WO2020155726A1 - Application of polysaccharide composite nano-selenium in production of selenium-enriched tea - Google Patents

Abstract

Disclosed is an application of polysaccharide composite nano-selenium in production of selenium-enriched tea. The present invention is proposed based on the fact that the inventor of the present invention discovers that, when applied to the tea planting process, the polysaccharide composite nano-selenium can effectively increase content of selenium in tea leaves. The polysaccharide composite nano-selenium is composed of lentinan composite nano-selenium, pachymaran composite nano-selenium, and chitosan composite nano-selenium. The selenium-enriched tea is obtained on the basis on the application, and is higher in selenium content compared with selenium-enriched tea on the market, and therefore is applicable to healthful selenium supplementing demands of different people.

Description

Application of polysaccharide composite nano-selenium in the production of selenium-enriched tea Technical field

The invention belongs to the field of selenium-enriched tea cultivation, and particularly relates to the application of polysaccharide composite nano-selenium in the production of selenium-enriched tea.

Background technique

Selenium is one of the essential micronutrients for humans and animals. A reasonable intake of selenium plays an important role in maintaining health and preventing diseases. Plants are the main food sources for humans and animals to take in selenium. Research results show that crops such as rice and tea have a bioaccumulation effect on selenium. By applying selenium fertilizer to crops, using the bioaccumulation and transformation effects of plants, increasing the selenium content of plants is a low-cost method to improve and meet the insufficient selenium level in the food chain. It has been reported and applied in production. Tea plant has a strong ability to absorb and accumulate selenium, and can convert non-biologically active and highly toxic inorganic selenium into safe, effective, and low-toxic organic selenium. The selenium-enriched tea obtained by applying selenium fertilizer is an ideal selenium supplement resource. Regular drinking of selenium-enriched tea can supplement the body's selenium element, solve the problem of selenium deficiency from the diet, and play a role in preventing diseases.

In China, inorganic selenium sodium selenite is commonly used as a selenium supplement. For example, the main components of many selenium-enriched medicines and selenium health products are sodium selenite. Sodium selenite is also used in selenium-enriched fertilizers and selenium-enriched feeds. universal. However, sodium selenite has strong toxicity and low absorption efficiency, and there are certain risks in its use. Organic selenium has high biological activity for animal absorption, but its absorption efficiency in crops is low and its toxicity is higher than that of nano-selenium. Compared with inorganic selenium and organic selenium, elemental nano-selenium (SeNPs) has attracted wide attention because of its low toxicity, high bioavailability, and high reaction yield. Therefore, it is more ideal to use nano-selenium to produce selenium-enriched tea. However, nano-sized substances are unstable. Some similar nano-selenium products are prone to agglomeration during storage and transportation, the particle size becomes larger, and gradually becomes invalid, and the commercial application value is not high. In addition, the particle size of similar products on the market is between 800 and 2000nm, and the average particle size is even more than 500nm. It is not easy to enter cells. Nano-selenium must enter cells more easily when the particle size is small enough to directly participate in metabolism.

According to the current recommended industry standard "Selenium-enriched tea" (NY/T 600-2002), tea leaves with a selenium content of 0.250-4mg/kg can be called selenium-enriched tea. According to the "Status of Nutrition and Health of Chinese Residents in 2002" (published on October 12, 2004), the consumption of dietary data-adults consume 12g of tea per day, when selecting the industry's highest standard of selenium-enriched tea of 4mg/kg At this time, 48μg of selenium was supplemented daily, which is far from the daily intake standard (200μg/d) recommended by scientists.

Therefore, the current poor stability and large particle size of nano-selenium limit its application efficiency in the production of selenium-enriched tea.

Summary of the invention

The primary purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and provide the application of polysaccharide composite nano-selenium in the production of selenium-enriched tea.

Another object of the present invention is to provide a selenium-enriched tea, which is obtained through the application of the above-mentioned polysaccharide composite nano-selenium in the production of selenium-enriched tea.

The purpose of the present invention is achieved through the following technical scheme: the application of polysaccharide-composite nano-selenium in the production of selenium-rich tea is to use polysaccharide-composite nano-selenium in the process of planting selenium-rich tea.

The present invention is based on the inventor's discovery that the polysaccharide composite nano-selenium applied in the tea planting process can effectively increase the selenium content in the tea, and can also increase the tea polyphenol content to a certain extent and increase the yield.

The particle size of the polysaccharide-composite nano-selenium is 50-200nm; preferably less than 120nm; more preferably, the particle size is adjusted to an appropriate size as required.

The polysaccharide-composite nano-selenium is preferably one or at least two of lentinan-composite nano-selenium (LET-SeNPs), Poria polysaccharide-composite nano-selenium (CMP-SeNPs) and chitosan-composite nano-selenium (CS-SeNPs) ; More preferably, lentinan compound nano-selenium.

The polysaccharide-composite nano-selenium is a polysaccharide-composite nano-selenium obtained by modifying nano-selenium with polysaccharides, and is preferably prepared by the following steps: mixing the polysaccharide used to modify nano-selenium with a nano-selenium solution, reacting, and purifying to obtain polysaccharide-compositing nano-selenium .

Said nano-selenium is nano-selenium prepared by an oxidation-reduction method, and is preferably prepared by the following steps: mixing inorganic selenium with a reducing agent and reacting to obtain nano-selenium.

The inorganic selenium is preferably one or at least two of selenite, selenite and selenium dioxide.

The selenite is one or at least two of sodium selenite (Na ₂ SeO ₃ ), potassium selenite (K ₂ SeO ₃ ) and zinc selenite (ZnSeO ₃ ).

The reducing agent is preferably one or at least two of vitamin C (Vc), sodium borohydride, mercaptoethanol, reduced glutathione, glucose and sodium thiosulfate pentahydrate.

The amount of the inorganic selenium and the reducing agent should be based on the excess of the reducing agent, so that the inorganic selenium can be fully reduced; it is more preferably calculated by a molar ratio of 1:1 to 6; most preferably it is 1 molar ratio. ：4 ratio calculation.

The mixing method is preferably: mixing the inorganic selenium solution and the reducing agent solution; more preferably, mixing the inorganic selenium solution in the reducing agent solution or adding the reducing agent solution to the inorganic selenium solution. in.

The manner of the reaction is preferably a stirring reaction.

The rotation speed of the stirring reaction is preferably 70-90 rpm; more preferably 70 rpm.

The temperature of the reaction is preferably 30-50°C.

The concentration of the inorganic selenium solution is preferably 5-50 mM; more preferably 30-35 mM.

When the reducing agent is vitamin C, the solution concentration is preferably 20-200 mM; more preferably 120-140 mM.

The concentration of the nano-selenium solution is preferably 5-50 mM; more preferably 30-35 mM.

The polysaccharide used to modify nano-selenium is preferably one or at least two of lentinan, poria polysaccharide and chitosan.

The concentration of the polysaccharide used to modify nano-selenium is preferably 5-25 g/L; more preferably 20-21 g/L.

The manner of the reaction is preferably a stirring reaction.

The rotation speed of the stirring reaction is preferably 70-90 rpm; more preferably 70 rpm.

The temperature of the reaction is preferably 30-50°C.

The reaction time is preferably 8-10h.

The method of purification is preferably ultrafiltration membrane filtration.

The specification of the ultrafiltration membrane is preferably 5-100kD.

The purification is purification until the conductivity of the permeate reaches 0.025 S/m or less.

The polysaccharide-composite nano-selenium must undergo inclusion treatment, and then used for the production of selenium-enriched tea.

The inclusion treatment is to mix the polysaccharide composite nano-selenium and the auxiliary material polysaccharide, and spray dry.

The said excipient polysaccharide is preferably an excipient polysaccharide with a concentration of 1 to 5% by mass and volume; more preferably, an excipient polysaccharide with a concentration of 2% by mass and volume.

The use of polysaccharide-composite nano-selenium in the process of planting selenium-enriched tea includes spraying the organs of the tea tree and/or spraying the soil on which the tea tree is grown.

The use of polysaccharide-composite nano-selenium is to prepare polysaccharide-composite nano-selenium into a polysaccharide-composite nano-selenium aqueous solution, preferably a polysaccharide-composite nano-selenium aqueous solution with a concentration of 0.05-0.5 g/L; more preferably, a concentration of 0.075 g /L polysaccharide composite nano-selenium aqueous solution.

The dosage of the polysaccharide composite nano-selenium is 0.5-5 g/mu; preferably 1.5 g/mu.

The organs for spraying the tea tree with polysaccharide composite nano-selenium include vegetative organs and reproductive organs; preferably stems, leaves and flowers; more preferably leaves.

The spraying period includes the peak period of tea bud development and growth.

The specific steps for spraying the organs of tea trees with polysaccharide composite nano-selenium are as follows: plant tea trees, and when the tea tree growth reaches its peak, prepare polysaccharide composite nano-selenium solution into polysaccharide composite nano-selenium solution, and spray the leaves, stems and/ Or flowers, up to the polysaccharide-composite nano-selenium aqueous solution to gather flow or just drop, and the picking can be completed within 10-15 days after spraying.

The spraying of the blade is to spray the polysaccharide composite nano-selenium aqueous solution on the front, back or both sides of the blade evenly.

The application of the polysaccharide-composite nano-selenium in the production of selenium-enriched tea further includes the following steps: after tea leaves are harvested, roasted tea is used to obtain selenium-enriched tea.

According to different seasons of harvest, the selenium-enriched tea is selenium-enriched spring tea, selenium-enriched summer tea, selenium-enriched autumn tea, and selenium-enriched winter tea.

The selenium-enriched autumn tea is preferably selenium-enriched Bailu tea.

The method of roasting tea is one of charcoal roasting and electric roasting; preferably, it is charcoal roasting.

The selenium-enriched tea includes selenium-enriched green tea and selenium-enriched black tea.

The selenium-enriched green tea is preferably selenium-enriched Dancong tea.

A selenium-enriched tea is obtained through the application of the polysaccharide composite nano-selenium in the production of selenium-enriched tea.

The selenium content of the selenium-enriched tea is 0.5-11.0 mg/kg; preferably 1.3-11.0 mg/kg; more preferably 2-11.0 mg/kg; most preferably 4-11.0 mg/kg.

A selenium-enriched tea with high tea polyphenol content is obtained through the application of the above-mentioned polysaccharide composite nano-selenium in the production of selenium-enriched tea; wherein the planting area is at an altitude of 700 meters or more; preferably at an altitude of 800 to 1300 meters .

The selenium-enriched and tea polyphenol tea has a selenium content of 3 mg/kg or more and a tea polyphenol of 500 mg/g or more; preferably, a selenium content of 3.65 to 8.11 mg/kg and a tea polyphenol of 554.51 mg/g.

The selenium-rich and tea polyphenol tea is preferably selenium-rich and tea polyphenol green tea.

A selenium-enriched tea is obtained through the application of the above-mentioned polysaccharide composite nano-selenium in the production of selenium-enriched tea; wherein the planting area is an area below an altitude of 600 meters; preferably an altitude of 100 to 500 meters.

The selenium-enriched tea has a selenium content of 5 mg/kg or more; preferably, the selenium content is 7-10.87 mg/kg.

The selenium-enriched tea is preferably selenium-enriched green tea.

Compared with the prior art, the present invention has the following advantages and effects:

1. In the present invention, only 0.5-5 g/mu of polysaccharide composite nano-selenium can be sprayed on tea trees to achieve a good selenium enrichment effect, and the selenium content of the obtained selenium-enriched tea is much higher than that of the selenium-enriched tea on the market. It is suitable for the healthy selenium supplement needs of different people.

2. The nano selenium used in the present invention is a polysaccharide composite nano selenium modified by polysaccharides, which has good stability, small particle size and size can be adjusted according to needs, and the selenium enrichment effect of spraying tea trees with it as a selenium enriching agent is good.

3. In the present invention, the high-altitude selenium-enriched Dancong tea obtained by spraying Dancong tea tree with lentinan compound nano-selenium has a higher tea polyphenol content by 77.9% than the control group.

4. The present invention adopts lentinan compound nano-selenium (LET-SeNPs) to spray green tea trees to obtain selenium-enriched green tea buds that are robust, and the average yield is increased by about 15-30%.

5. The preparation method of the polysaccharide composite nano-selenium used in the present invention is simple, and the ingredients are safer and more reliable.

Description of the drawings

Figure 1 is the particle size and potential analysis diagrams of CMP-SeNPs, CS-SeNPs and LET-SeNPs; among them, Figure A is the particle size diagram, Figure B is the Zeta potential diagram; CS-SeNPs are chitosan composite nano-selenium, LET -SeNPs are lentinan compounded with nano-selenium, and CMP-SeNPs are tuckahoe polysaccharides with compounded nano-selenium.

Figure 2 is a TEM image of composite nano-selenium; Figure A is LET-SeNPs, Figure B is LET-SeNPs, Figure C is CS-SeNPs, and Figure D is CMP-SeNPs; Figure A and Figure B have different magnifications .

Figure 3 is a graph showing the stability test results of CMP-SeNPs, CS-SeNPs and LET-SeNPs.

Figure 4 is a chromatogram for detecting the content of tea polyphenols in Se-enriched Dancong tea prepared by LET-SeNPs.

Specific embodiment

The present invention will be further described in detail below with reference to specific embodiments and drawings, but the implementation of the present invention is not limited thereto.

Example 1 Preparation of CMP-SeNPs, CS-SeNPs and LET-SeNPs

(1) Dissolve 692 g of sodium selenite (Tiancifu Biological Engineering Co., Ltd.) in 20 L of ultrapure water. Respectively mix 2.5 kg of Poria polysaccharides (CMP, molecular weight (0.7～70)×10 ⁷ , Ningxia Kaiyuan Biotechnology Co., Ltd.) and chitosan (CS, molecular weight 2×10 ⁵ , Sinopharm Chemical Reagent Co., Ltd.) , Lentinan (LET, Shaanxi Sovere Natural Products Co., Ltd., 1kg/package 50%, CAS No. 37339-90-5) and 2.81kg VC are dissolved in 100L ultrapure water, and then pumped into the reaction tank.

(2) Start the reaction tank, set the rotation speed to 70-90 rpm, and set the rotation speed to 90 rpm when stirring.

(3) Slowly add 20L of sodium selenite solution into the reaction tank, close it, set the number of revolutions to 70 rpm, and react for 8 hours.

(4) After the completion of the reaction, the polysaccharide composite nano-selenium is led out from the discharge port of the reaction tank and placed in a clean bucket (if there are large particles or impurities in the reaction tank, it needs to be screened at the discharge nozzle).

(5) Use 5kD ultrafiltration membrane to filter CMP-SeNPs, CS-SeNPs and LET-SeNPs polysaccharide composite nano-selenium, monitor the conductivity of the permeate in real time, and collect the polysaccharide when the conductivity of the permeate reaches 0.025S/m or less Composite nano-selenium solution.

(6) After the end of ultrafiltration, add 7.5 kg of lactose as an auxiliary material to the collected polysaccharide composite nano-selenium solution, the concentration of lactose is 2% by mass and volume, spray dry by spray dryer, and collect powder samples.

Example 2 Characterization of CMP-SeNPs, CS-SeNPs and LET-SeNPs

(1) The CMP-SeNPs, CS-SeNPs, and LET-SeNPs polysaccharide composite nano-selenium powders prepared in Example 1 were dissolved in ultrapure water and characterized: using Nano-ZS nanoparticle size analyzer (Malvern, UK, ) The particle size and Zeta potential of the polysaccharide-composite nano-selenium were detected. The hydrated particle diameters of CMP-SeNPs, CS-SeNPs and LET-SeNPs polysaccharide-composite nano-selenium were 150nm, 140nm, and 80nm respectively (Figure 1); For the characterization of the surface morphology of the three kinds of polysaccharide composite nano-selenium, a transmission electron microscope (Hitachi, H-7650) was used to take an electron microscope picture (as shown in Figure 2). The three kinds of polysaccharide composite nano-selenium have good dispersion and uniformity. .

(2) Dissolve the CMP-SeNPs, CS-SeNPs and LET-SeNPs polysaccharide composite nano-selenium powders prepared in Example 1 in ultrapure water, and place them at room temperature for 20 days, during which the Nano-ZS nanoparticle size analyzer is used for detection every day The particle size of nano-selenium (the first 10 days), the particle size will be tested again on the 20th day. The results are shown in Figure 3. The particle size of the three polysaccharides composite nano-selenium has little change and all have good stability.

Example 3 Toxicity test of polysaccharide composite nano-selenium

(1) The inventor performed the oral acute toxicity test of the composite polysaccharide nano-selenium prepared in Example 1 on the basis of GB15193.3-2014 "National Food Safety Standard Acute Oral Toxicity Test". The oral LD ₅₀ of female mice was 17.1 g/kg, and the oral LD ₅₀ of male mice was 20.0 g/kg. The results showed that the composite polysaccharide nano-selenium prepared in Example 1 was a non-toxic product.

Example 4 CMP-SeNPs, CS-SeNPs, LET-SeNPs are used to produce selenium-enriched green tea

(1) Production of selenium-enriched green tea

When the green tea Jinxuan tea tree germinates a lot (the tea tree growth peak is from March to April), the CMP-SeNPs, CS-SeNPs and LET-SeNPs prepared in Example 1 are fully dissolved in clean water. After they are completely dissolved, follow Spray 1.5g/mu evenly on the front and back leaves of the green tea, and it is advisable to spray it until just dripping water (the test site is in Yingfengshan Tea Garden, Heyuan, Guangdong Province. Before the test, the content of selenium in the finished green tea at this base is less than 250μg/kg, according to the Ministry of Agriculture The recommended standard is non-selenium-enriched tea); a control group is set up, and the same amount of water is sprayed on the green tea trees far away from the test group at the same time. The spraying time is selected before 10 am and after 4 pm. Avoid spraying under dew and hot sun, and avoid windy weather and rainy days of more than 1 day. Picking and spraying CMP-SeNPs, CS-SeNPs and LET-SeNPs on the tenth day after spraying the shoots (one bud and two leaves) of the experimental group and the control group, according to the tea picking season and tea making method (green tea production method) (Calming, rolling, drying) to prepare selenium-enriched green tea and a control group.

(2) Comparison of selenium content between selenium-enriched green tea and the control group

According to the detection step (1) of GB5009.93-2010 "National Food Safety Standard-Determination of Selenium in Food", the selenium-enriched green tea and control green tea products sprayed with CMP-SeNPs, CS-SeNPs and LET-SeNPs nano-selenium The selenium content. The results showed that the selenium background values of the CMP-SeNPs, CS-SeNPs and LET-SeNPs control groups were 0.062mg/kg, 0.066mg/kg, 0.071mg/kg, respectively, and the selenium content in selenium-enriched green tea was 1.02mg/kg, respectively. kg, 1.26mg/kg, 4.45mg/kg, the expected results were achieved. The selenium content of the LET-SeNPs-enriched green tea and the control group were nearly 63 times different, as shown in Table 1.

The selenium-enriched green tea obtained in step (1) and the organic selenium absorption and transformation conditions in the control group (tested according to the national standard DB3301/T117-2007, the total selenium content minus the inorganic selenium content is the organic selenium content). The organic selenium content in LET-SeNPs selenium-enriched green tea reached 4.28mg/kg, accounting for more than 96% of the selenium content, which was significantly higher than the 80% organic selenium content of selenium-enriched tea on the market, indicating that the selenium-enriched green tea of the present invention is safer health.

Table 1 Selenium content in green tea (mg/kg)

(3) Selenium extraction rate of LET-SeNPs selenium-enriched green tea

According to people's habit of drinking tea, the selenium soaked in tea water is really ingested by the human body. Therefore, it is necessary to explore the leaching rate of selenium in selenium-rich tea. The selenium-enriched green tea obtained by spraying step (1) LET-SeNPs was brewed with boiling water for 3 minutes, and the mass ratios of the tea to water of the two teas were 1:20 and 1:50, and each tea was brewed 3 times continuously, and Calculate the leaching rate of selenium content. The results are shown in Table 2. The selenium content of the three leaching of the two teas accounted for 19.7%-26.2%, and the first bubble accounted for more than 10%.

Table 2 The extraction rate of selenium in selenium-enriched green tea under different tea-water ratios

(4) Yield comparison of selenium-enriched green tea and control green tea

The test group and the control group on the tenth day after spraying LET-SeNPs in step (1) picked the shoots according to the specifications of "one bud and two leaves", and weighed them separately. The results proved that the tender shoots sprayed with LET-SeNPs The buds are more robust and the yield increases. The average weight of selenium-enriched buds is 46.4g per hundred buds, which is 18.4% higher than the 39.2g of the control group. However, the shoots sprayed with CMP-SeNPs and CS-SeNPs did not show the same phenomenon, indicating that spraying LET-SeNPs could use selenium-enriched green tea to grow and increase its yield.

Example 5 LET-SeNPs nano-selenium is used to produce selenium-enriched Bailu green tea

The selenium-enriched Bailu green tea was produced in September (the Bailu season), using the same method and dosage of spraying LET-SeNPs nano-selenium as in Example 4, and the test site was in the Yingfengshan Tea Garden in Heyuan, Guangdong Province. The selenium content in the finished products of selenium-enriched Bailu green tea and the control group was detected. The results showed that the selenium content of the control group was 0.038mg/kg, the selenium content of selenium-enriched Bailu green tea was 2.24mg/kg, sprayed with Bailu green tea and LET-SeNPs The selenium content of the control group differed by nearly 60 times, as shown in Table 3.

Table 3 Selenium content in Bailu green tea (mg/kg)

Example 6 LET-SeNPs nano-selenium is used for the production of selenium-enriched Shancong

The test site is 1,000 meters above Wuyu Mountain in Fenghuang Town, Chaozhou. In order to test whether areas at different altitudes can be enriched in selenium, the experiment designed high altitude group (800 to 1300 meters), low altitude group (100 to 500 meters) and the corresponding control group, spraying LET-SeNPs nano-selenium method And the amount is the same as in Example 4. After the test, the finished Shancong tea prepared from the buds of Shancong tea was treated with electric roasting and charcoal roasting, and then the selenium content of each group was tested. The results are shown in Table 4.

(1) Selenium content detection

Table 4 Selenium content in Dancong tea

The results are shown in Table 4. The selenium content of the high-altitude control group after electric roasting was 0.36mg/kg, which has reached the standard of selenium-enriched tea. The selenium content of the high-altitude selenium-enriched group was 3.65mg/kg after electric roasting, and the selenium content increased by 10. The selenium content after carbon roasting in the high altitude control group was 0.40 mg/kg, and the selenium content in the high altitude selenium-enriched group reached 8.11 mg/kg after carbon roasting, and the selenium content increased by 20 times; The content is 0.28mg/kg, which has also reached the standard of selenium-enriched tea. The selenium content of the low-altitude selenium-enriched group is 7.00mg/kg after electric roasting, which is 25 times higher; the selenium content of the low-altitude control group after charcoal roasting is 0.32mg/kg, the selenium content of the low altitude selenium-enriched group after charcoal roasting reached 10.87mg/kg, and the selenium content increased by 34 times

The results show that in the selenium-enriched tea treated by charcoal roasting and electric roasting, the selenium content of the low-altitude selenium-enriched group is higher than that of the high-altitude selenium-enriched group. The selenium content of the buds picked after the experiment is treated with different treatments The difference is that the selenium content in the selenium content of the Dancong tea is higher than that of the electric roasting treatment, indicating that the carbon roasting can better retain the selenium content in the tea.

(2) Analysis of tea polyphenol content

Tea polyphenol, also known as tea tannin, is the general term for polyphenols in tea, and it is also one of the main components of tea with pharmacological and health functions. Tea polyphenols include flavanols, anthocyanins, flavonoids, flavonols and phenolic acids, among which flavanols (catechins) are the main components. In recent years, a large number of studies have found that tea polyphenols have anti-oxidation, anti-inflammatory, anti-tumor, anti-radiation, anti-hyperlipidemia, prevention and treatment of atherosclerosis and anti-viral pharmacological activities. The selenium-enriched Dancong tea prepared in Example 6 was analyzed by high performance liquid chromatography (1260 Infinity II, Agilent) for the content of tea polyphenols (GB/T8313-2018 "Determination of tea polyphenols and catechins in tea Method "), the results are shown in Figure 4 and Table 5.

Table 5 Chromatographic data for detecting the content of tea polyphenols in Se-enriched Dancong tea prepared by LET-SeNPs

According to the standard equation y=8.18143*10 ^-4 x-0.0026 (R ² ＝0.99913), the content of tea polyphenols in LET-SeNPs selenium-enriched Dancong tea: the concentration of tea polyphenols in the low-altitude selenium-enriched group is 320.24mg /g, the concentration of tea polyphenols in the low altitude control group was 413.54 mg/g; the concentration of tea polyphenols in the high altitude selenium-enriched group was 554.51 mg/g; and the high altitude control group was 311.68 mg/g. Although the content of tea polyphenols in the low-altitude selenium-enriched group was lower than the control group, the content of tea polyphenols in the high-altitude selenium-enriched group was 77.9% higher than that in the control group. It can be seen that the high-altitude Dancong tea enriched with selenium can improve its nutritional quality to a certain extent.

Example 7 LET-SeNPs nano-selenium is used to produce selenium-enriched black tea

Spray Meizhan black tea and Baxian black tea (Meizhou tea garden) according to the method of spraying green tea with LET-SeNPs nano-selenium in Example 4. The spraying amount, spraying time and weather are the same, and a control group spraying the same amount of water is set . On the tenth day after spraying, the sprouts of the test group and the control group were picked, and selenium-enriched black tea products were prepared according to the tea picking season and tea-making methods (withering, rolling, fermentation, baking, and re-cultivation). The selenium content of Meizhan black tea and Baxian black tea and control products were tested. The test results are shown in Table 6.

Table 6 Test results of total selenium content in selenium-enriched black tea (mg/kg)

It can be seen from Table 6 that the control group did not reach the standard of selenium-enriched tea. Foliar spraying with 1.5g LET-SeNPs nano-selenium/mu can increase the selenium content in the above two black teas. Among them, the selenium content in Meizhan black tea increased from 0.06mg/kg to 1.37mg/kg, an increase of 23 times; the selenium content of Baxian black tea increased from 0.08mg/kg to 1.63mg/kg; an increase of 20 times.

In summary, spraying LET-SeNPs nano-selenium on the leaves of different varieties of tea plants can increase the selenium content in tea to varying degrees, ranging from 1.37 mg/kg to 10.87 mg/kg (Table 7). Comparing Examples 4-7, the carbon-baked low-altitude selenium-enriched Dancong tea in Example 6 has the highest selenium content, reaching 10.87mg/kg, which is 43 times that of the control group; the selenium-enriched effect of Meizhan black tea in Example 7 The worst, selenium content is only 1.37mg/kg. It is proved that the tea varieties, planting season, post-processing methods of tea and altitude all affect the selenium enrichment rate of tea.

Table 7 Comparison of detection results of selenium content in different varieties of selenium-enriched tea

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, etc. made without departing from the spirit and principle of the present invention Simplified, all should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. The application of polysaccharide-composite nano-selenium in the production of selenium-enriched tea is characterized in that: the polysaccharide-composite nano-selenium is used in the process of planting the selenium-enriched tea.
2. The application of polysaccharide composite nano-selenium in the production of selenium-enriched tea according to claim 1, characterized in that it further comprises the following steps: after the tea leaves are harvested, roasted tea is obtained to obtain selenium-enriched tea.
3. The application of polysaccharide composite nano-selenium in the production of selenium-enriched tea according to claim 1 or 2, characterized in that:

   The particle size of the polysaccharide composite nano-selenium is 50-200nm;

   The polysaccharide composite nano-selenium is one or at least two of lentinan composite nano-selenium, poria polysaccharide composite nano-selenium and chitosan composite nano-selenium;

   The polysaccharide-composite nano-selenium is prepared by the following steps: mixing the polysaccharide used to modify the nano-selenium and the nano-selenium solution, reacting, and purifying to obtain the polysaccharide-compositing nano-selenium.
4. The application of polysaccharide composite nano-selenium in the production of selenium-enriched tea according to claim 1 or 2, characterized in that:

   The use of polysaccharide-composite nano-selenium in the process of planting selenium-enriched tea includes spraying the organs of tea trees and/or spraying the soil for planting the tea trees with polysaccharide-composite nano-selenium;

   The use of polysaccharide-composite nano-selenium is to prepare polysaccharide-composite nano-selenium into a polysaccharide-composite nano-selenium aqueous solution with a concentration of 0.05-0.5 g/L;

   The dosage of the polysaccharide composite nano-selenium is 0.5-5 g/mu.
5. The application of polysaccharide composite nano-selenium in the production of selenium-enriched tea according to claim 4, characterized in that:

   The specific steps for spraying the organs of tea trees with polysaccharide composite nano-selenium are as follows: plant tea trees, and when the tea tree growth reaches its peak, prepare polysaccharide composite nano-selenium solution into polysaccharide composite nano-selenium solution, and spray the leaves, stems and/ Or flowers, until the nano-selenium water solution gathers flow or just dropped, the picking is completed within 10-15 days after spraying.
6. The application of polysaccharide composite nano-selenium in the production of selenium-enriched tea according to claim 2, characterized in that:

   The method of roasting tea is one of charcoal roasting and electric roasting.
7. A selenium-enriched tea, characterized in that it is obtained by using the polysaccharide composite nano-selenium according to any one of claims 1 to 6 in the production of selenium-enriched tea.
8. The selenium-enriched tea of claim 7, wherein the selenium content of the selenium-enriched tea is 0.5-11.0 mg/kg.
9. A selenium-enriched tea with high tea polyphenol content, characterized in that it is obtained by the application of the polysaccharide composite nano-selenium in the production of selenium-enriched tea according to any one of claims 1 to 6; wherein the planting area is 700 meters above sea level. The area above meters.
10. A selenium-enriched tea, characterized in that it is obtained by using the polysaccharide composite nano-selenium described in any one of claims 1 to 6 in the production of selenium-enriched tea; wherein the planting area is an area below 600 meters above sea level.

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