Extraction composite membrane for coffee concentrate and application

Abstract

The invention discloses an extraction composite membrane for coffee concentrate and application, the composite membrane comprises an upper layer and a lower layer, the lower layer is a modified ceramic membrane, and the upper layer is a modified gel membrane. The double-layer composite film is prepared and used for extracting the coffee concentrated solution, the extraction effect is good, coffee grounds are removed, and meanwhile coffee grease, coffee alcohol and coffee white alcohol which are harmful to human health can be removed; the amino group on the surface of the ceramic membrane and butanedioic anhydride are subjected to grafting modification, the modified membrane can adsorb caffeol and caffewhite alcohol, the interception capacity of the membrane on macromolecules in coffee liquid is improved, and the efficiency in the filtering process is improved.

Description

Technical Field

[0001] The invention relates to the technical field of coffee extraction and separation, and in particular to an extraction composite membrane for coffee concentrate and its application. Background Art

[0002] In the process of extracting coffee concentrate, the application of separation and extraction membranes has attracted widespread attention, mainly due to its superior performance in selective separation and improving extraction efficiency. However, the existing extraction membranes can only simply remove coffee grounds and do not improve the flavor of coffee. Therefore, how to improve its taste and flavor during the extraction process is a key issue in current research. Summary of the invention

[0003] In view of the deficiencies of the prior art, the object of the present invention is to provide a composite membrane for extracting coffee concentrate and its application, so as to enhance the flavor of the coffee concentrate during the extraction process.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme: The present invention provides a composite membrane for extracting coffee concentrate. The composite membrane comprises an upper and lower layer. The lower layer is a modified ceramic membrane, and the upper layer is a modified gel membrane.

[0005] Preferably, the preparation method of the modified ceramic membrane includes the following steps: treating the ceramic membrane with an ammonia atmosphere using plasma technology to make it amination, then placing it in a reaction container filled with dimethylformamide and succinic anhydride, adding catalyst phosphoric acid, heating for reaction, washing and drying after the reaction, and obtaining the modified ceramic membrane.

[0006] Preferably, the heating temperature is 40-50°C.

[0007] Preferably, the ceramic film includes an aluminum oxide film, a zirconium oxide film, a titanium oxide film or a silicon oxide film.

[0008] Preferably, the pore size of the modified ceramic membrane is 0.5-20 μm.

[0009] Preferably, the usage ratio of the ceramic membrane, dimethylformamide, succinic anhydride and phosphoric acid is (1-3 g): (3-10 mL): (0.2-0.4 g): (0.01-0.5 mL).

[0010] Preferably, the method for preparing the modified gel membrane comprises the following steps: S1. Add deionized water into a container containing sodium alginate and stir to obtain a sodium alginate solution; S2, dissolving chitosan in an acetic acid solution, then adding dopamine, stirring, then adding glutaraldehyde and NN-hydroxysuccinimide, cross-linking reaction, obtaining modified chitosan, adding the modified chitosan to a sodium alginate solution, stirring, and obtaining a mixed solution; S3, adding sodium hydroxide solution to the mixed solution, stirring to obtain a pre-gel, then injecting the pre-gel into a mold, adding calcium chloride solution for gelation, then eluting, freezing, and drying to obtain a preliminary gel film; S4, immersing the preliminary gel membrane in a lipase solution, and then washing and drying to obtain a modified gel membrane.

[0011] Preferably, in step S1, the usage ratio of sodium alginate and deionized water is (1-5 g): (100-150 mL); In step S2, the amount ratio of chitosan, acetic acid, dopamine, glutaraldehyde and NN-hydroxysuccinimide is (5-20 g): (10-50 mL): (2-5 g): (2-4 mL): (1-5 g); The mass ratio of sodium alginate to chitosan is (1-2): (15-25).

[0012] Preferably, in step S3, the mass fraction of the sodium hydroxide solution is 4% to 8%, and the mass fraction of the calcium chloride solution is 3% to 10%; In step S4, the mass concentration of the lipase solution is 1-20 mg / mL.

[0013] The present invention also proposes an application of the composite membrane as described above, which is applied to the extraction and separation of coffee concentrate.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention prepares a double-layer composite membrane for use in extracting coffee concentrate, which has a good extraction effect and can not only remove coffee grounds but also remove coffee oil, cafestol and kahweol that are harmful to human health.

[0015] (2) The present invention utilizes amino groups on the surface of the ceramic membrane to carry out grafting modification with succinic anhydride. The modified membrane is capable of adsorbing cafestol and kahweol, and the membrane's ability to retain macromolecules in the coffee liquid is enhanced, thereby improving the efficiency of the filtration process.

[0016] (3) The modified gel membrane prepared by the present invention first introduces more amino groups through chitosan modification to improve the adsorption of the gel membrane and prevent oxidation by lipase. Then, sodium alginate and modified chitosan form a three-dimensional cross-linked structure. Then, the adhesion property of sodium alginate is used to couple lipase to obtain a modified gel membrane. Under the action of lipase, the fat in the coffee liquid is degraded, which enables the gel membrane to remove impurities more efficiently and maintain a higher flow rate during the filtration process. At the same time, the selective permeability of the gel membrane can selectively filter out unnecessary lipids and solid particles, making the contents purer. The use of lipase helps to release more aroma and flavor substances, while the gel membrane helps to remove impurities and precipitation that may affect the flavor of the coffee, thereby improving the overall taste.

[0017] (4) The modified ceramic membrane and modified gel membrane provided by the present invention synergistically improve the extraction effect of coffee liquid, the flavor of coffee is better, the extraction time is significantly shortened, and the production efficiency is improved. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0019] It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention were purchased through commercial channels.

[0020] Example 1

[0021] A composite membrane for extracting coffee concentrate, the composite membrane comprising an upper and lower layer, the lower layer being a modified ceramic membrane, and the upper layer being a modified gel membrane; The preparation method of the modified ceramic membrane comprises the following steps: placing 2 g of the aminated ceramic membrane in a reaction container containing 5 mL of dimethylformamide and 0.3 g of succinic anhydride, adding 0.1 mL of phosphoric acid, heating for reaction, washing and drying after the reaction, and obtaining the modified ceramic membrane; The preparation method of the modified gel film comprises the following steps: S1. Add 120 mL of deionized water to a container containing 2 g of sodium alginate and stir to obtain a sodium alginate solution; S2, dissolving 10 g of chitosan in 20 mL of acetic acid solution, then adding 3 g of dopamine, stirring, then adding 3 mL of glutaraldehyde and 3 g of NN-hydroxysuccinimide, cross-linking reaction to obtain modified chitosan, adding the modified chitosan to the sodium alginate solution, stirring to obtain a mixed solution; S3, adding 10 mL of 6% sodium hydroxide solution to the mixed solution, stirring to obtain a pre-gel, then injecting the pre-gel into a mold, adding 20 mL of 8% calcium chloride solution for gelation, then eluting, freezing, and drying to obtain a preliminary gel film; S4, immersing the preliminary gel membrane in a 10 mg / mL lipase solution, and then washing and drying to obtain a modified gel membrane.

[0022] Example 2

[0023] A composite membrane for extracting coffee concentrate, the composite membrane comprising an upper and lower layer, the lower layer being a modified ceramic membrane, and the upper layer being a modified gel membrane; The preparation method of the modified ceramic membrane comprises the following steps: placing 1 g of the aminated ceramic membrane in a reaction container containing 3 mL of dimethylformamide and 0.2 g of succinic anhydride, adding 0.01 mL of phosphoric acid, heating for reaction, washing and drying after the reaction, and obtaining the modified ceramic membrane; The preparation method of the modified gel film comprises the following steps: S1. Add 100 mL of deionized water to a container containing 1 g of sodium alginate and stir to obtain a sodium alginate solution; S2, dissolving 5 g of chitosan in 10 mL of acetic acid solution, then adding 2 g of dopamine, stirring, then adding 2 mL of glutaraldehyde and 1 g of NN-hydroxysuccinimide, cross-linking reaction to obtain modified chitosan, adding the modified chitosan to the sodium alginate solution, stirring to obtain a mixed solution; S3, adding 10 mL of 4% sodium hydroxide solution to the mixed solution, stirring to obtain a pre-gel, then injecting the pre-gel into a mold, adding 20 mL of 3% calcium chloride solution for gelation, then eluting, freezing, and drying to obtain a preliminary gel film; S4, immersing the preliminary gel membrane in a 1 mg / mL lipase solution, and then washing and drying to obtain a modified gel membrane.

[0024] Example 3

[0025] A composite membrane for extracting coffee concentrate, the composite membrane comprising an upper and lower layer, the lower layer being a modified ceramic membrane, and the upper layer being a modified gel membrane; The preparation method of the modified ceramic membrane comprises the following steps: placing 3 g of the aminated ceramic membrane in a reaction container containing 10 mL of dimethylformamide and 0.4 g of succinic anhydride, adding 0.5 mL of phosphoric acid, heating for reaction, washing and drying after the reaction, and obtaining the modified ceramic membrane; The preparation method of the modified gel film comprises the following steps: S1. Add 150 mL of deionized water to a container containing 5 g of sodium alginate and stir to obtain a sodium alginate solution; S2, dissolving 20 g of chitosan in 50 mL of acetic acid solution, then adding 5 g of dopamine, stirring, then adding 4 mL of glutaraldehyde and 5 g of NN-hydroxysuccinimide, cross-linking reaction, to obtain modified chitosan, adding the modified chitosan to the sodium alginate solution, stirring, to obtain a mixed solution; S3, adding 10 mL of 8% sodium hydroxide solution to the mixed solution, stirring to obtain a pre-gel, then injecting the pre-gel into a mold, adding 20 mL of 10% calcium chloride solution for gelation, then eluting, freezing, and drying to obtain a preliminary gel film; S4, immersing the preliminary gel membrane in a 20 mg / mL lipase solution, and then washing and drying to obtain a modified gel membrane.

[0026] Comparative Example 1 A composite membrane for extracting coffee concentrate, the composite membrane comprising an upper and lower layer, the lower layer being a ceramic membrane, and the upper layer being a modified gel membrane; The preparation method of the modified gel film comprises the following steps: S1. Add 120 mL of deionized water to a container containing 2 g of sodium alginate and stir to obtain a sodium alginate solution; S2, dissolving 10 g of chitosan in 20 mL of acetic acid solution, then adding 3 g of dopamine, stirring, then adding 3 mL of glutaraldehyde and 3 g of NN-hydroxysuccinimide, cross-linking reaction to obtain modified chitosan, adding the modified chitosan to the sodium alginate solution, stirring to obtain a mixed solution; S3, adding 10 mL of 6% sodium hydroxide solution to the mixed solution, stirring to obtain a pre-gel, then injecting the pre-gel into a mold, adding 20 mL of 8% calcium chloride solution for gelation, then eluting, freezing, and drying to obtain a preliminary gel film; S4, immersing the preliminary gel membrane in a 10 mg / mL lipase solution, and then washing and drying to obtain a modified gel membrane.

[0027] Compared with Example 1, the ceramic membrane in Comparative Example 1 is not modified.

[0028] Comparative Example 2 A composite membrane for extracting coffee concentrate, the composite membrane comprising an upper and lower layer, the lower layer being a modified ceramic membrane, and the upper layer being a modified gel membrane; The preparation method of the modified ceramic membrane comprises the following steps: placing 2 g of the aminated ceramic membrane in a reaction container containing 5 mL of dimethylformamide and 0.3 g of succinic anhydride, adding 0.1 mL of phosphoric acid, heating for reaction, washing and drying after the reaction, and obtaining the modified ceramic membrane; The preparation method of the modified gel film comprises the following steps: S1. Add 120 mL of deionized water to a container containing 2 g of sodium alginate and stir to obtain a sodium alginate solution; S2, adding chitosan to the sodium alginate solution, stirring to obtain a mixed solution; S3, adding 10 mL of 6% sodium hydroxide solution to the mixed solution, stirring to obtain a pre-gel, then injecting the pre-gel into a mold, adding 20 mL of 8% calcium chloride solution for gelation, then eluting, freezing, and drying to obtain a preliminary gel film; S4, immersing the preliminary gel membrane in a 10 mg / mL lipase solution, and then washing and drying to obtain a modified gel membrane.

[0029] Comparative Example 2 Compared with Example 1, chitosan was not modified.

[0030] Comparative Example 3 A composite membrane for extracting coffee concentrate, the composite membrane comprising an upper and lower layer, the lower layer being a modified ceramic membrane and the upper layer being a gel membrane; The preparation method of the modified ceramic membrane comprises the following steps: placing 2 g of the aminated ceramic membrane in a reaction container containing 5 mL of dimethylformamide and 0.3 g of succinic anhydride, adding 0.1 mL of phosphoric acid, heating for reaction, washing and drying after the reaction, and obtaining the modified ceramic membrane; The preparation method of the gel film comprises the following steps: S1. Add 120 mL of deionized water to a container containing 2 g of sodium alginate and stir to obtain a sodium alginate solution; S2, dissolving 10 g of chitosan in 20 mL of acetic acid solution, then adding 3 g of dopamine, stirring, then adding 3 mL of glutaraldehyde and 3 g of NN-hydroxysuccinimide, cross-linking reaction to obtain modified chitosan, adding the modified chitosan to the sodium alginate solution, stirring to obtain a mixed solution; S3, adding 10mL of 6% sodium hydroxide solution to the mixed solution, stirring to obtain a pre-gel, then injecting the pre-gel into a mold, adding 20mL of 8% calcium chloride solution to gel, then eluting, freezing, and drying to obtain a gel film.

[0031] Comparative Example 3 Compared with Example 1, the gel film did not chelate lipase.

[0032] Test methods and results Fresh coffee beans were ground into medium to coarse sand. The composite membranes prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were placed on coffee filter baskets using gauze to grind the coffee beans. Boiling water was passed through the coffee beans. After waiting for 10 minutes, coffee concentrate was obtained.

[0033] A sensory evaluation panel of 20 professionals, including professional perfumers and professionals, conducted a sensory evaluation of the aroma and flavor of the coffee concentrate, and selected the coffee concentrate with better aroma and flavor through sensory scoring. The specific sensory evaluation criteria are shown in Table 1.

[0034] Table 1 Sensory evaluation criteria

[0035] The sensory evaluation results and extraction rate results are shown in Table 2.

[0036] Table 2 Sensory evaluation results and extraction rate

[0037] It can be seen from the results in Table 2 that, compared with Comparative Examples 1 to 3, the coffee concentrate extracted by the composite membrane prepared by Examples 1 to 3 of the present invention has a higher extraction rate, a higher sensory score, and a better flavor.

[0038] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, some modifications and improvements can be made to the present invention. Therefore, any modification or improvement made without departing from the spirit of the present invention belongs to the scope of protection claimed in the present invention.

Claims

1. A composite membrane for extracting coffee concentrate, characterized in that: The composite membrane comprises an upper and lower layer, wherein the lower layer is a modified ceramic membrane and the upper layer is a modified gel membrane; The ceramic membrane is treated with ammonia atmosphere by plasma technology to make it amination, and then placed in a reaction container filled with dimethylformamide and succinic anhydride, phosphoric acid as a catalyst is added, heated to react, and washed and dried after the reaction is completed to obtain a modified ceramic membrane; The preparation method of the modified gel film comprises the following steps: S1. Add deionized water into a container containing sodium alginate and stir to obtain a sodium alginate solution; S2, dissolving chitosan in an acetic acid solution, then adding dopamine, stirring, then adding glutaraldehyde and NN-hydroxysuccinimide, cross-linking reaction, obtaining modified chitosan, adding the modified chitosan to a sodium alginate solution, stirring, and obtaining a mixed solution; S3, adding sodium hydroxide solution to the mixed solution, stirring to obtain a pre-gel, then injecting the pre-gel into a mold, adding calcium chloride solution for gelation, then eluting, freezing, and drying to obtain a preliminary gel film; S4, immersing the preliminary gel membrane in a lipase solution, and then washing and drying to obtain a modified gel membrane.

2. The composite membrane for extracting coffee concentrate according to claim 1, characterized in that: The heating temperature is 40-50°C.

3. The composite membrane for extracting coffee concentrate according to claim 1, characterized in that: The ceramic film includes an aluminum oxide film, a zirconium oxide film, a titanium oxide film or a silicon oxide film.

4. The composite membrane for extracting coffee concentrate according to claim 1, characterized in that: The pore size of the modified ceramic membrane is 0.5-20 μm.

5. The composite membrane for extracting coffee concentrate according to claim 1, characterized in that: The usage ratio of the ceramic membrane, dimethylformamide, succinic anhydride and phosphoric acid is (1-3 g): (3-10 mL): (0.2-0.4 g): (0.01-0.5 mL).

6. The composite membrane for extracting coffee concentrate according to claim 1, characterized in that: In step S1, the dosage ratio of sodium alginate and deionized water is (1-5 g): (100-150 mL); In step S2, the amount ratio of chitosan, acetic acid, dopamine, glutaraldehyde and NN-hydroxysuccinimide is (5-20 g): (10-50 mL): (2-5 g): (2-4 mL): (1-5 g); The mass ratio of sodium alginate to chitosan is (1-2): (15-25).

7. The composite membrane for extracting coffee concentrate according to claim 1, characterized in that: In step S3, the mass fraction of the sodium hydroxide solution is 4% to 8%, and the mass fraction of the calcium chloride solution is 3% to 10%; In step S4, the mass concentration of the lipase solution is 1-20 mg / mL.

8. Use of the composite film according to any one of claims 1 to 7, characterized in that: Used in the extraction and separation of coffee concentrate.

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