Method, system and equipment for regenerating foam layer on cold chain coffee liquid

Abstract

The invention discloses a method, a system and equipment for regenerating a foam layer on cold-chain coffee liquid, and belongs to the technical field of coffee concoction.The method specifically comprises the steps that coffee liquid with the volume of V0 is put into a high-pressure container, and nitrogen with the initial mass of m0 is filled into the high-pressure container; the thickness deviation absolute value is calculated, if the deviation absolute value is larger than a preset deviation threshold value, the preset threshold value is gradually increased at the initial mass m0, and the increased mass serves as new mass mi; if the absolute value of the thickness deviation between the foam layer thickness of the mixed coffee liquid and the standard preset thickness under any initial mass mi is smaller than or equal to a preset deviation threshold value, recording the mass mi of the filled nitrogen at the moment; the volume Vs of the coffee liquid in the high-pressure container is obtained, the difference value between Vs and V0 is calculated, and if the difference value is larger than or equal to the preset volume threshold value, the mass of nitrogen in the high-pressure container is corrected, self-adaptive adjustment of the nitrogen filling amount is achieved, and a coffee foam layer is reproduced.

Description

Technical Field

[0001] The present invention relates to the technical field of coffee brewing, and in particular to a method, system and equipment for regenerating a foam layer on cold chain coffee liquid. Background Art

[0002] The coffee foam layer, commonly known as "crema", mainly appears in concentrated coffee (such as Italian espresso). During the extraction process of coffee, carbon dioxide is released with high-pressure extraction and forms a foam layer called "crema" on the surface of the coffee. The foam layer contains a large amount of volatile aroma substances, which can lock the aroma of coffee and release it when drinking, enhancing the overall flavor experience.

[0003] However, in actual coffee shops, in order to improve work efficiency, ensure coffee quality and reduce costs, the practice of cold extraction of coffee beans in large quantities in advance is usually adopted. In this way, a large amount of concentrated coffee liquid can be made in advance and stored in refrigerated equipment for easy access at any time. The preparation time of each cup of coffee can be significantly shortened. However, during the refrigeration process, due to the low temperature, the carbon dioxide in the coffee liquid will be quickly released, causing the originally rich crema layer to gradually disappear. At this time, the aroma and taste of the coffee will also be affected.

[0004] In the prior art, a kind of "nitrogen coffee" is specially introduced for this purpose. Nitrogen coffee is a kind of coffee made by injecting high-pressure nitrogen into cold-brewed coffee. This production method can form a stable foam layer on the surface of the cold chain coffee liquid, which not only enhances the visual effect, but also presents a beer-like taste, maintaining the unique flavor and aroma of coffee. However, in the production process, the pressure in the high-pressure container is usually kept constant to allow the nitrogen to fully blend into the coffee liquid. However, in actual use, the coffee liquid will be continuously sold, causing the pressure in the high-pressure container to drop. In order to ensure that the pressure in the high-pressure container remains unchanged, more nitrogen will be added in the prior art, resulting in excessive nitrogen pressure in the high-pressure container. Excessive nitrogen pressure may cause the released coffee liquid bubbles to be too large and the foam layer to be too thick, affecting the taste and foam quality of the coffee. Summary of the invention

[0005] The purpose of the present invention is to provide a method, system and equipment for regenerating a foam layer on cold chain coffee liquid to solve the following technical problems: However, in actual use, coffee liquid will be continuously sold, resulting in a decrease in the pressure in the high-pressure container. In order to ensure that the pressure in the high-pressure container remains unchanged, more nitrogen will be added in the prior art, resulting in excessive nitrogen pressure in the high-pressure container. Excessive nitrogen pressure may cause the bubbles in the released coffee liquid to be too large and the foam layer to be too thick, thereby affecting the taste of the coffee and the quality of the foam.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for regenerating a foam layer on a cold chain coffee liquid comprises the following steps: S1, put a volume of coffee liquid V0 into a high-pressure container and fill it with nitrogen gas with an initial mass of m0. After standing in the high-pressure container for T time, extract a volume of mixed coffee liquid V'; S2, obtaining the foam layer thickness d of the mixed coffee liquid and the standard preset thickness D, calculating the thickness deviation absolute value |Δd|=Dd, if |Δd| is greater than the preset deviation threshold, gradually increasing the initial mass m0 by the preset threshold, taking the increased mass as the new mass mi, and repeating S1; If the absolute value of the thickness deviation |Δd| between the foam layer thickness d of the mixed coffee liquid and the standard preset thickness D under any initial mass mi is less than or equal to the preset deviation threshold, the mass mi of the nitrogen filled at this time is recorded and marked as the optimal nitrogen mass under the current preset volume V0; S3, obtaining the volume Vs of the coffee liquid in the high-pressure container in real time under actual conditions, calculating the difference between Vs and V0, and if the difference is greater than or equal to a preset volume threshold, correcting the nitrogen mass in the high-pressure container.

[0007] As a further solution of the present invention: the temperature in the high-pressure container is stably maintained at 3 degrees Celsius, and the nitrogen filled is food-grade nitrogen.

[0008] As a further solution of the present invention: In S3, the specific formula for correcting the nitrogen mass in the high-pressure container is: ; ; △m=m'*α-mi; If △m is greater than 0, nitrogen with a mass of △m is filled into the high-pressure container; if △m is less than 0, nitrogen with a mass of △m is released into the high-pressure container; wherein R is the gas constant, T is the temperature in the high-pressure container, Mi is the molar mass of nitrogen, Vr is the volume of the high-pressure container, m' is the theoretical nitrogen mass corresponding to the volume Vs of the coffee liquid, △m is the nitrogen mass correction, and α is the correction coefficient.

[0009] As a further solution of the present invention: the specific calculation process of the preset correction coefficient is: S11, respectively obtaining the optimal nitrogen masses m1, m2, …, mn corresponding to the coffee liquid with volumes V0−v, V0−2v, …, V0−nv in the high-pressure container; S12, according to the calculation formula The theoretical nitrogen mass m1', m2', ..., mn' corresponding to any volume of coffee liquid is calculated; where q belongs to n, and mq' is the theoretical nitrogen mass corresponding to the volume of coffee liquid V0-qv; S13, according to the calculation formula Get the correction coefficient of the nitrogen mass filled in any coffee liquid volume, get the correction coefficient set K1, K2, ..., Kn, calculate the correction coefficient variance σ² of the correction coefficient set, if the correction coefficient variance is less than or equal to the preset threshold, then according to the calculation formula The correction coefficient α is calculated; If the variance of the correction coefficient is greater than a preset threshold, a curve of the correction coefficient changing with the volume of coffee liquid is generated with the volume of coffee liquid as the horizontal coordinate and the correction coefficient as the vertical coordinate. A linear fit is performed on the curve to obtain a fitting function. The volume of coffee liquid Vs is substituted into the fitting function to obtain the correction coefficient α.

[0010] As a further solution of the present invention: the specific calculation process of the fitting function is: The variation curve is fitted by the least square method to obtain a fitting straight line equation: K=k×V+b, wherein k represents the slope of the fitting straight line, V is the volume of the coffee liquid, b represents the intercept of the fitting straight line, and k and b are constants.

[0011] As a further solution of the present invention: the specific calculation process of the correction coefficient variance σ² is: ; ; Where vagK is the mean value of the correction coefficient.

[0012] A system for regenerating a foam layer on a cold chain coffee liquid, characterized by comprising: A preparation module, for placing a coffee liquid with a volume of V0 in a high-pressure container and charging nitrogen with an initial mass of m0, and extracting a mixed coffee liquid with a volume of V' after standing in the high-pressure container for T time; A data acquisition module is used to obtain the foam layer thickness d of the mixed coffee liquid and the standard preset thickness D, and calculate the thickness deviation absolute value |Δd|=Dd. If |Δd| is greater than a preset deviation threshold, the initial mass m0 is gradually increased by the preset threshold, and the increased mass is used as the new mass mi, and S1 is repeated; If there is any initial mass mi, the absolute value of the thickness deviation |Δd| between the thickness d of the foam layer of the mixed coffee liquid and the standard preset thickness D is less than or equal to the preset deviation threshold, the mass mi of the nitrogen filled at this time is recorded and marked as the optimal nitrogen mass under the current preset volume V0; The data correction module is used to obtain the volume Vs of the coffee liquid in the high-pressure container in real time under actual conditions, calculate the difference between Vs and V0, and if the difference is greater than or equal to a preset volume threshold, correct the nitrogen mass in the high-pressure container.

[0013] A device for regenerating a foam layer on cold-chain coffee liquid, characterized in that it comprises: a memory, a processor and a transceiver; the memory, the processor and the transceiver are communicatively connected in sequence; the memory is used to store computer programs, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute a method for regenerating a foam layer on a cold-chain coffee liquid as described in any one of claims 1-6.

[0014] Beneficial effects of the present invention: The thickness of coffee foam plays an important role in coffee quality. Foam not only affects the appearance of coffee, but also has a significant impact on taste, flavor and texture. Too thin foam will make the coffee taste monotonous, while too thick foam may weaken the rich taste of coffee. The ideal foam thickness can help maintain the aroma and concentration of coffee while bringing a smooth taste experience. Therefore, the standard thickness of coffee foam is set in the present invention to provide a reference point for further analysis. It can be understood that the foam thickness of nitrogen coffee is mainly related to the nitrogen content in the coffee liquid. The greater the nitrogen content, the thicker the foam, and the lower the nitrogen content, the thicker the foam. The thinner the foam, the better the quality of nitrogen. Therefore, the present invention gradually increases the quality of nitrogen in the high-pressure container to obtain the best nitrogen quality, ensuring that the thickness of the foam layer can be consistent with the standard requirements. Considering that the coffee liquid in the container may decrease intermittently in actual situations, the pressure in the container changes, so the solubility of nitrogen in the coffee liquid will also change. If only nitrogen is filled to keep the pressure in the container stable, the nitrogen pressure will be too high, so that the bubbles of the released coffee liquid are too large, the foam layer is too thick, and the taste of the coffee and the foam quality are affected. Therefore, according to Henry's law C=k H *P By calculating the solubility of nitrogen in the liquid, an appropriate amount of nitrogen is filled to keep the partial pressure of nitrogen in the container at an appropriate level to avoid excessive bubbles. The present invention dynamically adjusts the quality of nitrogen to avoid over-inflation or under-inflation, achieves adaptive adjustment, and reproduces the coffee foam layer, thereby ensuring the consistency of the quality and taste of each cup of coffee. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings.

[0016] Figure 1 The present invention is a schematic flow chart of a method for regenerating a foam layer on cold chain coffee liquid. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1 As shown, the present invention is a method for regenerating a foam layer on a cold chain coffee liquid, comprising the following steps: S1, put a volume of coffee liquid V0 into a high-pressure container and fill it with nitrogen gas with an initial mass of m0. After standing in the high-pressure container for T time, extract a volume of mixed coffee liquid V'; S2, obtaining the foam layer thickness d of the mixed coffee liquid and the standard preset thickness D, calculating the thickness deviation absolute value |Δd|=Dd, if |Δd| is greater than the preset deviation threshold, gradually increasing the initial mass m0 by the preset threshold, taking the increased mass as the new mass mi, and repeating S1; If the absolute value of the thickness deviation |Δd| between the foam layer thickness d of the mixed coffee liquid and the standard preset thickness D under any initial mass mi is less than or equal to the preset deviation threshold, the mass mi of the nitrogen filled at this time is recorded and marked as the optimal nitrogen mass under the current preset volume V0; S3, obtaining the volume Vs of the coffee liquid in the high-pressure container in real time under actual conditions, calculating the difference between Vs and V0, and if the difference is greater than or equal to a preset volume threshold, correcting the nitrogen mass in the high-pressure container.

[0019] The thickness of coffee foam plays an important role in coffee quality. Foam not only affects the appearance of coffee, but also has a significant impact on taste, flavor and texture. Too thin foam will make the coffee taste monotonous, while too thick foam may weaken the rich taste of coffee. The ideal foam thickness can help maintain the aroma and concentration of coffee while bringing a smooth taste experience. Therefore, the standard thickness of coffee foam is set in the present invention to provide a reference point for further analysis. It can be understood that the foam thickness of nitrogen coffee is mainly related to the nitrogen content in the coffee liquid. The greater the nitrogen content, the thicker the foam, and the lower the nitrogen content, the thicker the foam. The thinner the foam, the better the quality of nitrogen. Therefore, the present invention gradually increases the quality of nitrogen in the high-pressure container to obtain the best nitrogen quality, ensuring that the thickness of the foam layer can be consistent with the standard requirements. Considering that the coffee liquid in the container may decrease intermittently in actual situations, the pressure in the container changes, so the solubility of nitrogen in the coffee liquid will also change. If only nitrogen is filled to keep the pressure in the container stable, the nitrogen pressure will be too high, so that the bubbles of the released coffee liquid are too large, the foam layer is too thick, and the taste of the coffee and the foam quality are affected. Therefore, according to Henry's law C=kH *P By calculating the solubility of nitrogen in the liquid, an appropriate amount of nitrogen is filled to keep the partial pressure of nitrogen in the container at an appropriate level to avoid excessive bubbles. The present invention dynamically adjusts the quality of nitrogen to avoid over-inflation or under-inflation, achieves adaptive adjustment, and reproduces the coffee foam layer, thereby ensuring the consistency of the quality and taste of each cup of coffee.

[0020] In a preferred embodiment of the present invention, the temperature in the high-pressure container is stably maintained at 3 degrees Celsius, and the nitrogen filled is food-grade nitrogen.

[0021] In another preferred embodiment of the present invention, in S3, the specific formula for correcting the nitrogen mass in the high-pressure container is: ; ; △m=m'*α-mi; If △m is greater than 0, nitrogen with a mass of △m is filled into the high-pressure container; if △m is less than 0, nitrogen with a mass of △m is released into the high-pressure container; wherein R is the gas constant, T is the temperature in the high-pressure container, Mi is the molar mass of nitrogen, Vr is the volume of the high-pressure container, m' is the theoretical nitrogen mass corresponding to the volume Vs of the coffee liquid, △m is the nitrogen mass correction, and α is the correction coefficient.

[0022] In another preferred embodiment of the present invention, the specific calculation process of the preset correction coefficient is: S11, respectively obtaining the optimal nitrogen masses m1, m2, …, mn corresponding to the coffee liquid with volumes V0−v, V0−2v, …, V0−nv in the high-pressure container; S12, according to the calculation formula The theoretical nitrogen mass m1', m2', ..., mn' corresponding to any volume of coffee liquid is calculated; where q belongs to n, and mq' is the theoretical nitrogen mass corresponding to the volume of coffee liquid V0-qv; S13, according to the calculation formula Obtain the correction coefficient of the nitrogen mass filled under any coffee liquid volume, obtain the correction coefficient set K1, K2, ..., Kn, calculate the correction coefficient variance σ² of the correction coefficient set, and if the correction coefficient variance is less than or equal to the preset threshold, calculate the correction coefficient α according to the calculation formula; If the variance of the correction coefficient is greater than a preset threshold, a curve of the correction coefficient changing with the volume of coffee liquid is generated with the volume of coffee liquid as the horizontal coordinate and the correction coefficient as the vertical coordinate. A linear fit is performed on the curve to obtain a fitting function. The volume of coffee liquid Vs is substituted into the fitting function to obtain the correction coefficient α.

[0023] By obtaining the optimal nitrogen mass corresponding to different volumes of coffee liquid and calculating the correction coefficient based on the theoretical value, the difference between the actual situation and the theoretical model can be more accurately reflected. In the actual process, various factors may cause the actual required nitrogen mass to deviate from the theoretical calculated value, such as the particle size, temperature, pressure, etc. of the coffee powder. By quantifying and correcting these deviations, the accuracy of nitrogen mass calculation can be improved to ensure that the coffee liquid reaches the best taste and quality after being filled with nitrogen. It can be understood that when the variance of the correction coefficient is small, it means that various factors have little influence on the correction coefficient, which means that under different volumes of coffee liquid, the deviation between the actual nitrogen mass and the theoretical nitrogen mass is relatively stable and there is no large fluctuation, so the mean of the correction coefficient is directly calculated as the correction coefficient α; when the variance of the correction coefficient is greater than the preset threshold, it means that various factors have a greater influence on the correction coefficient, which means that under different volumes of coffee liquid, the deviation between the actual nitrogen mass and the theoretical nitrogen mass has a fluctuation in amplitude, so the correction coefficient should be a variable value. The fitting function is obtained by using the linear fitting method to further optimize the calculation of the correction coefficient. This dynamic adjustment method can adapt to changes under different production conditions, making the calculation model more flexible and accurate, thereby improving the control accuracy of nitrogen quality.

[0024] In another preferred embodiment of the present invention, the specific calculation process of the fitting function is: The variation curve is fitted by the least square method to obtain a fitting straight line equation: K=k×V+b, wherein k represents the slope of the fitting straight line, V is the volume of the coffee liquid, b represents the intercept of the fitting straight line, and k and b are constants.

[0025] In another preferred embodiment of the present invention, the specific calculation process of the correction coefficient variance σ² is: ; ; Where vagK is the mean value of the correction coefficient.

[0026] A system for regenerating a foam layer on a cold chain coffee liquid, characterized by comprising: A preparation module, for placing a coffee liquid with a volume of V0 in a high-pressure container and charging nitrogen with an initial mass of m0, and extracting a mixed coffee liquid with a volume of V' after standing in the high-pressure container for T time; A data acquisition module is used to obtain the foam layer thickness d of the mixed coffee liquid and the standard preset thickness D, and calculate the thickness deviation absolute value |Δd|=Dd. If |Δd| is greater than a preset deviation threshold, the initial mass m0 is gradually increased by the preset threshold, and the increased mass is used as the new mass mi, and S1 is repeated; If there is any initial mass mi, the absolute value of the thickness deviation |Δd| between the thickness d of the foam layer of the mixed coffee liquid and the standard preset thickness D is less than or equal to the preset deviation threshold, the mass mi of the nitrogen filled at this time is recorded and marked as the optimal nitrogen mass under the current preset volume V0; The data correction module is used to obtain the volume Vs of the coffee liquid in the high-pressure container in real time under actual conditions, calculate the difference between Vs and V0, and if the difference is greater than or equal to a preset volume threshold, correct the nitrogen mass in the high-pressure container.

[0027] A device for regenerating a foam layer on cold-chain coffee liquid, characterized in that it comprises: a memory, a processor and a transceiver; the memory, the processor and the transceiver are communicatively connected in sequence; the memory is used to store computer programs, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute a method for regenerating a foam layer on a cold-chain coffee liquid as described in any one of claims 1-6.

[0028] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for regenerating a foam layer on a cold chain coffee liquid, characterized in that: The following steps are involved: S1, put a volume of coffee liquid V0 into a high-pressure container and fill it with nitrogen gas with an initial mass of m0. After standing in the high-pressure container for T time, extract a volume of mixed coffee liquid V'; S2, obtaining the foam layer thickness d of the mixed coffee liquid and the standard preset thickness D, calculating the thickness deviation absolute value |Δd|=Dd, if |Δd| is greater than the preset deviation threshold, gradually increasing the initial mass m0 by the preset threshold, taking the increased mass as the new mass mi, and repeating S1; If the absolute value of the thickness deviation |Δd| between the foam layer thickness d of the mixed coffee liquid and the standard preset thickness D under any initial mass mi is less than or equal to the preset deviation threshold, the mass mi of the nitrogen filled at this time is recorded and marked as the optimal nitrogen mass under the current preset volume V0; S3, obtaining the volume Vs of the coffee liquid in the high-pressure container in real time under actual conditions, calculating the difference between Vs and V0, and if the difference is greater than or equal to a preset volume threshold, correcting the nitrogen mass in the high-pressure container.

2. The method for regenerating a foam layer on a cold chain coffee liquid according to claim 1, characterized in that: It also includes that the temperature in the high-pressure container is stably maintained at 3 degrees Celsius, and the nitrogen filled is food-grade nitrogen.

3. The method for regenerating a foam layer on a cold chain coffee liquid according to claim 1, characterized in that: In S3, the specific formula for correcting the nitrogen mass in the high-pressure container is: ； ； △m=m'*α-mi; If △m is greater than 0, nitrogen with a mass of △m is filled into the high-pressure container; if △m is less than 0, nitrogen with a mass of △m is released into the high-pressure container; wherein R is the gas constant, T is the temperature in the high-pressure container, Mi is the molar mass of nitrogen, Vr is the volume of the high-pressure container, m' is the theoretical nitrogen mass corresponding to the volume Vs of the coffee liquid, △m is the nitrogen mass correction, and α is the correction coefficient.

4. The method for regenerating a foam layer on a cold chain coffee liquid according to claim 3, characterized in that: The specific calculation process of the preset correction coefficient is: S11, respectively obtaining the optimal nitrogen masses m1, m2, …, mn corresponding to the coffee liquid with volumes V0−v, V0−2v, …, V0−nv in the high-pressure container; S12, according to the calculation formula The theoretical nitrogen mass m1', m2', ..., mn' corresponding to any volume of coffee liquid is calculated; where q belongs to n, and mq' is the theoretical nitrogen mass corresponding to the volume of coffee liquid V0-qv; S13, according to the calculation formula Get the correction coefficient of the nitrogen mass filled in any coffee liquid volume, get the correction coefficient set K1, K2, ..., Kn, calculate the correction coefficient variance σ² of the correction coefficient set, if the correction coefficient variance is less than or equal to the preset threshold, then according to the calculation formula The correction coefficient α is calculated; If the variance of the correction coefficient is greater than a preset threshold, a curve of the correction coefficient changing with the volume of coffee liquid is generated with the volume of coffee liquid as the horizontal coordinate and the correction coefficient as the vertical coordinate. A linear fit is performed on the curve to obtain a fitting function. The volume of coffee liquid Vs is substituted into the fitting function to obtain the correction coefficient α.

5. The method for regenerating a foam layer on a cold chain coffee liquid according to claim 4, characterized in that: The specific calculation process of the fitting function is: The variation curve is fitted by the least square method to obtain a fitting straight line equation: K=k×V+b, wherein k represents the slope of the fitting straight line, V is the volume of the coffee liquid, b represents the intercept of the fitting straight line, and k and b are constants.

6. The method for regenerating a foam layer on a cold chain coffee liquid according to claim 4, characterized in that: The specific calculation process of the correction coefficient variance σ² is: ； ； Where vagK is the mean value of the correction coefficient.

7. A system for regenerating a foam layer on a cold chain coffee liquid, characterized in that: include: A preparation module, for placing a coffee liquid with a volume of V0 in a high-pressure container and charging nitrogen with an initial mass of m0, and extracting a mixed coffee liquid with a volume of V' after standing in the high-pressure container for T time; A data acquisition module is used to obtain the foam layer thickness d of the mixed coffee liquid and the standard preset thickness D, and calculate the thickness deviation absolute value |Δd|=Dd. If |Δd| is greater than a preset deviation threshold, the initial mass m0 is gradually increased by the preset threshold, and the increased mass is used as the new mass mi, and S1 is repeated; If there is any initial mass mi, the absolute value of the thickness deviation |Δd| between the thickness d of the foam layer of the mixed coffee liquid and the standard preset thickness D is less than or equal to the preset deviation threshold, the mass mi of the nitrogen filled at this time is recorded and marked as the optimal nitrogen mass under the current preset volume V0; The data correction module is used to obtain the volume Vs of the coffee liquid in the high-pressure container in real time under actual conditions, calculate the difference between Vs and V0, and if the difference is greater than or equal to a preset volume threshold, correct the nitrogen mass in the high-pressure container.

8. A device for regenerating a foam layer on a cold chain coffee liquid, characterized in that: include: memory, processors, and transceivers; The memory, the processor and the transceiver are communicatively connected in sequence; The memory is used to store computer programs, the transceiver is used to send and receive messages, and the processor is used to read the computer program and execute the method for regenerating a foam layer on cold chain coffee liquid as described in any one of claims 1-6.

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