CA2098224C - Process for making dry coffee aroma oil - Google Patents
Process for making dry coffee aroma oilInfo
- Publication number
- CA2098224C CA2098224C CA 2098224 CA2098224A CA2098224C CA 2098224 C CA2098224 C CA 2098224C CA 2098224 CA2098224 CA 2098224 CA 2098224 A CA2098224 A CA 2098224A CA 2098224 C CA2098224 C CA 2098224C
- Authority
- CA
- Canada
- Prior art keywords
- coffee
- cryofied
- particles
- mass
- aroma
- 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
- A23F5/46—Coffee flavour; Coffee oil; Flavouring of coffee or coffee extract
- A23F5/48—Isolation or recuperation of coffee flavour or coffee oil
- A23F5/486—Isolation or recuperation of coffee flavour or coffee oil by distillation from beans, ground or not, e.g. stripping; Recovering volatile gases, e.g. roaster or grinder gases
Landscapes
- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Polymers & Plastics (AREA)
- Tea And Coffee (AREA)
Abstract
A dry coffee aroma oil is produced by passing coffee aroma gas through a desiccant bed of calcium sulfate granules, combining the resulting dry aroma gas with a cryofied aroma carrier, equilibrating the resulting mixture until it reaches above -109°F at which point substantially all solid carbon dioxide has sublimed, and then quickly melting the remaining product at temperatures of between 70°F and 110°F. The dry coffee aroma oil product can be used to aromatize coffee substrates such as dry soluble coffee extracts.
Description
~ ~ 9 ~ ~ ~ 4 PROCESS FOR MAKING DRY COFFEE AROMA OIL
TECHNICAL FIELD
The present invention relates to a process for making dry coffee aroma oils for use in aromatizing various coffee substrates, especially soluble coffee.
BACKGROUND OF THE lNV~N-lION
Soluble coffee solids, e.g. instant coffees, typically lack the desirable aroma common to roasted and ground coffee. There have been many attempts at making a soluble coffee product with this desirable aroma. One such method involves the addition of coffee aroma oils to the dry soluble coffee solids.
To obtain dry coffee aroma oils, coffee aroma gases are captured during coffee processing steps such as roasting, grinding, steam distillation, and dry distillation. They are then condensed onto a low temperature surface as aroma frost. The condensation usually involves a surface cooled by liquid nitrogen, producing a frost comprising about 87% carbon dioxide, 10% water, and 3% coffee aroma materials. The aroma frost is combined with an aroma carrier such as coffee oil, bland tasting vegetables oils, and the like to produce a "wet" coffee aroma oil. Water is then removed from the "wet" oil by one of many different methods known in the art, one such method being centrifugation of the "wet" oil.
Once the water is removed, the dry coffee aroma oil product is added to soluble coffee to improve the typically bland aroma of such coffee solids.
One common and highly desirable type of coffee aroma gas is grinder gas which is released from roasted whole coffee beans when their internal cell structure is disrupted during grinding. Grinder gases continue to evolve from the disrupted or fractured beans for a short time, during which the gases are collected.
TECHNICAL FIELD
The present invention relates to a process for making dry coffee aroma oils for use in aromatizing various coffee substrates, especially soluble coffee.
BACKGROUND OF THE lNV~N-lION
Soluble coffee solids, e.g. instant coffees, typically lack the desirable aroma common to roasted and ground coffee. There have been many attempts at making a soluble coffee product with this desirable aroma. One such method involves the addition of coffee aroma oils to the dry soluble coffee solids.
To obtain dry coffee aroma oils, coffee aroma gases are captured during coffee processing steps such as roasting, grinding, steam distillation, and dry distillation. They are then condensed onto a low temperature surface as aroma frost. The condensation usually involves a surface cooled by liquid nitrogen, producing a frost comprising about 87% carbon dioxide, 10% water, and 3% coffee aroma materials. The aroma frost is combined with an aroma carrier such as coffee oil, bland tasting vegetables oils, and the like to produce a "wet" coffee aroma oil. Water is then removed from the "wet" oil by one of many different methods known in the art, one such method being centrifugation of the "wet" oil.
Once the water is removed, the dry coffee aroma oil product is added to soluble coffee to improve the typically bland aroma of such coffee solids.
One common and highly desirable type of coffee aroma gas is grinder gas which is released from roasted whole coffee beans when their internal cell structure is disrupted during grinding. Grinder gases continue to evolve from the disrupted or fractured beans for a short time, during which the gases are collected.
-2- ~ 4 It is known that coffee aroma oils formed from coffee aroma gas should be substantially anhydrous since water can react with sulfurous coffee materials resulting in excessive sulfurous aromas. One method of reducing this reaction involves extending hold-times of just-roasted coffee beans prior to grinding. This reduces the sulfurous materials available for reaction. Sulfurous materials chemically react within the beans to reduce available sulfurous material. Some of the sulfurous materials also evolve from the beans during the extended hold-times.
Other methods of reducing the aqueous/sulfurous reaction are known. Such methods frequently involve removal of water from the condensed aroma frost and/or removal of water immediately after forming an aroma oil product. For example, a commonly used method involves centrifuging the coffee aroma oil to remove water immediately after the coffee aroma oil is formed. This results in an acceptable product but a significant amount (up to about 30%) of the coffee aroma materials are also lost during the centrifugation. Furthermore, there is still some contact time between the water and the sulfurous materials such that some excessive sulfurous aromas typically develop. Use of centrifugation and extended hold-times techniques can be combined to further reduce excessive production of sulfurous aromas. Longer hold-times, however, hamper coffee processing operations in as much as only a portion of the grinding operations can be used to capture the grinder gases.
It is also known that, in addition to undesirable aqueous/sulfurous reactions, excessive heating of coffee aroma materials while manufacturing coffee aroma oils results in aroma degradation and loss.
20~224 3 ; ~
Given the foregoing, it can be seen tX~t~there is a continuing need to develop processes for producing coffee aroma oils without excessive heating of coffee aroma materials or with procedures that minimize undesirable reactions that can produce off-flavors during the manufacture of coffee aroma oil.
It iB therefore an obje~t of an a~pect of this invention to provide such an improved proces~ ~or producing coffee aroma oils, which method mlnimi zes the occurrence of aqueous/sulfurous reactions that can result in excessive sulfurous aromas.
It is an object of an aspect of this invention to provide such a process while m;n;mi zing degradation and 1088 of aroma oils by reducing the amount of heat exposure of the aroma oil materials during the manufacture of coffee aroma oils.
It is an object of an aspect of this invention to provide such a process which optimizes the efficiency of manufacturing coffee aroma oils.
These and other objects of this invention will become evident from the dis~losure herein.
SUMMARY OF THE INVENTION
The present invention provides a process for making dry coffee aroma oils useful for aromatizing coffee substrates.
In a first step (calcium sulfate drying step) of such a process, a moisture and carbon dioxide-containing coffee aroma gas is passed through a bed of granules comprising hydratable calcium sulfate. The granules remove substan-tially all moisture from the coffee aroma gas, thereby forming dry, carbon dioxide-containing coffee aroma gas. In a second step (condensation step) of the process herein, the carbon dioxide-containing coffee aroma gas is condensed and combined with cryofled particles of normally liquid aroma carrier oil. This condensation step results in a cryofied mass of particles comprising condensed dry, carbon dioxide containing coffee aroma gas and cryofied aroma carrier oil.
During this condensation step, the cryofied mass of parti-cles are typically maintained at a temperature sufficiently low to maintain the carbon dioxide-containing aroma gas in condensed form. ~n a third step (controlled temperature equilibration step) of the process herein, the cryofied mass 0 of particles from the condensation step are subjected to a medium having a temperature of between about -lO9-F
(-78.3-C) and lOO-F (37.7-C) until the temperature within the mass of particles increases to a value of from about -lO9-F (-78.3-C) to -105-F t-76-l-c)~ to thereby remove substantially all of the carbon dioxide from the cryofied mass of particles. ~n a fourth step (melting step), the carbon dioxide-free cryofied mass of particles is subjected to a temperature of from aboùt 45-F (7-C) to 1l0-F (43-C) for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
Other aspects of this invention are as follows:
A process for making dry coffee aroma oils useful for aromatizing coffee substrates, which process comprises the steps of (a) passing a moisture- and carbon dioxide-containing coffee aroma gas through a bed of granules comprising hydratable calcium sulfate to thereby remove substantially all moisture from the coffee aroma gas, thereby forming dry, carbon dioxide--containing coffee aroma gas; then (b) condensing the dry, carbon dioxide-containing coffee aroma gas of step (a) and combining said condensed aroma gas with cryofied particles of normally liquid aroma carrier oil to thereby form a cryofied mass of particles comprising condensed dry, carbon dioxide-containing coffee aroma gas Jr j~ 9 ~
- 4a - 2 0 9 8 2 2 4 and cryofied aroma carrier oil, the cryofied mass of particles being maintained at a temperature sufficiently low to maintain the carbon dioxide-containing aroma gas in condensed form; then (c) equilibrating the cryofied mass of particles of step (b) by subjecting said mass of particles to a surrounding temperature of between about -lO9-F
and lOO-F until the temperature within the mass of particles increases to a value of from about -lO9-F to -105-F, to thereby remove substantially all of the carbon dioxide from said cryofied mass of particles; and then (d) melting the resulting carbon dioxide-free cryofied mass of particles from step (c) by subjecting said mass to a temperature of from about 45-F to llO-F
for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
A process for making dry coffee aroma oils useful for aromatizing coffee substrates, which process comprises the steps of (a) passing a moisture- and carbon dioxide-containing coffee grinder gas through a bed of granules comprising hydratable calcium sulfate to thereby remove substantially all moisture from the coffee aroma gas, thereby forming dry, carbon dioxide-containing coffee grinder gas; then (b) condensing the dry, carbon dioxide-containing coffee grinder gas of step (a) onto cryofied coffee oil particles to thereby form a cryofied mass of particles comprising condensed dry, carbon dioxide-containing coffee grinder gas and cryofied - 4b - 2 0 9 ~ 2 2 4 coffee oil, the cryofied mass of particles being maintained at a temperature of between about -210-F and about -290-F; then (c) equilibrating the cryofied mass of particles of step (b) by subjecting said mass of particles to a surrounding temperature of about 68-F until the temperature within the mass of particles increases 0 to a value of from about -109-F to about -105-, to thereby remove substantially all of the carbon dioxide from said cryofied mass of particles; and then (d) melting the resulting carbon dioxide-free cryofied mass of particles from step (c) by subjecting said mass to a temperature of from about 70-F to about 100-F for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
DEFINITIONS
The term "coffee oil~ as used herein means the natural product obtained by solvent extraction of coffee beans or obtained by expelling such a natural product from beans as described in Sivetz, Coffee Processing TechnoloqY, Vol.2, pages 21-30, Avi Publishing Company (1963).
The term "normally liquid aroma carrier oil n as used herein means any suitable substrate or sorbent which is liquid at room temperature and to which roasted coffee aroma materials can be transferred such that the substrate or sorbent acts as a carrier for the roasted coffee aroma materials.
The term "aroma oil" or "coffee aroma oil" as used herein means the aroma carrier that has been aromatized with or combined with the roasted coffee aroma materials from a coffee aroma gas.
The term "cryogenic fluid" as used herein means liquified gases having a boiling point ~at atmospheric pressure) below -109~F (-78.3~C) such as liquid nitrogen, liquid hydrogen, liquid air, liquid helium, and mixtures thereof.
The terms "substantially anhydrous" or "dry" as used herein mean a moisture content of less than about 0.5%.
The terms "aroma gas", "grinder gas" or "coffee aroma gas" as used herein refer to the coffee gases actually released from coffee before they are admixed with air or other inert carrier gas. Such terms, also refer to such coffee gas as a component of a mixture of coffee gas and air (or other inert carrier gas).
All percents are weight percents unless otherwise specified.
DETAILED DESCRIPTION OF THE INVENTION
The process of the present invention involves four key steps: 1) an aroma gas drying step wherein calcium sulfate is used to remove water from a moisture and carbon dioxide containing coffee aroma gas, b) an aroma carrier formulation step wherein aroma gas is condensed or combined with a cryofied aroma carrier material, c) a controlled temperature equilibration step that results in a carbon dioxide-free cryofied aroma/aroma carrier mixture that can be melted. quickly and with little heat, and d) a melting step to form the desired coffee aroma oil. Each of these four essential steps, as well as additional preferred embod.iments or elements, is described in detail as follows.
A) Aroma Gas Dryinq In connection with the first step of the instant process, a moisture and carbon dioxide-containing coffee aroma gas is provided in known and conventional manner.
Such aroma gas is the material which is captured during coffee manufacturing operations such as roasting, grinding, steam distillation, or dry distillation. The aroma gas obtained during the grinding of roasted coffee beans (grinder gas) is preferred. Various types of coffee beans can be used including robusta, arabica, mixtures thereof, and the like. The most readily available source of grinder gas may be obtained by enclosing or hooding coffee grinding equipment, such as commercial grinders. The grinder gases liberated from the ground coffee may be removed by a pump, rotary blower, or the like. Additionally, it is known that a stream of inert, moisture free, gas may be used to sweep the aroma gas from the ground coffee. If pumping is employed, it may be desirable to cool the gas ahead of the pump so that the heat added by pumping will not degrade the aroma materials contained in the gas.
Grinder gas typically contains about 70-90% carbon dioxide, 10-20% water and 2-3% coffee aroma materials (coffee volatiles). When mixed with air after capture, the resulting mixture comprises an aroma gas component (about 5-7%) and an air component (about 93-97%).
Overall, the aroma gas/air mixture will frequently contain about 4-5% carbon dioxide, less than about 1 water, and less than 1% coffee aroma materials.
As an optional step prior to the drying step, herein-after described, the aroma gas/air mixture can be passed through a pre-condenser cooled to between about 35~F (1.7~C) and about 50~F (10~C). Up to about 50% of the gaseous moisture can be condensed on cooled surfaces within the pre-condenser. By using a pre-condenser, the calcium sulfate beds used in the drying step as hereinafter described can be used longer before being replaced or regenerated.
In accordance with the first step of the process herein, the moisture and carbon dioxide-containing coffee aromatic gas as hereinafter described (typically as a mixture of aroma gas and air) is passed through a desiccant bed of hydratable calcium sulfate, typically in the form of calcium sulfate granules. Contact of the aroma gas with the calcium sulfate bed serves to remove substantially all of the moisture from the aroma gas, thereby forming dry coffee aroma gas.
The calcium sulfate bed can comprise a vessel (desiccant vessel), preferably a closed vessel, having an inlet and outlet for entry and exit of an aroma gas stream. The vessel can have a length to diameter ratio of from about 10:1 to about 3:1, preferably from about 9:1 to about 7:1. The vessel is packed with the calcium sulfate, typically as granules. Such granules can have an average diameter of from about 2mm to about 26.9mm, more typically from about 2.38mm to about 12mm. When granules become too fine, air flow through the column requires increased pressure. Although not critical to the present invention, it is generally desirable to avoid the added complications (i.e., safety measures) associated with pressure vessels.
The calcium sulfate in the bed can absorb up to about 6.5% of its weight as water. The aroma gas/air mixture enters the calcium sulfate bed having a water content typically exceeding about 3000 ppm (0.3%) and exits the bed having less than about 50 ppm (0.005%).
The aroma gas component of the dried aroma gas/air mixture then contains less than about 0.5% water.
The aroma gas/air mixture can be passed through the bed in a continuous or, more typically, intermittent manner. Initially, the calcium sulfate bed will 2 ~ ~
generally contain less than about 0.5% moisture prior to contacting the aroma gas/air mixture. A given calcium sulfate bed can be used in the drying operation until it contains about 6.5~ water, preferably about 5% water, at which point the desiccant vessel is taken off-line and the hydrated calcium sulfate is regenerated (air dried to contain less than 0.5% water). Calcium sulfate is preferably taken off-line at the 5% rather than 6.5%
moisture level to avoid accidental moisture overflow beyond the 6.5% moisture threshold.
Once the calcium sulfate bed contains up to about 6.5% water, preferably not more than about 5% water, the desiccant vessel is taken off-line from the aroma gas stream and the calcium sulfate is regenerated (i.e., its water content is reduced). To effect calcium sulfate regeneration, air having a temperature of about 350~F
(177~C) to about 450~F (232~C) is pumped or blown into the vessel inlet, passes through the calcium sulfate bed, and exits at the vessel outlet. The flow rate will be consistent with the volume of the desiccant vessel. For a typical vessel containing about 375 lbs (170kg) (dry basis) of dry calcium sulfate granules, the flow rate is maintained at about 300 cubic feet/minute (8.5 cubic meter / minute) to about 550 cubic feet/minute (15.6 cubic meter / minute), typically at about 375 cubic feet/minute (10.62 cubic meter/minute). The stream of hot air is passed continuously through the vessel until the calcined sulfate contains not more than about 0.5%
moisture. It typically takes between about 3-8 hours to sufficiently dry a vessel of calcium sulfate although lesser and greater times may also be required.
Moisture levels of the hot air stream can be monitored at the vessel inlet and outlet to indirectly identify the point at which the calcium sulfate is .
8 ~ ~ ~
g sufficiently regenerated. When the moisture content at the outlet is about equal to that of the inlet, the calcium sulfate is sufficiently regenerated (less than about 0.5% water). Temperatures at the inlet and outlet can also be monitored to indirectly measure moisture content. When the outlet temperature is about equal to the inlet temperature, the calcium sulfate is sufficient-ly regenerated.
When the calcium sulfate is regenerated, the heating device warming the inlet air stream is turned off. The air continues to be pumped through the desiccant vessel until the outlet air temperature drops below about 100~F
(38~C), preferably to aboul 68~F (20~C). The vessel can then be placed on-line with the aroma gas stream to resume desiccation of the aroma gas. Alternatively, the inlet and outlet are capped and the vessel is stored for later use.
A vessel of calcium sulfate can be regenerated and subsequently reused in the drying sequence according to the present invention for typically between about 20-30 times before the calcium sulfate granules need to be replaced, most typically about twenty times.
It has been found that calcium sulfate, surprising-ly, removes water from the aroma gas stream withoutremoving substantial amounts of coffee aroma materials.
It was also found that by using calcium sulfate to dry the gaseous aroma, there was no longer a need to remove residual moisture from the coffee aroma oil by centri-fugation or other inefficient methods. Compared tocentrifugation, calcium sulfate drying results in up to about 30% more dry coffee aroma material from a given volume of grinder gas.
It should be noted that other known methods of reducing the moisture of aroma gases can also be used to complement the calcium sulfate gas drying operation of the present invention. Examples of such known methods include, but are not limited to, roasting under dry conditions and using low-moisture quenches or quenching mediums during roasting.
It has been found that drying coffee aroma gases with calcium sulfate, when used in conjunction with the controlled temperature equilibration as hereinafter described, reduces the production of excessive sulfurous aromas and increased aroma oil yield.
The calcium sulfate drying step of the present invention reduces contact of moisture with sulfurous coffee volatiles during the manufacture of coffee aroma oils. Such contact can result in the rapid development of undesirably excessive sulfurous aromas in the resulting coffee aroma oil. By reducing water contact, the production of sulfurous aromas is also reduced. The sulfurous coffee volatiles and their aqueous reaction by-products are as yet not fully identified. Nonetheless, excessive sulfurous aromas are easily detected organ-oleptically as a sharp hydrogen sulfide-type odor.
Reducing the water content of the aroma gas during its gaseous phase will reduce subsequent aqueous reactions that might have occurred while manufacturing the coffee aroma oil.
B) Cryofied Aroma Oil Particles In a second step of the process herein, the dried coffee aroma gas from the calcium sulfate drying step is condensed and combined with cryofied particles of a normally liquid aroma carrier oil.
The aroma carrier oil which is to be utilized in the process of this invention can be obtained from a variety of sources. The source of any carrier oil utilized to aromatize substrates will, of course, generally depend upon the product whose aroma is to be enhanced. For example, coffee oil is the preferred carrier when the aroma to be carried is coffee aroma and the product whose aroma is to be enhanced is coffee. Other types of carriers, however, may also be used to aromatize coffee products. Typical of such other aroma carriers are edible oils, which can be of either animal or vegetable origin and can include common triglyceride oils such as soybean oil, rapeseed oil, corn oil, marine oils, animal oils, oils extracted from fruits, berries and vegetables.
Glycerin, propylene glycol, and other similar materials can also be used as the aroma carrier "oil" in the present invention.
Coffee oil is described herein as the preferred aroma carrier oil but the invention applies to and encompasses other aroma carrier oils such as those described previously.
Coffee oil is obtained by utilizing extraction methods well known in the art to recover the coffee oil from roasted coffee beans. The coffee oil can be obtained from various types of coffee beans such as robusta, arabica, mixtures thereof, and the like.
Generally, two basic extraction methods are used. The first comprises an extraction process wherein organic solvents and/or super critical carbon dioxide are used to remove coffee oil from roasted and ground coffee. In this process, the organic solvent and/or super-critical carbon dioxide, after contact with the roasted and ground coffee, is removed from the extract to yield a residue of coffee oil.
The second and more common method involves express-ing coffee oil from roasted coffee by subjecting the roasted coffee to extreme mechanical pressures. The product of this process is often referred to as expeller coffee oil. Expeller oil is preferred since it does not require the addition of foreign materials (i.e., organic solvents) to coffee substrates to obtain the coffee oil.
Coffee oil useful in the present invention should be substantially anhydrous (less than about 0.5% water) prior to combining it with the coffee aroma gas. Dry coffee oil can be obtained by any of the many known processes for removing water from such materials.
These processes typically include centrifugation, ultracentrifugation, molecular filtration, contact with drying agents, use of glass wool packed columns, and combinations of such techniques. Other drying operations that do not adulterate or degrade the coffee oil can also be used.
As with other aroma carriers, coffee oils fix or retain the volatile coffee aromas (coffee aroma materials) so that they can be retained and later used to aromatize various substrates, especially coffee substrates such as roasted and ground coffee, flaked coffee, soluble coffee and mixtures thereof.
In this second step of the process herein, dry coffee aroma gas is condensed and combined with aroma oil in the form of cryofied particles. Cryofied aroma carrier oil such as coffee oil can be produced in a manner similar to that disclosed by U. S. Patent 3,783,163 (Patel), issued January 1, 1974.
In making, for example, a cryofied coffee oil, the coffee oil is added to a cryogenic fluid to form a cryogenic slurry. Such a slurry thus contains a mixture of cryogenic fluid and solidified coffee oil particles.
The cryogenic fluid is continuously agitated during the addition of the coffee oil. Such addition typically takes about 10-15 minutes depending on the relative amounts of coffee oil and cryogenic fluid. The slurry contains less than about 0.5~ water.
Acceptable cryogenic fluids for use in such a procedure are those having a boiling point (at ~ ~ $ ~
atmospheric pressure) less than -109~F (-78.3~C). These include liquid nitrogen, liquid hydogen, liquid helium, liquid air, and mixtures thereof. Liquid nitrogen is highly preferred since it is easily obtained and is also substantially inert. The other liquid gases are typically more volatile and consequently may present a safety concern. The weight ratio of cryogenic fluid to coffee oil is typically greater than about 1:1, preferably within a range of from 5:1 to about 2:1. This ratio, however, is not critical to the present invention.
Since liquid nitrogen is the preferred cryogenic fluid for use herein, the invention is described herein-after as employing liquid nitrogen. It shall be understood, however, that other cryogenic fluids described above can also be used and are encompassed by the present invention.
After the cryofied slurry (liquid nitrogen and cryofied coffee oil particles) is formed, the slurry temperature is allowed to increase above the boiling point of the liquid nitrogen (-320~F/-195.6~C). This results in evaporation of the liquid nitrogen from the slurry. Complete evaporation typically occurs over 10-30 minutes. Evaporation times can be accelerated by using continuous or intermittent agitation of the slurry.
After evaporation, a mass of cryofied coffee oil particles, substantially free of liquid nitrogen, remalns .
The cryofied coffee oil is then combined with the dry coffee aroma, preferably by one of two methods. In a less preferred method, this is done by first condensing the dry aroma gas into dry aroma frost and by adding this frost to the cryofied coffee oil particles. This is accomplished by passing the dry aroma gas over a cooled surface having a temperature sufficient to condense the dry aroma gas onto the cooled surface. Preferably, the . ,j,9, . ~
5~ ~4 temperature of the surface will be below about -150~F
(-101~C), most preferably below about -210~F (-134~C).
More of the aroma gas will condense (about 90~) when the 5 surface temperatures are below -210~F (-134~C). A
suitable condenser may comprise a jacketed, vertically-mounted, scraped-wall heat exchanger cooled by a liquid gas refrigerant such as liquid nitrogen. Other similar condensers can also be used. The dry aroma frost so formed can then be added directly to the cryofied coffee oil particles.
Rather than adding a pre-condensed aroma frost to the cryofied oil particles as hereinafter described, the dry aroma gas is more preferably condensed directly onto 15 the cryofied coffee oil particles. This referred process results in the formation of a mass of cryofied aroma/coffee oil particles wherein the particles have an inner solidified coffee oil core and an outer layer of condensed aroma gas, i.e., solidified carbon dioxide, 20 coffee aroma materials, and ice (less than 0. 5%
ice/water).
In the preferred method, the dry aroma gas is intro-duced into a cooled container of the cryofied coffee oil particles (substantially free of liquid nitrogen). The 25 cryofied coffee oil particles in this container can be maintained at a temperature of from about -210~F (-134~C) to about -290~F (-179~C) . Temperatures below about -290~F
(-179~C) can be used but oxygen may then condense on the particles. Oxygen condensates can represent a safety risk during manufacturing and are preferably avoided.
Temperatures above about -210~F (-134~C) can also be used, but the condensing fraction of aroma gas is thereby undesirably reduced (less than 90% at above -210~F/-134~C) 8 ~
As the dry aroma gas enters the cooled container, it condenses onto the cryofied coffee oil particles. Some condensation may also occur onto the walls of the cooled 5 container but preferably most of the condensation occurs directly onto the cryofied coffee oil particles. The container preferably contains a means for agitating the cryofied oil particles as the dry aroma gas enters the container. By agitating the particles during 10 condensation, the coffee aroma materials more uniformly condense onto the particles within the mass. The cooled container can be an open or vented container with a means for cooling the contents therein to less than about -210~F
(-138~C). The cooling means typically is provided by, but 15 is not limited to, a jacket of liquid nitrogen associated with the walls of the cooled container.
C. Controlled Equilibration of Cryofied Aroma Oil Particles In a third step of the process herein, the cryofied 20 mass of aroma oil particles is subjected to controlled temperature equilibration procedure. Such a controlled temperature equilibration procedure allows substantially all of the solid carbon dioxide to sublime from the coffee oil particles. The equilibration procedure also 25 allows the coffee aroma materials to migrate into or to affix thereafter within the coffee oil while the carbon dioxide sublimes and is removed from the cryofied particles.
During equilibration, the mass of cryofied 30 aroma/coffee oil particles can be maintained in a vented vessel, the vessel being bathed in a surrounding medium having a temperature of between about -109~ F (-78.3~C) and 100~F (37.7~C), preferably from about -50~F (-45.6~C) to about 70~F (21.1~C), most preferably at about room temperature (68~F/20~C). The vented vessel can be kept in an area or room maintained at these temperatures or, more preferably, the vented vessel can be surrounded by a circulating jacket of gas, the gas having the temperatures just recited. At these surrounding temperatures, the solid carbon dioxide within the cryofied mass sublimes and can be removed from the vented vessel, the sublimation temperature of solid carbon dioxide being about -109~F (-78.3~C). Intra-vessel pressures above or below atmospheric pressure can be used but are not necessary for the practice of the present invention. Typically, atmospheric pressure is maintained within the vented vessel in which the cryofied mass is equilibrated.
It has been found that controlled temperature equilibration of a cryofied mass of carbon dioxide-containing aroma/coffee oil particles is an essential element of the present invention. When equilibration begins, the cryofied mass will typically have a temperature below about -210~F (-134~C). The temperature then initially rises as the particle mass is warmed and eventually plateaus at -109~F (-78.3~C). At -109~F
(-78.3~C), the solid carbon dioxide begins to sublime.
When substantially all of the carbon dioxide has sublimed, the temperature of the particle mass begins to increase above -109~F (-78.3~C). At that point, the equilibration is complete. The cryofied mass then contains cryofied coffee oil fixed with coffee aroma materials with less than about 0.5% water and substantially no solid carbon dioxide. To assure a complete equilibration (e.g. substantially all solid carbon dioxide sublimed), equilibration is preferably -7 ~
allowed to proceed until the particle mass temperature is about -105~F (-76.1~C). Allowing the temperature to rise above about -105~F (76.1~C) can result in an unnecessary loss of volatile coffee aroma materials.
Preferably, the cryofied mass of aroma/coffee oil particles during the equilibration step is agitated in an intermittent or continuous manner, preferably in a continuous manner. Agitating reduces equilibration times and the temperatures needed to bathe the vented vessel during equilibration. In a typical example within the present invention, the equilibration requires from about 3 to about 7 hours using continuous agitation in a vented vessel exposed to room temperature air. Without agitation, this equilibration time would increase to about 7 to 14 hours. In an extreme example, the equilibration can require between 15-30 days when agitation is not used (static equilibration) and the vented vessel is bathed in -20~F (-29~C) air.
It has been found, surprisingly, that the control-led equilibration step of the present invention results in not more than about a 5~ loss of the coffee aroma materials. This is especially surprising during shorter equilibration operations involving continuous agitation.
Thus about 100% of the cryofied carbon dioxide can be driven off in about 3-7 hours while at least about 95~ of the coffee volatiles (coffee aroma materials) are retained.
D Meltinq of Cryofied Aroma Oil Particles In the fourth step of the process herein, the cryofied mass of aroma oil particles, rendered substantially free of moisture during the calcium sulfate drying step and substantially free of carbon dioxide during the controlled temperature equilibration step, is melted to form the liquid dry coffee aroma oil product.
7~ ~ ~ K ~ 7 ~
Melting, which is preferably carried out relatively quickly and in an enclosed space, is achieved by subjecting the equilibrated cryofied mass of aroma oil particles to temperatures of from about 45~F to about 110~F, preferably from about 80~F (27~C) to about 100~F
(38~C), for a period of time sufficient to melt the particles.
The melting step of the process herein is preferably carried out using a high surface-area heater/melter. The temperature of the heater surfaces (warming surfaces) are maintained at between about 45~F (7~C) and about 110~F
(43~C), preferably from about 80~F (27~C) to about 100~F
(38~C). The melting period can vary but melting typically occurs over a time period of about 1-3 hours. Melting times can extend beyond the 1-3 hour range depending on the size of the equilibrated mass to be melted and the heating parameters selected (i.e. amount of heat, amount of surface area per volume of equilibrated mass). The melted product can then be used as a dry coffee aroma oil for aromatizing soluble coffee powders and other food substrates. Alternatively, the melted product can be refrozen and sealed for later use.
By removing substantially all of the solid carbon dioxide from the cryofied mass of aroma/coffee oil particles in the controlled temperature equilibration step, less energy is subsequently needed to melt the cryofied mass in the melter/heater. Since less energy is needed, the composition can be melted over a shorter period of time. Also, it has been found that the lower energy melting made possible by the process of the present invention reduces the degradation of the coffee aroma materials in the aroma/coffee oil composition.
The coffee aroma oil preparation process of the instant invention is illustrated by the following example:
-7' Example I
A batch of roasted coffee beans (162,000 lbs-73,548kg) is held at about room temperature for 7 hours (post-roasting) before grinding. The beans are ground, producing 35,000 cubic feet (991 cubic meters) of a grinder gas/air mixture. As the grinder gas evolves during grinding, it is captured in an overhead hood and pumped through a water-cooled pre-condenser having a surface temperature of about 40~F (4.4~C).
The grinder gas (as a grinder gas/air mixture) is then pumped through a calcium sulfate bed at 50 cubic feet/minute (1.4 cubic meter/minute). The bed comprises a closed vessel having an 8:1 length to diameter ratio filled with 375 lbs (170kg) of regenerated calcium sulfate granules (approximately 10mm diameter granules), the granules containing less than 0.1% moisture. The dry aroma gas (with air) exiting the bed has a moisture content of about 5Oppm.
Dry coffee oil (expeller oil) 150 lbs/68kg) is poured into and continuously mixed (over about 15 minutes) with 300 pounds (136kg) of liquid nitrogen contained within a cryofication tank. Once combined, the slurry is washed (using liquid nitrogen) into a cryo-mixer. The cryomixer comprises a vented vessel jacketed in liquid nitrogen and equipped for agitating the vessel contents.
The slurry is continuously agitated (slurry temperature -250~F/-157~C) for 10-15 minutes in the cryo-mixer until all of the liquid nitrogen evaporates,leaving a particle mass comprising cryofied coffee oil particles. While continuously agitating the particle mass (cryofied coffee oil particles) and maintaining a particle mass temperature of about -250~F (-157~C), the dry aroma gas is then vented into the cryomixer. When 7 ~
all of the aroma gas has been vented into and condensed within the vessel (approximately 12 hours), the liquid nitrogen is removed from the surrounding jacket.
Nitrogen gas is circulated through the jacket surrounding the cryomixer. The circulating gas initially enters the jacket having the temperature of about 68~F
(20~C). The temperature of the cryofied mass increases from about -250~F (-157~C) to a plateau of -109~F (-78.3~C) as carbon dioxide is vented from the cryomixer. When the temperature of the cryofied mass reaches -105~F (-76.1~C), the resulting equilibrated carbon dioxide-free cryofied mass (150 lbs/68kg) is immediately placed in a high-surface area melter. The heating surfaces within the melter are kept at about 90~F (32~C). As the equilibrated mass liquifies, it is collected in a closed container.
The liquified product is a dry coffee aroma oil having less than about 0.15% water which is then used to aromatize a soluble coffee powder.
Other methods of reducing the aqueous/sulfurous reaction are known. Such methods frequently involve removal of water from the condensed aroma frost and/or removal of water immediately after forming an aroma oil product. For example, a commonly used method involves centrifuging the coffee aroma oil to remove water immediately after the coffee aroma oil is formed. This results in an acceptable product but a significant amount (up to about 30%) of the coffee aroma materials are also lost during the centrifugation. Furthermore, there is still some contact time between the water and the sulfurous materials such that some excessive sulfurous aromas typically develop. Use of centrifugation and extended hold-times techniques can be combined to further reduce excessive production of sulfurous aromas. Longer hold-times, however, hamper coffee processing operations in as much as only a portion of the grinding operations can be used to capture the grinder gases.
It is also known that, in addition to undesirable aqueous/sulfurous reactions, excessive heating of coffee aroma materials while manufacturing coffee aroma oils results in aroma degradation and loss.
20~224 3 ; ~
Given the foregoing, it can be seen tX~t~there is a continuing need to develop processes for producing coffee aroma oils without excessive heating of coffee aroma materials or with procedures that minimize undesirable reactions that can produce off-flavors during the manufacture of coffee aroma oil.
It iB therefore an obje~t of an a~pect of this invention to provide such an improved proces~ ~or producing coffee aroma oils, which method mlnimi zes the occurrence of aqueous/sulfurous reactions that can result in excessive sulfurous aromas.
It is an object of an aspect of this invention to provide such a process while m;n;mi zing degradation and 1088 of aroma oils by reducing the amount of heat exposure of the aroma oil materials during the manufacture of coffee aroma oils.
It is an object of an aspect of this invention to provide such a process which optimizes the efficiency of manufacturing coffee aroma oils.
These and other objects of this invention will become evident from the dis~losure herein.
SUMMARY OF THE INVENTION
The present invention provides a process for making dry coffee aroma oils useful for aromatizing coffee substrates.
In a first step (calcium sulfate drying step) of such a process, a moisture and carbon dioxide-containing coffee aroma gas is passed through a bed of granules comprising hydratable calcium sulfate. The granules remove substan-tially all moisture from the coffee aroma gas, thereby forming dry, carbon dioxide-containing coffee aroma gas. In a second step (condensation step) of the process herein, the carbon dioxide-containing coffee aroma gas is condensed and combined with cryofled particles of normally liquid aroma carrier oil. This condensation step results in a cryofied mass of particles comprising condensed dry, carbon dioxide containing coffee aroma gas and cryofied aroma carrier oil.
During this condensation step, the cryofied mass of parti-cles are typically maintained at a temperature sufficiently low to maintain the carbon dioxide-containing aroma gas in condensed form. ~n a third step (controlled temperature equilibration step) of the process herein, the cryofied mass 0 of particles from the condensation step are subjected to a medium having a temperature of between about -lO9-F
(-78.3-C) and lOO-F (37.7-C) until the temperature within the mass of particles increases to a value of from about -lO9-F (-78.3-C) to -105-F t-76-l-c)~ to thereby remove substantially all of the carbon dioxide from the cryofied mass of particles. ~n a fourth step (melting step), the carbon dioxide-free cryofied mass of particles is subjected to a temperature of from aboùt 45-F (7-C) to 1l0-F (43-C) for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
Other aspects of this invention are as follows:
A process for making dry coffee aroma oils useful for aromatizing coffee substrates, which process comprises the steps of (a) passing a moisture- and carbon dioxide-containing coffee aroma gas through a bed of granules comprising hydratable calcium sulfate to thereby remove substantially all moisture from the coffee aroma gas, thereby forming dry, carbon dioxide--containing coffee aroma gas; then (b) condensing the dry, carbon dioxide-containing coffee aroma gas of step (a) and combining said condensed aroma gas with cryofied particles of normally liquid aroma carrier oil to thereby form a cryofied mass of particles comprising condensed dry, carbon dioxide-containing coffee aroma gas Jr j~ 9 ~
- 4a - 2 0 9 8 2 2 4 and cryofied aroma carrier oil, the cryofied mass of particles being maintained at a temperature sufficiently low to maintain the carbon dioxide-containing aroma gas in condensed form; then (c) equilibrating the cryofied mass of particles of step (b) by subjecting said mass of particles to a surrounding temperature of between about -lO9-F
and lOO-F until the temperature within the mass of particles increases to a value of from about -lO9-F to -105-F, to thereby remove substantially all of the carbon dioxide from said cryofied mass of particles; and then (d) melting the resulting carbon dioxide-free cryofied mass of particles from step (c) by subjecting said mass to a temperature of from about 45-F to llO-F
for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
A process for making dry coffee aroma oils useful for aromatizing coffee substrates, which process comprises the steps of (a) passing a moisture- and carbon dioxide-containing coffee grinder gas through a bed of granules comprising hydratable calcium sulfate to thereby remove substantially all moisture from the coffee aroma gas, thereby forming dry, carbon dioxide-containing coffee grinder gas; then (b) condensing the dry, carbon dioxide-containing coffee grinder gas of step (a) onto cryofied coffee oil particles to thereby form a cryofied mass of particles comprising condensed dry, carbon dioxide-containing coffee grinder gas and cryofied - 4b - 2 0 9 ~ 2 2 4 coffee oil, the cryofied mass of particles being maintained at a temperature of between about -210-F and about -290-F; then (c) equilibrating the cryofied mass of particles of step (b) by subjecting said mass of particles to a surrounding temperature of about 68-F until the temperature within the mass of particles increases 0 to a value of from about -109-F to about -105-, to thereby remove substantially all of the carbon dioxide from said cryofied mass of particles; and then (d) melting the resulting carbon dioxide-free cryofied mass of particles from step (c) by subjecting said mass to a temperature of from about 70-F to about 100-F for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
DEFINITIONS
The term "coffee oil~ as used herein means the natural product obtained by solvent extraction of coffee beans or obtained by expelling such a natural product from beans as described in Sivetz, Coffee Processing TechnoloqY, Vol.2, pages 21-30, Avi Publishing Company (1963).
The term "normally liquid aroma carrier oil n as used herein means any suitable substrate or sorbent which is liquid at room temperature and to which roasted coffee aroma materials can be transferred such that the substrate or sorbent acts as a carrier for the roasted coffee aroma materials.
The term "aroma oil" or "coffee aroma oil" as used herein means the aroma carrier that has been aromatized with or combined with the roasted coffee aroma materials from a coffee aroma gas.
The term "cryogenic fluid" as used herein means liquified gases having a boiling point ~at atmospheric pressure) below -109~F (-78.3~C) such as liquid nitrogen, liquid hydrogen, liquid air, liquid helium, and mixtures thereof.
The terms "substantially anhydrous" or "dry" as used herein mean a moisture content of less than about 0.5%.
The terms "aroma gas", "grinder gas" or "coffee aroma gas" as used herein refer to the coffee gases actually released from coffee before they are admixed with air or other inert carrier gas. Such terms, also refer to such coffee gas as a component of a mixture of coffee gas and air (or other inert carrier gas).
All percents are weight percents unless otherwise specified.
DETAILED DESCRIPTION OF THE INVENTION
The process of the present invention involves four key steps: 1) an aroma gas drying step wherein calcium sulfate is used to remove water from a moisture and carbon dioxide containing coffee aroma gas, b) an aroma carrier formulation step wherein aroma gas is condensed or combined with a cryofied aroma carrier material, c) a controlled temperature equilibration step that results in a carbon dioxide-free cryofied aroma/aroma carrier mixture that can be melted. quickly and with little heat, and d) a melting step to form the desired coffee aroma oil. Each of these four essential steps, as well as additional preferred embod.iments or elements, is described in detail as follows.
A) Aroma Gas Dryinq In connection with the first step of the instant process, a moisture and carbon dioxide-containing coffee aroma gas is provided in known and conventional manner.
Such aroma gas is the material which is captured during coffee manufacturing operations such as roasting, grinding, steam distillation, or dry distillation. The aroma gas obtained during the grinding of roasted coffee beans (grinder gas) is preferred. Various types of coffee beans can be used including robusta, arabica, mixtures thereof, and the like. The most readily available source of grinder gas may be obtained by enclosing or hooding coffee grinding equipment, such as commercial grinders. The grinder gases liberated from the ground coffee may be removed by a pump, rotary blower, or the like. Additionally, it is known that a stream of inert, moisture free, gas may be used to sweep the aroma gas from the ground coffee. If pumping is employed, it may be desirable to cool the gas ahead of the pump so that the heat added by pumping will not degrade the aroma materials contained in the gas.
Grinder gas typically contains about 70-90% carbon dioxide, 10-20% water and 2-3% coffee aroma materials (coffee volatiles). When mixed with air after capture, the resulting mixture comprises an aroma gas component (about 5-7%) and an air component (about 93-97%).
Overall, the aroma gas/air mixture will frequently contain about 4-5% carbon dioxide, less than about 1 water, and less than 1% coffee aroma materials.
As an optional step prior to the drying step, herein-after described, the aroma gas/air mixture can be passed through a pre-condenser cooled to between about 35~F (1.7~C) and about 50~F (10~C). Up to about 50% of the gaseous moisture can be condensed on cooled surfaces within the pre-condenser. By using a pre-condenser, the calcium sulfate beds used in the drying step as hereinafter described can be used longer before being replaced or regenerated.
In accordance with the first step of the process herein, the moisture and carbon dioxide-containing coffee aromatic gas as hereinafter described (typically as a mixture of aroma gas and air) is passed through a desiccant bed of hydratable calcium sulfate, typically in the form of calcium sulfate granules. Contact of the aroma gas with the calcium sulfate bed serves to remove substantially all of the moisture from the aroma gas, thereby forming dry coffee aroma gas.
The calcium sulfate bed can comprise a vessel (desiccant vessel), preferably a closed vessel, having an inlet and outlet for entry and exit of an aroma gas stream. The vessel can have a length to diameter ratio of from about 10:1 to about 3:1, preferably from about 9:1 to about 7:1. The vessel is packed with the calcium sulfate, typically as granules. Such granules can have an average diameter of from about 2mm to about 26.9mm, more typically from about 2.38mm to about 12mm. When granules become too fine, air flow through the column requires increased pressure. Although not critical to the present invention, it is generally desirable to avoid the added complications (i.e., safety measures) associated with pressure vessels.
The calcium sulfate in the bed can absorb up to about 6.5% of its weight as water. The aroma gas/air mixture enters the calcium sulfate bed having a water content typically exceeding about 3000 ppm (0.3%) and exits the bed having less than about 50 ppm (0.005%).
The aroma gas component of the dried aroma gas/air mixture then contains less than about 0.5% water.
The aroma gas/air mixture can be passed through the bed in a continuous or, more typically, intermittent manner. Initially, the calcium sulfate bed will 2 ~ ~
generally contain less than about 0.5% moisture prior to contacting the aroma gas/air mixture. A given calcium sulfate bed can be used in the drying operation until it contains about 6.5~ water, preferably about 5% water, at which point the desiccant vessel is taken off-line and the hydrated calcium sulfate is regenerated (air dried to contain less than 0.5% water). Calcium sulfate is preferably taken off-line at the 5% rather than 6.5%
moisture level to avoid accidental moisture overflow beyond the 6.5% moisture threshold.
Once the calcium sulfate bed contains up to about 6.5% water, preferably not more than about 5% water, the desiccant vessel is taken off-line from the aroma gas stream and the calcium sulfate is regenerated (i.e., its water content is reduced). To effect calcium sulfate regeneration, air having a temperature of about 350~F
(177~C) to about 450~F (232~C) is pumped or blown into the vessel inlet, passes through the calcium sulfate bed, and exits at the vessel outlet. The flow rate will be consistent with the volume of the desiccant vessel. For a typical vessel containing about 375 lbs (170kg) (dry basis) of dry calcium sulfate granules, the flow rate is maintained at about 300 cubic feet/minute (8.5 cubic meter / minute) to about 550 cubic feet/minute (15.6 cubic meter / minute), typically at about 375 cubic feet/minute (10.62 cubic meter/minute). The stream of hot air is passed continuously through the vessel until the calcined sulfate contains not more than about 0.5%
moisture. It typically takes between about 3-8 hours to sufficiently dry a vessel of calcium sulfate although lesser and greater times may also be required.
Moisture levels of the hot air stream can be monitored at the vessel inlet and outlet to indirectly identify the point at which the calcium sulfate is .
8 ~ ~ ~
g sufficiently regenerated. When the moisture content at the outlet is about equal to that of the inlet, the calcium sulfate is sufficiently regenerated (less than about 0.5% water). Temperatures at the inlet and outlet can also be monitored to indirectly measure moisture content. When the outlet temperature is about equal to the inlet temperature, the calcium sulfate is sufficient-ly regenerated.
When the calcium sulfate is regenerated, the heating device warming the inlet air stream is turned off. The air continues to be pumped through the desiccant vessel until the outlet air temperature drops below about 100~F
(38~C), preferably to aboul 68~F (20~C). The vessel can then be placed on-line with the aroma gas stream to resume desiccation of the aroma gas. Alternatively, the inlet and outlet are capped and the vessel is stored for later use.
A vessel of calcium sulfate can be regenerated and subsequently reused in the drying sequence according to the present invention for typically between about 20-30 times before the calcium sulfate granules need to be replaced, most typically about twenty times.
It has been found that calcium sulfate, surprising-ly, removes water from the aroma gas stream withoutremoving substantial amounts of coffee aroma materials.
It was also found that by using calcium sulfate to dry the gaseous aroma, there was no longer a need to remove residual moisture from the coffee aroma oil by centri-fugation or other inefficient methods. Compared tocentrifugation, calcium sulfate drying results in up to about 30% more dry coffee aroma material from a given volume of grinder gas.
It should be noted that other known methods of reducing the moisture of aroma gases can also be used to complement the calcium sulfate gas drying operation of the present invention. Examples of such known methods include, but are not limited to, roasting under dry conditions and using low-moisture quenches or quenching mediums during roasting.
It has been found that drying coffee aroma gases with calcium sulfate, when used in conjunction with the controlled temperature equilibration as hereinafter described, reduces the production of excessive sulfurous aromas and increased aroma oil yield.
The calcium sulfate drying step of the present invention reduces contact of moisture with sulfurous coffee volatiles during the manufacture of coffee aroma oils. Such contact can result in the rapid development of undesirably excessive sulfurous aromas in the resulting coffee aroma oil. By reducing water contact, the production of sulfurous aromas is also reduced. The sulfurous coffee volatiles and their aqueous reaction by-products are as yet not fully identified. Nonetheless, excessive sulfurous aromas are easily detected organ-oleptically as a sharp hydrogen sulfide-type odor.
Reducing the water content of the aroma gas during its gaseous phase will reduce subsequent aqueous reactions that might have occurred while manufacturing the coffee aroma oil.
B) Cryofied Aroma Oil Particles In a second step of the process herein, the dried coffee aroma gas from the calcium sulfate drying step is condensed and combined with cryofied particles of a normally liquid aroma carrier oil.
The aroma carrier oil which is to be utilized in the process of this invention can be obtained from a variety of sources. The source of any carrier oil utilized to aromatize substrates will, of course, generally depend upon the product whose aroma is to be enhanced. For example, coffee oil is the preferred carrier when the aroma to be carried is coffee aroma and the product whose aroma is to be enhanced is coffee. Other types of carriers, however, may also be used to aromatize coffee products. Typical of such other aroma carriers are edible oils, which can be of either animal or vegetable origin and can include common triglyceride oils such as soybean oil, rapeseed oil, corn oil, marine oils, animal oils, oils extracted from fruits, berries and vegetables.
Glycerin, propylene glycol, and other similar materials can also be used as the aroma carrier "oil" in the present invention.
Coffee oil is described herein as the preferred aroma carrier oil but the invention applies to and encompasses other aroma carrier oils such as those described previously.
Coffee oil is obtained by utilizing extraction methods well known in the art to recover the coffee oil from roasted coffee beans. The coffee oil can be obtained from various types of coffee beans such as robusta, arabica, mixtures thereof, and the like.
Generally, two basic extraction methods are used. The first comprises an extraction process wherein organic solvents and/or super critical carbon dioxide are used to remove coffee oil from roasted and ground coffee. In this process, the organic solvent and/or super-critical carbon dioxide, after contact with the roasted and ground coffee, is removed from the extract to yield a residue of coffee oil.
The second and more common method involves express-ing coffee oil from roasted coffee by subjecting the roasted coffee to extreme mechanical pressures. The product of this process is often referred to as expeller coffee oil. Expeller oil is preferred since it does not require the addition of foreign materials (i.e., organic solvents) to coffee substrates to obtain the coffee oil.
Coffee oil useful in the present invention should be substantially anhydrous (less than about 0.5% water) prior to combining it with the coffee aroma gas. Dry coffee oil can be obtained by any of the many known processes for removing water from such materials.
These processes typically include centrifugation, ultracentrifugation, molecular filtration, contact with drying agents, use of glass wool packed columns, and combinations of such techniques. Other drying operations that do not adulterate or degrade the coffee oil can also be used.
As with other aroma carriers, coffee oils fix or retain the volatile coffee aromas (coffee aroma materials) so that they can be retained and later used to aromatize various substrates, especially coffee substrates such as roasted and ground coffee, flaked coffee, soluble coffee and mixtures thereof.
In this second step of the process herein, dry coffee aroma gas is condensed and combined with aroma oil in the form of cryofied particles. Cryofied aroma carrier oil such as coffee oil can be produced in a manner similar to that disclosed by U. S. Patent 3,783,163 (Patel), issued January 1, 1974.
In making, for example, a cryofied coffee oil, the coffee oil is added to a cryogenic fluid to form a cryogenic slurry. Such a slurry thus contains a mixture of cryogenic fluid and solidified coffee oil particles.
The cryogenic fluid is continuously agitated during the addition of the coffee oil. Such addition typically takes about 10-15 minutes depending on the relative amounts of coffee oil and cryogenic fluid. The slurry contains less than about 0.5~ water.
Acceptable cryogenic fluids for use in such a procedure are those having a boiling point (at ~ ~ $ ~
atmospheric pressure) less than -109~F (-78.3~C). These include liquid nitrogen, liquid hydogen, liquid helium, liquid air, and mixtures thereof. Liquid nitrogen is highly preferred since it is easily obtained and is also substantially inert. The other liquid gases are typically more volatile and consequently may present a safety concern. The weight ratio of cryogenic fluid to coffee oil is typically greater than about 1:1, preferably within a range of from 5:1 to about 2:1. This ratio, however, is not critical to the present invention.
Since liquid nitrogen is the preferred cryogenic fluid for use herein, the invention is described herein-after as employing liquid nitrogen. It shall be understood, however, that other cryogenic fluids described above can also be used and are encompassed by the present invention.
After the cryofied slurry (liquid nitrogen and cryofied coffee oil particles) is formed, the slurry temperature is allowed to increase above the boiling point of the liquid nitrogen (-320~F/-195.6~C). This results in evaporation of the liquid nitrogen from the slurry. Complete evaporation typically occurs over 10-30 minutes. Evaporation times can be accelerated by using continuous or intermittent agitation of the slurry.
After evaporation, a mass of cryofied coffee oil particles, substantially free of liquid nitrogen, remalns .
The cryofied coffee oil is then combined with the dry coffee aroma, preferably by one of two methods. In a less preferred method, this is done by first condensing the dry aroma gas into dry aroma frost and by adding this frost to the cryofied coffee oil particles. This is accomplished by passing the dry aroma gas over a cooled surface having a temperature sufficient to condense the dry aroma gas onto the cooled surface. Preferably, the . ,j,9, . ~
5~ ~4 temperature of the surface will be below about -150~F
(-101~C), most preferably below about -210~F (-134~C).
More of the aroma gas will condense (about 90~) when the 5 surface temperatures are below -210~F (-134~C). A
suitable condenser may comprise a jacketed, vertically-mounted, scraped-wall heat exchanger cooled by a liquid gas refrigerant such as liquid nitrogen. Other similar condensers can also be used. The dry aroma frost so formed can then be added directly to the cryofied coffee oil particles.
Rather than adding a pre-condensed aroma frost to the cryofied oil particles as hereinafter described, the dry aroma gas is more preferably condensed directly onto 15 the cryofied coffee oil particles. This referred process results in the formation of a mass of cryofied aroma/coffee oil particles wherein the particles have an inner solidified coffee oil core and an outer layer of condensed aroma gas, i.e., solidified carbon dioxide, 20 coffee aroma materials, and ice (less than 0. 5%
ice/water).
In the preferred method, the dry aroma gas is intro-duced into a cooled container of the cryofied coffee oil particles (substantially free of liquid nitrogen). The 25 cryofied coffee oil particles in this container can be maintained at a temperature of from about -210~F (-134~C) to about -290~F (-179~C) . Temperatures below about -290~F
(-179~C) can be used but oxygen may then condense on the particles. Oxygen condensates can represent a safety risk during manufacturing and are preferably avoided.
Temperatures above about -210~F (-134~C) can also be used, but the condensing fraction of aroma gas is thereby undesirably reduced (less than 90% at above -210~F/-134~C) 8 ~
As the dry aroma gas enters the cooled container, it condenses onto the cryofied coffee oil particles. Some condensation may also occur onto the walls of the cooled 5 container but preferably most of the condensation occurs directly onto the cryofied coffee oil particles. The container preferably contains a means for agitating the cryofied oil particles as the dry aroma gas enters the container. By agitating the particles during 10 condensation, the coffee aroma materials more uniformly condense onto the particles within the mass. The cooled container can be an open or vented container with a means for cooling the contents therein to less than about -210~F
(-138~C). The cooling means typically is provided by, but 15 is not limited to, a jacket of liquid nitrogen associated with the walls of the cooled container.
C. Controlled Equilibration of Cryofied Aroma Oil Particles In a third step of the process herein, the cryofied 20 mass of aroma oil particles is subjected to controlled temperature equilibration procedure. Such a controlled temperature equilibration procedure allows substantially all of the solid carbon dioxide to sublime from the coffee oil particles. The equilibration procedure also 25 allows the coffee aroma materials to migrate into or to affix thereafter within the coffee oil while the carbon dioxide sublimes and is removed from the cryofied particles.
During equilibration, the mass of cryofied 30 aroma/coffee oil particles can be maintained in a vented vessel, the vessel being bathed in a surrounding medium having a temperature of between about -109~ F (-78.3~C) and 100~F (37.7~C), preferably from about -50~F (-45.6~C) to about 70~F (21.1~C), most preferably at about room temperature (68~F/20~C). The vented vessel can be kept in an area or room maintained at these temperatures or, more preferably, the vented vessel can be surrounded by a circulating jacket of gas, the gas having the temperatures just recited. At these surrounding temperatures, the solid carbon dioxide within the cryofied mass sublimes and can be removed from the vented vessel, the sublimation temperature of solid carbon dioxide being about -109~F (-78.3~C). Intra-vessel pressures above or below atmospheric pressure can be used but are not necessary for the practice of the present invention. Typically, atmospheric pressure is maintained within the vented vessel in which the cryofied mass is equilibrated.
It has been found that controlled temperature equilibration of a cryofied mass of carbon dioxide-containing aroma/coffee oil particles is an essential element of the present invention. When equilibration begins, the cryofied mass will typically have a temperature below about -210~F (-134~C). The temperature then initially rises as the particle mass is warmed and eventually plateaus at -109~F (-78.3~C). At -109~F
(-78.3~C), the solid carbon dioxide begins to sublime.
When substantially all of the carbon dioxide has sublimed, the temperature of the particle mass begins to increase above -109~F (-78.3~C). At that point, the equilibration is complete. The cryofied mass then contains cryofied coffee oil fixed with coffee aroma materials with less than about 0.5% water and substantially no solid carbon dioxide. To assure a complete equilibration (e.g. substantially all solid carbon dioxide sublimed), equilibration is preferably -7 ~
allowed to proceed until the particle mass temperature is about -105~F (-76.1~C). Allowing the temperature to rise above about -105~F (76.1~C) can result in an unnecessary loss of volatile coffee aroma materials.
Preferably, the cryofied mass of aroma/coffee oil particles during the equilibration step is agitated in an intermittent or continuous manner, preferably in a continuous manner. Agitating reduces equilibration times and the temperatures needed to bathe the vented vessel during equilibration. In a typical example within the present invention, the equilibration requires from about 3 to about 7 hours using continuous agitation in a vented vessel exposed to room temperature air. Without agitation, this equilibration time would increase to about 7 to 14 hours. In an extreme example, the equilibration can require between 15-30 days when agitation is not used (static equilibration) and the vented vessel is bathed in -20~F (-29~C) air.
It has been found, surprisingly, that the control-led equilibration step of the present invention results in not more than about a 5~ loss of the coffee aroma materials. This is especially surprising during shorter equilibration operations involving continuous agitation.
Thus about 100% of the cryofied carbon dioxide can be driven off in about 3-7 hours while at least about 95~ of the coffee volatiles (coffee aroma materials) are retained.
D Meltinq of Cryofied Aroma Oil Particles In the fourth step of the process herein, the cryofied mass of aroma oil particles, rendered substantially free of moisture during the calcium sulfate drying step and substantially free of carbon dioxide during the controlled temperature equilibration step, is melted to form the liquid dry coffee aroma oil product.
7~ ~ ~ K ~ 7 ~
Melting, which is preferably carried out relatively quickly and in an enclosed space, is achieved by subjecting the equilibrated cryofied mass of aroma oil particles to temperatures of from about 45~F to about 110~F, preferably from about 80~F (27~C) to about 100~F
(38~C), for a period of time sufficient to melt the particles.
The melting step of the process herein is preferably carried out using a high surface-area heater/melter. The temperature of the heater surfaces (warming surfaces) are maintained at between about 45~F (7~C) and about 110~F
(43~C), preferably from about 80~F (27~C) to about 100~F
(38~C). The melting period can vary but melting typically occurs over a time period of about 1-3 hours. Melting times can extend beyond the 1-3 hour range depending on the size of the equilibrated mass to be melted and the heating parameters selected (i.e. amount of heat, amount of surface area per volume of equilibrated mass). The melted product can then be used as a dry coffee aroma oil for aromatizing soluble coffee powders and other food substrates. Alternatively, the melted product can be refrozen and sealed for later use.
By removing substantially all of the solid carbon dioxide from the cryofied mass of aroma/coffee oil particles in the controlled temperature equilibration step, less energy is subsequently needed to melt the cryofied mass in the melter/heater. Since less energy is needed, the composition can be melted over a shorter period of time. Also, it has been found that the lower energy melting made possible by the process of the present invention reduces the degradation of the coffee aroma materials in the aroma/coffee oil composition.
The coffee aroma oil preparation process of the instant invention is illustrated by the following example:
-7' Example I
A batch of roasted coffee beans (162,000 lbs-73,548kg) is held at about room temperature for 7 hours (post-roasting) before grinding. The beans are ground, producing 35,000 cubic feet (991 cubic meters) of a grinder gas/air mixture. As the grinder gas evolves during grinding, it is captured in an overhead hood and pumped through a water-cooled pre-condenser having a surface temperature of about 40~F (4.4~C).
The grinder gas (as a grinder gas/air mixture) is then pumped through a calcium sulfate bed at 50 cubic feet/minute (1.4 cubic meter/minute). The bed comprises a closed vessel having an 8:1 length to diameter ratio filled with 375 lbs (170kg) of regenerated calcium sulfate granules (approximately 10mm diameter granules), the granules containing less than 0.1% moisture. The dry aroma gas (with air) exiting the bed has a moisture content of about 5Oppm.
Dry coffee oil (expeller oil) 150 lbs/68kg) is poured into and continuously mixed (over about 15 minutes) with 300 pounds (136kg) of liquid nitrogen contained within a cryofication tank. Once combined, the slurry is washed (using liquid nitrogen) into a cryo-mixer. The cryomixer comprises a vented vessel jacketed in liquid nitrogen and equipped for agitating the vessel contents.
The slurry is continuously agitated (slurry temperature -250~F/-157~C) for 10-15 minutes in the cryo-mixer until all of the liquid nitrogen evaporates,leaving a particle mass comprising cryofied coffee oil particles. While continuously agitating the particle mass (cryofied coffee oil particles) and maintaining a particle mass temperature of about -250~F (-157~C), the dry aroma gas is then vented into the cryomixer. When 7 ~
all of the aroma gas has been vented into and condensed within the vessel (approximately 12 hours), the liquid nitrogen is removed from the surrounding jacket.
Nitrogen gas is circulated through the jacket surrounding the cryomixer. The circulating gas initially enters the jacket having the temperature of about 68~F
(20~C). The temperature of the cryofied mass increases from about -250~F (-157~C) to a plateau of -109~F (-78.3~C) as carbon dioxide is vented from the cryomixer. When the temperature of the cryofied mass reaches -105~F (-76.1~C), the resulting equilibrated carbon dioxide-free cryofied mass (150 lbs/68kg) is immediately placed in a high-surface area melter. The heating surfaces within the melter are kept at about 90~F (32~C). As the equilibrated mass liquifies, it is collected in a closed container.
The liquified product is a dry coffee aroma oil having less than about 0.15% water which is then used to aromatize a soluble coffee powder.
Claims (19)
1. A process for making dry coffee aroma oils useful for aromatizing coffee substrates, which process comprises the steps of (a) passing a moisture- and carbon dioxide-containing coffee aroma gas through a bed of granules comprising hydratable calcium sulfate to thereby remove substantially all moisture from the coffee aroma gas, thereby forming dry, carbon dioxide-containing coffee aroma gas; then (b) condensing the dry, carbon dioxide-containing coffee aroma gas of step (a) and combining said condensed aroma gas with cryofied particles of normally liquid aroma carrier oil to thereby form a cryofied mass of particles comprising condensed dry, carbon dioxide-containing coffee aroma gas and cryofied aroma carrier oil, the cryofied mass of particles being maintained at a temperature sufficiently low to maintain the carbon dioxide-containing aroma gas in condensed form; then (c) equilibrating the cryofied mass of particles of step (b) by subjecting said mass of particles to a surrounding temperature of between about -109°F and 100°F
until the temperature within the mass of particles increases to a value of from about -109°F to -105°F, to thereby remove substantially all of the carbon dioxide from said cryofied mass of particles; and then (d) melting the resulting carbon dioxide-free cryofied mass of particles from step (c) by subjecting said mass to a temperature of from about 45°F to 110°F
for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
until the temperature within the mass of particles increases to a value of from about -109°F to -105°F, to thereby remove substantially all of the carbon dioxide from said cryofied mass of particles; and then (d) melting the resulting carbon dioxide-free cryofied mass of particles from step (c) by subjecting said mass to a temperature of from about 45°F to 110°F
for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
2. A process according to Claim 1 wherein the cryofied particles are subjected to agitation during the condensation of step (b) and the equilibration of step (c).
3. A process according to Claim 2 wherein said agitation is continuous.
4 . A process according to Claim 1 wherein the coffee aroma gas is a coffee grinder gas.
5. A process according to Claim 1 wherein the aroma carrier is a coffee oil.
6. A process according to Claim 1 wherein the cryofied mass of particles are maintained at a temperature of from about -210°F to -290°F during the step (b).
7. A process according to Claim 1 wherein the temperature surrounding the cryofied mass of particles is maintained at between about - 50°F and 70°F.
8. A process according to Claim 1 wherein the temperature surrounding the cryofied mass of particles in step (c) is maintained at about 68°F.
9. A process according to Claim 1 wherein the temperature utilized in the melting step (d) is between about 80°F and 100°F.
10. A process according to Claim 1 wherein the water content of the calcium sulfate granules used in the drying step (a) ranges from less than about 0.5% to 5%.
11. A process according to Claim 1 wherein the calcium sulfate bed utilized in the drying step (a) comprises a vessel packed with calcium sulfate granules, the vessel having a length to diameter ratio of from about 10:1 to about 3:1.
12. A process according to Claim 11 wherein the vessel has a length to diameter ratio of from about 9:1 to about 7:1.
13. A process according to claim 1 wherein the dry calcium sulfate granules used in the drying step (a) have an average diameter of from about 2mm to about 27mm.
14. A process according to Claim 1 further comprising the step of intermittently regenerating the calcium sulfate granules used in the drying step (a) after said granules during step (a) have obtained not more than about 5% moisture from the coffee aroma gas, by disconnecting contact of the coffee aroma gas from the bed of hydrated calcium sulfate granules, then by passing air having a temperature between about 380°F and 420°F
through the calcium sulfate bed to thereby form regenerated calcium sulfate granules having less than about 0.5% moisture, and then by using the regenerated calcium sulfate to dry coffee aroma gas as in step (a).
through the calcium sulfate bed to thereby form regenerated calcium sulfate granules having less than about 0.5% moisture, and then by using the regenerated calcium sulfate to dry coffee aroma gas as in step (a).
15. A process for making dry coffee aroma oils useful for aromatizing coffee substrates, which process comprises the steps of (a) passing a moisture- and carbon dioxide-containing coffee grinder gas through a bed of granules comprising hydratable calcium sulfate to thereby remove substantially all moisture from the coffee aroma gas, thereby forming dry, carbon dioxide-containing coffee grinder gas; then (b) condensing the dry, carbon dioxide-containing coffee grinder gas of step (a) onto cryofied coffee oil particles to thereby form a cryofied mass of particles comprising condensed dry, carbon dioxide-containing coffee grinder gas and cryofied coffee oil, the cryofied mass of particles being maintained at a temperature of between about -210°F and about -290°F; then (c) equilibrating the cryofied mass of particles of step (b) by subjecting said mass of particles to a surrounding temperature of about 68°F until the temperature within the mass of particles increases to a value of from about -109°F to about -105°F, to thereby remove substantially all of the carbon dioxide from said cryofied mass of particles; and then (d) melting the resulting carbon dioxide-free cryofied mass of particles from step (c) by subjecting said mass to a temperature of from about 70°F to about 100°F
for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
for a period of time sufficient to liquify the cryofied mass of particles and to thereby form dry coffee aroma oil.
16. A process according to Claim 15 wherein the cryofied particles are subjected to agitation during the condensation of step (b) and the equilibration of step (c) .
17. A process according to Claim 16 wherein said agitation is continuous.
18. A process according to Claim 15 wherein the water content of the calcium sulfate granules used in the drying step (a) ranges from less than about 0.5% to 5%.
19. A process according to Claim 15 further comprising the step of intermittently regenerating the calcium sulfate granules used in the drying step (a) after said granules during step (a) have obtained not more than about 5% moisture from the coffee aroma gas, by disconnecting contact of the coffee aroma gas from the bed of hydrated calcium sulfate granules, then by passing air having a temperature between about 380°F and 420°F
through the calcium sulfate bed to thereby form regenerated calcium sulfate granules having less than about 0.5% moisture, and then by using the regenerated calcium sulfate to dry coffee aroma gas as in step (a).
through the calcium sulfate bed to thereby form regenerated calcium sulfate granules having less than about 0.5% moisture, and then by using the regenerated calcium sulfate to dry coffee aroma gas as in step (a).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US90274792A | 1992-06-23 | 1992-06-23 | |
| US902,747 | 1992-06-23 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2098224A1 CA2098224A1 (en) | 1993-12-24 |
| CA2098224C true CA2098224C (en) | 1998-07-14 |
Family
ID=25416344
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2098224 Expired - Lifetime CA2098224C (en) | 1992-06-23 | 1993-06-11 | Process for making dry coffee aroma oil |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2098224C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5342639A (en) * | 1993-11-18 | 1994-08-30 | The Procter & Gamble Company | Making dry coffee aroma gas with improved aroma characteristics |
-
1993
- 1993-06-11 CA CA 2098224 patent/CA2098224C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2098224A1 (en) | 1993-12-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR860000909B1 (en) | Process for preparation a microporus structured freeze dried coffee product | |
| CA1043154A (en) | Method for fixing coffee grinder gas | |
| CA1109324A (en) | Method for the selective extraction of caffeine from vegetable materials | |
| US3532506A (en) | Process for preparing freeze dried extract of coffee,tea or chicory and product produced thereby | |
| US3821447A (en) | Method for producing stabilized coffee aromas | |
| CA1061171A (en) | Method for fixing cryogenically condensed coffee aromatics in a glyceride carrier | |
| CA1043153A (en) | Grinder gas fixation | |
| US3979528A (en) | Pressure fixation of coffee grinder gas | |
| US4008340A (en) | Method for stabilizing coffee grinder gas aroma | |
| US4574089A (en) | Process for preparing a liquid coffee aroma | |
| US4551345A (en) | Process for preparing a liquid aroma and aromatizing a dry coffee substrate with same | |
| EP0729304B1 (en) | Making dry coffee aroma gas with improved aroma characteristics | |
| PL204233B1 (en) | Method of preparing coffee aromatizing compositions | |
| CA2098224C (en) | Process for making dry coffee aroma oil | |
| US4556575A (en) | Method for aromatizing soluble coffee | |
| JPS61254145A (en) | Extremely low temperature recovery of aroma | |
| EP0213247B1 (en) | Improved method for aromatizing soluble coffee | |
| JPS6010690B2 (en) | How to flavor soluble coffee | |
| US3443961A (en) | Method of freeze-drying coffee | |
| US4551344A (en) | Method for aromatizing soluble coffee | |
| US3486907A (en) | Method of freeze drying coffee extracts | |
| CA1042706A (en) | Grinder gas fixation high pressure with reflux | |
| CA1063864A (en) | Process for producing roasted and ground coffee | |
| CA1242922A (en) | Method for aromatizing soluble coffee | |
| CA1242921A (en) | Method for aromatizing soluble coffee |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request |