Pretreatment method for sweet tea leaf extraction

Abstract

The invention belongs to the technical field of sweet tea extraction, and particularly relates to a pretreatment method for sweet tea leaf extraction. According to the sweet tea leaves, fatty acid in cell membranes in the sweet tea leaves can be effectively changed by utilizing low temperature, so that the texture of the cell membranes is hardened, the toughness of cell walls is reduced, gaps in the leaves are expanded by utilizing high pressure, and impurities in the leaves are removed; the method has the advantages that gaps in the sweet tea leaves can be effectively expanded by the aid of early-stage low-temperature and high-pressure effects, complete infiltration of dilute sulphuric acid can be guaranteed, accordingly, the sweet tea leaves can be sufficiently in contact with internal alkaloids and the like to form soluble salts, the soluble salts can be removed, impurities such as tannin can be effectively removed by the aid of treatment agents, and the treated sweet tea leaves are high in quality and excellent in quality. And effective placement can be performed for subsequent use, so that the subsequent extraction efficiency and the extraction quality are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sweet tea extraction, and in particular relates to a pretreatment method for sweet tea leaf extraction. Background Art

[0002] Lilhocarpus Polyst achys Rehd Tea, with the Latin name of Lilhocarpus Polyst achys Rehd Tea, belongs to the Fagaceae family, the evergreen plant of the genus Lith oearpus, and is commonly known as sweet tea or sweet tea. It is widely distributed in the Guizhou Plateau and has a huge resource reserve.

[0003] The tea tastes sweet and refreshing. It not only promotes the production of body fluids and quenches thirst, but also has good pharmacological effects and health functions for the human body. According to the records in the "Chinese Materia Medica" and related literature, "It can prevent and treat high blood pressure, treat damp-heat dysentery, itchy skin, carbuncle, malignant ulcers and other symptoms. It also has the functions of nourishing the liver, kidneys, stomach, relieving adverse reactions, moistening the lungs and relieving coughs, and relieving fatigue and sobering up. The "Compendium of Materia Medica" records: "It has a sweet and flat smell", "non-toxic, treats hemorrhoids, stops bleeding and bloody dysentery, quenches thirst, promotes blood circulation, and promotes urination". It is not difficult to see that sweet tea is beneficial to the human body without any harm.

[0004] The sweet ingredients in sweet tea are mainly phlorizin-1, trilobation-2, and 3-hydroxy phlorizin-3. Among them, trilobation-2 has the highest content. Currently, there are many studies on its extraction in existing technologies.

[0005] For example, CN201510187280.6 discloses a method for separating and preparing phloridzin monomers of Polyspicate, CN201810780192.0 discloses a method for extracting phloridzin from Polyspicate leaves, and CN202010692211.1 discloses a method for separating trifoliatin and phloridzin from Zhijiang wild sweet tea. The current prior art pre-treatment is crushing and then direct extraction, which results in a large number of impurities and causes trouble in subsequent treatment, reducing the purity and yield of the extraction. Therefore, there is an urgent need for a pre-treatment method for sweet tea leaf extraction. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for effectively pre-treating sweet tea leaves, reducing subsequent treatment methods, and improving the yield and content of sweet tea products.

[0007] The technical solution adopted by the present invention to solve the technical problem is as follows: A pretreatment method for extracting sweet tea leaves, the method comprising the following steps: (1) Place the sweet tea leaves at low temperature overnight to process the sweet tea leaves in one step; (2) placing the first-step processed sweet tea leaves under high pressure to obtain the second-step processed sweet tea leaves; (3) Soak the sweet tea leaves treated in the second step in dilute sulfuric acid, keep the temperature at -3 to -1°C, then add the treatment agent, mix well, and let it stand; (4) After the standing period is over, the tea leaves are filtered to obtain the three-step processed sweet tea leaves, and then washed and dried to complete the pretreatment of the sweet tea leaves.

[0008] Preferably, the low temperature in step (1) is -5 to 0°C.

[0009] Preferably, in step (2), the high pressure is 0.2-0.4 mPa, and the standing time is 15-20 min.

[0010] Preferably, the concentration of the dilute sulfuric acid in step (3) is a sulfuric acid solution with a mass fraction of 10%.

[0011] Preferably, the treatment agent in step (4) is any one of potassium aluminum sulfate dodecahydrate and ferrous sulfate, and the amount of the treatment agent added is 10-15% of the mass of the sweet tea leaves treated in the second step.

[0012] The principle of the pretreatment method of the present invention is as follows: by utilizing low temperature, the fatty acids in the cell membrane of the sweet tea leaves can be effectively changed, thereby hardening the texture of the cell membrane and reducing the toughness of the cell wall; high pressure is then used to expand the gaps in the leaves and remove the internal impurities; the early low temperature and high pressure can effectively expand the gaps inside the sweet tea leaves, ensuring complete infiltration of dilute sulfuric acid, and then fully contacting with the internal alkaloids to form soluble salts for removal; finally, a treating agent can be used to effectively remove impurities such as tannins; at the same time, the treated sweet tea leaves can be effectively placed for subsequent use, thereby improving subsequent extraction efficiency and extraction quality.

[0013] The beneficial effects of the method of the present invention are as follows: (1) After the sweet tea leaves are extracted by the pretreatment method of the present invention, the extraction rate of trilobatin is increased to more than 99%; the extraction rate of phlorizin obtained by the method of the present invention is as high as more than 98%. That is, the purity and yield of the two products are guaranteed and improved.

[0014] (2) The pretreatment method of the present invention can effectively reduce the subsequent treatment methods, so that the yield and content of trilobatin and phlorizin are high, the operability is strong, and it is suitable for industrial production. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, it should be understood that the embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications or replacements all fall within the protection scope of the present invention. Example 1

[0016] A pretreatment method for extracting sweet tea leaves, the method comprising the following steps: (1) Place the sweet tea leaves at -5°C for 24 hours to process the sweet tea leaves in one step; (2) placing the first-step processed sweet tea leaves at 0.2 mPa for 15 min to obtain the second-step processed sweet tea leaves; (3) Soak the two-step treated sweet tea leaves in a 10% sulfuric acid solution, keep the temperature at -3°C, add potassium aluminum sulfate dodecahydrate, the amount of the treatment agent added is 10% of the mass of the two-step treated sweet tea leaves, mix well, and let stand for 4 hours; (4) After the standing period is over, the tea leaves are filtered to obtain the three-step processed sweet tea leaves, and then washed and dried to complete the pretreatment of the sweet tea leaves. Example 2

[0017] A pretreatment method for extracting sweet tea leaves, the method comprising the following steps: (1) Place the sweet tea leaves at -3°C for 24 hours to process the sweet tea leaves in one step; (2) placing the first-step processed sweet tea leaves at 0.3 mPa for 18 min to obtain the second-step processed sweet tea leaves; (3) Soak the two-step treated sweet tea leaves in a 10% sulfuric acid solution, keep the temperature at -2°C, add potassium aluminum sulfate dodecahydrate, the amount of the treatment agent added is 13% of the mass of the two-step treated sweet tea leaves, mix well, and let stand for 4 hours; (4) After the standing period is over, the tea leaves are filtered to obtain the three-step processed sweet tea leaves, and then washed and dried to complete the pretreatment of the sweet tea leaves. Example 3

[0018] A pretreatment method for extracting sweet tea leaves, the method comprising the following steps: (1) Place the sweet tea leaves at 0°C for 24 hours to process the sweet tea leaves in one step; (2) placing the first-step processed sweet tea leaves at 0.4 mPa for 20 min to obtain the second-step processed sweet tea leaves; (3) Soak the two-step treated sweet tea leaves in a 10% sulfuric acid solution, keep the temperature at -1°C, add ferrous sulfate, the amount of the treatment agent is 15% of the mass of the two-step treated sweet tea leaves, mix well, and let stand for 4 hours; (4) After the standing period is over, the tea leaves are filtered to obtain the three-step processed sweet tea leaves, and then washed and dried to complete the pretreatment of the sweet tea leaves. Example 4

[0019] The process is basically the same as Example 2, except that the temperature in step (1) is -6°C. Example 5

[0020] The process is basically the same as Example 2, except that the temperature in step (1) is 1°C. Example 6

[0021] The process is basically the same as that of Example 2, except that the pressure in step (2) is 0.19 mPa. Example 7

[0022] The process is basically the same as that of Example 2, except that the pressure in step (2) is 0.41 mPa. Example 8

[0023] The method is basically the same as Example 2, with the only difference being that there is no treatment agent or dilute sulfuric acid in step (3). Example 9

[0024] Take 200g of sweet tea leaves, crush them to a particle size of 3mm, put them into an extraction tank, extract them twice with hot water at a temperature of 100°C, filter them to obtain an extract, cool the extract to room temperature, flocculate it with a flocculant, centrifuge it, filter it, and obtain a filtrate; pass the filtrate through a macroporous adsorption resin column for adsorption, elute, and obtain an eluate.

[0025] Examples 10 to 17 It is basically the same as Example 9, the only difference being that the sweet tea leaves are the pretreated sweet tea leaves prepared in Examples 1 to 8.

[0026] The eluents obtained in Examples 9 to 17 were tested by high performance liquid chromatography (HPLC) external standard method to detect the extraction rate and purity of trilobatin and phlorizin. The results are as follows: In summary, after the pretreated sweet tea leaves of the present invention are extracted, the extraction rate of trilobatin will be increased to more than 99%; the extraction rate of phlorizin obtained according to the method of the present invention is as high as more than 98%. That is, the purity and yield of the two products are guaranteed and improved. The pretreatment method of the present invention can effectively reduce the subsequent treatment method, so that trilobatin and phlorizin have high yields and high contents, strong operability, and are suitable for industrial production.

Claims

1. A pretreatment method for extracting sweet tea leaves, characterized in that: The method comprises the following steps: (1) Place the sweet tea leaves at low temperature overnight to process the sweet tea leaves in one step; (2) placing the primary treatment under high pressure to obtain the second step treatment sweet tea leaves; (3) Soak the sweet tea leaves treated in the second step in dilute sulfuric acid, keep the temperature at -3 to -1°C, then add the treatment agent, mix well, and let it stand; (4) After the standing period is over, the tea leaves are filtered to obtain the three-step processed sweet tea leaves, and then washed and dried to complete the pretreatment of the sweet tea leaves.

2. The pretreatment method for extracting sweet tea leaves according to claim 1, characterized in that: The low temperature in step (1) is -5 to 0°C.

3. The pretreatment method for extracting sweet tea leaves according to claim 2, characterized in that: In the step (2), the high pressure is 0.2-0.4 mPa, and the standing time is 15-20 min.

4. The pretreatment method for extracting sweet tea leaves according to claim 3, characterized in that: The concentration of the dilute sulfuric acid in step (3) is a sulfuric acid solution with a mass fraction of 10%.

5. The pretreatment method for extracting sweet tea leaves according to claim 4, characterized in that: In the step (4), the treatment agent is any one of potassium aluminum sulfate dodecahydrate and ferrous sulfate, and the amount of the treatment agent added is 10-15% of the mass of the sweet tea leaves treated in the second step.