Method for preparing spice by taking green tea as raw material

Abstract

The invention provides a method for preparing spice by using green tea as a raw material, which comprises the following steps: 1) green tea pretreatment: firstly crushing the green tea raw material, and then soaking the green tea in hot water; 2) performing enzymolysis-ultrasonic treatment: adding a compound enzyme composed of cellulase and pectinase into the pretreated green tea, performing enzymolysis treatment, performing ultrasonic treatment after enzyme deactivation, and filtering to obtain an enzymatic hydrolysate; 3) mixed fermentation: inoculating aspergillus niger and candida utilis into the enzymatic hydrolysate for liquid fermentation, sterilizing and filtering to obtain a crude extract; 4) distilling and concentrating: distilling and concentrating the crude extract to obtain a concentrated green tea extract; the green tea extract, the flavor enhancer and the solvent are mixed and subjected to vacuum drying, and the spice is obtained.The preparation method has the advantages that caffeine is efficiently removed, the spice is heavy in bitter taste and low in aroma quality, the preparation method is suitable for the fields of food, beverages, cosmetics and the like, the quality of the green tea spice is improved, and the application range of the green tea spice is widened.

Description

Technical Field

[0001] The present invention belongs to the technical field of spice preparation, and specifically relates to a method for preparing spices using green tea as a raw material. Background Art

[0002] Green tea spice is a natural spice widely used in the fields of food, beverages, cosmetics, etc. Green tea spice can not only endow products with a unique fresh aroma, but also has certain antioxidant and antibacterial functions. Therefore, it has broad application prospects in products such as food additives, perfumes, and skin care products.

[0003] The main components of green tea spice include tea polyphenols, caffeine, aromatic hydrocarbon compounds, etc. Among them, aromatic hydrocarbon compounds are the main components that endow green tea with a unique aroma. There are mainly two methods for preparing green tea spice. The first method is solvent extraction. Its principle is based on the fact that the solubility of caffeine in organic solvents (such as ethanol, ethyl acetate, etc.) is higher than that in water. By contacting green tea with organic solvents, caffeine will transfer from the tea leaves to the solvent, thus achieving separation. However, some aroma components may be lost during the extraction process, affecting the aroma quality of the spice. The second method is supercritical carbon dioxide extraction, a technology that uses carbon dioxide (CO2) in a supercritical state as a solvent to extract and remove caffeine from green tea. Its principle is based on the special physical and chemical properties of supercritical CO2. At a certain temperature and pressure, CO2 reaches the supercritical state, having both the high diffusivity of a gas and the high solubility of a liquid. Utilizing the high permeability and selectivity of supercritical carbon dioxide, caffeine in green tea is dissolved in supercritical carbon dioxide and then separated. This method has high equipment costs, requires precise control of temperature and pressure, has high requirements for operating technology, and has limited extraction efficiency for aroma components, making it difficult to be applied on a large scale.

[0004] CN115433637A discloses a method for preparing green tea spice, including: Step 1, dry heat treatment of green tea raw materials; Step 2: Solvent vapor extraction; Step 3: Fraction collection. By combining dry heat treatment and solvent vapor extraction, this method can effectively extract the aroma components in green tea and recover and enrich the aroma substances through a secondary condensation recovery system. Although this method can extract the aroma components in green tea, due to the caffeine contained in green tea and the boiling point of caffeine being higher than 170°C, during the solvent vapor extraction process, caffeine cannot be effectively removed and enters the fraction, making the prepared spice contain a bitter taste, which in turn affects the flavor and application effect of the spice. Especially in the application in food and beverages, the bitter taste of caffeine may affect the taste of the product and reduce the acceptance of consumers.

[0005] Therefore, there is an urgent need for a method for preparing spices that can effectively remove caffeine from green tea while retaining the aroma components of green tea, so as to improve the quality and application range of green tea spices. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing spices that can efficiently remove caffeine from green tea while retaining the aroma components, so as to solve the problems of heavy bitter taste and low aroma quality in the existing spices. In order to achieve the above purpose, the present invention provides the following technical solutions: A method for preparing spices with green tea as the raw material, comprising the following steps: 1) Pretreatment of green tea: First, crush the green tea raw material, and then soak the green tea with hot water. 2) Enzymolysis-ultrasonic treatment: Add a complex enzyme composed of cellulase and pectinase to the pretreated green tea for enzymolysis treatment. After inactivating the enzyme, perform ultrasonic treatment, and filter to obtain an enzymolysis solution. 3) Mixed fermentation: Inoculate Aspergillus niger and Candida utilis into the enzymolysis solution for liquid fermentation. After sterilization, filter to obtain a crude extract. 4) Distillation and concentration: Distill and concentrate the crude extract to obtain a concentrated green tea extract. 5) Formulation: Mix the green tea extract, flavor enhancer, and solvent, and perform vacuum drying to obtain the spice.

[0007] Further, in the step 1), the particle size of the crushed green tea is 20-40 mesh, the temperature of the hot water is 80-90 °C, and the soaking time is 10 min.

[0008] Further, the temperature of the enzymolysis treatment is 45-55 °C, the enzymolysis time is 2-4 h, the addition amount of the complex enzyme is 0.5-1.5% of the mass of the green tea raw material, and the mass ratio of cellulase to pectinase in the complex enzyme is 2:1.

[0009] Further, the frequency during the ultrasonic treatment is 25-35 kHz, and the treatment time is 40-60 min.

[0010] Further, the specific operation steps of the step 3) are: First, prepare an Aspergillus niger suspension and a Candida utilis suspension, then mix the enzymolysis solution, the Aspergillus niger suspension, and the Candida utilis suspension according to a mass ratio of 100:10:1, adjust the pH to 5.0-6.0, and ferment at 28-30 °C for 24-36 hours; after sterilization, filter to obtain a crude extract.

[0011] Further, the concentration of the Aspergillus niger suspension is 1×10 6 -1×10 7 cfu / mL, and the concentration of the Candida utilis suspension is 1×10 8 -1×109 cfu / mL.

[0012] Furthermore, in step 3), the sterilization temperature is 80° C. and the sterilization time is 10 min.

[0013] Furthermore, the temperature of the distillation and concentration is 60-70°C, and the volume after concentration is 1 / 5-1 / 10 of the original volume.

[0014] Furthermore, the flavoring agent is composed of isobutyric acid vanillin ester, ethyl vanillin 1,2-propylene glycol acetal and vanillin 1,2-propylene glycol acetal in a mass ratio of 1:1:1; the solvent is any one of ethanol or propanol, and the mass ratio of green tea extract, flavoring agent and solvent when mixed is 1:0.1-0.5:10-20.

[0015] Furthermore, the vacuum drying temperature is 85-90° C., the vacuum degree is -0.08 to -0.1 MPa, and the drying time is 3-5 hours.

[0016] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention uses the method of cooperative fermentation of Aspergillus niger and Candida utilis. Aspergillus niger converts caffeine into paraxanthine and theobromine through caffeine demethylase, and Candida utilis further degrades the intermediate products (xanthine and theobromine) into low-activity uric acid through paraxanthine oxidase, thereby reducing the influence of the accumulation of intermediate products on the inhibition of Aspergillus niger activity, improving the degradation efficiency of caffeine, and making the removal rate of caffeine as high as 93%, significantly reducing the bitter taste of spices, and improving the quality and application range of spices; 2. The present invention uses the enzymatic hydrolysis-ultrasonic synergistic technology to use the synergistic action of cellulase and pectinase to destroy the tea cell wall, and ultrasonic-assisted extraction to promote the dissolution of aroma components and caffeine. The combination of the two can effectively enrich the aroma components and significantly improve the aroma intensity and quality of the spices. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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] The preparation methods of the Aspergillus niger suspension and the Candida utilis suspension in the following examples and comparative examples are as follows: Preparation of Aspergillus niger suspension: (1) Activation culture: Prepare PDA medium (4 g / L potato powder, 20 g / L glucose, 15 g / L agar), sterilize at 121°C for 20 minutes. After cooling, streak inoculate Aspergillus niger on the PDA slant medium and culture at 28°C for 5 days until the PDA slant medium is covered with black spores; (2) Aspergillus niger spore suspension: Add 10 mL of sterile normal saline to the cultured Aspergillus niger slant; gently scrape the spores with a sterile inoculation loop and transfer the spores to a sterile Erlenmeyer flask. Add sterile glass beads and shake for 10 min to fully disperse the spores, filter to remove mycelia and impurities, and obtain an Aspergillus niger suspension; measure the concentration with a hemocytometer and adjust it to 1×10 6 -1×10 7 cfu.

[0019] Preparation of Candida utilis spore suspension: (1) Activation culture: Prepare yeast extract peptone dextrose (YPD) agar medium (10 g / L yeast extract, 20 g / L peptone, 20 g / L glucose, 15 g / L agar, pH 6.0 - 6.5), autoclave at 121°C for 20 minutes. After cooling, streak inoculate Candida utilis on the YPD slant medium and culture in a constant temperature incubator at 30°C for 36 h until the slant is covered with milky white colonies; (2) Candida utilis spore suspension: Add 10 mL of sterile normal saline to the cultured Candida utilis slant; gently scrape the spores with a sterile inoculation loop and transfer the spores to a sterile Erlenmeyer flask. Add sterile glass beads and shake for 10 min to fully disperse the spores, filter to remove mycelia and impurities, and obtain an Aspergillus niger suspension; measure the concentration with a hemocytometer and adjust it to 1×10 8 -1×10 9 cfu / mL.

[0020] Example 1 This example provides a method for preparing a spice from green tea, comprising the following steps: 1) Green tea pretreatment: First, crush the green tea raw material to 30 mesh, and then soak the green tea in hot water at 85°C for 10 min; 2) Enzymolysis - ultrasonic treatment: Add a composite enzyme composed of cellulase and pectinase (mass ratio of cellulase to pectinase is 2:1) to the pretreated green tea at 1% of the green tea mass, carry out enzymolysis treatment at 50°C for 3 h, inactivate the enzyme at 80°C for 10 min and then carry out ultrasonic treatment. The frequency during ultrasonic treatment is 30 kHz, the treatment time is 50 min, filter to obtain an enzymolysis solution; 3) Mixed fermentation: First, prepare a concentration of 1×10 7Aspergillus niger spore suspension at cfu / mL and Candida utilis spore suspension at a concentration of 1×10 9 cfu / mL. Then, the enzymolysis solution, Aspergillus niger spore suspension and Candida utilis spore suspension were mixed at a mass ratio of 100:10:1, the pH was adjusted to 5.0 - 6.0, and fermentation was carried out at 30 °C for 30 hours; after sterilization at 80 °C for 10 min, filtration was performed to obtain a crude extract; 4) Distillation and concentration: The crude extract was distilled and concentrated at a temperature of 65 °C, and the volume after concentration was 1 / 8 of the original volume to obtain a concentrated green tea extract; 5) Formulation: The green tea extract, flavor enhancer and ethanol were mixed at a mass ratio of 1:0.3:15. The flavor enhancer was composed of vanillin isobutyrate, ethyl vanillin 1,2 - propanediol acetal and vanillin 1,2 - propanediol acetal at a mass ratio of 1:1:1. Then, vacuum drying was carried out at a temperature of 85 °C and a vacuum degree of - 0.08 to - 0.1 MPa for 4 h to obtain a spice.

[0021] Example 2 This example provides a method for preparing a spice from green tea, including the following steps: 1) Pretreatment of green tea: First, the green tea raw material was crushed to 20 mesh, and then the green tea was soaked in hot water at 80 °C for 10 min; 2) Enzymolysis - ultrasonic treatment: A composite enzyme composed of cellulase and pectinase (the mass ratio of cellulase to pectinase was 2:1) was added to the pretreated green tea at 0.5% of the mass of the green tea. Enzymolysis was carried out at 45 °C for 2 h, and after inactivating the enzyme at 80 °C for 10 min, ultrasonic treatment was carried out. The frequency during ultrasonic treatment was 25 kHz, the treatment time was 40 min, and filtration was performed to obtain an enzymolysis solution; 3) Mixed fermentation: First, prepare Aspergillus niger spore suspension at a concentration of 1×10 6 cfu / mL and Candida utilis spore suspension at a concentration of 1×10 8 cfu / mL. Then, the enzymolysis solution, Aspergillus niger spore suspension and Candida utilis spore suspension were mixed at a mass ratio of 100:10:1, the pH was adjusted to 5.0 - 6.0, and fermentation was carried out at 28 °C for 24 hours; after sterilization at 80 °C for 10 min, filtration was performed to obtain a crude extract; 4) Distillation and concentration: The crude extract was distilled and concentrated at a temperature of 60 °C, and the volume after concentration was 1 / 5 of the original volume to obtain a concentrated green tea extract; 5) Ingredients: Mix green tea extract, flavor enhancer, and ethanol in a mass ratio of 1:0.1:10. The flavor enhancer consists of vanillin isobutyrate, ethyl vanillin 1,2 - propanediol acetal, and vanillin 1,2 - propanediol acetal in a mass ratio of 1:1:1. Then, conduct vacuum drying at a temperature of 85°C and a vacuum degree of -0.08 to -0.1 MPa for 3 hours to obtain the spice.

[0022] Example 3 This example provides a method for preparing a spice using green tea as a raw material, including the following steps: 1) Green tea pretreatment: First, crush the green tea raw material to 40 mesh, and then soak the green tea in hot water at 90°C for 10 minutes. 2) Enzymolysis - ultrasonic treatment: Add a composite enzyme composed of cellulase and pectinase (the mass ratio of cellulase to pectinase is 2:1) to the pretreated green tea at 1.5% of the mass of the green tea. Conduct enzymolysis treatment at 55°C for 4 hours, inactivate the enzyme at 80°C for 10 minutes, and then conduct ultrasonic treatment. The frequency during ultrasonic treatment is 35 kHz, and the treatment time is 60 minutes. Filter to obtain the enzymolysis solution. 3) Mixed fermentation: First, prepare an Aspergillus niger fungal suspension with a concentration of 1×10 7 cfu / mL and a Candida utilis fungal suspension with a concentration of 1×10 8 cfu / mL. Then, mix the enzymolysis solution, Aspergillus niger fungal suspension, and Candida utilis fungal suspension in a mass ratio of 100:10:1, adjust the pH to 5.0 - 6.0, and ferment at 30°C for 36 hours. Sterilize at 80°C for 10 minutes and then filter to obtain the crude extract. 4) Distillation and concentration: Distill and concentrate the crude extract. The temperature of distillation and concentration is 70°C, and the volume after concentration is 1 / 10 of the original volume to obtain the concentrated green tea extract. 5) Ingredients: Mix the green tea extract, flavor enhancer, and ethanol in a mass ratio of 1:0.5:20. The flavor enhancer consists of vanillin isobutyrate, ethyl vanillin 1,2 - propanediol acetal, and vanillin 1,2 - propanediol acetal in a mass ratio of 1:1:1. Then, conduct vacuum drying at a temperature of 85 - 90°C and a vacuum degree of -0.08 to -0.1 MPa for 5 hours to obtain the spice.

[0023] Comparative Example 1 The difference between this comparative example and Example 1 is that no strains are used for mixed fermentation, that is, step 3) is not included, and the obtained enzymolysis solution is directly distilled and concentrated.

[0024] Comparative Example 2 The difference between this comparative example and Example 1 is that only Aspergillus niger single - strain fermentation is used in step 3). The operating steps of this step are: First, prepare a solution with a concentration of 1×107 A Aspergillus niger spore suspension with a concentration of cfu / mL, then the enzymolysis solution, the Aspergillus niger spore suspension and the Candida utilis spore suspension were mixed at a mass ratio of 100:10, the pH was adjusted to 5.0 - 6.0, and fermentation was carried out at 30 °C for 36 hours; after sterilization at 80 °C for 10 min, filtration was performed to obtain a crude extract.

[0025] Comparative Example 3 The difference between this comparative example and Example 1 is that in step 3), only Candida utilis was used for single-strain fermentation. The operation steps of this step were as follows: First, a Candida utilis spore suspension with a concentration of 1×10 8 cfu / mL was prepared, then the enzymolysis solution and the Candida utilis spore suspension were mixed at a mass ratio of 100:1, the pH was adjusted to 5.0 - 6.0, and fermentation was carried out at 30 °C for 36 hours; after sterilization at 80 °C for 10 min, filtration was performed to obtain a crude extract.

[0026] Comparative Example 4 The difference between this comparative example and Example 1 is that enzymatic hydrolysis-ultrasonic treatment was not used, that is, step 2) was not included, and in step 3), the mixed strains were inoculated into the pretreated green tea for mixed fermentation. The specific operation of this step was as follows: First, an Aspergillus niger spore suspension with a concentration of 1×10 7 cfu / mL and a Candida utilis spore suspension with a concentration of 1×10 8 cfu / mL were prepared, then the pretreated green tea, the Aspergillus niger spore suspension and the Candida utilis spore suspension were mixed at a mass ratio of 100:10:1, the pH was adjusted to 5.0 - 6.0, and fermentation was carried out at 30 °C for 36 hours; after sterilization at 80 °C for 10 min, filtration was performed to obtain a crude extract.

[0027] The present invention measured the caffeine content in the green tea raw material and the fragrances prepared in Examples 1 - 3 and Comparative Examples 1 - 4 according to the method in GB / T 8312 - 2013, and sensory evaluation was carried out on the fragrances prepared in Examples 1 - 3 and Comparative Examples 1 - 4. The sensory evaluation was scored by 10 professional perfume evaluators for the aroma and bitterness of the fragrances, with a full score of 10 points. The results are shown in the following table: Table 1 Caffeine content and sensory evaluation results ; After detection, the caffeine content in the green tea raw material is 1.5%. And from the above performance test results, it can be seen that the caffeine content in the spices prepared in Examples 1-3 is all lower than 0.4%, the caffeine removal rate reaches more than 80%, and the highest can reach 93.3%. Moreover, the scores all reach above 9.0. In particular, the comprehensive performance of Example 1 is the most prominent, and the caffeine removal rate can reach 93.3%. This is mainly because by means of the co-fermentation of Aspergillus niger and Candida utilis, based on the complementary and synergistic effects of the metabolic pathways of the two strains, the technical effect of efficiently removing caffeine is achieved, significantly reducing the bitterness and astringency of the spice, and improving the quality and application range of the spice.

[0028] In Comparative Example 1, no bacterial fermentation was used, the caffeine content was high (1.5%), the score was low (7.0 points), and the bitterness and astringency of the spice were obvious. This shows that without the co-fermentation of Aspergillus niger and Candida utilis, the caffeine in the spice cannot be effectively reduced, making the spice show a very obvious bitterness and astringency, greatly reducing the application effect of the spice, and proving that the co-fermentation of Aspergillus niger and Candida utilis has an important impact on the removal effect of the bitterness and astringency of the spice; In Comparative Example 2, only Aspergillus niger was used for fermentation, the caffeine removal rate was relatively low (46.6%), the score was low (8.0 points), and the bitterness and astringency of the spice were relatively obvious. This shows that only using Aspergillus niger for fermentation cannot effectively reduce the caffeine in the spice, because the intermediate products generated during the fermentation of Aspergillus niger will accumulate rapidly during the fermentation process and inhibit the activity of Aspergillus niger, thus reducing the caffeine removal rate, and further making the spice show a relatively obvious bitterness and astringency, proving that only when Aspergillus niger and Candida utilis are co-fermented can caffeine be effectively removed; In Comparative Example 3, only Candida utilis was used for fermentation, the caffeine removal rate was relatively low (33.3%), the score was low (7.8 points), and the bitterness and astringency of the spice were relatively obvious. This shows that only using Candida utilis cannot effectively reduce the caffeine in the spice, and further makes the spice show a relatively obvious bitterness and astringency, also proving that only when Aspergillus niger and Candida utilis are co-fermented can caffeine be effectively removed; In Comparative Example 4, without enzymatic hydrolysis-ultrasonic treatment, although the caffeine content can be effectively reduced, the sensory evaluation score of the spice is low (7.5 points), making the aroma intensity of the spice insufficient, greatly affecting the obviousness of the spice fragrance, proving that enzymatic hydrolysis-ultrasonic treatment has a significant impact on the aroma sensory.

[0029] The above is the preferred implementation manner of the present invention. It should be pointed out that for those of ordinary skill in the art of this technology, without departing from the principle described in the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a spice using green tea as a raw material, characterized in that, It includes the following steps: 1) Pretreatment of green tea: First, crush the green tea raw materials, and then soak the green tea with hot water; 2) Enzymolysis-ultrasonic treatment: Add a composite enzyme composed of cellulase and pectinase to the pretreated green tea for enzymolysis treatment. After inactivating the enzyme, perform ultrasonic treatment and filter to obtain an enzymolysis solution; 3) Mixed fermentation: Inoculate Aspergillus niger and Candida utilis into the enzymolysis solution for liquid fermentation. After sterilization, filter to obtain a crude extract; 4) Distillation and concentration: Distill and concentrate the crude extract to obtain a concentrated green tea extract; 5) Formulation: Mix the green tea extract, flavor enhancer and solvent, and perform vacuum drying to obtain a spice.

2. A method for preparing a spice using green tea as a raw material according to claim 1, characterized in that, In the step 1), the particle size of the crushed green tea is 20-40 mesh, the temperature of the hot water is 80-90 °C, and the soaking time is 10 min.

3. A method for preparing a spice using green tea as a raw material according to claim 1, characterized in that, The temperature of the enzymolysis treatment is 45-55 °C, the enzymolysis time is 2-4 h, the addition amount of the composite enzyme is 0.5-1.5% of the mass of the green tea raw materials, and the mass ratio of cellulase to pectinase in the composite enzyme is 2:

1.

4. A method for preparing a spice from green tea according to claim 1, characterized in that, The frequency during the ultrasonic treatment is 25-35 kHz, and the treatment time is 40-60 min.

5. A method for preparing a spice using green tea as a raw material according to claim 1, characterized in that, The specific operation steps of the step 3) are: First, prepare an Aspergillus niger suspension and a Candida utilis suspension, then mix the enzymolysis solution, Aspergillus niger suspension and Candida utilis suspension according to a mass ratio of 100:10:1, adjust the pH to 5.0-6.0, and ferment at 28-30 °C for 24-36 hours; after sterilization, filter to obtain a crude extract.

6. A method for preparing a spice using green tea as a raw material according to claim 5, characterized in that, The concentration of the Aspergillus niger spore suspension is 1×10 6 -1×10 7 cfu / mL, and the concentration of the Candida utilis spore suspension is 1×10 8 -1×10 9 cfu / mL.

7. A method for preparing a spice from green tea according to claim 1, characterized in that, In the step 3), the temperature during sterilization is 80 °C, and the sterilization time is 10 min.

8. A method for preparing a spice from green tea according to claim 1, characterized in that, The temperature of the distillation and concentration is 60-70 °C, and the volume after concentration is 1 / 5-1 / 10 of the original volume.

9. A method for preparing a spice using green tea as a raw material according to claim 1, characterized in that, The flavor enhancer is composed of isobutyrate vanillin ester, ethyl vanillin 1,2-propanediol acetal and vanillin 1,2-propanediol acetal with a mass ratio of 1:1:1; the solvent is any one of ethanol or propanol, and the mass ratio of the green tea extract, flavor enhancer and solvent during mixing is 1:0.1-0.5:10-20.

10. A method for preparing a spice from green tea according to claim 1, characterized in that, The temperature of the vacuum drying is 85-90 °C, the vacuum degree is -0.08 to -0.1 MPa, and the drying time is 3-5 h.