Method of manufacturing coffee-aroma material

(54) Name: Methods of making coffee aroma material

7505549-1

The present invention relates to a method of making caffeine material.

The present invention is related to the invention disclosed in Swedish Patent Application No. 731pO7'j-7, which describes a method of condensing the aromatic gases emitted during grinding of stainless steel coffee in a vertically mounted heat exchanger with wall scrapers, which is cooled by means of liquid nitrogen. The condensed gases are collected at the bottom of the heat exchanger in the form of frost or snow and this frost is mixed with a liquid glyceride and can then be combined with a coffee extract before the extract is dried (e.g. freeze-dried) or combined with a soluble coffee powder.

Paint gas, ie gas, which is released from roasted whole coffee beans when their internal cell structure is destroyed, such as when painting the beans and which also continues to develop from the broken and / or fractured beans for a short period thereafter, has long been known in the art as a highly desirable one. natural coffee aroma material. However, it has proved difficult to assemble and stabilize this aroma, especially when it has been required for use in commercial scale soluble coffee cisterns.

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The use of grinding gas, which in effect increases the storage space of soluble cassette powder, is disclosed in U.S. Patent No. 3,021,218, each. canned cream space can be flavored and US Patent No. 2,306,061 wherein aromatic milling gas is condensed on cooled soluble coffee powder. The use of milling gas condensate, which is added to a liquid extract and dried to give an improved copper space when the powder is dissolved in hot water, is described in U.S. Patent No. 5.2-^!1533 wherein coffee oil is homogenized in extracts and then aromatic milling gas ingredients are added. Condensed milling gas frost can be mixed with a liquid glyceride, which is then processed to remove the excess water, such as by refrigeration, before combining it with soluble attached coffee ingredients (e.g., soluble coffee powder).

The addition of condensed aromatics to a glyceride material is a known way of trying to stabilize the aromatics. Such glycerides as coffee oil, blending vegetable oils and triacefcin have been found to be particularly useful for these purposes; however, other oils and low-melting fats have also been used. However, it has been found desirable to maximize the amount of aromatic substances which are fixed in the glycerine carrier as this would reduce the aroma losses and reduce the amount of glyceride to be incorporated into the soluble k-product product to achieve the desired degree of aromatization.

According to the invention, therefore, there is provided a method of making a coffee flavoring material which can be added to solid coffee ingredients wherein a flavoring containing frost with a carbon dioxide content is condensed from a gas containing flavoring substances, wherein the frosting is placed in an ice-cold vessel and pressurized. a liquid glyceride in an amount of 1 g glyceride to 0.5 - 6 g of frost under the atfc vessel is isolated from the atmosphere; and that the pressure is released at a rate which avoids the formation of liquid carbon dioxide and atfc glyceride material containing coffee aroma, is recovered.

Preferably, the pressure should be at least 70 kg / cm for the afct to obtain or maintain the glyceride in a liquid state, and preferably the temperature of the vessel is preferably increased to at least room temperature (i.e., 15.5 ° C). According to a preferred embodiment, the internal temperature of the vessel is increased to above 31 ° C, preferably to 52 ° -19 ° C.

The contents can be kept under pressure for at least one hour. According to the most common embodiment, the frost and the glyceride are placed

7505549-1 together in the vessel before the heat is applied. Heat can be applied to provide an internal pressure of at least 50 kg / cm^- and an internal temperature greater than the solidification temperature of the glyneride. The pressure is usually released at a rate which keeps the glyceride in liquid state. Heat can be applied through a water bath.

The process of the present invention uses the principle of liquefaction or liquefied glyceride condensation to increase the absorption of flavoring and flavoring agents contained in a gas-containing frost. The process according to the invention is suitable for fixing aromatic substances which are present in an aroma-bearing gas having a high (for example above 8o weight percent).⁵!) carbon dioxide content and which has been condensed as a flavor-bearing frost. The present invention is specifically described for coffee grinding gas, but it should be understood that other flavor-bearing gases, with a high carbon dioxide content, such as road additives from coffee percolators and caffeine nitrogen gas, can also be used and must be considered within the scope of the invention. The process, which can be carried out as a simple batch process in a simple pressure vessel or as a semi-continuous countercurrent method in a battery pressure vessel, eliminates the need for mixing the gas-containing frost and the liquid or condensed glyceride. This mixing process has proved to be difficult on a commercial scale since contact between the condensed frost and the glyceride rapidly solidifies the glyceride, thereby making even mixing of the two components very difficult. If the mixture is heated to a point where the glyceride is a liquid, many of the desirable condensed aromatic substances disappear into the atomic sphere.

According to one embodiment of the invention, the aroma-bearing carbon dioxide frosting, which can be obtained from a heat exchanger cooled with liquid nitrogen and provided with surface scrapers, is placed in a vessel together with a glyceride material having a ratio of g frost to g glyceride of about 0, p: l to 6: 1. The vessel is isolated from the atmosphere and the vessel contents are continuously fed with the aid of a water jacket. Host is added in a sufficient amount to increase the temperature of the glyceride above its solidification point, preferably the contents of the pressure vessel should at least reach room temperature. As the temperature of the carbon dioxide frost increases, a gaseous carbon dioxide phase develops with increased pressure and as the temperature rises above about -b6.63 ° C, the remaining condensed carbon dioxide is transferred from a solid phase to a liquid phase. When the temperature of the vessel contents exceeds the melting point of the glycride, the aromatic substances become easily soluble in the liquid glyceride. It may be desirable to keep the vessel contents at one

7505549-1 particular temperature above the melting point of the glyceride to extend the contact time between the liquid glyceride and the aromatics by one hour or more. According to the embodiment in which formation of liquid 003 is particularly avoided, the temperature of the contents is increased to above 31 ° C. It may also be desirable to stir the vessel contents with the aid of an internal stirrer to increase the absorption of the aromatics in the liquid glyceride therein. It has also been found advantageous to regulate the amount of frost placed in the vessel together with the glyceride to a level where no condensed flavor-bearing CO 2 phase exists at the temperature to which the vessel content is finally increased; however, it may still be desirable to prepare a saturated gas phase in the vessel. It may be desirable to avoid a liquid aromatic CO 2 phase since some of the aromatic substances may be more soluble in the liquid CO 2 phase than in the liquid glyceride phase.

Alternatively, instead of placing the glyceride in the vessel at the same time as the frost (i.e. before any heat is added to the vessel), the frost inside the vessel may be heated, for example, above the stiffness point of the glyceride, before the glyceride is placed in the vessel.

The method by which this invention is carried out may be a simple batch process in a simple pressure vessel or a semi-continuous countercurrent method in a battery, pressure vessel.

Once the frost and the glyceride in the vessel have reached the desired temperature, preferably about room temperature and possibly after a period of residence, the pressure in the vessel can be slowly, preferably isothermally, released, making sure that the temperature is lowered below the glyceride solidification point. The resulting glyceride has been found to contain more than twice the amount of aromatics obtained by manual mixing of the two components at atmospheric pressure, and then the aromatized glyceride should then be processed in a normal manner to remove excess water, such as by centrifuging.

In general, contact between the gaseous frost and the glyceride in an insulated pressure vessel, as described above, has been found to be a desirable method of increasing the level of aromatic substances fixed in the glyceride. However, certain final temperatures and pressures as set forth below (e.g. 21.1 ° C and 6l, 1 kg / cm²) the presence of liquid carbon dioxide. Conditions that allow the presence of liquid CCD. in the pressure vessel 'also permits some of the aromatic painting gas constituents to dissolve in the liquid COg phase according to equilibrium distribution conditions, based on complicated relationships

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between vapor pressure, solubility and chemical potential. When a pressure vessel containing a non-curing liquid CO. Is evaporated, almost all the desirable organic materials dissolved in the liquid carbon dioxide are co-distilled and lost with the valve gas and although this valve gas can be recirculated in the system, almost all the desirable aromatic substances lost.

In one embodiment, a process is based on a process based on the critical properties of carbon dioxide, which eliminates the flow of the CO 2 phase and allows further aromatic compounds to dissolve in the waxy phase present in the vessel (i.e., water, liquid glyceride and gaseous CO 2).

The elimination of liquid CO 2, which is an excellent solvent for non-polar or slightly polar compounds, is desirable because it competes? with the liquid glyceride phase for many of the desirable aromatic substances such as mercaptans and long chain aldehydes. Since liquid CO 2 cannot exist above the critical temperature 31, 0 ° C, this embodiment requires contact between the frost and the liquid glyceride phase in the pressure vessel to occur at a temperature above 50 ° C, preferably in the range of about 32 -). and the vessel is then slowly, preferably isothermally ventilated so that liquid CO? not formed.

The flavored glyceride, which in itself is a commercial. oral material, may be stored or may be combined with solid coffee constituents, either in the form of dry soluble coffee, such as by conventional spray coating or any other technique, as exemplified in U.S. Patent No. 3 · 769 · θ38 or with liquid coffee or coffee-like extract before drying the extract. The aromatic.ser? the glyceride can be solidified, such as by freezing, and comminuted, such as by grinding, before mixing it with the soluble coffee powder or before combining it with a liquid coffee extract or a slurried coffee extract as described in U.S. Patent No. 3-809-770, or a partially frozen slice of coffee extract as disclosed in U.S. Patent No. 3-809,766.

The most readily available source of grinding gas Jean is obtained by closing or protecting the coffee grinding equipment, such as a commercial grinding device. The gases »released from the ground coffee can be removed by a pump or rotary compressor; furthermore, if desired, a stream of inert, preferably moisture-free gas can be used to remove the gas from the coffee, and allow the grinding process to shake in a substantially inert atmosphere. Such a process is disclosed in U.S. Patent No. 2,130,212, which discloses one

7505549-1 method of collecting gas, which develops during roasting, but which can equally be used to collect gas, which develops during painting or cell decomposition of whole freshly roasted coffee beans. If pumping is used, it may be desirable to cool the gas in front of the pump so that the heat generated by the pumping does not destroy the aromatic substances present in the gas.

The chemical composition of the evolved gas is largely (i.e. over 90 wt /) carbon dioxide along with water vapor and the characteristic aromatic constituents of roasted coffee. Quantities: Humidity in the gas can be reduced by using green beans with low humidity, dry roasting conditions and low moisture cooling medium. The evolved gas is preferably passed through a first condenser where it is cooled to between 1.7 - 10.0 ° C and substantial quantities of water are removed. The relatively low-moisture gas is then fed to a condenser, such as a sheathed vertically mounted heat exchanger with wall scrapers, which is cooled by means of liquid gas cooling devices.

Preferably, the condenser is cooled by liquid nitrogen and the gas flow in the heat exchanger is maintained in the range of about 0.3 - 1.5 m / min. per m of the surface of the heat exchanger. The nitrogen gas which develops from the cooling system is useful as an inert gas stream which can be used elsewhere in the process for the production of soluble coffee, such as over-gas from the milling arrangement or inert gas in the packaging of the soluble coffee product.

The aroma-carrying gas is condensed in the form of a frost when it comes into contact with the heat transfer walls of the condenser. The frost is removed from the condenser walls and collected to subsequently be contacted with a liquid glyceride phase. The frost can be kept for a short period of time at low temperatures, such as liquid nitrogen, without being destroyed; however, it is preferred to immediately combine the frost with a glyceride of the present invention. The glyceride, which is preferably?¹ coffee oil or a blending vegetable oil, such as cottonseed, corn or coconut oil, is combined with the frost at a level of about 0.5 - 6g of frost per gram of glyceride, preferably about 1 - 1g of frost per gram of glyceride.

In accordance with the invention, contact between the milling gas frost and the liquid glyceride phase takes place in a pressure vessel. The amount of milling gas added is normally such that an unsaturated CO 2 vapor phase is avoided. Heat is applied to the frost in the vessel, such as by means of a water jacket at 21.1 - 2y, 4 ° C, to sublimate the grinding gas frost and form a head space pressure. According to a preferred embodiment, the water jacket has a temperature of 38.2 ° - 8.9 ° 0 to form a main space pressure overgrowth * 95.2 kg / cm² (31, O ° C). At about 5.25 kg / cm² switches the fixed C0_?phase to liquid. The temperature corresponding to this phase change is -56.7 ° C (preferably -56.6 ° C). In this state, the water and possibly present glycerides and some of the organic aromatics are in a solid state. The temperature of the vessel contents is increased to a point above the solidification point of the glyceride, preferably about room temperature, as the aromatic milling gas diffuses and establishes an equilibrium with the CO 2, glyceride and aqueous phases, which may be present in the pressure vessel. In one embodiment, temperatures above about 29.4 ° C are to be avoided as deterioration of the aromatic coffee constituents can occur. Rapid heating of the vessel contents to above the glyceride solidification point may be desirable to increase the time period during which liquid glyceride is present. The final pressure, which develops in the vessel due to the frost, must be above 8.0 kg / cm²and 50 kg / cm² to transfer a significant proportion of the vaporized aromatic constituents in liquid form and to cause some of these aromatic substances transferred in liquid form to dissolve in the glyceride. When the contents of the vessel have reached the desired temperature and possibly after an equilibrium period of up to several hours, the pressure is released slowly, preferably in such a way that the glyceride is maintained in a liquid state. In accordance with the present invention, isothermal ventilation is considered to be the most preferred method. Since the ventilation gas may contain desirable aromatic substances, it should be possible to recycle or regenerate aromatic ventilation gases.

As previously mentioned, a typical feature of one of the embodiments of the present invention is the elimination of liquid GOp, which is a good solvent for many aromatic amps. An increase in the temperature of the vessel contents above 51 ° C, preferably between about 32.2 - 48.9 ° C, which is the critical temperature of liquid CO 2, excludes the existence of liquid CO 2 and consequently further aromatic substances are forced to disperse. between the remaining three phases, ie. water, glyceride and gaseous CO

The vessel may be kept under supercritical CO. Conditions for a period of time over a ten minute period in order to. achieve equilibrium and maximize the absorption of aromatic substances in liquid liquids. When the vessel is slowly ventilated as indicated above, care should be taken to prevent the formation of liquid CO 2. It can be done by man

7505549-1 ventilates the vessel through a section of small diameter tubes whose length provides a sufficient pressure drop to prevent a rapid pressure drop in the vessel. Preferably, the ventilation should be carried out isothermally.

The vent gas contains at least a small amount of aromatics and, of course, it should be possible to recycle or regenerate these aromatics.

As already mentioned, the formation of liquid C0₂ cause problems. As an alternative method or as additional methods to those already described to solve this particular problem, air flow heating can be arranged after the pressure vessel.

This embodiment relates to a method in which the pressure vessel is directly connected, such as through an open valve, to an upper packed column and a partial condenser located above the column. A pressure or gas flow regulator should be located in the upstream direction of the condenser and is usually used as a device for isolating the pressure vessel from the atmosphere. Instead of venting pressure vessels directly to the atmosphere where the aromatics are lost, the boiling CO 2 gas passes through a filled column in which liquid CO₂ refluxed from the partial condenser. Contact in the column between gaseous C0₂ and refluxing liquid C0₂ enriches the liquid phase with aromatic substances. As the concentration of aromatic substances increases in the liquid C0₂The phase in the pressure vessel is transmitted at least one proportion of these aromatic substances in the liquid glyceride phase. Thus, through this technique, a higher level of aromatic substances can be fixed in the glyceride.

During release of the pressure, liquid is transferred and refluxed in the condenser, a portion of the aroma-containing gases (mostly COp) which disappears from the pressure vessel and the condensate is returned to the vessel through the filled column.

The accompanying drawing illustrates a cross-section of a pressure vessel equipped with high-pressure return devices and also illustrates the multiple phases that may exist in the vessel.

The drawing shows an apparatus suitable for preparing batch according to the present invention wherein the figures show the conditions that would exist at equilibrium with the contents of pressure vessel 1 at about 21.1 ° C and a pressure of about 60.1 kg / cm². The pressure vessel 1 is surrounded by a water jacket 2 and the vessel is provided with an outlet which is directly connected to a filled column. The partial condenser 4 is preferably adapted for a countercurrent flow of a liquid-friendly transfer medium such as brine or water at low temperature.

7505549-1

-1.1. to +1.4 ° C. A pressure regulator 5 controls the discharge of gas from the system and may consist of a simple shut-off valve and a small diameter capillary or tube, which provides a sufficiently small pressure drop to prevent a rapid pressure drop in the vessel.

The vessel contents are displayed for. four separate phases including a boctene aqueous phase 6, a liquid glyceride phase 7, a liquid COg phase 8, and a saturated gaseous COp phase 9 ·

Other ways of carrying out the process of the invention are:

(A) When the frost is placed in the vessel, the vessel and its contents are isolated:

p may be heated to a point where the pressure is about 8.0 kg / cm (about -48.3 ° 0, calculated on pure COg) develops. Liquid CO 2 is then 'evaporated by vascularization of the vessel and the pressure controlled is approximately 8.0 kg / cin'. When a substantial portion of the COp gas is removed, the vessel is isolated again and the content is heated above the solidification point of the glyceride, preferably about room temperature. A final pressure of 15 - 35 kg / cm must be obtained. Thereafter, this pressure is released slowly with the glyceride present and preferably after a period of residence.

(B) Here the frost is placed in the vessel, the vessel is insulated and heat is applied (eg 21.1 - 23.9 ° C water bath). This pressure may be between 6.25 - 9.4 kg / cm, after which the vessel is rapidly ventilated to o 'kg / cm The vessel is repeatedly isolated, pressure is applied and ventilation shoes again until the built up residual pressure is less than 8.0 kg / cm. c / o The vessel may be heated to approximately room temperature. Thereafter, the vessel is completely ventilated with the glyceride present. According to this process, the amount of volatile constituents which disappear from the vessel with the COp gas when the pressure is released is attempted to be as small as possible. During rapid vein ventilation, heat must be applied for the atfc gas to expand and this heat is given almost entirely adiabatically, with the result atfc the residual milling gas frosting with the volatiles and glyceride, which may be presently cooled. The repeated vein filtration attempts to remove the COp gas and provides a concentrated level of volatiles to dissolve in the glyceride.

(C) When the frost is placed in the vessel, the vessel is insulated and heat is applied. The vessel contents temperature is allowed to rise above the solidification point of the glyceride; however, the pressure is released quickly before reaching room temperature and with the glyceride present in the vessel. As a result of the rapid freeze release, the material remains in the frozen state and the aromatic-containing glycerides get additional grinding gas aroma components condensed on the surface.

7505549-1 (D) The toast is placed in a vessel and COg is sublimated at atmospheric pressure (about -γ8 ·, 9 ° θ) · Here, a substantial proportion of the CO 2 gas is removed, the vessel is isolated and the temperature of the contents allowed to increase to about room temperature and, the vessel is then ventilated, with glyceride present. One pressure of 8.0 - 15.0kg / cm must be reached before ventilation.

(E) The grinding gas frost is placed in a pressure vessel and the pressure is allowed to increase to about 8.0 kg / cm. The pressure is then rapidly reduced to 0 kg / cm² and this procedure is repeated two or three more times. The vessel is then sealed and the contents heated to an internal temperature of about 21.1 ° C. Thereafter, the vessel is ventilated with the glyceride present and possibly after a period of residence. As an improvement to this process, it may be desirable to transfer the sublimated freezing gases through a column of liquid or

i. liquid state transferred glyceride, which is then placed in the vessel.

(F) Both the grinding gas frost and the glyceride are placed in the vessel. The vessel is sealed and the contents heated to about room temperature. After cooling to below -1.1 ° C and, if desired, as low as -7-5> 3 ° C, the residual CO 2 pressure is removed. The flavored glyceride can be removed and used as a solid or otherwise heated and removed as liquid.

When the pressure in the vessel is reduced, the aromatized glyceride is removed from the vessel. If it is in liquid state, this can be done by a simple decantation or by diverting the liquid through a valve in the bottom of the vessel. It may also be possible to allow residual pressure in the vessel to force the liquid out through a vertical stripping tube projecting through the upper portion of the vessel. This glyceride is then preferably processed to remove an excess of water. .

If a liquid is removed from a pressure vessel, any residual gas present in the vessel may be retained for use in subsequent pressure fixing cycles.

The aromatized glyceride phase and any aqueous phase that may be present in the vessel can be separated as they are removed from the vessel. Alternatively, it would be possible to remove the lower liquid water during the pressure fixing cycle since the water is the heaviest material in the vessel.

The removal of the water from the aromatized glyceride, preferably down to a level of 0.5 weight / or less, appears to further stabilize the aromatic constituents of the paint gas. Centrifugation, ultracentrifugation, molecular fractionation, desiccants and similar methods have been found to be useful techniques for removing water from the flavored glyceride. As a further step in this water removal process, it is possible to separate any flavorings from the removed water, such as by vacuum distillation and return these separated aromatics to the flavored glyceride.

The flavored glyceride can be combined with soluble coffee powder or with coffee extract before drying the extract according to any technique known to those skilled in the art. Typical levels for the addition of flavored glycerides are 0.1 to 2 wt / glyceride, based on the weight of soluble solids in the final product. The aromatized powder of the present invention may consist wholly or partially of the powder in the final product as will also be appreciated by those skilled in the art.

The term coffee powder and coffee extract used in the present invention is intended to include materials which contain, in whole or in part, coffee substitutes such as powder or extracts wholly or partially obtained from roasted cereals such as wheat, rye, barley and the like. One such product is the water-extracted dried powder of wheat, barley and molasses known as Instant Postum (registered trademark).

The invention is further illustrated by the following examples, wherein the temperature refers to degrees Celsius.

Example 1

A mixture of 130 g of liquid nitrogen condensed milling gas frost and 110 g of coffee oil was placed in a high-pressure stainless steel bomb of 2 o steel and heated to 26.7 °. A pressure of 50 kg / crn was obtained. The pressure was released and the remainder_rwhich remained stored at -17.8 ° for 14 days and then applied to the surface of soluble coffee powder to a level of 0.5 / ·

Example 2.

Coffee grinding gas, developed during grinding of freshly roasted coffee beans, was passed through a water-cooled condenser, where 2.002 g of water per cm of gas was removed. The gas was then transferred to a liquid nitrogen-cooled wall-scrapped heat exchanger where it was condensed and collected as frost.

36.3 kg of the frost was placed in a pressure vessel with a volume of 0.113 V together with 18.1 kg of pressed coffee oil. The pressure vessel was immersed in a water bath maintained at about 21.1 °. After 3 hours, the contents of the vessel had reached a temperature of about 21.1 ° and the pressure was about 60.5 kg / cm 2. The vessel was ventilated slowly

7505549-1 until atmospheric pressure was obtained for a period of about 3 hours, thus preventing such a rapid pressure drop very carefully that the oil would solidify. The vessel contents were centrifuged and approximately 0.023 kg of water per liter of liquid was removed. This aromatized dry oil was found to remain stable for at least 3 days at -6.67 °.

The frozen oil was thawed in a water bath with tap water and then sprayed onto the surface of agglomerated spray-dried coffee in an amount of 0.4% by weight. The coated product was packed under an inert atmosphere and was judged to have canned cream after several weeks of storage. A pleasant roasted coffee-like aroma was developed by the product ..

Comparative example.

The procedure of Example 2 was repeated except that the coffee oil frost contact was performed by manual mixing in a pressure vessel. Although comparable stability was obtained in the frozen oil, the can of the coated coffee powder was found to be less dense, although of comparable quality to that of Example 2. Gas crotch nanographic analysis of the two samples shows an aroma level of the can of aroma of Example 2, which was about 2 times as strong as the one according to the comparative example.

Example 3 A 1-liter pressure bomb fitted with etfc glass windows was charged with 300 g of condensed milling gas frost (5% H, 0) and 150 ml of pressed coffee oil. The bomb was then sealed and placed in a water bath with a temperature of 21.1 °. After several hours, the contents had reached a temperature of about 21.1 ° and the pressure was about 60.3 kg / cm. Observation of the bomb content showed the presence of a yellow-green layer of liquid carbon dioxide, which was estimated to be approximately 124 g. The bomb was then ventilated isothermally and the flavored oil was centrifuged to remove the water.

Example 4

The procedure of Example 3 was used and one was wagered

1-liter bomb with 200 g of milling gas frost and 100 ml of oil. When the o 2 content reached a temperature of 21.1 °, the bomb pressure was 56.3 kg / cm⁴¹and no layer of liquid carbon dioxide was observed. The bomb was again ventilated isothermally and the oil was centrifuged.

Example 5 The dry oils of Examples 3 and 4 were qualitatively determined for aroma and found to be comparable and to contain a fresh coffee aroma. Gas chromatography analysis of the canister head cream serum

7505549-1 of the two oils showed a higher level of aromatic substances for the oil of Example 4.

Example 6

Coffee grinding gas, which was developed during painting of freshly roasted coffee beans was passed through a water-cooled condenser where 2,002 g of water per cm³ gas was removed. The gas was then passed to a liquid-nitrogen-cooled wall-scrapped heat exchanger where it was condensed and collected as frost.

•5

36.3 kg of the frost is placed in a 0.113 m pressure vessel together with 1.8 kg of the pressed coffee oil. The pressure vessel was immersed in a water bath maintained at about 21.1 °. After one hour, the contents of the vessel had reached a temperature of about 21.1 ° and a pressure of 84 kg / cm. The vessel is then allowed to slowly ventilate to room temperature for a period of about three hours, ensuring that not a rapid, pressure drop causes the formation of liquid CO 2. The vessel contents are centrifuged and approximately 0.023 kg of water per liter of liquid is removed. This aromatized dry oil was found to remain stable for at least 3 days frozen to -6.67 ° and was found to possess a pleasant coffee aroma which can be transferred to a soluble coffee product by spray coating.

Example 7.

Coffee grinding gas, which was developed during grinding of freshly roasted coffee beans was passed through a water-cooled condenser where 2,002 g

3.

water per gallon was removed. The gas was then passed to a liquid-nitrogen-cooled wall-scraped heat exchanger where it was condensed and collected as frost.

36.3 kg of this frost was placed in a pressure vessel with a volume of 0.113 m 2 (shown in the accompanying drawing) together with 18.1 kg of pressed coffee oil. The pressure vessel is immersed in a water bath maintained at about 21.1 °. After three hours, the contents of the vessel have reached a temperature of about 21.1 ° and a pressure of about 60.5 kg / cm². Water at 1.67 ° is then circulated countercurrently through the condenser and the pressure regulator valve is then easily opened to slowly release the pressure for a period of three hours, ensuring that no rapid pressure drop which causes the oil to solidify occurs. During the ventilation process reflux of C0 was observed₂ and the liquid condensate was returned to the vessel through the column, filled with Raschig rings, the vessel contents centrifuged and about 0.023 kg of water per liter of liquid off; removed. This flavored dry oil was found to remain stable for at least 3 days frozen to -6.67 ° and possess a pleasant coffee aroma which can be transferred to a soluble coffee product by spray coating.

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