Cold brew coffee, the process of brewing coffee with room-temperature or cold water, is an idea that has been around for at least four centuries, but has very recently seen an exponential increase in demand. Consumers of cold brew are drawn by the lower acidity and more appealing flavor, but the advantages are counter-balanced by much shorter shelf-life and much longer brewing time. Cold brew coffee is not to be confused with iced coffee, which generally refers to coffee that is brewed hot and then chilled by pouring over or adding ice.
There are currently several products available to make cold brew coffee in small or industrial quantities. Some examples are Filtron, Toddy, and Japanese slow-drip, all of which require that the coffee and water are exposed to the ambient air during the brewing process. Because the constituent parts of coffee grounds are more soluble at higher temperatures, the cold brewing process requires steeping of four to thirty hours, or sometimes even longer. The largest deficiency of the currently-used cold brew processes is that they cannot properly extract the character, identity or terroir of the coffee beans. Therefore the end product is nondescript and it is often impossible to differentiate one cold brewed coffee from another. The three primary reasons for this inefficiency are brewing temperature, contamination and oxidation.
Brewing with these methods creates oxidation and opportunities for microbial development, thus decreasing the shelf life of the product before it begins to sour and/or degrade. This exposure to environmental elements occurs due to the physics of extraction. In order for the liquid to penetrate inside the structure of the coffee, the liquid must displace the captured CO2 in the coffee before extraction and hydrolysis can occur. Therefore, by the time the extraction is complete, the CO2 that once partially protected the coffee from oxidation has now dissipated and has been replaced with ambient air which includes oxygen, bacteria, microbes and yeasts. The exposure of the coffee and water to these elements contaminates the beverage, oxidizes the organic materials and causes volatile flavor compounds to dissipate and/or deteriorate. The longer the product is exposed to these elements, the more it becomes contaminated.
Flavor extraction from coffee and other botanicals with room temperature water is difficult. Specific flavor compounds are released through temperature of the solvent, which acts as a catalyst to release and/or develop acids and volatiles. All existing cold brew coffee methods use room temperature water during the process. This temperature is responsible for creating the “smooth” and “low acid” nature of this beverage. Water temperature has three primary effects: acidity, bitterness and flavor compounds.
One method commonly used in cold brewing to increase flavor development is to use hot water for the first wetting of the coffee (also called the bloom), followed by using room-temperature water for the remainder of the process to minimize bitterness. This short heating stage releases flavor volatiles, but only for a limited time after brewing is complete. The flavors deteriorate as the volatiles have a very short effective life. If the hot water is applied for more than a few seconds, the resulting product will have higher acidity and the grounds will release more bittering compounds, just the same as when brewing a hot cup of coffee. This changes the character of the beverage from smooth and low acid to the same as that of hot brewed or iced coffee if served cold. Such a beverage will no longer fit in the definition of cold brew coffee. Also, if the temperature of the water is too high, extraction occurs and oxidation is expedited.
Cold brew coffee is sometimes produced as a concentrate. The water-to-coffee ratio is typically around 14 mL/g for hot brew coffee versus approximately 5 mL/g for cold brew. Due to the decreased extraction effectiveness of cold water, more coffee must be used to create a beverage with acceptable flavor concentration. Depending on the type of coffee and water quality, final concentration of the beverage can vary. However, typically when the brewing is complete the final product results in a concentrate-to-water dilution ratio of 1:1 while retaining 25-30% of the liquid. Therefore, even if the concentrate is reconstituted at a rate of 1:1, the ratio of coffee to water is typically around 7.5 mL/g, because 30% of the liquid is lost prior to the reconstitution. In this way, the yield from the process is extremely low.
The inefficiency of the cold brew process also limits the density of any concentrated extract. Cold brew coffee requires more grounds per unit of water to brew, so any brewing vessel necessarily produces less cold brew coffee than hot brew coffee. Therefore, there is a natural limit to the density or concentration of the final product.
Thus, there is a need for a cold brew process that is faster and cleaner than those currently known in the art, and one that is capable of producing a concentrate with a higher dilution ratio. The present invention addresses this need.
The present invention relates to methods and systems of vacuum-extraction for brewing beverages. In one embodiment, the present invention relates to a vacuum-extraction method, comprising preparing a liquid water or solvent to a desired temperature; combining the liquid water or solvent with a first brewing material in a brewing vessel; removing air from the brewing vessel until a first desired pressure set point is reached; steeping the mixture of the liquid water or solvent and the first brewing material in the brewing vessel for a desired low-pressure steeping time; adding a filler gas to the brewing vessel until a second desired pressure set point is reached; steeping the mixture of the liquid water or solvent and the first brewing material in the brewing vessel for a desired steeping time at atmospheric or high-pressure; and directing the liquid water or solvent and the first brewing material through a filtration system to yield a filtered brewed beverage.
In one embodiment, the first brewing material comprises coffee. In another embodiment, the first brewing material comprises tea. In some embodiments, the filler gas is atmospheric air. In other embodiments, the filler gas comprises an inert gas.
In some embodiments, the methods comprise additional steps. In some embodiments, the method includes the steps of directing the filtered brewed beverage into a holding vessel; adding a second brewing material to the brewing vessel; directing the filtered brewed beverage into the brewing vessel; removing air from the brewing vessel until the first desired pressure set point is reached; steeping the mixture of the filtered brewed beverage and the second brewing material in the brewing vessel for the desired low-pressure steeping time; adding the filler gas to the brewing vessel until the second desired pressure set point is reached; steeping the mixture of the filtered brewed beverage and the second brewing material in the brewing vessel for a desired steeping time at atmospheric or high-pressure; and directing the filtered brewed beverage and the second brewing material through a filtration system to yield a twice-filtered brewed beverage.
The present invention also relates to a system capable of vacuum-extraction brewing, the system comprising a brewing vessel, a gas valve connected on a first port to the brewing vessel, a vacuum pump connected on a first end to the pressure tank, a filtration system, and a holding tank; wherein an output port of the brewing vessel is connected to an input port of the filtration system; wherein an output port of the filtration system is connected to an input port of the holding tank; wherein the vacuum pump removes gas from the brewing vessel in order to reach or maintain a pressure set point; and wherein the gas valve opens to expose the brewing vessel to a filler gas source.
In some embodiments, the system also comprises a circulation vessel wherein an input port of the circulation vessel is connected using a first valve or pump to a second output port of the brewing vessel and wherein an output port of the circulation vessel is connected using a second valve or pump to a second input port of the brewing vessel.
In some embodiments, the system further comprises a brite tank. In some embodiments the system further comprises a packaging step. In some embodiments the system further comprises a water or solvent tank.
The foregoing purposes and features, as well as other purposes and features, will become apparent with reference to the description and accompanying figures below, which are included to provide an understanding of the invention and constitute a part of the specification, in which like numerals represent like elements, and in which:
It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for the purpose of clarity, many other elements found in typical beverage brewing systems and methods. Those of ordinary skill in the art may recognize that other elements and/or steps are desirable and/or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein. The disclosure herein is directed to all such variations and modifications to such elements and methods known to those skilled in the art.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described.
As used herein, each of the following terms has the meaning associated with it in this section.
The articles “a” and “an” are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.
“About” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20%, ±10%, ±5%, ±1%, and ±0.1% from the specified value, as such variations are appropriate.
As used herein, “low-pressure” may mean any pressure that is below atmosphere, such as a vacuum or partial vacuum.
As used herein, “high-pressure” may mean any pressure that is greater than open or atmosphere.
Throughout this disclosure, various aspects of the invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, 6 and any whole and partial increments therebetween. This applies regardless of the breadth of the range.
The present invention is designed to overcome the deficiencies of the prior art as described above. One aspect of the present invention is to provide a beverage brewing system which creates cold brewed coffee using the most optimal means of production.
The improved production method of the present invention yields an extracted concentrate that has significantly higher density than current methods of cold brew coffee production, while also brewing up to 100× faster, minimizing potential contamination, and generating a final product that is more shelf stable than what is known in the art. The present invention accomplishes this without making the beverage more acidic than currently-used methods of cold brewing. The present invention may incorporate any of several vacuum-brewing beverage machines known in the art, for example the device described in Vastardis et al., U.S. Pat. No. 9,295,358, the contents of which is incorporated by reference in its entirety.
In one embodiment of the present invention, the right amount of coffee or other botanicals are added to a first chamber. All or a portion of the water is added to the liquid in the first chamber and a vacuum is created in the first chamber. The vacuum is created using a vacuum pump, which removes air from the first chamber until a set pressure is reached. The set pressure may be measured by a pressure sensor disposed within the first chamber, or by other means. When the set pressure is attained, the system will start a vacuum brewing timer that will run for a set period of time and maintain the vacuum at the set pressure. Once the vacuum brewing time has expired, the chamber will return to atmospheric pressure and the system will start an ambient pressure steeping timer. Once the ambient pressure steeping timer has completed, a vacuum is then re-applied using the vacuum pump, and the steps repeat themselves one or more times until gases are no longer being drawn from the coffee or botanicals and the coffee material is completely saturated with the water or solvent.
After the brewing cycles have completed, the liquid is separated from the extracted coffee or other organic materials using one or more filters. This liquid is then used as the starting liquid and or solvent for the next brew cycle. Therefore, with each recirculation of the materials, the liquid gains more density and dissolves additional organic materials making the liquid more and more concentrated with flavors and/or compounds.
Reference is now made to the drawings. Although the figures show a series of large tanks, the drawings are not meant as a limitation on the scale of possible embodiments of this invention. Unless explicitly stated, the vessels used in each stage of this process may be of any size, shape, or structure possible for the brewing of coffee as known by those skilled in the art. The vessels and the tubing or conduits connecting them may be composed of any material or materials known in the art.
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An example of this this process is the creation of cold brew espresso. Espresso is considered the highest form of specialty coffee, and is the most popular way coffee is consumed globally. However, espresso lacks an ability to tap into massive consumer demand for cold refreshment or on-the-go energy. Due to the heat and positive pressure utilized by the traditional extraction process, espresso needs to be consumed immediately after the shot is pulled and cannot be stabilized for ready-to-drink applications. Through applying the method shown in
Brewing temperatures for these described methods have been shown to be optimal in the range of 85-205 F. Although it has been noted that the most flavorful and balanced coffee products have been produced above room temperature at a range of approximately 115 F, and botanicals at approximately 165 F, the temperature range may be dependent on the coffee and/or botanicals. Although the temperature plays a role in the flavor development, it is the combination of the right temperature for the right material plus the controlled vacuums with the slope and hold time which create the stable product. The pH can fluctuate in food over the course of its shelf life as the result of precipitating out or enzymatic activity. As a result of the brew process as compared to a control of standard methods, the product produced by the method of the present invention creates a pH with fewer fluctuations over time. Given the circumstances, the pH stability is likely the result of prohibition of enzymatic activity in the present invention.
Alternatively, liquid may be pumped directly from the vacuum/brewing vessel 602 through the filtration system 604. The filtered liquid is then moved to a holding tank 605 before being cycled back into the vacuum/brewing vessel 602, which has been filled with additional coffee or brewing material. The liquid repeats these circulation steps as many times as necessary before moving to the brite tank 606 for packaging 607.
This application is a national stage filing of PCT international application No. PCT/US2017/056877 filed on Oct. 17, 2017, which claims priority U.S. provisional application No. 62/409,268 filed on Oct. 17, 2016, both of which are incorporated herein by reference in their entireties.
Filing Document | Filing Date | Country | Kind |
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PCT/US17/56877 | 10/17/2017 | WO | 00 |
Number | Date | Country | |
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62409268 | Oct 2016 | US |