METHODS AND SYSTEMS FOR FORMING CONCENTRATED CONSUMABLE EXTRACTS
Typical known methods for producing large quantities of concentrated extracts from solid raw materials such as ground, roasted coffee are not ideally suited to producing high quality coffee extracts that are rich in flavor and fragrance, and which maintain the varietal characteristics of the roasted coffee from which they are produced. The current invention provides filtration methods e.g. reverse osmosis or nanofiltration for producing such high quality concentrated extracts from more dilute extracts via solvent removal. The invention provides methods that have sufficient flexibility and scalability to be used for a wide variety of applications, including for producing industrial—scale quantities of extracts for the food and beverage industry. The invention provides methods and apparatus that can produce highly concentrated, “gourmet quality” extracts for use as flavoring agents, beverage concentrates, and fragrances. The solvent—reduced, concentrated extracts produced according to the inventive solvent removal methods can be advantageously used for applications where high quality coffee extracts, with a high concentration of soluble coffee solids, for example of at least 6 wt. %-40 wt. %, and a high level of retention of varietal flavor and fragrance characteristics are desired.
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This application is a national stage filing under 35 U.S.C. §371 of International Application No. PCT/US00/29651 filed 27 Oct. 2000, which was published under PCT Article 21(2) in English. This International application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application Ser. No. 60/161,981, filed Oct. 28, 1999.
FIELD OF THE INVENTION
The present invention relates to methods and systems for producing a consumable aqueous extract from a solid raw material, and, more specifically, to methods and systems for concentrating such consumable extracts through the use of filtration. Specific embodiments of the invention involve methods for forming concentrated aqueous extracts of roasted coffee useful in food, fragrance, and beverage products.
BACKGROUND OF THE INVENTION
A variety of solid raw materials are commonly extracted with aqueous solvents, such as hot water, to form consumable aqueous extracts for use in foods, fragrances, or beverages. Common materials include roasted ground coffee, tea, and cocoa just to name a few. Typical and representative of currently employed methods and systems for performing such extractions are those used for brewing and extracting roasted coffee. Generally the prior art systems fall into two broad categories: small-scale home or commercial brewing equipment for producing beverages; and large-scale industrial extractors for producing concentrated extracts for use as flavorings or as raw materials for the production of instant coffee products. When used for the production of instant coffee products, the aqueous solvent is typically removed from the dissolved coffee solids by processes such as freeze drying or spray drying.
Typical prior art large-scale coffee extractors and associated extraction methods, especially when used to produce coffee extracts for the subsequent production of instant coffee, are designed to exhaustively extract a given quantity of ground roasted coffee and hydrolyze the cellulose of the roasted coffee. This is done for economic reasons: the more soluble coffee solids extracted from a given quantity of roasted coffee raw material, the greater the quantity of final instant coffee product derived upon removal of the water by drying. To this end, typical prior art large-scale coffee extractors are designed for the exhaustive extraction and hydrolysis of typically low-grade ground coffee and not for production of a high quality, flavorful, fragrant extract or for the production of various grades of extract from a given quantity of ground, roasted coffee. Many typical prior art extractor systems of this type employ one or more columns having fixed beds of ground roasted coffee. Representative of such a system is the one described in U.S. Pat. No. 3,830,940 to Sivetz. While such systems and methods are useful for exhaustive extraction with hydrolysis, they are not ideally suited for producing high quality coffee extracts with desirable sweetness and flavor characteristics or for production of various grades of extracts from a given choice of ground, roasted coffee. The relatively long extraction times (for example greater than 1 hour), high water temperatures, and levels of dilution used in certain prior art extraction processes can result in extracts having poor flavor or fragrance characteristics, which are often passed on to the dried instant coffee products produced from such extracts. Furthermore, the process of de-watering the extracts by typical prior art methods, such as spray drying or freeze drying, in forming the instant coffee products can result in the loss or degradation of desirable varietal flavor and fragrance components of the ground, roasted coffee. Many of the concentrated coffee extracts commonly employed as flavor components in the food industry (e.g. as flavorings for coffee ice cream, iced coffee beverages, and coffee syrups) are produced by reconstituting such poor quality instant coffee products with water or other materials.
It is understood that sweeter and more flavorful coffee extract can be produced near the beginning of an extraction cycle, when the fresh ground coffee has been in contact for a relatively short period of time with only a relatively small quantity of water, than can be produced later in the extraction process after the coffee has been exposed to additional quantities of water and more exhaustive extraction. Attempts have been made to improve upon the quality and flavor of coffee extracts and instant coffee products produced by large scale extraction processes. One such method described in U.S. Pat. No. 4,534,985 to Gasau ('985) discloses an industrial scale continuous extraction process and apparatus for the extraction of coffee or tea. The apparatus involves a complex system using a number of extractant beds and extraction zones, where the beds are movable between zones by rotation of the apparatus. The process reduces the total time of the extraction process when compared to more conventional prior art extraction methods. The '985 patent also discloses the use of compressed air or an inert gas in a “recovery station” of the apparatus to maximize recovery of the residual liquid present in the spent grounds after extraction.
Various smaller scale brewing/extraction methods for home or commercial use are known in the prior art for producing beverages from solid raw materials such as coffee, tea and cocoa. Common methods include steeping or infusion in a static volume of hot water (i.e. steeping a tea bag in a cup of hot water), steam-driven percolation, and extraction via a continuous flow of hot water under the force of gravity through a bed of solid extractable material, typically coffee. The latter method described is the one typically employed in home “drip method” coffee makers. All of these methods typically produce a relatively dilute beverage-strength extract (typically, 1 lb of ground, roasted coffee will yield about 320 oz. of beverage-strength extract). In addition, because of the continuous addition of water used to drive the flow of extract through the bed, the beverages produced can contain flavor and/or fragrance undesirable quantities of certain bitter components, which may be undesirable for certain applications. Also, because these prior art methods brew in the presence of oxygen, the flavor and fragrance of the resulting extract can be degraded by undesirable oxidation.
An improvement to most of the above described methods for applications where it is desired to produce a more concentrated coffee beverage having a sweeter flavor and fragrance, is the espresso method of coffee extraction. The espresso method of extraction typically employs a small-scale home or commercial brewing apparatus utilizing a less exhaustive extraction method to produce a relatively sweet, more concentrated beverage. Typically, a higher ratio of ground coffee to hot water is employed, for example about 1 lb. of ground roasted coffee may typically yield about 64-128 oz of coffee beverage. In order to allow sufficient contact time between water and the ground coffee, the method typically utilizes a finely ground coffee (e.g. 14 gram weight) with hot water being forced through the bed of grounds contained in the brew chamber by additional pressurized hot water. Most typical currently employed espresso type extraction devices are capable of producing only relatively small quantities of extract during each extraction cycle. In addition the quality of the beverage can be very dependant on the grind and packing of the coffee, which dictates the back pressure developed by the flowing water during the extraction, and the extraction time for a given total volume of beverage. A lack of control over these variables can lead to a poor or inconsistent quality of extract. Also, since hot water is typically used to force extract from the bed of ground coffee during the entire extraction process, a level of extraction that is undesirable for certain applications may still occur, yielding an extract which may be too dilute for certain applications, and may not be ideally suited for use as a food or flavor additive.
A variety of small-scale espresso style coffee brewers have been described which attempt to improve upon the performance of conventional espresso brewers. U.S. Pat. No. 5,127,318 to Selby ('318) and U.S. Pat. No. 5,473,973 to Cortese ('973) both disclose an apparatus and process for extracting espresso type coffee in which the pressure within the extraction region is regulated by a biased valving arrangement on the outlet line downstream of the coffee bed. The valves are designed to remain closed during the initial pressurization of the extraction chamber by hot water until a preset pressure is reached that can overcome the bias of the regulating valve. When such pressure is reached, the valve opens for flow and maintains a relatively constant pressure in the extraction chamber during the remainder of the extraction process relatively independent of the grind or packing of the coffee. In the disclosed systems, the pressure constantly rises until a predetermined pressure is reached, at which point, flow immediately commences.
U.S. Pat. No. 5,267,506 to Cai ('506) discloses an apparatus for automatically brewing espresso coffee and includes one embodiment where pressurized steam generated by a heating unit is passed through the coffee grounds to purge liquid so that the grounds will not drip when the brew chamber is removed.
U.S. Pat. No. 5,337,652 to Fischer et al. ('652) discloses an espresso machine and method utilizing a biased pressure relief valve down stream of the brewing chamber similar to U.S. Pat. No. 5,127,318 ('318) and U.S. Pat. No. 5,473,973 ('973) described above. The biased valve prevents flow from leaving the discharge line until the pressure within the chamber rises to a fixed predetermined level; immediately thereafter, the valve opens and maintains a relatively constant pressure within the brew chamber during the remainder of the extraction. The '652 system also includes an air pump with an outlet line in fluid communication with the water heating chamber. The air pump is used at the end of the brewing cycle to pump air through the coffee grounds in order to dry the coffee and produce a foamy head. The air from the pump is directed to the brewing chamber from the hot water compartment via a relatively complex automated valving/switching mechanism on a flow control manifold located within the water heating chamber. The air supplied to the brewing chamber in the '652 system passes through the water heating chamber before entering the brewing chamber thus adding heat and moisture to the gas. While some of the above cited systems and methods for producing consumable extracts from solid raw materials represent, in some cases, useful contributions to the art of producing consumable extracts, there exists a need for improved methods and systems for producing variable quantities, including large volumes, of consumable extracts, including highly concentrated extracts, from solid raw materials, the extracts having a desirable combination of sweetness, flavor, and fragrance characteristics.
SUMMARY OF THE INVENTION
Accordingly, the present invention, in some embodiments, can provide improved methods and apparatuses able to controllably produce highly concentrated or less highly concentrated consumable extracts having excellent and desirable sweetness, flavor, and fragrance qualities from solid raw materials. In other embodiments, methods and apparatuses are provided that utilize filtration methods, such as reverse osmosis and/or nanofiltration, to remove excess solvent from consumable extracts to produce more concentrated extracts with minimal loss of desirable flavor and fragrance characteristics.
In one aspect, a method is described for increasing the concentration of a consumable material in a consumable extract. In one embodiment, the method comprises supplying the extract to the retentate side of a filter and passing at least a portion of the solvent component of the extract through a filtration medium to form a permeate on the permeate side of the filter while retaining at least a portion of the consumable material on the retentate side of the filter, thereby forming a solvent-reduced consumable extract. This solvent-reduced consumable extract is more concentrated in the consumable material and is collected from the retentate side of the filter.
In another embodiment, a method for producing a blended coffee extract is disclosed. The method comprises extracting a quantity of roasted coffee with a quantity of aqueous solvent to form a first-pass coffee extract having a concentration of dissolved coffee solids of a first value. The method further involves extracting the same quantity of roasted coffee previously extracted in the above step with an additional quantity of aqueous solvent to form a second-pass coffee extract having a concentration of dissolved coffee solids therein of a second value that is less than the first value. The method further comprises increasing the concentration of dissolved coffee solids in the second-pass coffee extract by removing a quantity of aqueous solvent from the second-pass extract. The method further includes mixing a quantity of the first-pass extract with a quantity of the second-pass extract, concentrated in the above step, to form a blended extract.
In another aspect, an aqueous coffee extract is disclosed. The extract is obtained by extraction of a quantity of roasted coffee that includes at least one chosen variety of roasted coffee. The extract contains at least about 15% wt. dissolved coffee solids and retains an effective amount of the varietal flavor and fragrance components characterizing the at least one chosen variety of roasted coffee from other varieties of roasted coffee.
Other advantages, novel features, and objects of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings, which are schematic and which are not intended to be drawn to scale. In the Figures, each identical or similar component that is illustrated in various Figures is represented by a single numeral. For purposes of clarity, not every component is labeled in every Figure.
BRIEF DESCRIPTION OF THE DRAWINGS
DETAILED DESCRIPTION OF THE INVENTION
The present invention involves methods for forming consumable extracts containing a consumable material from a variety of solid raw materials, which extracts can be of superior quality with regard to flavor and fragrance compared to similar extracts produced according to typical prior art extraction methods. Some embodiments of the invention also involve novel methods for removing excess solvent from consumable extracts to form a more concentrated extract, without substantially degrading the flavor and fragrance characteristics of the extract. The term “consumable extract” as used herein, refers to a solution containing a dissolved or suspended consumable material in a consumable solvent. A “consumable solvent” refers to an essentially non-toxic, ingestible liquid that has the ability to dissolve or suspend a non-zero quantity of the consumable material. “Consumable material” as used herein, refers to an extractable component of a solid raw material that is extracted by, and can be dissolved or suspended in, the consumable solvent. A “solid raw material” as used herein, refers to a solid material including at least one solid component that is insoluble in the consumable solvent and at least one other component that is a consumable material. Preferred consumable solvents for use in the invention are aqueous solvents. An “aqueous solvent” according to the invention comprises water, and may additionally include other components that are soluble or miscible in the water, which components may be useful or desired for particular applications. When an aqueous solvent is employed in the invention, the consumable extracts produced will be aqueous extracts.
The solid raw materials that may be advantageously employed according to the invention can include a variety of organic solids from which consumable materials can be extracted, for example, tea leaves, cocoa, fruit, vanilla beans, and roasted coffee. While it should be understood that the methods and apparatus described herein in accordance with the invention can potentially be used for any suitable solid raw material, including but not limited to those listed above, to exemplify the method for the purpose of the detailed description, specific reference will be made to roasted coffee.
Unlike typical prior art methods and apparatus for producing aqueous extracts from roasted coffee (i.e. coffee extracts), the current invention enables the production of relatively concentrated coffee extracts that exhibit a high level of sweetness and flavor quality and retain the varietal characteristics specific to the particular variety of coffee being extracted. Unlike typical prior art methods for producing concentrated coffee extracts, for example for use in producing instant coffee, the inventive methods, in some embodiments, avoid exhaustive extraction of the roasted coffee with high water temperatures that can lead to hydrolysis (typically above the boiling point of water at atmospheric pressure), which can lead to loss of fragrance and extraction of an undesirable quantity of bitter components and acids that can adversely affect the flavor and fragrance of the extract. In some embodiments, more than one different grade of extract may be produced from a given quantity of ground roasted coffee, with each extract produced at a different level of exhaustion of the coffee. As described in more detail below, these extracts can be concentrated and combined in a variety of ways to yield combined extracts having a variety of flavor/fragrance characteristics.
Coffee's sweetest flavors are typically produced during the first part of any brewing (extraction) cycle for typical prior art methods. Rich flavors, sugars, and aroma are extracted first. Oils, acids, and more bitter flavor components brew out in the later phase of brewing when more extensive extraction has occurred. This, for example, is why some percolated coffee beverage and coffee extract produced by exhaustive extraction is often bitter in flavor, has weak aroma, and has oils on the surface.
For applications where coffee extracts having superior fragrance and flavor are typically not considered crucial, for example for production of instant coffee products, exhaustive extraction with hydrolysis has been utilized in an attempt to maximize the total yield of consumable material (i.e. soluble coffee solids) that can be obtained from a given quantity of solid raw material (i.e. roasted coffee). However, because of harsh extraction conditions and solvent removal conditions often employed in these prior art processes, when reconstituted with water or another solvent to form a coffee beverage or coffee extract for use as a food, flavoring, or fragrance component, such prior art products typically do not provide the flavor and/or fragrance characteristics demanded by consumers who appreciate superior quality coffee. Specifically, these prior art exhaustive extraction methods typically produce coffee extracts that do not retain the desirable varietal flavor and fragrance components that can distinguish extracts produced from coffee grown in one particular region or country or blends of two or more such coffees over other, different varieties. The extracts produced according to the present invention can provide flavor and fragrance attributes that enable them to be utilized in “specialty” coffee applications, and for those embodiments designed for such specialty coffee applications, retain an effective amount of the varietal flavor and fragrance components characterizing the particular variety of roasted coffee from which the extract was produced. The varietal flavor and fragrance components, advantageously retained in coffee extracts produced according to these embodiments of the invention, are relatively volatile extractable chemical compounds, or combinations of chemical compounds, present in the roasted coffee. Different coffee varieties (e.g. Costa Rican Tarrazu vs. Sumatran Mandheling), or defined mixtures or blends of such varieties, will typically possess different relative amounts of and/or types of these varietal flavor and fragrance components that distinguishes the flavors and fragrances of the different brewed coffees. The presence of these varietal flavor and fragrance components is conventionally determined by cupping (taste and smell testing) by those skilled in the art. Unlike typical prior art methods of producing relatively concentrated coffee extracts, which do not contain effective amounts of these varietal components, the present invention can provide relatively concentrated coffee extracts that do retain effective amounts.
“Relatively concentrated coffee extract” as used herein, refers to a coffee extract that is more concentrated than coffee beverage-strength extract (typically about 1-4% wt. dissolved coffee solids) and contains at least about 6% wt. dissolved coffee solids. An “effective amount” as used herein in reference to the amount of varietal components retained in a coffee extract refers to a concentration of such components in the extract sufficient to be detected, in the concentrated extract itself or in a coffee beverage obtained by diluting the extract to beverage strength with additional water, by taste and/or smell by one of ordinary skill in the art of cupping (taste-testing) coffee. “Detected” as used above refers to the ability of such a taste tester to distinguish, due to the presence of the varietal components, extracts produced by the same method but from different varieties of roasted coffee. Alternatively, the presence of an effective amount of varietal components can be determined and defined by performing standard chemical analysis on the coffee extracts. Such analysis can be performed by a variety of methods apparent to one skilled in the art, for example, gas chromatography, liquid chromatography, mass spectrometry, etc. An “effective amount” of varietal components as measured by such methods can be defined by comparing the analysis of a beverage-strength extract produced by a typical prior art beverage brewing method, such as the drip method or espresso method, both discussed in more detail herein, with a concentrated extract that has been diluted with additional water to have the same total dissolved solids as the beverage-strength extract to which it is being compared. A diluted concentrated extract so analyzed with an “effective amount” of varietal components, will contain about the same or greater concentration of such components as the beverage-strength extract produced by the typical prior art beverage brewing method.
In addition, because the inventive methods provide flexibility to produce coffee extracts having a wide range of solubles concentration, including highly concentrated extracts, many of the extracts produced according to the invention can, in some embodiments, be used directly for applications where highly concentrated coffee extracts are desirable, without the need for additional concentration by solvent removal. For example, concentrated coffee extracts produced according to some embodiments of the invention can be used for producing coffee syrups, coffee ice creams, iced coffee beverages, coffee perfume, etc., all of which can display excellent flavor, sweetness, and/or fragrance and maintain the varietal characteristics of the coffee from which the products were produced. For other embodiments where it may be desirable to even further concentrate the extracts produced by extraction of the ground, roasted coffee, the invention provides novel filtration-based methods, for example reverse osmosis methods, for removing excess solvent (e.g. de-watering) from the extract, preferably without unduly degrading the flavor and fragrance qualities of the dilute extract. Such solvent removal methods can be especially useful for forming concentrated extracts in embodiments involving exhaustive or relatively high levels of extraction of the ground, roasted coffee with relatively large quantities of extraction solvent.
The current invention also provides methods and apparatus that are flexible enough to allow for production of a wide variety of extracts having different concentrations and degrees of extraction to suit a variety of purposes and applications. The inventive methods and apparatus are also easily scalable to provide a means for producing any desired quantity of extract. Small-scale versions of the apparatus, according to the invention, could be used for home or retail/commercial use, while larger scale apparatus, more specifically described herein, may be used for industrial production of coffee extracts.
The current methods for forming extracts and for de-watering extracts, according to the invention, allow the level of extraction, and concentration of coffee extract to be more precisely controlled than with typical prior art devices and methods. For example, typical drip-style coffee brewers, commonly employed for home and commercial use, typically produce about 2.5 gallons of coffee beverage per 1 lb. of ground roasted coffee, yielding a typical dissolved solids concentration of about 1-1.5% wt. Another popular method of producing coffee beverage is the “espresso method,” which typically involves forcing hot water through finely ground, roasted coffee under pressure (typically about 120-140 psig depending on the fineness of the grind and the water flow rate) over a short period of time to create an “espresso beverage.” Such methods typically create about 1 gallon of coffee beverage from about 1 lb. of coffee and produce a beverage containing up to about 4% wt. dissolved coffee solids. In general, the “espresso method” typically produces a sweeter, more concentrated beverage than the drip method because it utilizes a greater ratio of coffee to water, while also reducing the level of extraction of the raw material (ground coffee). Apparatus for producing coffee beverage according to the espresso method is typically limited to small scale devices having a maximum capacity of about 14 grams of dry, ground roasted coffee. In contrast, the present invention provides, in certain embodiments, methods and apparatus for producing coffee extracts from large quantities, in some embodiments 300-1300 lb., of roasted coffee. The invention also allows for a variety of coffee extracts having a variety of flavor/fragrance characteristics and/or concentrations to be produced according to the needs of the user by allowing the user to easily adjust the ratio of extract produced to roasted coffee employed according to need. For example, the extracts produced according to the invention can range from those of drip coffee strength (1 lb. dry coffee per 2.5 gallons of extract) or less, to highly concentrated extracts, for example using 2.5 lb., 5 lb, 7 lb., 10 lb., 15 lb., 20 lb., 25 lb., 30 lb., or 40 lb. of dry coffee or even more, per 1 gallon of extract produced, yielding concentrations of dissolved coffee solids that can be in excess of 10% wt., 15% wt., 20% wt., 25% wt., 30% wt., or 40% wt. The flavor and fragrance quality of the extracts produced according to the invention varies according to the degree of dilution and extraction during the extraction process, with extracts produced at lower levels of extraction of the roasted coffee typically having the greatest sweetness, and extracts produced at higher levels of extraction and greater solvent dilution, which extracts can subsequently be concentrated by filtration/reverse osmosis as described in more detail below, having more bitter and acidic flavor components. As described in more detail below, for certain applications, extracts produced at relatively low levels of extraction can be selectively combined with extracts produced at higher levels of extraction to produce combined extracts having a desired level of balance of sweetness and flavor/fragrance qualities. Such extracts can be selectively formulated to yield a flavor/fragrance balance for particular applications; for example, in one preferred embodiment, a quantity of high-sweetness extract produced at a low level of extraction can be combined with an extract produced at a higher level of extraction, and subsequently de-watered to a solubles concentration level similar to that of the high-sweetness extract, to produce a concentrated extract which yields a well-balanced, flavorful coffee beverage upon reconstitution of the extract with sufficient water to yield beverage strength coffee.
The basic features of the inventive methods for producing consumable extracts from solid raw materials will now be explained in reference to the formation of coffee extracts. Following the basic description, a more detailed description of each step will be given with reference to one illustrative embodiment of an extraction apparatus shown in
The inventive extraction methods, in some embodiments, are similar, in some respects, to the “espresso method” of coffee extraction previously described. The inventive method utilizes an extraction vessel, chamber, or enclosure having an enclosed internal volume sufficient to contain a desired quantity of solid raw material, for example roasted coffee. A wide variety of extraction vessel sizes and configurations can potentially be employed for various applications as apparent to the skilled artisan. The vessel should be sealable, so that the internal volume can be pressurized to a desired level without undesirable leakage, and have at least one inlet line and at least one outlet line for fluid flow therethrough to enable a continuous flow of solvent through the solid raw material (e.g. coffee) contained within the internal volume of the vessel. The vessel should also have means for filling the internal volume with roasted coffee; for example, the vessel can comprise two or more separable parts that may be separated to expose the internal volume for filling, and/or may have one or more lines through a wall of the vessel and in communication with the internal volume through which roasted coffee may be inserted into the internal volume. The inlet and outlet lines for fluid flow are preferably located on the vessel on opposite sides of the internal volume containing the coffee so that essentially all of the fluid flow entering the vessel through the inlet line and leaving the vessel through the outlet line passes through essentially the entire quantity of coffee as it flows through the vessel. A preferred configuration of the vessel has one or more inlet lines located at or near a top surface of the vessel and one or more extract outlet lines located at or near a bottom surface of the vessel, thus allowing, in preferred embodiments, a flow of aqueous solvent through the coffee to proceed from above the level of the coffee in the internal volume and through the quantity of coffee in the internal volume in the direction of gravity. Such flow through the coffee in the direction of gravity acts to compress the coffee during flow-through extraction and improve contact between the solvent and the coffee, thus improving the extraction process performance as compared to a solvent flow against the direction of gravity or perpendicular to the direction of gravity.
One embodiment of a method for forming a coffee extract according to the invention involves first at least partially, and preferably essentially entirely, filling the internal volume of the vessel with roasted coffee. With the certain lines closed and at least one valve on a line in fluid communication with the internal volume of the vessel open, the vessel is at least partially filled with an aqueous solvent. The aqueous solvent can be filled, in some embodiments, through inlet line(s) on the top of the vessel, or, more preferably, at least a portion of the initial filling of the vessel with aqueous solvent can be performed by flowing the aqueous solvent into the vessel through one or more lines positioned near the bottom of the vessel, for example below the filter screen used, in other steps of the extraction process as extract outlet lines or washout lines. This latter filling process can help reduce potential clogging of the filter screen (see
Preferably, enough aqueous solvent is added to fill the void volume of the quantity of roasted coffee in the vessel and completely cover and wet the roasted coffee. The outlet lines are preferably closed through means of at least one controllable valve. A “controllable valve” as used herein refers to a valve that may be manually or automatically operated, for example by hand turning or computer control and actuation, as desired by an operator to open, close, and/or partially open or close the valve at any desired time and under a variety of desired operating conditions. Such valves may be gate valves, globe valves, ball valves, needle valves, etc. as apparent to the skilled artisan and are distinguished from valves which open and close at one preset condition without operator control, such as, for example, a biased pressure relief valve. In preferred embodiments, the temperature of the aqueous solvent in contact with the coffee is above ambient temperature, most preferably, it is between 190 and 212 degrees Fahrenheit.
Preferred embodiments of the extraction method, subsequent to the filling steps outlined above, next subject the roasted coffee to a novel “pressure-treat” step, which facilitates thorough wetting of the coffee and the elimination of air pockets or channels, as well as penetration of the aqueous solvent into the coffee particles themselves to increase the efficiency of extraction. The pressure-treat step is performed by increasing the static pressure in the vessel containing the coffee and aqueous solvent to a predetermined and controllable pressure above atmospheric pressure while maintaining the outlet valves in a closed configuration so as to prevent any flow of extract from the vessel. The vessel can be pressurized by addition of additional pressurized aqueous solvent, or alternatively by addition of a pressurized gas to the vessel from an external source of pressurized gas through an inlet line to the vessel. The pressure is maintained for a desired period of time before flow of extract is established. The optimal level of pressure for use in this “pressure-treat” step depends on whether the roasted coffee is in the form of whole beans or ground, the fineness of the grind (for ground coffee), the type of coffee, the degree of roasting, etc., and should be determined by the operator, using routine experimentation and/or optimization, for a given set of conditions to produce an extract with desired characteristics. In general, the coarser the grind of coffee, the higher the pressure should be to yield maximum benefit from the pressure-treatment. It has been found that for many types of ground coffee (e.g. roasted coffee ground using a Bunn coffee grinder (HVG, Bunn-o-matic, Springfield, Ill., on a setting of 4.0, or roasted coffee ground to a similar average coarseness using a roller mill grinder) the pressure during the pressure-treat step is preferably at least about 40-50 psig, in some embodiments at least about 100 psig, and, in certain preferred embodiments, between about 120 and 132 psig. For embodiments where coarser ground coffee or whole bean coffee is used, the pressure is preferably higher than this range, for example 150-1000 psig or more. The pressure is maintained under non-flow conditions for a predetermined and controllable period of time before the onset of flow. The time of treatment can vary from several seconds to several minutes, with a typical static pressure treatment time being about 10-30 min.
Upon completion of the static pressure-treat step, an outlet valve is at least partially opened to establish flow of extract from the vessel, and, for some embodiments, additional aqueous solvent is simultaneously fed to the vessel through an inlet line. The valve on the outlet line can be controlled to maintain a desired level of pressure within the vessel during the flow-through extraction. Thus, the ability of the operator to select and control the pressure in the vessel via control of an outlet valve allows the pressure during extraction and to be adjusted and controlled within the vessel independent of the fineness of the grind of coffee or the inlet solvent and/or gas flow rate. For embodiments where a very concentrated extract is desired, very little or no additional aqueous solvent is supplied during flow of the extract from the vessel. For other embodiments, a measured, desired quantity of additional aqueous solvent is supplied to yield a desired level of extraction and final extract concentration.
After a desired quantity of additional solvent has been supplied, the flow of solvent is discontinued and extract is collected through the outlet line, typically until the vessel is equilibrated with atmospheric pressure. At this point, in preferred embodiments of the method, residual extract present within the void volume of the ground coffee is removed and recovered by supplying the vessel with a flow of fluid that is a gas (at standard temperature and pressure) through an inlet line to the vessel, which is in direct fluid communication with the enclosed internal volume, from a source of compressed gas external to the vessel. The gas flow to the vessel displaces the extract from the wet coffee, which extract is collected from the outlet line and added to the extract collected during the previous step. Purging the wet coffee with a gas allows the concentrated extract present within the void volume, defined by interstices between and within the wet coffee particles, to be recovered instead of wasted as in typical espresso-type coffee extractors. It also allows for a given volume of extract to be collected with less dilution and a lower degree of extraction when compared to prior art methods where all of the extract collected is forced from the coffee with additional solvent. The gas used to purge the coffee, in preferred embodiments, does not act as a solvent and, therefore, does not further extract or dilute the coffee extract collected. Preferred gases for use in the invention are relatively inert with respect to the solvent, extract, and solid raw material. Compressed air may be used in this context, but particularly preferred gases include oxygen-free inert gases such as nitrogen, or noble gases such as argon, helium, etc. “Inert gas” as used herein, refers to gases that are not reactive with the solid raw material, aqueous solvent, and aqueous extract and that do not significantly affect the flavor or fragrance characteristics of the aqueous extract. Preferred gases, so as not to adversely affect the flavor of the extract, are also essentially insoluble, only sparingly soluble, or not very soluble in the aqueous solvent. For example, gases such as carbon dioxide, which is very soluble in the aqueous solvent and causes “carbonation” thereof, are generally not preferred for use in the invention. It is also preferable to supply the gas to the vessel at ambient or sub-ambient temperature so as to beneficially cool the solid raw material and prevent release of off-flavors/fragrances into the extract.
The steps of the inventive method outlined above may be modified, or certain steps may be deleted, or additional steps added, according to the needs and desires of the operator. For example, in some embodiments of the method, the static pressure-treat step can be omitted. In such an embodiment, after filling the internal volume of the vessel with dry roasted coffee, a continuous flow of aqueous solvent can be established through the coffee whose dynamic pressure drop is controllable by adjustment of the controllable outlet valve on the outlet line through which extract is collected, and/or by controlling the inlet flow rate of aqueous solvent. Then, after supplying a desired predetermined volume of aqueous solvent for extraction, the solvent flow is discontinued and the extract remaining in the wet coffee is purged with a gas as previously described. In some embodiments where a particularly concentrated extract is desired, the predetermined volume of aqueous solvent supplied as described above is essentially equal to the void volume of the bed of the dry, roasted coffee contained within the vessel.
The inventive methods outlined above are also flexible and can be used to provide a variety of extracts of differing concentration and degree of extraction from a single quantity of solid raw material. For example, the same quantity of solid raw material can be subjected to multiple, repetitive application of the methods described above to produce a variety of extracts from the same given quantity of solid raw material, each extract having a different concentration and flavor/fragrance characteristics indicative of the degree of extraction, with the extracts produced by the first-pass extraction procedure being the most concentrated and having the sweetest flavor/fragrance characteristics, and with subsequent extracts being progressively weaker and including more bitter and acidic taste/flavor components. Using such a multi-cycle method to perform multiple extractions can allow for custom production of a variety of extracts for a variety of purposes, with even more extracts being obtainable by selective combinations of two or more of the above extracts, while at the same time increasing the utilization and yield from a given batch of raw material. The modified, multi-cycle method here described can be analogous, in some embodiments, to the production of various quality olive oils (e.g. extra virgin, virgin, etc.) from multiple pressings of the same olives. In the present case, various quality coffee extracts can be produced from multiple cycles utilizing the same batch of roasted coffee. In addition, if desired, the extract produced from one cycle of the extraction can be recycled and used as the aqueous solvent for a subsequent extraction cycle either with the same charge of solid raw material or a fresh load of solid raw material.
Also, as described in more detail below, the extracts produced at higher levels of extraction of the roasted coffee, which are typically more diluted with aqueous solvent, can, in some embodiments, be advantageously concentrated in coffee solids by removing a portion of the aqueous solvent from the extract as a permeate using the inventive filtration methods, so that they have a solids concentration similar to or exceeding that of the extract produced by the first-pass extraction. Blended extracts, having more balanced sweet/bitter flavor/fragrance characteristics, can then be produced by selective mixing of first-pass extracts with subsequent extracts that have been concentrated without any dilution in the overall solids concentration. Alternatively, the extracts may be mixed together after extraction and prior to de-watering, and the combined extract then subjected to de-watering to a desired final coffee solids concentration. Furthermore, the aqueous solvent removed from the extracts by certain of the inventive filtration methods, such as reverse osmosis or nanofiltration, may contain substances (e.g. caffeine) that render it commercially valuable as a product. The aqueous solvent removed as permeate from the extracts by certain inventive filtration methods, such as reverse osmosis, may also have enhanced salvation power for performing subsequent coffee extractions owing to the solvent having a lower level of mineral hardness. Such a permeate can be re-used, in some embodiments, as the aqueous solvent, or a component thereof, for performing subsequent extraction cycles on a previously extracted quantity of roasted coffee, or can be used as the aqueous solvent, or a component thereof, for performing a new, first-pass extraction on a fresh charge of roasted coffee.
One embodiment of an industrial-scale extraction apparatus and system 10 for performing the methods according to the invention is shown schematically in
The positioning of the raw material lines is more clearly seen in the top view shown in
While the vessel 11 is being filled with the solid raw material, in some embodiments, the vessel can be agitated in order to promote settling of the material within the internal volume 75 of the vessel. For the embodiment shown in
As shown in
Also included on the top plate 12 of the vessel 11 is a gas inlet/vent line 33 (see
As shown in
In order to prevent the solid raw material from exiting the vessel via line 23 during flow-through extraction, a filter element is included within vessel 11 upstream of line 23. A preferred arrangement of filter element is shown in
As previously mentioned, extraction apparatus 10 also includes a novel arrangement of components for flushing spent solid raw material from the internal volume 75 of the vessel 11, and for cleaning out the vessel after an extraction has been performed and prior to a subsequent extraction. The arrangement of components illustrated allows spent raw material to be flushed from extraction apparatus 10, and allows for clean-out without the need for disassembly of the apparatus. In the illustrated embodiment, as shown in
A preferred wash out configuration includes a fluid supply line constructed and arranged to back-flush the filter element. In the illustrated embodiment, the back flush is performed through line 23 by first closing valve 25, and then opening valve 26 so that a fluid, in the illustrated embodiment hot water from pressurized hot water supply 32, will enter the vessel 11 via line 23, which now acts as an inlet flush line, and thereby back flush the porous screen 58. Typically, valve 22 will be open during the flush-out procedure to allow spent material to be removed from the vessel 11; although, in some embodiments, valve 22 may be closed during at least part of the flush-out procedure to allow the internal volume 75 of the vessel 11 to at least partially fill with liquid in order to disperse and fluidize the spent material. In alternative embodiments, line 31 may also be in fluid communication with a source of pressurized gas. In such embodiments, either gas, liquid, or a two-phase gas-liquid fluid can be used to back flush the filter element and wash out the spent solid raw material.
Also included in the preferred embodiment are additional tangential flush lines 42 and 55 (see
Also included, in the illustrated embodiment, and seen most clearly in
Operation of the Extraction Apparatus
With reference to the apparatus illustrated by
A desired quantity of dry coffee is next added to the vessel by opening valves 18 and 20 on raw material lines 17 and 19 and pouring or feeding coffee into the vessel through lines 17 and 19 until the vessel is essentially full. The dry coffee can then be settled by opening valve 71 to supply gas flow to bin vibrator 70, or alternatively, tapping the vessel with a mallet, if desired. Alternatively, the coffee can be settled without agitation of the vessel by briefly opening valve 52 and/or 47, and/or 26, and/or 43, and/or 56 to apply hot water to the coffee at one or more intervals during the addition of dry coffee, or after the coffee has been added, to moisten and settle the coffee. If desired, more coffee may now be added to more completely fill the vessel before closing valves 18 and 20. Valve 47 is then partially opened to supply pressurized hot water to the vessel via aqueous solvent inlet line 46. Upon the first sign of extract discharge from line 29, valve 25 downstream of extract outlet line 23 is closed and the vessel is filled with a desired quantity of hot water. Valve 35 on vent line 36 is at least partially opened, either manually or via automatic control, at some point during the process of filling the vessel with water to “burp” out gas; the valve 35 is closed when extract is observed to flow from line 36. The volume of hot water added to the coffee is preferably equal to or greater than the void volume of the bed of coffee so that all of the coffee is wetted. In some embodiments, the volume is essentially equal to the void volume present in the bed. As discussed above, the vessel can also be filled with hot aqueous solvent at this stage through one or more of lines 46, 23, 42, and 55. The vessel is then further pressurized, either with pressurized hot water by opening valve 47, or with pressurized gas by opening valve 38, to a desired pressure (typically about 40-132 psig) for performing the static pressure-treat step. The pressure is maintained in the vessel without flow for a desired period of time (typically about 10-30 min.). Next, valve 25 downstream of the extract outlet line 23 is controllably opened to initiate a desired flow rate of extract through line 27 and chiller 28 and into collection container 30. For some embodiments during this step, depending on the desired strength of the extract and degree of extraction, valve 47 can be opened and a measured quantity of hot water can be added to the vessel to further extract the coffee within the vessel via a flow-through extraction step. During such flow-through extraction, the pressure within the vessel can be controlled by adjusting valve 25 on the extract outlet line 23, and/or valve 47 on the hot water inlet line 46. For embodiments where additional hot water has been added after the pressure treat step, after the desired quantity of additional solvent water has been supplied during the flow-through extraction, valve 47 is closed to discontinue flow from the hot water supply. Valve 38 is then opened so that compressed gas enters the vessel via line 33 in order to purge residual extract from the void volume of the bed of coffee. Valve 47 is closed when gas flow is observed from extract collection line 29. At this point, extraction is complete and the vessel may be reused for a subsequent extraction with the same charge of coffee to produce an extract having more bitter/acidic flavor/fragrance characteristics of a more exhaustively extracted roasted coffee, or the spent coffee can be removed from the vessel. For embodiments where a maximum-strength extract is desired, the extract can be purged from the bed with the gas flow immediately after the pressure-treat step without supplying additional hot solvent water for a flow-through extraction step.
In order to remove the spent grounds from the vessel, valve 25 on the extract outlet line 23 is closed and valve 22 on spent material waste line 21 is opened. Valve 26 is then opened to back flush the porous screen 58 with pressurized water through line 23; valves 43 and 56 are opened to supply pressurized water flow to tangential flush lines 42 and 55 respectively, and valve 51 or 52 is opened to supply pressurized cold or hot water to rotating spray nozzle 64 via line 62. After the flow of liquid exiting the waste line 21 is observed to be clear and clean, the valves supplying pressurized water to the various lines for flush out are closed; valve 22 on waste line 21 is closed, and the process is complete. The extract exit line 27, chiller 28, and extract collection line 29 can also be flushed by opening valve 25 followed by valve 26 to direct pressurized water from source 32 through line 31, valve 26, tee 24, valve 25, line 27, chiller 28, and line 29.
As discussed previously, the invention also provides methods for removing excess solvent from consumable extracts in order to concentrate the extracts with respect to a dissolved or suspended consumable material. It should be understood that the inventive filtration-based concentration methods described herein can be utilized for concentrating a wide variety of consumable extracts produced from extracting a wide variety of solid raw materials, such as those discussed previously in the context of the inventive extraction methods. It should also be understood that, while in some preferred embodiments, the inventive concentration methods are utilized for concentrating extracts produced using the above-described inventive extraction methods and apparatuses, the novel concentration methods described herein can also, in other embodiments, be utilized for concentrating consumable extracts produced by a wide variety of other extraction methods for forming consumable extracts known in the prior art. As with the above-discussed extraction methods, the inventive extract concentration methods will be described below with reference to a particular embodiment involving the concentration of an aqueous extract of roasted coffee; however, it should be understood that the methods and apparatuses described herein are not so limited and that the methods and apparatuses may be employed with a wide variety of other consumable extracts produced by a wide variety of extraction methods within the scope of the present invention.
Filters that may be utilized according to the invention can include a wide variety of configurations as known in the art, for examples, gel permeation filters, and membrane-based filters in a wide variety of configurations, such as flat sheet filters, hollow fiber filters, spiral filters, tube membrane filters, and other configurations as apparent to those of ordinary skill in the art. Preferred filters employ a filtration medium comprising a semipermeable membrane(s). Such membranes can be fabricated from a wide variety of materials, such as ceramics and other inorganic materials, or organic materials, such as polymers. Certain preferred embodiments of the invention utilize a filtration medium comprising a semipermeable polymeric membrane(s). Such polymeric membranes can be fabricated from a wide variety of polymeric materials and can be constructed to have a wide variety of porosity and molecular size exclusion characteristics. Such membranes are well known in the filtration arts, and are widely commercially available. Polymeric membranes can potentially be constructed, for example, from polymers including, but not limited to, polyamides, cellulose and/or cellulose esters, polysulfone, polycarbonate, polyesters, polyethylene oxide, polypropylene oxide, polyvinylidene fluoride, poly(tetrafluoroethylene), poly(acrylates), others, and in co-polymers and/or combinations as known in the filtration and membrane separation arts.
Filter medium 102 is preferably selected to have a porosity and molecular weight cutoff able to allow passage of a solvent component of the extract, for example water, while retaining on the retentate side of the filter dissolved or suspended solutes which form flavor and/or fragrance components of the extract. For embodiments where the method is used for de-watering a coffee extract, filter membrane 102 is preferably selected so that it is able to freely pass water, while, at the same time, retaining, on the retentate side, a substantial fraction of the dissolved coffee solids in the extract. A “substantial fraction” as used herein in the present context refers to a fraction of coffee solids that is necessary to impart to the retained extract an “effective amount” of varietal components, as defined previously. In some preferred embodiments, at least 90% of the coffee solids are retained, and in even more preferred embodiments, essentially all of the dissolved solids comprising flavor and/or fragrance components are retained on the retentate side of the filter by the filtration membrane. For preferred embodiments involving de-watering of coffee extracts, the filtration membrane 102 comprises a reverse osmosis membrane or a nanofiltration membrane. A “reverse osmosis membrane” as used herein refers to a membrane having an average pore size of less than about 0.003 μm and a molecular weight cutoff of less than about 1,000 Da. A “nanofiltration membrane” as used herein refers to a membrane having an average pore size within the range of between about 0.001 μm and about 0.01 μm, with a molecular weight cutoff within the range of between about 300 Da and about 20,000 Da. In one preferred embodiment, filter membrane 102 comprises a polyamide nanofiltration membrane, in another preferred embodiment, the filter membrane comprises a spiral-wound, multi-layer, thin film composite reverse osmosis membrane such as FILMTEC® reverse osmosis membranes available from The Dow Chemical Company.
The concentration method, according to the invention, for forming a concentrated coffee extract via de-watering a more dilute precursor extract can proceed by supplying the relatively dilute coffee extract to the retentate side 104 of filter 100 at a pressure P1 sufficiently in excess of pressure P2 on permeate side 106 of the filter to force solvent through membrane 102 while retaining a substantial fraction of coffee solvents on retentate side 104, and, thus, increasing the concentration c1 of dissolved coffee solids in the retentate above that of the concentration in the precursor coffee extract. The filtration process can be continued until a desired concentration c1 is achieved. The system can be monitored by, for example, measuring the volume of permeate collected from permeate side 106 of the filter and comparing the volume of permeate collected to the initial volume of coffee extract before commencement of the filtration process and/or by measuring the conductivity of the retentate and determining the dissolved solids concentration by comparison with a calibration curve. For example, for embodiments where it is desired to reduce the volume of solvent in the initial coffee extract by a factor of 2, and thus increase the concentration of coffee solids in the concentrated extract by approximately a factor of 2, the filtration process can be continued until a volume of permeate approximately equal to one half the initial volume of extract supplied to the retentate side of the filter is collected.
The filter size, for example as measured by the total area of the planar surface 110 of membrane 102 available for filtration, the applied differential pressure (P2−P1), flow rates, and other operating parameters of the filter, as well as the molecular weight cutoff and pore size of the filter membrane, must be selected according to the needs of each particular desired application. The selection of such operating parameters can be based upon the total volume of extract desired to be concentrated within a particular time period, the concentration and size of the dissolved and/or suspended components in the extract which are desired to be retained, the particular configuration of the filter, and other factors as apparent to those of ordinary skill in the filtration arts, and as described, for example in many standard texts such as Perry's Chemical Engineers' Handbook (Sixth Edition, Robert H. Perry, Don W. Green, and James O. Maloney, Eds., 1984, Chapter 17), incorporated herein by reference. As described below with reference to
The particular selection of operating parameters must be made, for a particular application, by routine experimentation and optimization. For example, screening tests may be performed for selecting appropriate types of filtration membranes and molecular weight cutoffs by performing a trial filtration of a dilute, for example beverage strength, coffee extract with a particular membrane until a desired degree of de-watering is obtained, followed by collecting the concentrated extract from the retentate side of the filter, reconstituting the concentrated extract with a volume of fresh solvent water equal to the volume of permeate removed during filtration, and comparing the taste and/or flavor characteristics of the reconstituted extract to that of the initial, beverage-strength extract, for example by cupping as described previously. Operating pressures, filter sizes, flow rates, and other operating parameters may be selected on the basis of well known principles of membrane filtration/separations, described in many well known and readily available texts describing filtration/reverse osmosis, for example in Perry's Chemical Engineers' Handbook referenced above and McCabe, Smith, and Harriott, Unit Operations of Chemical Engineering, Fourth Edition, Kiran Verma and Madelaine Eichberg, Eds., 1985, incorporated herein by reference, combined with routine experimentation and optimization. Typically, for a given filtration membrane, having a molecular weight cutoff and porosity selected as described above, the total membrane area is selected to provide a desired range of permeate throughput (i.e., volume filtered/time) within an acceptable range of differential pressure, as dictated by the material limitations of the filtration medium and filter system components.
As shown in
One illustrative embodiment of a filtration system for use, according to the invention for de-watering and concentrating a coffee extract is shown in
System 150 can operate as follows for de-watering and concentrating a coffee extract, according to the invention. Unconcentrated extract 164 in container 30 can be produced, for example, as described above by utilizing the inventive extraction methods and apparatuses. “Unconcentrated” extract as used herein refers specifically to an extract forming a feed stream to the retentate side of the filters contained within the system. It should be understood that such “unconcentrated” extracts will, in many cases, already, as produced from the inventive extraction methods and apparatus, have a level of coffee solids concentration exceeding that typical for typical beverage-strength extracts. Conversely, a “concentrated” extract, as used in the following description, refers to an extract comprising a water-reduced (i.e. de-watered) retentate product recovered from the retentate side of the filters contained within the system. As described previously, in some preferred embodiments, unconcentrated extract 164 can comprise an extract produced from a second or subsequent extraction step of a given charge of roasted coffee. For embodiments where extract 164 is produced from a second or subsequent extraction step of a given charge of roasted coffee, typically, the concentration of coffee solids in the extract will be lower, and the degree of dilution with water will be higher, than for extracts produced during the first-pass extraction of the roasted coffee. It is, therefore, sometimes desirable to concentrate the second, or subsequent pass extract so that it has a concentration of coffee solids and degree of dilution that is similar to that of the first-pass extract. In this way, as described in more detail below, the extracts produced according to the invention during the first-pass extraction may be blended with extracts produced during a second or subsequent stage extraction, which have been de-watered to have an overall concentration similar to that of the first-pass extract, to form blended coffee extracts without substantially diluting the overall concentration of coffee solids in the first-pass extract.
Extract 164 can be fed, for example by gravity, through valve 172 and line 176 to pump 162 where it is pressurized to the operating pressure of filtration cartridges 152, 154, 156, and 158. The extract then passes from pump 162 through line 178 and through pre-filter 160 to manifold 180 including a pressure gauge or transducer 182 thereon for monitoring the retentate side pressure of filtration cartridges 152, 154, 156, and 158. In other embodiments, additional pressure gauges/transducers may be located directly on the individual filtration cartridges 152, 154, 156, and 158. In addition, while in the illustrated embodiment filtration cartridges 152, 154, 156, and 158 are connected in parallel to a manifold 180, in other embodiments, the filtration cartridges may instead be connected in series with respect to each other. From manifold 180, extract 164 passes through each of filtration cartridges 152, 154, 156, and 158 via line 184 and valve 186, line 188 and valve 190, line 192 and valve 194, and line 196 and valve 198 respectively. Unconcentrated extract 164 is fed to the retentate side of the filter cartridges. While flowing through the retentate side of the filter cartridges, at least a portion of the solvent component of the extract passes through the filtration membrane to the permeate side of the filtration cartridges, thus forming a more concentrated coffee extract on the retentate side of the filter cartridges and a relatively dilute or coffee solid free permeate on the permeate side of the filter cartridges. The concentrated coffee extract retentate then flows out of the filter cartridges and into a concentrated extract manifold 199 via line 200 and valve 202, line 204 and valve 206, line 208 and valve 210, and line 212 and valve 214 for filtration cartridges 152, 154, 156, and 158 respectively. Concentrated extract manifold 199 may include a pressure gauge/transducer 216 thereon for monitoring the pressure on the retentate sides of the filter cartridges. The concentrated coffee extract in manifold 199 flows via line 218 and valve 220 to collection container 222, for containing concentrated extract 224.
In some preferred embodiments for operating filtration system 150, unconcentrated extract 164 passes through filtration cartridges 152, 154, 156, and 158 only single time to form concentrated extract 224 in a single-pass through the system. In other embodiments, system 150 may be operated as a multi-pass system, where, in such embodiments, the concentrated extract is recycled back to container 30 via line 226 and valve 228. For such embodiments, extract would continue to be pumped from container 30, through the filter cartridges, and recycled to container 30 until a desired quantity of solvent has been removed, as permeate, and a desired level of concentration of the extract contained in container 30 has been achieved.
Permeate is collected from the filter cartridges via lines 230, 232, 234, and 236 and flows into manifold 238, which can have a pressure gauge/transducer 240 thereon, and into permeate collection container 242. As previously discussed, permeate 244 may be saved and utilized as an ingredient for additional food/pharmaceutical products or, may be discarded. In another preferred embodiment, especially where the solvent water comprising permeate 244 has been substantially demineralized by passage through filtration cartridges 152, 154, 156, and 158, aqueous permeate 244 can be beneficially used as an extraction solvent for performing an extraction of fresh, or previously extracted, roasted coffee, and, for such purposes, may be recycled back to line 46 on extraction system 10, as shown previously in
A second illustrative embodiment of a filtration system for use, according to the invention for de-watering and concentrating a coffee extract is shown in
System 300 can operate as follows for de-watering and concentrating a coffee extract, according to the invention. Unconcentrated extract 164 in container 30 can be produced, for example, as described above by utilizing the inventive extraction methods and apparatuses. Extract 164 can be fed, for example by gravity, through valve 326 and line 328 to booster pump 314. Alternatively, or concurrently, extract can be fed to the system directly from the outlet line of the extractor via line 330 and valve 332. The extract is pressurized by booster pump to a pressure, measured by pressure gauge 334, sufficient to pass the extract through the prefilter 312. Pressure drop across the prefilter can be determined by comparison of the pressure measured downstream of the prefilter by pressure gauge 336 to that measured upstream by gauge 334. A conductivity meter 338 is included to enable the determination of the concentration of solids in the extract prior to de-watering in cartridges 302, 304, 306, 308, and 310, as previously discussed.
The extract is then pressurized to the operating pressure of filtration cartridges 302, 304, 306, 308, and 310 by R/O pump 316. The extract then passes from pump 316 through line 340 and through throttling valve 342, including located upstream and downstream thereof pressure gauges 344 and 346 respectively, to manifold 348. In other embodiments, pressure gauges/transducers may be located on the manifold or directly on the individual filtration cartridges 302, 304, and 306. From manifold 348, extract 164 passes through each of filtration cartridges 302, 304, and 306 via line 350, line 352, and line 354 respectively. Unconcentrated extract 164 is fed to the retentate side of the filter cartridges. While flowing through the retentate side of the filter cartridges, at least a portion of the solvent component of the extract passes through the filtration membrane to the permeate side of the filtration cartridges, thus forming a more concentrated coffee extract on the retentate side of the filter cartridges and a relatively dilute or coffee solid free permeate on the permeate side of the filter cartridges. The concentrated coffee extract retentate then flows out of the filter cartridges and into a concentrated extract manifold 356 via line 358, line 360, and line 362 for filtration cartridges 302, 304, and 306 respectively. The concentrated coffee extract in manifold 356 flows via line 364 to inlet manifold 366 which feeds filter cartridges 308 and 310 via lines 368 and 370 respectively. The extract is then further concentrated by filter cartridges 308 and 310 to produce a concentrated a coffee extract retentate which flows out of the filter cartridges 308 and 310 into a concentrated extract manifold 372 via lines 374 and 376. The concentrated extract then flows via line, including pressure gauge 380 thereon, through throttling valve 382 to chiller 384. Included on line 378 downstream of throttling valve 382 is a flow meter 386 for measuring volumetric fluid flow of the retentate and a conductivity meter 388 for determination of solids content of the concentrated extract. If the solids concentration of the retentate stream, as determined from the conductivity measurement or otherwise, meets the desired product value, then the concentrated extract can be collected as final product from line 390 by opening valve 392; otherwise, the extract can be recycled to tank 30 via opening valve 394 on line 396 for further processing.
Permeate is collected from the filter cartridges via lines 398, 400, 402, and 404 and flows into manifold 408. Manifold 408, in turn, feeds permeate line 410, which has a flow meter 412 thereon. Permeate can either be sent to drain or collection via opening valve 414 on line, or, if desired, recycled to tank 30 via opening valve 418 on line 420. As discussed previously, for some embodiments, filtration cartridges 302, 304, 304, 306, 308, 310 may be briefly back-pulsed or back-flushed, for example by reversing pump 316 and/or supplying a pressurized quantity of permeate or other back-flush solvent to manifold 408. For such embodiments, the filtration media in the filtration cartridges may be at least partially cleaned and regenerated, and additional coffee solids may be collected from the retentate side of the filter cartridges for addition to the product concentrated extract during the back-flush procedure.
A third illustrative embodiment of a filtration system for use, according to the invention for de-watering and concentrating a coffee extract is shown in
As discussed previously, the inventive solvent reduction and de-watering methods for forming concentrated consumable extracts, for example coffee extracts, provide a variety of beneficial features and advantages to the inventive extract producing methods and systems. For example, in some embodiments involving the production of coffee extracts, a de-watering process such as that described above in reference to
Also, as discussed above, the inventive extraction and concentration methods allow for the formation of concentrated coffee extracts having a variety of different fragrance and flavor characteristics to be produced by extracting a given charge of roasted coffee. The nature of the inventive extraction processes described herein is that the less water that is used for a coffee extraction, the higher will tend to be the concentration level of coffee solids in the extract produced, but also, the more flavor and extractable coffee solids will tend to be left behind in the non-exhaustively extracted grinds remaining in the extractor. Using the inventive concentration method, a first-pass, high concentration coffee extract can be produced by extracting a fresh charge of roasted coffee with a relatively small quantity of water and set aside as an “extra virgin” coffee concentrate. The roasted coffee in the extractor may then be subjected to one or more additional extraction cycles utilizing an increased amount of water during the extraction in order to more exhaustively extract the roasted coffee and improve extraction efficiency. The extracts obtained from these secondary and subsequent extraction cycles can then be de-watered using the inventive concentration methods described above to have, in some embodiments, an overall coffee solids concentration similar to that of the “extra virgin” concentrate. The “extra virgin” concentrate and the de-watered concentrates produced from subsequent extraction cycles can then be blended to form an extract having a balance of relatively sweet flavor/fragrance attributes imparted by the “extra virgin” extract and more bitter/acidic flavor/fragrance attributes imparted by the extracts produced by secondary or subsequent extractions of the roasted coffee. These blended extracts often have an overall flavor/fragrance more typical of beverage quality coffee produced by many prior art coffee beverage making methods. Such a combined extract may then be used as a flavoring agent, or may be reconstituted by dilution with water to a final dissolved coffee solid concentration typical of a beverage strength extract, for example containing between about 1% wt. dissolved coffee solids and about 4% wt. coffee solids, to produce a flavorful and well balanced coffee beverage therefrom. The particular balance between sweetness and bitterness/acidity can be readily adjusted, as desired, for example by adjusting the relative proportions of “extra virgin” extract and extracts produced by subsequent extraction and concentration in the blended extract. For embodiments where the overall coffee solids concentration of the “extra virgin” extracts and of the extracts produced by subsequent extraction of the roasted coffee, followed by concentration of the extract by de-watering, is about the same, where a richer, sweeter extract/beverage is desired, the amount of the “extra virgin” extract added to the blend should be greater than the amount of extract produced by subsequent extraction and concentration, for embodiments where a tarter, more bitter extract/beverage is desired, the amount of the “extra virgin” extract added to the blend should be less than the amount of extract produced by subsequent extraction and concentration, and for embodiments where a more evenly balanced extract/beverage is desired, the amount of the “extra virgin” extract added to the blend should be about equal to the amount of extract produced by subsequent extraction and concentration.
In general, the inventive extraction and de-watering methods provide a wide range of flexibility for producing “extra virgin” extracts and other extracts produced by more thorough extraction of a roasted coffee, each having a high level of concentration of dissolved coffee solids, for example at least about 6% wt. dissolved coffee solids, which may be combined in a variety of proportions to produce extracts having customized flavor/fragrance profiles, or which may be sold separately to different markets.
Alternatively, in other embodiments, a single charge of roasted coffee can be exhaustively extracted in a single extraction to produce a beverage strength or lower than beverage strength extract having flavor characteristics typical of conventionally brewed coffees, and this extract can subsequently be de-watered and concentrated as described above to produce a concentrated extract having reduced volume and weight, which can subsequently be reconstituted with water to produce a coffee beverage having the same flavor characteristics typical of conventionally brewed coffees. Because the flavor, quality, and shelf-life of coffee extracts can be reduced by prolonged exposure to oxygen, in preferred embodiments of the invention, the exposure of the extract, during extraction, de-watering, and any subsequent handling, and packaging, to atmospheric air is minimized, for example by utilizing inert gases, such as nitrogen, as blanket/purge gases for contacting the extract during production and processing, as described previously.
The function and advantage of the invention will be more fully understood from the examples below. The following examples are intended to illustrate the operation of the invention, but not to exemplify the full scope of the invention.
One Pass Extraction Without Subsequent De-Watering
The industrial scale extractor described in connection with
The vessel was filled with the dry ground coffee forming a bed and the system was wetted with hot water, from a supply maintained at 193 degrees F. and 90 psig, as described above. Valve 25 on the extract outlet line 23 was then closed and about 40 gallons of the hot water was added to the vessel via inlet line 46 yielding a final vessel pressure of about 90 psig. the vessel was then “burped” to remove excess air as previously described and then pressurized to about 120 psig with pressurized air. The coffee was “pressure-treated” at this pressure without flow for about 10 min., at which time, valve 25 was opened to allow the extract to flow from the vessel, through a stainless steel heat exchanger (chiller 28) operated to lower the temperature of the exiting extract from about 165 degrees to about 55 degrees F. in approximately 2 min., and into a collection container. When the pressure in the vessel dropped to about 90 psig, the hot water supply to the vessel was reestablished by opening valve 47 on aqueous solvent inlet line 46. An additional 90 gallons of hot water were then passed through the bed of coffee before closing valve 47. When no more extract was observed flowing from the vessel, pressurized air was supplied to the vessel at 120 psig to purge residual extract from the bed for collection. The total yield of extract was about 100 gallons from the 265 lb of dry coffee.
The extract was judged by taste and smell testing to have exceptional sweetness with a clear coffee flavor retaining the varietal components, and substantially free of acidic off-flavors. The extract had a Brix reading of about 8.0 (about 6.5% dissolved solubles) and can be reconstituted with about 7 lbs. water per pound of extract to yield a coffee beverage of normal drip brew strength, but with superior sweetness and flavor.
Two Pass Extraction with Subsequent De-Watering of the Second-Pass Extract and Formation of a Blended Coffee Extract
The industrial scale extractor described in connections with
The extraction vessel was filled with the dry ground coffee and about 60 gallons of a first-pass coffee extract was produced as described previously for Example 1, except that in the present example pressurized nitrogen was utilized in place of the pressurized air in Example 1. Also, the step, in Example 1, of passing additional hot water through the bed of coffee performed immediately prior to the purging of residual extract from the bed with gas was omitted in the present example. The total yield of the first-pass extract was about 60 gallons from the 200 lbs. of dry coffee. This extract was set aside.
A second-pass extract was prepared, as described above, except using the same charge of ground coffee used previously for producing the first-pass extract, and except that after extract was collected from the vessel immediately subsequent to the pressure treat step and before purging residual extract from the bed with nitrogen, an additional of 60 gals. of hot water was passed through the bed of coffee in a similar fashion as that described above in Example 1. The total yield of second-pass extract was about 120 gals.
The second-pass extract was then de-watered using the PROSYS Model No. 400 Series Reverse Osmosis System (configured with four Model No. 4921S Koch nanofiltration membrane cartridges, arranged in parallel) described above in the context of
The blended extract was judged by taste and smell testing to have a clear coffee flavor that was well balanced with respect to sweet and bitter/acidic flavor components. The extract also was judged to retain the varietal components indicative of the Sumatran roasted coffee from which it was prepared. The extract had a Brix reading of about 8.0 (about 6.5% wt. dissolved solubles), and can be reconstituted with about 7 lbs. water per pound of extract to yield a coffee beverage of normal brew strength, and with well-balanced coffee flavor including desirable varietal flavor and fragrance components.
One Pass Extraction with Subsequent De-Watering to Produce a Highly Concentrated Coffee Extract
An industrial scale extractor similar to that described in connection with
The vessel was filled with the dry ground coffee forming a bed and the system was wetted with hot water, from a supply maintained at 193 degrees F. and 90 psig, as described above, except the first about 250 gallons of hot water added to the extractor were added through the bottom screen via line 23 and through tangential lines 42 and 55. At 250 gallons, the vent line was closed, and an additional about 50 gallons of hot water was added to the closed extractor via line 46 and water spray head 63, raising the internal pressure of the extractor to about 40-50 psig. The coffee was “pressure-treated” at this pressure without flow for about 30 min., at which time, valve 25 was controllably opened to allow the extract to flow from the vessel at a flow rate of about 6-8 gal./min., through a basket filter and stainless steel heat exchanger (chiller 28), which cooled the extract to a temperature of about 50 degrees F., and into a collection container. The hot water supply to the vessel was then reestablished at a controlled supply pressure of about 40 psig by opening valve 47 on aqueous solvent inlet line 46 and pumping hot water to the extractor at the above-mentioned pressure and at a controlled flow rate of about 6-8 gal./min., until an additional about 600 gallons of hot water were passed through the bed of coffee, at which point the flow was discontinued and valve 47 was closed. When no more extract was observed flowing from the vessel, pressurized nitrogen was supplied to the vessel to purge residual extract (about 100 gallons) from the bed for collection. The total yield of extract was about 1000 gallons from the 1300 lbs. of dry coffee.
The 1000 gallons of the above extract was then de-watered using the Fluid Solutions Model No. 10037 Reverse Osmosis System (configured with 15 FILMTEC Model No. BW30-4040 reverse osmosis membrane cartridges) described above in the context of
The concentrated extract was judged by taste and smell testing to have a clear coffee flavor that was well balanced with respect to sweet and bitter/acidic flavor components. The extract also was judged to retain the varietal components indicative of the Sumatran roasted coffee from which it was prepared. The extract had a Brix reading of about 30 (about 25% wt. dissolved solubles), and can be reconstituted with about 30 lbs. water per pound of extract to yield a coffee beverage of normal brew strength, and with well-balanced coffee flavor including desirable varietal flavor and fragrance components.
While the invention has been shown and described above with reference to various embodiments and specific examples, it is to be understood that the invention is not limited to the embodiments or examples described and that the teachings of this invention may be practiced by one skilled in the art in various additional ways and for various additional purposes. Those skilled in the art would readily appreciate that all parameters and configurations described herein are meant to be exemplary and that actual parameters and configurations will depend upon the specific application for which the systems and methods of the present invention are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described. The present invention is directed to each individual feature, system, or method described herein. In addition, any combination of two or more such features, systems, or methods, provided that such features, systems, or methods are not mutually inconsistent, is included within the scope of the present invention.
25. An aqueous coffee extract obtained by extraction of a quantity of roasted coffee, said quantity including at least one chosen variety of roasted coffee, said extract having at least about 15% wt. dissolved coffee solids, and retaining an effective amount of the varietal flavor and fragrance components characterizing said at least one chosen variety of roasted coffee from other varieties of roasted coffee.
26. The aqueous coffee extract as recited in claim 25, wherein the extract contains at least about 20% wt. dissolved coffee solids.
27. The aqueous coffee extract as recited in claim 26, wherein the extract contains at least about 25% wt. dissolved coffee solids.
28. The aqueous coffee extract as recited in claim 27, wherein the extract contains at least about 30% wt. dissolved coffee solids.
29. The aqueous coffee extract as recited in claim 28, wherein the extract contains at least about 40% wt. dissolved coffee solids.
30. A method for producing a blended coffee extract, the method comprising:
- a. extracting a quantity of roasted coffee with a quantity of aqueous solvent to form a first-pass coffee extract having a concentration of dissolved coffee solids therein of a first value;
- b. extracting the same quantity of roasted coffee previously extracted in step (a) with an additional quantity of aqueous solvent to form a second-pass coffee extract having a concentration of dissolved coffee solids therein of a second value less than first value;
- c. increasing the concentration of dissolved coffee solids in the second-pass coffee extract by removing a quantity of aqueous solvent therefrom; and
- d. mixing a quantity of the first-pass extract with a quantity of the second-pass extract concentrated in step (c) to form a blended extract.
31. The method as recited in claim 30, wherein in step (c) the concentration of dissolved coffee solids in the second-pass coffee extract is increased by removing by filtration a quantity of aqueous solvent therefrom.
32. The method as recited in claim 30, wherein in step (d) the quantity of the first-pass extract is greater than the quantity of the second-pass concentrated in step (c).
33. The method as recited in claim 30, wherein in step (d) the quantity of the first-pass extract is less than the quantity of the second-pass concentrated in step (c).
34. The method as recited in claim 30, wherein in step (d) the quantity of the first-pass extract and the quantity of the second-pass concentrated in step (c) are essentially equal.
35. The method as recited in claim 30, wherein in step (c) the concentration of dissolved coffee solids in the second-pass extract is increased to about said first value.
36. The method as recited in claim 35, wherein in step (d) the quantity of the first-pass extract and the quantity of the second-pass concentrated in step (c) are essentially equal.
37. A blended coffee extract produced according to the method recited in claim 30.
38. The method as recited in claim 30, wherein the blended extract has a concentration of dissolved coffee solids of at least about 6% wt.
39. A blended coffee extract produced according to the method recited in claim 38.
40. The method as recited in claim 38, further comprising after step (d):
- e. diluting the blended extract with aqueous solvent so that the concentration of dissolved coffee solids is between about 1% wt. and about 4% wt.
International Classification: A23F 5/24 (20060101);