White tea phenolic substance concentration and component optimization treatment process

Abstract

The invention relates to the field of food science and natural product extraction, and discloses a white tea phenolic substance concentration and component optimization treatment process, which adopts ultrafiltration and OSN membrane technologies to effectively separate pigment, caffeine and other substances from tea polyphenol and improve the product purity, and meanwhile, compared with a traditional evaporation concentration method, a double-membrane technology is carried out at low temperature, so that the product quality is improved. Loss of heat-sensitive effective components is effectively avoided, higher-multiple concentration is realized, and subsequent operation is facilitated; and the concentrated solution after concentration is subjected to resin adsorption and ethanol gradient elution, and the product is further purified, so that the purity of the finally produced white tea polyphenol substances can reach 95% or above under the condition of avoiding the loss of heat-sensitive and oxidizing components.

Description

Technical Field

[0001] The invention belongs to the fields of food science and natural product extraction, and particularly relates to a process for concentrating white tea phenols and optimizing their components. Background Art

[0002] As one of the six traditional Chinese teas, white tea has a unique processing technology and rich biological activity. The tender buds or the newly unfolded buds and leaves are made through simple processes such as natural withering and drying, which retains the original polyphenols in the tea (such as catechins, flavonoids, phenolic acids, etc.) to the greatest extent. These phenols have significant antioxidant, anti-inflammatory, antibacterial, anti-cancer and lipid-regulating physiological functions, making them of great value in the development of health products.

[0003] In recent years, with increasing consumer demand for natural plant extracts, white tea extracts, particularly those rich in phenolic compounds, have become a hot topic in the market. However, conventional water or alcohol extraction methods, while simple to operate, are not highly selective for the target phenolic compounds and are often accompanied by the dissolution of large amounts of impurities, resulting in low extraction efficiency. Some phenolic compounds are heat-sensitive and easily degrade during conventional evaporation and concentration processes, leading to loss of active ingredients. Furthermore, the wide variety of phenolic compounds with diverse structures makes them prone to oxidative polymerization during storage and use, resulting in low stability. Summary of the Invention

[0004] In response to the problems of low extraction efficiency, large loss of heat-sensitive active ingredients and high production energy consumption in the prior art of water extraction or alcohol extraction mentioned in the above background technology, the present invention provides a process for concentrating and optimizing the components of white tea polyphenols, which introduces ultrafiltration plus organic solvent nanofiltration membrane technology to concentrate white tea polyphenols and significantly improve the extraction efficiency; membrane separation is a low-temperature operation, which can avoid the loss of heat-sensitive active ingredients caused by high-temperature distillation and reduce energy consumption; resin adsorption plus ethanol gradient elution is used to significantly improve the purity of tea polyphenols, increase the retention rate of catechins, and enhance biological activity.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A process for concentrating and optimizing the composition of white tea polyphenols comprises the following steps:

[0007] 1) Crush the white tea leaves, extract with hot water 3-5 times, combine the extracts, cool the extracts, extract with a stripping agent, and collect the supernatant to obtain a stripping solution;

[0008] 2) acidifying the stripping solution obtained in step 1) and extracting with the extract solution, separating the organic phase to obtain an extract solution;

[0009] 3) ultrafiltration of the extract obtained in step 2) followed by organic solvent nanofiltration (OSN) to obtain a concentrate;

[0010] 4) The concentrated solution obtained in step 3) is sequentially subjected to resin adsorption, ethanol gradient elution, and spray drying to obtain white tea phenols.

[0011] The present invention adopts ultrafiltration plus OSN membrane technology to effectively separate pigments, caffeine and other substances from tea polyphenols, thereby improving the purity of the product. At the same time, compared with the traditional evaporation concentration method, the double membrane technology is carried out at a low temperature, which effectively avoids the loss of heat-sensitive effective ingredients and achieves a higher multiple of concentration, which is convenient for subsequent operations; the concentrated liquid is subjected to resin adsorption and ethanol gradient elution to further purify the product. While avoiding the loss of heat-sensitive and oxidizing components, it can ensure that the purity of the white tea polyphenols finally produced reaches more than 95%.

[0012] Furthermore, in step 1), the temperature of the hot water is 80-95°C.

[0013] Preferably, in step 1), hot water extraction is performed with the assistance of ultrasound / microwave to improve the extraction rate of white tea polyphenols.

[0014] Furthermore, in step 1), the stripping agent is one of chloroform and benzene.

[0015] Furthermore, in step 2), the extractant is one of ethyl acetate, methanol, and acetone.

[0016] Preferably, the extraction process is repeated 2 to 3 times.

[0017] Furthermore, in step 2), the pH of the stripping solution after acidification is 3-4.

[0018] Furthermore, in step 3), the pore size of the ultrafiltration membrane is 0.01 to 0.1 μm.

[0019] Furthermore, in step 3), the ultrafiltration membrane is a ceramic membrane or a hollow fiber membrane.

[0020] Furthermore, in step 3), the organic solvent nanofiltration membrane is a polybenzimidazole membrane or a polyetheretherketone membrane.

[0021] Furthermore, in step 3), the pore size of the organic solvent nanofiltration membrane is 1 to 10 nm.

[0022] Furthermore, in step 4), the resin is one of D101 resin, BYX resin, and DM-16X resin.

[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1) The present invention improves the purity and yield of white tea phenols by ultrafiltration plus OSN membrane technology. At the same time, the concentration operation carried out at low temperature effectively reduces the degradation of heat-sensitive active ingredients, thereby improving the performance of the product.

[0025] 2) The present invention purifies the concentrated solution by sequentially subjecting it to resin adsorption and gradient elution, so that the purity of the final white tea polyphenol product produced is above 95%, while ensuring the mildness of the purification process, reducing the loss of heat-sensitive and oxidative components, and improving the biological activity of the product.

[0026] 3) The process adopted by the present invention can greatly reduce energy consumption, while reducing the use of harmful solvents and reducing the risk of environmental pollution. DETAILED DESCRIPTION

[0027] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0028] Example 1

[0029] 1) Hot water extraction

[0030] Fresh white tea leaves were ground into powder, 5 g of the powdered white tea leaves were weighed, and they were extracted with 100 ml of hot water at 85°C for 30 min, and extracted 5 times. The extraction process was assisted by ultrasound. All the extracts were combined, the temperature was lowered to 20°C, and mixed with chloroform in a volume ratio of 1:1. After being fully stirred for 10 min, the mixture was allowed to stand and separate into layers, and the aqueous phase was taken to obtain a back extract.

[0031] 2) Extraction

[0032] The pH of the back extract obtained in step 1) was adjusted to 3.5 with hydrochloric acid, and then mixed with ethyl acetate in a volume ratio of 1:1 for extraction. After sufficient stirring for 5 minutes, the mixture was allowed to stand and separate. The extraction was repeated twice, and all organic phases were mixed to obtain an extract.

[0033] 3) Concentration

[0034] The extract obtained in step 2) is ultrafiltered through a ceramic membrane with a pore size of 0.05 μm at 20° C. and 0.2 MPa. Larger molecules such as proteins and other impurities are throttled, while smaller white tea polyphenols pass through the membrane to form a clear permeate. The extract is then passed through a polybenzimidazole membrane with a pore size of 5 nm at 20° C. and 1.5 MPa to further remove impurities and concentrate the white tea polyphenols to obtain a concentrated solution.

[0035] 4) Purification

[0036] The concentrated solution obtained in step 3) is flowed into an adsorption column filled with BYX resin. The concentrated solution passes through the resin layer at a rate of 6 BV / h. Non-polyphenolic substances are discharged from the system along with the mobile phase. After the resin adsorption is completed, elution is performed with a 70% ethanol solution which is gradually increased to 80% to remove the adsorbed polyphenolic substances. The eluate is spray-dried to obtain white tea polyphenols.

[0037] 5) Performance testing

[0038] The white tea polyphenols obtained in step 4) were subjected to purity testing and extraction rate testing. The extraction rate of the white tea polyphenols in this embodiment was 81.6%.

[0039] Comparative Example 1

[0040] The only difference between this comparative example and Example 1 is that the extract is not subjected to ultrafiltration in this comparative example, and the rest of the process is the same as that of Example 1.

[0041] Comparative Example 2

[0042] The only difference between this comparative example and Example 1 is that in this comparative example, the extract is not subjected to organic solvent nanofiltration, and the rest of the process is the same as in Example 1.

[0043] Table 1 Effect of concentration process on the purity and extraction rate of white tea polyphenols

[0044] Whether to perform ultrafiltration Whether to perform organic solvent nanofiltration Product purity Example 1 yes yes 96％ Comparative Example 1 no yes 85％ Comparative Example 2 yes no 90％

[0045] From the data in Table 1, it can be concluded that if the extract is not subjected to ultrafiltration or organic solvent nanofiltration during the concentration process, the purity of the final white tea polyphenols will decrease. The presumed reasons are: ultrafiltration can effectively remove large molecular impurities, ensuring that a purer target product can be obtained in the subsequent organic solvent nanofiltration process; organic solvent nanofiltration can further remove small molecular impurities and concentrate the target components, further improving the purity of the product.

[0046] Example 2

[0047] 1) Hot water extraction

[0048] Grind fresh white tea leaves into powder, weigh 5 g of the powdered white tea leaves, and extract them with 100 ml of hot water at 85°C for 30 minutes. Extract them 5 times, combine all the extracts, lower the temperature to 20°C, and mix them with chloroform in a volume ratio of 1:1. After fully stirring for 10 minutes, let it stand to separate the layers, and take the aqueous phase to obtain the back extract.

[0049] 2) Extraction

[0050] The pH of the back extract obtained in step 1) was adjusted to 4 with hydrochloric acid, and then mixed with acetone at a volume ratio of 1:1 for extraction. After sufficient stirring for 5 minutes, the mixture was allowed to stand and separate, and all organic phases were mixed to obtain an extract.

[0051] 3) Concentration

[0052] The extract obtained in step 2) is ultrafiltered through a ceramic membrane with a pore size of 0.05 μm at 20° C. and 0.2 MPa. Larger molecules such as proteins and other impurities are throttled, while smaller white tea polyphenols pass through the membrane to form a clear permeate. The extract is then passed through a polybenzimidazole membrane with a pore size of 5 nm at 20° C. and 1.5 MPa to further remove impurities and concentrate the white tea polyphenols to obtain a concentrated solution.

[0053] 4) Purification

[0054] The concentrated solution obtained in step 3) is flowed into an adsorption column filled with BYX resin. The concentrated solution passes through the resin layer at a rate of 6 BV / h. Non-polyphenolic substances are discharged from the system along with the mobile phase. After the resin adsorption is completed, elution is performed with a 70% ethanol solution which is gradually increased to 80% to remove the adsorbed polyphenolic substances. The eluate is spray-dried to obtain white tea polyphenols.

[0055] 5) Performance testing

[0056] The white tea polyphenols obtained in step 4) are subjected to purity testing and extraction rate testing.

[0057] Unless otherwise specified, the raw materials and equipment used in the present invention are commonly used in the art; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0058] The above-described embodiments merely represent specific implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of protection of the present application. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the technical concept of the present application, and all such variations and improvements fall within the scope of protection of the present application.

Claims

1. A process for concentrating and optimizing the composition of white tea phenols, characterized in that: The following steps are involved: 1) Crush the white tea leaves, extract with hot water 3-5 times, combine the extracts, cool the extracts, extract with a stripping agent, and collect the supernatant to obtain a stripping solution; 2) acidifying the stripping solution obtained in step 1) and extracting with the extract solution, separating the organic phase to obtain an extract solution; 3) ultrafiltration of the extract obtained in step 2) followed by nanofiltration with an organic solvent to obtain a concentrate; 4) The concentrated solution obtained in step 3) is sequentially subjected to resin adsorption, ethanol gradient elution, and spray drying to obtain white tea phenols.

2. The process for concentrating and optimizing the composition of white tea phenols according to claim 1, wherein: In step 1), the temperature of the hot water is 80-95°C.

3. The process for concentrating and optimizing the composition of white tea phenols according to claim 2, wherein: In step 1), the stripping agent is one of chloroform and benzene.

4. The process for concentrating and optimizing the composition of white tea phenols according to claim 1, wherein: In step 2), the extractant is one of ethyl acetate, methanol and acetone.

5. A process for concentrating and optimizing the composition of white tea phenols according to claim 1 or 4, characterized in that: In step 2), the pH of the stripping solution after acidification is 3-4.

6. The process for concentrating and optimizing the composition of white tea phenols according to claim 1, wherein: In step 3), the pore size of the ultrafiltration membrane is 0.01 to 0.1 μm.

7. The process for concentrating and optimizing the composition of white tea phenols according to claim 6, characterized in that: In step 3), the ultrafiltration membrane is a ceramic membrane or a hollow fiber membrane.

8. A process for concentrating and optimizing the composition of white tea phenols according to claim 6 or 7, characterized in that: In step 3), the organic solvent nanofiltration membrane is a polybenzimidazole membrane or a polyetheretherketone membrane.

9. The process for concentrating and optimizing the composition of white tea phenols according to claim 1, wherein: In step 3), the pore size of the organic solvent nanofiltration membrane is 1 to 10 nm.

10. The process for concentrating and optimizing the composition of white tea phenols according to claim 1, characterized in that: In step 4), the resin is one of D101 resin, BYX resin, and DM-16X resin.