A method for removing caffeine from tea and its application

Abstract

This invention provides a method and application for removing caffeine from tea leaves; fresh tea leaves are rinsed with water containing Lactobacillus plantarum, centrifuged, fermented, and extracted with acetic acid as an entrainer using supercritical carbon dioxide to obtain decaffeinated tea leaves; the tea leaves prepared by the method provided by this invention have a caffeine content ≤0.05% and an EGCG retention rate ≥95%, exhibiting a high caffeine removal rate and a high EGCG retention rate.

Description

Technical Field

[0001] This invention relates to the field of food technology, and more specifically to a method for removing caffeine from tea leaves and its application. Background Technology

[0002] Tea is a traditional and distinctive agricultural product in my country, containing various active ingredients, such as tea polyphenols, which possess antioxidant, anti-radiation, anti-aging, lipid-lowering, and blood sugar-lowering physiological activities. However, tea contains a relatively high amount of caffeine, approximately 2%-5%. Caffeine stimulates the central nervous system and strengthens muscle contractions. For individuals with neurasthenia, arteriosclerosis, or hypertension, excessive consumption of high-caffeine tea can produce certain side effects. Therefore, removing caffeine from tea and producing low-caffeine tea suitable for specific populations has a broad market prospect.

[0003] Currently, methods such as organic solvent extraction, water extraction, supercritical fluid extraction, enzymatic methods, and adsorption elution are commonly used to remove caffeine from tea leaves. However, these methods still have many drawbacks, such as low caffeine removal rate, significant loss of tea polyphenols, significant loss of tea aroma substances, and unsuitability for processing whole tea leaves.

[0004] Therefore, a new solution for removing caffeine from tea is needed to improve the above problems. Summary of the Invention

[0005] This invention aims to provide a method for removing caffeine from tea leaves and its application, improving upon existing technologies that suffer from low caffeine removal rates, significant loss of tea polyphenols and aroma compounds, and unsuitability for processing whole tea leaves. The invention provides a method with high caffeine removal rates, minimal loss of tea polyphenols and aroma compounds, and is suitable for processing whole tea leaves.

[0006] In a first aspect, the present invention provides a method for removing caffeine from tea leaves, comprising the following steps:

[0007] S1. Rinse fresh tea leaves with water containing Lactobacillus plantarum, centrifuge after rinsing, and spread them out to ferment until the moisture content of the tea leaves is 60-80%; the preservation number of Lactobacillus plantarum is CGMCC1.573.

[0008] S2. The fermented tea leaves are extracted with 1-5% acetic acid as an entrainer by supercritical carbon dioxide to obtain decaffeinated fresh tea leaves.

[0009] Optionally, the concentration of *Lactobacillus plantarum* in the water containing *Lactobacillus plantarum* in step S1 is 1-5 × 10⁻⁶. 6 CFU / mL.

[0010] Optionally, the centrifugation conditions in step S1 are 100-500 rpm for 1-10 min.

[0011] Optionally, the conditions for spreading and fermenting in step S1 are: spreading thickness of 10-30cm, fermentation at 10-40℃ for 10-20h.

[0012] Optionally, the supercritical carbon dioxide extraction process described in step S2 is as follows: extraction is carried out for 1-4 hours at 30-90℃, 15-50MPa pressure, and a carbon dioxide flow rate of 10-100L / h.

[0013] Secondly, the present invention provides the application of decaffeinated tea leaves prepared by the method in the preparation of decaffeinated products.

[0014] Optionally, the product includes tea powder, tea paste, tea liquid, effervescent tablets, and capsules.

[0015] Biological Preservation Information of this Invention

[0016] Lactobacillus plantarum, deposited on September 1, 1968, at the China General Microbiological Culture Collection Center, with accession number CGMCC1.573.

[0017] The beneficial effects of this invention include:

[0018] (1) The method for removing caffeine from tea leaves provided by the present invention uses fresh tea leaves as raw materials. When the whole fresh leaves are spread out for fermentation, the permeability of the leaf tissue is improved under the action of Lactobacillus plantarum, which is conducive to the release of caffeine in the leaves.

[0019] (2) The method for removing caffeine from tea provided by the present invention uses acetic acid as an entrainer in supercritical carbon dioxide extraction. The amount used is small, the volume fraction is small, and the extraction time is shortened. It has good selectivity and high selectivity for extracting caffeine. The retention rate of epigallocatechin gallate (EGCG) in tea is high. The caffeine content in the treated tea is ≤0.05%, and the retention rate of epigallocatechin gallate (EGCG) is ≥95%.

[0020] (3) The method for removing caffeine from tea leaves provided by the present invention first removes caffeine from whole fresh tea leaves, and then processes the decaffeinated fresh leaves into decaffeinated tea leaves by fixing, rolling and drying. The tea leaves have a rich aroma, which solves the problem of weak aroma after supercritical carbon dioxide extraction of finished tea leaves. Detailed Implementation

[0021] The present invention will be further illustrated by the following embodiments.

[0022] In a first aspect, embodiments of the present invention provide a method for removing caffeine from tea leaves, comprising the following steps:

[0023] S1. Rinse fresh tea leaves with water containing Lactobacillus plantarum, centrifuge after rinsing, and spread them out to ferment until the moisture content of the tea leaves is 60-80%; the preservation number of Lactobacillus plantarum is CGMCC1.573.

[0024] S2. The fermented tea leaves are extracted with 1-5% acetic acid as an entrainer by supercritical carbon dioxide to obtain decaffeinated fresh tea leaves.

[0025] In some embodiments, the concentration of *Lactobacillus plantarum* in the water containing *Lactobacillus plantarum* in step S1 is 1-5 × 10⁻⁶. 6 CFU / mL.

[0026] In some embodiments, the centrifugation conditions in step S1 are 100-500 rpm for 1-10 min.

[0027] In some embodiments, the conditions for spreading and fermenting in step S1 are: spreading thickness of 10-30cm, fermentation at 10-40℃ for 10-20h.

[0028] In some embodiments, the supercritical carbon dioxide extraction process described in step S2 is as follows: extraction is performed for 1-4 hours at 30-90°C, 15-50 MPa pressure, and 10-100 L / h carbon dioxide flow rate.

[0029] Secondly, embodiments of the present invention provide an application of decaffeinated tea leaves prepared by the method in the preparation of decaffeinated products.

[0030] Specifically, the products include tea powder, tea paste, tea liquid, effervescent tablets, and capsules.

[0031] Example 1

[0032] Embodiment 1 of the present invention provides a method for removing caffeine from tea leaves and its application, comprising the following steps:

[0033] S1. Use freshly picked tea leaves (Longjing 43) containing 2×10 6 The tea leaves were rinsed with water containing CFU / mL of Lactobacillus plantarum and centrifuged at 300 rpm for 3 min using a drum centrifuge. The centrifuged tea leaves were then spread out in a spreading room for fermentation at a thickness of 20 cm and a temperature of 28℃ for 15 h until the moisture content of the fresh tea leaves was 70%.

[0034] S2. After the fermentation is completed, fresh leaves with a moisture content of 70% are placed in a supercritical carbon dioxide extraction tank. Acetic acid with a volume fraction of 2% is used as an entrainer. The extraction is carried out at a temperature of 55℃ and a pressure of 32MPa, with a carbon dioxide flow rate of 80L / h for 1.5h to obtain decaffeinated fresh tea leaves.

[0035] Example 2

[0036] Embodiment 2 of the present invention provides an application of decaffeinated tea, comprising the following steps:

[0037] The decaffeinated fresh tea leaves obtained in Example 1 were pulverized and passed through a 60-mesh sieve. The sieved tea powder was then soaked in purified water at 80°C for 15 minutes. The mass ratio of tea powder to purified water was 1:20.

[0038] After steeping, filter to obtain decaffeinated tea liquid;

[0039] Decaffeinated tea paste is prepared by vacuum concentration of tea liquid; decaffeinated tea powder is prepared by spray drying of tea liquid.

[0040] Tea paste or tea powder is mixed with other edible ingredients to produce decaffeinated capsules and effervescent tablets;

[0041] Edible ingredients include baking soda, starch, gelatin, and citric acid.

[0042] Comparative Example 1

[0043] Comparative Example 1 of the present invention provides a method for removing caffeine from tea leaves and its application. The difference from Example 1 is that step S1 is not performed, and no entrainer is added during extraction in step S2, so as to obtain decaffeinated fresh tea leaves.

[0044] Comparative Example 2

[0045] Comparative Example 2 of the present invention provides a method for removing caffeine from tea leaves and its application. The difference from Example 1 is that only step S1 is performed to obtain decaffeinated fresh tea leaves.

[0046] Comparative Example 3

[0047] Comparative Example 3 of the present invention provides a method for removing caffeine from tea leaves and its application. The difference from Example 1 is that step S1 is not performed, and decaffeinated fresh tea leaves are obtained.

[0048] Property testing

[0049] Determination of caffeine and EGCG content in fresh tea leaves prepared in the examples and comparative examples:

[0050] The decaffeinated fresh tea leaves obtained in Example 1 and Comparative Examples 1 to 3 were subjected to fixation at 100°C for 4 minutes and mechanical rolling for 30 minutes.

[0051] After kneading, the product was dried at 110℃ in a dryer until the moisture content was 4-6%. It was then tested at the Nanchang Customs Technology Center, and the Nanchang Customs Technology Center Test Report W202204881 was obtained.

[0052] The caffeine and EGCG contents of the fresh tea leaves obtained in Example 1 and Comparative Examples 1 to 3 are shown in Table 1.

[0053] Table 1. Effects of different processing methods on the retention rates of caffeine and EGCG in the product.

[0054] Grouping Processing technology Caffeine content (%) EGCG retention rate (%) Comparative Example 1 No fermentation, no entrainer 1.1 90 Comparative Example 2 Fermentation only 0.5 91 Comparative Example 3 Add only entrainer 0.7 92 Example 1 Fermentation, adding entrainer 0.05 95

[0055] Referring to Table 1, by comparing the effects of different processes on the caffeine and EGCG content in fresh tea leaves, the results showed that the combined use of Lactobacillus plantarum fermentation and the addition of acetic acid entrainer provided by the present invention had the best effect, with a caffeine content of 0.05% and an EGCG retention rate of 95%. Compared with the process without fermentation and without the use of entrainer, the caffeine content was reduced by 1.05%, and the EGCG retention rate was increased by 5%.

[0056] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for removing caffeine from tea leaves, characterized in that, Includes the following steps: S1. Fresh tea leaves are rinsed with water containing *Lactobacillus plantarum*, centrifuged after rinsing, and then spread out to ferment until the moisture content of the tea leaves reaches 60-80%; the *Lactobacillus plantarum* has the preservation number CGMCC1.573; the concentration of *Lactobacillus plantarum* in the water is 1-5 × 10⁻⁶. 6 CFU / mL; the conditions for spreading and fermenting are: spreading thickness 10-30 cm, fermentation at 10-40 ℃ for 10-20 h; S2. The fermented tea leaves are extracted with 1-5% acetic acid as an entrainer by supercritical carbon dioxide to obtain decaffeinated fresh tea leaves. The supercritical carbon dioxide extraction process is as follows: extraction is carried out for 1-4 hours at 30-90 ℃, 15-50 MPa pressure, and a carbon dioxide flow rate of 10-100 L / h.

2. The method according to claim 1, characterized in that, The centrifugation conditions described in step S1 are 100-500 rpm for 1-10 min.

3. The use of the decaffeinated tea obtained by the method of claim 1 in the preparation of decaffeinated products.

4. The application according to claim 3, characterized in that, The products include powders, pastes, liquids, effervescent tablets, and capsules.