the supply pipe directly connected to the grinding equipment should retain the aromatic substances generated in the grinding and released in the ground state.
Many methods have been developed for generating aromas from roast and ground coffee by passing steam therethrough, and condensing externally the resultant aroma - steam mixture to a liquid. Occasionally, it has been proposed to fractionate such mixtures to reduce the amount of water together with the more undesirable acid components by taking off a 'bottoms' fraction, and retaining the 'top' fraction containing a higher proportion of the more desirable coffee aromatics. Such distillates or fractionates are then added to instant coffee in different ways or at different stages of the manufacture to obtain more flavor-ful products than might otherwise be produced without this pre-process. In particular such distillates may be added to soluble coffee extracts immediately before freeze-drying.
As, however, the steamed roast and ground coffee has subsequently to be extracted by hot water to obtain the water soluble substances for which the well-known system of percolation column battery is widely-used in practice, it has been found convenient to carry out this preliminary steaming with the roast and ground coffee already filled into percolation columns.
Nearly all prior methods for the steaming of roast and ground coffee for aroma production are based upon an in-column and batch system of operation. The variables in such methods are steam pressure applied, and therefore its temperature, the time of passage of the steam, and the amount of condensate collectedr expressed conveniently as millilitres per lb. of roast and ground coffee steamed. The prior art is now replete with such in-column methods of steaming. - 1 - ~F
~7S65 However, it has been found that the prior methods suffer in that the conditions necessary for steaming result in the pro-duction of water-soluble extracts which are degraded, primarily on account of an excessively high acidity, while the re-addition of aromatic distillate only partially restores acceptable quality.
When it is considered that steaming conditions may be severe in respect of time and temperature, and are determined to a large extent by the pressure of the steam that must be applied to pass steam through a static and deep bed of coffee in a conventional percolation column, this degrading effect may not be surprising.
A further objection to an in-column system of steaming roast and ground coffee is that such a batch system does not lend itself conveniently to subsequent uniform condensation and fractionation of the distillate. It has been proposed to discard the roast and ground coffee after steaming, and add the distillate to the extract obtalned from fresh unsteamed roast and ground coffee, but clearly this is an expensive expedient.
Accordingly, it has been further considered to steam roast and ground coffee under such conditions that the degrading effect already described is minimized or eliminated. One method which has been proposed is by contacting the particles o roast and ground coffee in a separate, moving agitated bed with steam under pressure. However, this method still proposes the use of elevated temperatures in the steaming process from which the degrading effects upon the roast and ground coffee will still be evident.
It has now been found that good quality aromatic distillates without impairment of the subsequent water-soluble extract can be obtained by steaming roast and ground coffee in a continuous counter-current manner under vacuum conditions, viz.
where the pressure of the steam applied is less than atmospheric, that is 14.7 lbs. per sq. in.
In accordance with the present invention, there is pro-vided a process for the production of volatile aqueous aromatic distillates, especially from roast and ground coffee, which comprises passing steam through a moving and agitated bed con-tained in a closed cylindrical vessel, fitted with a helical screw conveyor. The steam is passed through the bed counter-currently to the passage of the roast and ground coffee, with arrangements for the introduction of the coffee and its exit from the chamber under vacuum. The resultant water-aroma vapours are withdrawn under vacuum and subsequently condensed or fractionated. The steam is introduced at a temperature less than 100C, that is vacuum steam is used.
The precise temperature of the steam at the entrance and exit, together with the feed rate of roast and ground coffee, determined in part by the speed of the screw, may be variedj according to the particular conditions and type of coffee, and the aroma quality desired. By having the steam temperature always less than 100C, and having the residence time of the roast and ground coffee less than about 5 minutes, the degrading effect, observed on subsequent examination of the water-soluble extract, with or without the added aromatics, is avoided.
The steamed coffee as it emerges from the continuous vacuum steaming apparatus is in a reasonably flowable condition, and may be conveyed with weighing to a fresh column awaiting filling of a conventional percolation bettery for the extraction of its water soluble coffee substances in the usual or desired manner. The grind of roast and ground coffee used should be that desired in the water extraction.
The aroma-water vapour mixture after condensing in a suitable manner, as for example, by a condenser with surfaces at 0C or lower, should normally constitute 10 ml or less of liquid per lb. of roast and ground coffee used. It may be subsequently added to the aqueous water extract, either dilute as extracted or to a concentrated evaporated extract as desired. In all cases, it is desirable to homogenize the extract with a small quantity of expressed coffee oil, that is about 0.5~ based on the weight of soluble solids. Such aroma-enriched extracts may be subse-quently freeze-dried or processed in other ways as desired to retain these aromatic volatile substances in a finished powder or granular product.
The process of the present invention may be carried out in an apparatus such as that illustrated in the accompanying drawing. The apparatus comprises a continuous counter-current contactor consisting of a chamber of cylindrical cross-section, about 5 feet long and 6 inches diameter. The chamber contains an open scroll-type helical screw conveyor 2 driven by a motor 3 to cause movement of roast and ground coffee from one end to the other; at one end fresh roast and ground coffee is continuously fed into the chamber through a rotary valve device 4, and the steamed grounds removed through another rotary valve 5 at the other end. The feed of roast and ground coffee and the speed of the screw is adjusted accord ng to the residence time of the coffee required, which may be about 1 minute or more. A feed rate of about 300 lbs/hr of coffee would provide a residence time of about 5 minutes ln substantially full bore flow. Steam is intro-duced through an opening 6 into the chamber, where the de-aromatized or steamed coffee is being discharged, and exits at the other end through another opening 7, and piping 8 connected to a condenser 9 and fractionater 10 to a vacuum pump 11 maintain-ing a flow of steam under vacuum, and therefore a temperature of less than 100C. The pressure differential across the chamber is monitored by pressure gauges 12 and 13. The flow of steam and its temperature may be adjusted according to the aromatic quality and quantity desired in the distillate. For example, some 6 lbs/
hr. distillate may be found desirable, with a vacuum at the steam exit point of 20 inches.
1~57565 The accompanying drawing illustrates but one embodiment of the present invention, and is for the purposes of illustration only. Various changes may be made from the illustrated embodi-ment although an essential feature of the invention is that the steam within the contacting vessel should be under vacuum to pro-vide the particular advantages desired. This vacuum measured at the exit point for the steam will normally be between 15 inches and 25 inches of mercury, a higher vacuum may not provide a suf-ficiently high temperature of the steam to cause rapid wetting of the coffee, and thus generate the steam aromas required. In addition, a very high vacuum results in very large volumes of steam-vapour-aromatics to be condensed, which results in the need for large heat transfer surfaces. It is also desirable for optimum quality of aromatic distillate that the roast and ground coffee used should be freshly ground and the supply pipe directly connected to the grinding equipment should retain the aromatic substances generated in the grinding and released in the ground state.
Claims (3)
1. A process for the production of volatile aqueous aromatic distillates comprising the steps of feeding roasted and ground coffee through a closed cylindrical vessel by means of a helical screw conveyor, feeding steam in a continuous, counter-current manner through the vessel and condensing the resulting aroma-steam mixture in a condenser with services at O°C. or lower, said coffee having a residence time within the vessel of less than about five minutes, said vessel being under a vacuum, measured at the exit point for the steam, of from 15 to 25 inches of mercury and said steam being fed to the vessel at a temperature of less than 100°C.
2. The process of Claim 1 wherein the condensate is collected of 10 ml or less per pound of roasted and ground coffee.
3. Volatile aromatic aqueous distillates whenever produced by a process according to any one of Claims 1 and 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA232,829A CA1057565A (en) | 1975-08-05 | 1975-08-05 | Continuous production of aromatic distillates under vacuum |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA232,829A CA1057565A (en) | 1975-08-05 | 1975-08-05 | Continuous production of aromatic distillates under vacuum |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1057565A true CA1057565A (en) | 1979-07-03 |
Family
ID=4103770
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA232,829A Expired CA1057565A (en) | 1975-08-05 | 1975-08-05 | Continuous production of aromatic distillates under vacuum |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1057565A (en) |
-
1975
- 1975-08-05 CA CA232,829A patent/CA1057565A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5225223A (en) | Process for the preparation of soluble coffee | |
| EP0363529B1 (en) | A process for hydrolyzing a partially extracted roasted and ground coffee | |
| DE2119678B2 (en) | Process for the production of decaffeinated coffee extract | |
| US3762930A (en) | Mechanical pressure roasting of coffee | |
| JPH0394640A (en) | Making of cocoa extract | |
| KR0137747B1 (en) | A process for the production of soluble instant coffee in powder form | |
| GB1563230A (en) | Production of soluble coffee | |
| US3035922A (en) | Production of instant coffee | |
| US5972409A (en) | Soluble instant coffee prepared from extract obtained from green coffee | |
| US3554761A (en) | Coffee concentrate and process of producing the same | |
| CA1186552A (en) | Coffee extraction process | |
| US3244532A (en) | Method for steam distillation of coffee aromas | |
| CA1057565A (en) | Continuous production of aromatic distillates under vacuum | |
| US3689278A (en) | Tea process | |
| US4204464A (en) | Continuous desorption apparatus for aroma flavor concentrate | |
| US4154866A (en) | Method of producing from wood tar a liquid smoke product for use in food processing, and product of said method | |
| US5840360A (en) | Process for extracting roasted and ground coffee | |
| US2929717A (en) | Dehydrating coffee extract | |
| EP0569474B1 (en) | Process of extracting roasted and ground coffee | |
| Clarke | Extraction | |
| US3615666A (en) | Heat treatment of steam distillate | |
| JPH0147132B2 (en) | ||
| US2912334A (en) | Powdered soluble tea extract and process for its manufacture | |
| EP0001850A2 (en) | Continuous desorption process and apparatus for aroma and flavour concentrate | |
| GB1308249A (en) | Process for treating green coffee |