Corn stigma Pu'er tea beverage and preparation method thereof

Abstract

The invention discloses a corn stigma Pu'er tea beverage and a preparation method thereof. The tea beverage is prepared by taking a co-fermentation product of corn stigma and large-leaf sunned raw tea and mulberry leaves as raw materials. Wherein the corn stigma and large-leaf sunned raw tea co-fermentation product is prepared by fermenting a corn stigma aqueous extract and large-leaf sunned raw tea through specific fungi. The fermentation time of Pu'er tea can be effectively shortened and the production efficiency can be improved by introducing the corn stigma aqueous extract and the special thermomyces lanuginosus in the fermentation process of the large-leaf sunned raw tea and fermenting at the constant temperature of 55 + / -2 DEG C. Meanwhile, the raw materials can be endowed with abundant bioactive components. The prepared tea beverage contains antioxidant components such as tea polyphenol and flavone, has good antioxidant activity, also contains natural caffeine, has the effects of boosting spirit and enhancing memory, does not contain any additive or preservative, can be eaten for a long time, and is beneficial to prevention of occurrence and development of chronic diseases.

Description

Technical Field

[0001] The present invention relates to the technical field of tea beverage preparation. More specifically, it relates to a corn silk Pu-erh tea beverage and a preparation method thereof. Background Art

[0002] Currently, the raw materials of commercially available plant-based functional beverages mainly include green tea, black tea, Pu-erh tea, dandelion, chrysanthemum, honeysuckle, tangerine peel, monk fruit, wolfberry, hawthorn, mulberry, aloe, and coffee, etc., which are rich in bioactive components such as plant polysaccharides, sterols, flavonoids, isoflavones, and saponins. The development of plant-based functional beverages will become the development direction of the beverage industry.

[0003] Currently, compared with the countless edible plant species, the number of plant-based beverages developed in the current beverage market is actually not large, and the concentration is relatively high. There are very few functional beverages. Therefore, based on the basic concept that the majority of consumers pursue health more, it is of great significance to develop new plant-based beverages with health and health care functions. Summary of the Invention

[0004] One object of the present invention is to provide a corn silk Pu-erh tea beverage. This tea beverage contains antioxidant components such as tea polyphenols and flavonoids, has good antioxidant activity, and also contains natural caffeine, which has the effects of boosting spirits and enhancing memory. It does not contain any additives or preservatives and can be consumed for a long time, which is beneficial to preventing the occurrence and development of chronic diseases.

[0005] Another object of the present invention is to provide a preparation method of the above-mentioned corn silk Pu-erh tea beverage. Among them, modern biotechnology is applied to process and improve the raw materials, enriching the efficacy of traditional Pu-erh tea and shortening the fermentation time of Pu-erh tea.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a corn silk Pu-erh tea beverage, which is prepared from the co-fermentation product of corn silk and sun-dried green tea of large-leaf species, and mulberry leaves as raw materials.

[0008] Optionally, based on 1000 parts by weight of the above tea beverage, the co-fermentation product of corn silk and sun-dried green tea of large-leaf species is 1.5 - 5 parts, and mulberry leaves are 0.8 - 1.5 parts, and the balance is pure water.

[0009] Furthermore, different from the raw materials of traditional Pu-erh tea, the present invention processes and improves the raw materials by using modern biotechnology. Among them, the co-fermentation product of corn silk and sun-dried green tea of large-leaf species is obtained by the following method:

[0010] Weigh dry corn silk, add pure water with a weight 12 - 20 times that of the dry corn silk, and perform vacuum reflux extraction at an extraction temperature of 100 °C for 20 - 30 minutes. Filter the extract, and under the condition of 80 °C, perform reduced-pressure concentration. Finally, spray-dry the concentrated solution to obtain powdered aqueous extract of corn silk.

[0011] Prepare a spore suspension of Thermomyces lanuginosus PE - 3 with the preservation number CGMCC No.21065.

[0012] According to the weight ratio of raw materials: 0.05 - 0.3 parts of aqueous extract of corn silk, 4 parts of sun-dried green tea of large-leaf variety. Mix the aqueous extract of corn silk and sun-dried green tea of large-leaf variety, add the spore suspension of Thermomyces lanuginosus PE - 3, control the water content of the raw materials to be 35% - 40%, and inoculate 2.0×10 4 -2×10 6 spores per 1 kg of dry weight of the raw materials.

[0013] Load it into a stainless-steel container, cover it with a wet gauze on top, cover the container lid, and place it in a fermentation chamber. The fermentation temperature is 55 ± 2 °C, the relative humidity is 30% - 40%, and after 22 - 30 days of fermentation, end the fermentation.

[0014] Perform ventilation and drying, and conduct re-screening and sorting.

[0015] In the above method, Thermomyces lanuginosus PE - 3 is the fungus with the highest upper growth temperature among the thermophilic fungi isolated from commercially available Pu-erh tea products, and it can be applicable to fermentation under relatively high temperature conditions. Especially, it can grow well under the condition of 55 ± 2 °C. Due to the ability of Thermomyces lanuginosus PE - 3 to grow well under the condition of 55 ± 2 °C, it can be inoculated to become the dominant bacterium in the fermentation process, making the fermentation temperature constant at 55 ± 2 °C throughout the fermentation process, thereby inhibiting the growth of mesophilic and psychrophilic microorganisms in traditional Pu-erh tea fermentation, including the main producing bacteria of mycotoxins (species of Aspergillus, Penicillium, Alternaria, and Fusarium), and preventing the production of mycotoxins, thus ensuring the quality of the product from the source.

[0016] In addition, in the fermentation process of Pu-erh tea of the present invention, an appropriate amount of aqueous extract of corn silk is introduced. The aqueous extract of corn silk is rich in nutrients, such as water-soluble carbohydrates, crude proteins, trace elements, and various vitamins, providing sufficient available carbon and nitrogen sources for the fermentation strains, enabling the fermentation strains to grow rapidly, effectively shortening the fermentation time of Pu-erh tea. At the same time, the aqueous extract of corn silk also contains bioactive components, such as water-soluble polysaccharides, flavonoids, and polyphenols, which can be catalytically biotransformed by extracellular enzymes of the fermentation strains together with the sun-dried green tea of large-leaf variety, thereby enriching the bioactive components in the co-fermentation product of the aqueous extract of corn silk and the sun-dried green tea of large-leaf variety.

[0017] According to the specific embodiments of the present application, during the above fermentation process, the stainless-steel container is opened to turn the fermented material 3-5 times to facilitate sufficient and uniform fermentation.

[0018] According to the specific embodiments of the present application, during the above fermentation process, the water content of the raw material is controlled at 35%-40% by adding water.

[0019] According to the specific embodiments of the present application, the specific method for preparing the spore suspension of Thermomyces lanuginosus PE-3 is as follows: Inoculate Thermomyces lanuginosus PE-3 with the preservation number of CGMCC No.21065 onto a potato agar medium, place it in a constant-temperature incubator at 55±2°C for 3-5 days, transfer it 2-3 times. When the mycelium grows well and forms abundant mature spores, add sterile pure water, scrape the spores with an inoculation loop to obtain a spore suspension. Transfer the spore suspension into a sterilized triangular flask containing glass beads and shake it well. Count using a hemocytometer and set aside for use.

[0020] In the present invention, the mulberry leaves are preferably the mulberry leaves picked after the Frost's Descent and dried in a cool place after picking.

[0021] In a second aspect, the present invention provides a method for preparing a corn silk Pu-erh tea beverage. The method uses the co-fermentation product of corn silk and large-leaf sun-dried green tea, and mulberry leaves as raw materials, and is processed according to traditional tea-making processes, including but not limited to, extraction, filtration, sterilization, hot filling, etc. to obtain the corn silk Pu-erh tea beverage.

[0022] Further, the preparation method includes: Weigh the co-fermentation product of corn silk and large-leaf sun-dried green tea and mulberry leaves as raw materials, preheat the pure water, and perform hot extraction on the raw materials at 90°C - 95°C for 2-3 times, with each extraction for 25-35 minutes. Filter, combine the filtrates, sterilize, and then perform hot filling and spray cooling to obtain the product.

[0023] Further, in the above method, the sterilization is carried out by high-temperature short-time sterilization.

[0024] The beneficial effects of the present invention are as follows:

[0025] In the present invention, the preparation of the co-fermentation product of corn silk and large-leaf sun-dried green tea has obvious controllability compared with the traditional pile fermentation in the prior art. The strain is specifically added to ensure the consistency of the microbial species in each fermentation process, so that the quality of the Pu-erh tea obtained after fermentation in different batches can be continuously stable and uniform. At the same time, compared with pile fermentation, the fermentation cycle of the co-fermentation product of corn silk and large-leaf sun-dried green tea is shortened and can be completed within 22-30 days, improving the production efficiency.

[0026] The tea beverage of the present invention has controllable production, short production cycle and high production efficiency; constant high-temperature cultivation inhibits the growth and metabolism of molds that produce mycotoxins, is not troubled by mycotoxins, and improves the quality and hygienic quality of the product; the tea beverage contains antioxidant components such as tea polyphenols and flavonoids, has good antioxidant activity, reduces the accumulation of free radicals and the generation of peroxidation reactions, and is beneficial to preventing the occurrence and development of chronic diseases; the tea beverage contains natural caffeine, which has the effects of boosting spirits and enhancing memory; it is convenient to use, does not add any additives or preservatives, and is suitable for long-term consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Shows the process flow chart of making the tea beverage.

[0028] Figure 2 Shows the hydroxyl radical scavenging ability of the tea beverage.

[0029] Figure 3 Shows the fluorescence decay curve of the tea beverage.

[0030] Figure 4 Shows the total reducing power of the tea beverage.

[0031] Figure 5 Shows the ABTS cation radical scavenging ability of the tea beverage. DETAILED DESCRIPTION OF THE INVENTION

[0032] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0033] The materials in the following embodiments, unless otherwise specified, are commonly used materials in the art and can be obtained from commercial channels.

[0034] Preservation Information:

[0035] Biological material (strain) referred to: PE-3;

[0036] Suggested taxonomic name: Thermomyces lanuginosus;

[0037] Preservation institution: General Microbiology Center of China Committee for Culture Collection of Microorganisms;

[0038] Abbreviation of the preservation institution: CGMCC;

[0039] Address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing;

[0040] Preservation date: November 23, 2020;

[0041] Accession number registered with the preservation center: CGMCC No. 21065.

[0042] Example 1

[0043] Preparation of the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety

[0044] Using the water extract of corn silk and sun-dried green tea of large-leaf variety as raw materials, inoculating Thermomyces lanuginosus PE-3 with the preservation number of CGMCC No. 21065 for fermentation to prepare the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety.

[0045] The weight ratio of the water extract of corn silk to the sun-dried green tea of large-leaf variety is: 0.21 part of the water extract of corn silk and 4 parts of the sun-dried green tea of large-leaf variety.

[0046] The specific preparation method includes the following steps:

[0047] (1) Preparation of the spore suspension: Inoculate Thermomyces lanuginosus PE-3 with the preservation number of CGMCC No. 21065 onto the potato agar medium, place it in a constant temperature incubator at 55 ± 2 °C for 3 - 5 days, transfer it 2 - 3 times. When the mycelium grows well and forms abundant mature spores, add sterile pure water, scrape the spores with an inoculation loop to obtain a spore suspension, transfer it to a sterilized Erlenmeyer flask containing glass beads and shake well to prepare the spore suspension for standby;

[0048] (2) Preparation of the water extract of corn silk: Weigh dry corn silk, which can be dry corn silk obtained by drying fresh corn silk, with a moisture content of less than 8% and an impurity rate of less than 5%. Add 15 times the weight of the corn silk of pure water, use vacuum reflux extraction, the extraction temperature is 100 °C, the extraction time is 30 min. Filter one-third of the extract and transfer it to the concentration tank. Under the condition of 80 °C, concentrate it under reduced pressure. The generated steam is condensed into water by the condenser. After collecting 100 L of the condensed water, reflux it to the extraction tank and then perform hot extraction. Repeat the above operation 2 times. Then the extract continuously enters the distillation tank, is concentrated under reduced pressure, and the distilled water is discharged. Finally, spray-dry the concentrated liquid to obtain the powdered water extract of corn silk;

[0049] (3) According to the above raw material weight ratio, mix the water extract of corn silk prepared in step (2) with the sun-dried green tea of large-leaf variety, add the spore suspension prepared in step (1), control the moisture content of the raw materials to be 36%, and inoculate 2.0×10 5 spores of Thermomyces lanuginosus PE-3 per 1 kg of dry weight of the raw materials;

[0050] (4) Load it into a stainless-steel container, cover it with 8 layers of wet gauze on top to prevent the evaporation of surface moisture of the fermented matter, cover the container lid, and place it in a fermentation chamber. The temperature of the fermentation chamber is controlled at 55 ± 2 °C, and the relative humidity in the chamber is 32%. During the fermentation process, turn the fermented matter 3 - 5 times and appropriately add water to control the moisture content of the raw materials at 36%. After 23 days of fermentation, end the fermentation;

[0051] (5) Ventilate and dry, conduct re-screening and picking to obtain the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety.

[0052] Example 2

[0053] Preparation of the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety

[0054] Using the water extract of corn silk and sun-dried green tea of large-leaf variety as raw materials, inoculate Thermomyces lanuginosus PE-3 with the preservation number of CGMCC No.21065 for fermentation to prepare the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety.

[0055] The weight ratio of the water extract of corn silk to sun-dried green tea of large-leaf variety is: 0.12 part of the water extract of corn silk and 4 parts of sun-dried green tea of large-leaf variety.

[0056] The specific preparation method includes the following steps:

[0057] (1) Preparation of spore suspension: Inoculate Thermomyces lanuginosus PE-3 with the preservation number of CGMCC No.21065 onto a potato agar medium, place it in a constant temperature incubator at 55 ± 2 °C for 3 - 5 days, transfer it 2 - 3 times. When the mycelium grows well and forms abundant mature spores, add sterile pure water, scrape the spores with an inoculation loop to obtain a spore suspension, transfer it into a sterilized Erlenmeyer flask containing glass beads and shake it well to prepare the spore suspension for standby;

[0058] (2) Preparation of the water extract of corn silk: Weigh dry corn silk, and the dry corn silk can be the dry corn silk obtained by drying fresh corn silk, with a moisture content less than 8% and an impurity rate less than 5%. Add 15 times the weight of the corn silk of pure water, and adopt vacuum reflux extraction. The extraction temperature is 100 °C and the extraction time is 30 min. Filter one-third of the extract and transfer it to a concentration tank. Under the condition of 80 °C, carry out vacuum concentration. The generated steam is condensed into water by a condenser. After collecting 100 L of condensed water, reflux it to the extraction tank and then conduct heat extraction. The above operations are repeated 2 times. Then the extract continuously enters the distillation tank and is concentrated under reduced pressure, and the distilled water is discharged. Finally, spray-dry the concentrated solution to obtain the powdery water extract of corn silk;

[0059] (3) According to the above raw material weight ratio, mix the aqueous extract of corn silk prepared in step (2) with sun-dried green tea of large-leaf variety, add the spore suspension prepared in step (1), control the water content in the raw materials to be 36%, and inoculate 2.0×10 6 spores of Thermomyces lanuginosus PE-3 per 1 kg of dry weight of the raw materials;

[0060] (4) Load it into a stainless steel container, cover it with 8 layers of wet gauze on top to prevent the water on the surface of the fermented material from volatilizing, cover the container lid, put it into the fermentation chamber, control the temperature of the fermentation chamber at 55±2 °C, the indoor relative humidity is 32%, turn the fermented material 3-5 times during the fermentation process, and appropriately replenish water to control the water content of the raw materials at 36%. After 23 days of fermentation, end the fermentation;

[0061] (5) Ventilate and dry, conduct re-screening and sorting to obtain the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety.

[0062] Example 3

[0063] Determine the main component content of the aqueous extract of corn silk in Example 1 and Example 2. The specific detection method is as follows:

[0064] (1) Determination of the content of water-soluble total sugar. It is determined by the sulfuric acid-phenol method.

[0065] (2) Determination of the content of water-soluble polysaccharide. Accurately weigh 0.5000 g of the sample to be measured into a 50 mL round-bottom centrifuge tube, moisten the sample with 5 mL of pure water, slowly add 20 mL of absolute ethanol, vortex and mix evenly, extract ultrasonically for 30 min, then centrifuge at 4000 r / min for 15 min, and discard the supernatant. Wash the precipitate with 10 mL of 80% ethanol solution, centrifuge, and discard the supernatant. Add 30 mL of pure water to the precipitate, extract ultrasonically for 20 min, filter, wash the filter residue with pure water 2-3 times, and repeat 3 times. Transfer the filtrate to a 200 mL volumetric flask, add pure water to the scale, and shake well. This solution is the sample determination solution. The content of water-soluble polysaccharide is determined by the sulfuric acid-phenol method.

[0066] (3) Determination of the content of crude protein. Refer to GB5009.5-2016, Determination of Protein in Foods, and it is determined by the Kjeldahl method.

[0067] (4) Determination of the content of total flavonoids. It is determined by the aluminum trichloride colorimetric method.

[0068] (5) Determination of the content of total polyphenols. It is determined by the Folin-phenol colorimetric method.

[0069] The detection results of the above (1)-(5) are shown in Table 1:

[0070] Table 1 Content of Active Ingredients in the Aqueous Extract of Corn Silk

[0071]

[0072] Example 4

[0073] The co-fermentation product of corn silk and sun-dried big-leaf raw tea was prepared by the preparation methods of Example 1 and Example 2, and the fermentation was completed in 23 days. The weight ratio of the raw materials was as follows: the water extract of corn silk: sun-dried big-leaf raw tea was 0.21:4 and 0.12:4 respectively, and the inoculation of Thermomyces lanuginosus PE-3 spores was 2.0×10 5 and 2.0×10 6 respectively. The obtained corn silk Pu-erh teas were named sample S1 and sample S2 respectively. At the same time, a control sample of Pu-erh tea was prepared. The specific preparation method was as follows: Take sun-dried big-leaf raw tea, add pure water to make the water content 36%, mix well and put it into a stainless-steel container, cover it with 8 layers of wet gauze on top to prevent the evaporation of surface moisture of the fermented product, and ensure air circulation at the same time. Cover the container lid and put it into the fermentation room. The temperature of the fermentation room was controlled at 55±2°C, and the indoor relative humidity was 32%. During the fermentation process, open the stainless-steel container and turn the fermented product 4 times, and appropriately add water to control the water content of the raw materials at 36%. After 23 days of fermentation, the fermentation was completed; ventilate and dry, and conduct re-screening and picking to obtain the control sample of loose Pu-erh tea without adding the water extract of corn silk and Thermomyces lanuginosus PE-3, named AC1. In addition, the weight ratio of the water extract of corn silk and sun-dried big-leaf raw tea was: 0.21 parts of the water extract of corn silk and 4 parts of sun-dried big-leaf raw tea. Add pure water to make the water content 36%, mix well and put it into a stainless-steel container, cover it with 8 layers of wet gauze on top to prevent water evaporation, and ensure air circulation at the same time. Cover the container lid and put it into the fermentation room. The temperature of the fermentation room was controlled at 55±2°C, and the indoor relative humidity was 32%. During the fermentation process, open the stainless-steel container and turn the fermented product 4 times, and appropriately add water to control the water content of the raw materials at 36%. After 23 days of fermentation, the fermentation was completed; ventilate and dry, and conduct re-screening and picking to obtain the control sample of loose Pu-erh tea without adding Thermomyces lanuginosus PE-3, named AC2.

[0074] The above samples were detected for main physical and chemical indexes, microbial indexes and mycotoxins. The specific detection methods were as follows:

[0075] (1) Determination of water extract. Referring to GB 8305-2013, the determination of tea water extract was carried out by the extraction method.

[0076] (2) Determination of the contents of tea polyphenols and catechins. Referring to GB / T 8313-2018, the detection method of the contents of tea polyphenols and catechins in tea, the content of tea polyphenols was determined by the Folin-phenol colorimetric method, and the contents of catechins and caffeine were determined by HPLC method.

[0077] (3) Determination of free amino acid content. Referring to GB / T 8314-2013 Determination of total free amino acids in tea, the ninhydrin colorimetric method was used for determination.

[0078] (4) Determination of water-soluble polysaccharide content. Accurately weigh 0.5000 g of the sample to be tested into a 50 mL round-bottom centrifuge tube, moisten the sample with 5 mL of pure water, slowly add 20 mL of absolute ethanol, vortex and mix evenly, extract ultrasonically for 30 min, then centrifuge at 4000 r / min for 15 min, and discard the supernatant. Wash the precipitate with 10 mL of 80% ethanol solution and centrifuge, discard the supernatant. Add 30 mL of pure water to the precipitate, extract ultrasonically for 20 min, filter, wash the filter residue with pure water 2 - 3 times, and repeat 3 times. Transfer the filtrate to a 200 mL volumetric flask, add pure water to the scale for volume fixation, and shake well. This solution is the sample determination solution. The water-soluble polysaccharide content was determined by the sulfuric acid-phenol method.

[0079] The test results of the above (1)-(4) are shown in Table 2:

[0080] Table 2 Relationship between fermentation time and main components

[0081]

[0082] Compared with the control sample AC1, the raw material of the control sample AC2 was added with aqueous extract of corn silk, and the ratio to sun-dried green tea of large-leaf variety was 0.21:4, but there was no artificial inoculation of Thermomyces lanuginosus PE-3. As can be seen from Table 2, at the end of 23 days of fermentation, the addition of aqueous extract of corn silk in AC2 contributed to the biotransformation of the main components of Pu-erh tea. The contents of water extract, tea polyphenols, gallic acid and total catechins were slightly lower, the content of water-soluble polysaccharides was slightly higher, and the amino acid content was similar. The caffeine content in AC1 and AC2 increased slightly during fermentation. Although the corn silk extract contributed to the biotransformation of the main components in Pu-erh tea, after 23 days of constant temperature fermentation at 55 ± 2 °C, the content of tea polyphenols decreased from 24.28% (w / w) to 15.65% (w / w), which did not meet the requirements of the national standard "GB / T 22111-2008 Geographical indication product - Pu-erh tea".

[0083] Compared with the control sample AC2, the ratio of the aqueous extract of corn silk to sun-dried green tea of large-leaf variety in the sample S1 was 0.21:4, and at the same time, Thermomyces lanuginosus PE-3 (2.0×10 5 CFU) was artificially inoculated. As can be seen from Table 2, at the end of 23 days of fermentation, Thermomyces lanuginosus PE-3 further enhanced the biotransformation of the main components of Pu-erh tea. The main physical and chemical indicators met the requirements of the national standard "GB / T 22111-2008 Geographical indication product - Pu-erh tea".

[0084] The ratio of the aqueous extract of corn silk of sample S2 to sun-dried green tea of large-leaf variety was 0.12:4, and at the same time, Thermomyces lanuginosus PE-3 (2.0×10 6 CFU) was inoculated artificially. As can be seen from Table 2, at the end of 23 days of fermentation, compared with sample S1, the bioconversion rate of the main components in Pu-erh tea was further improved. The main physical and chemical indicators met the requirements of the national standard "GB / T 22111-2008 Geographical Indication Product - Pu-erh Tea".

[0085] During the fermentation process of samples S1 and S2, it was found that with the prolongation of fermentation time, the contents of water extract, tea polyphenols, total catechins and amino acids gradually decreased, and decreased rapidly in the initial stage of fermentation; the content of gallic acid increased in the initial stage of fermentation and then decreased. The content of gallic acid in sample S1 was higher than its initial content, while the opposite was true for sample S2; the content of caffeine did not change significantly. The content of water-soluble polysaccharides in sample S1 increased in the initial stage and then decreased, while that in sample S2 gradually increased and was greater than its initial content. At the same time, during the fermentation process, it was also found that Thermomyces lanuginosus PE-3 grew and reproduced rapidly in the initial stage of fermentation, uniform and white mycelia appeared in the fermented product, and a special and fragrant aroma was produced. The aroma was positively correlated with the growth of Thermomyces lanuginosus PE-3.

[0086] Since the aqueous extract of corn silk is rich in sugars and has a certain viscosity, when the ratio of the aqueous extract of corn silk to large-leaf variety Pu-erh tea exceeds 0.3:4, it is easy to cause caking, which is not conducive to the fermentation of Pu-erh tea.

[0087] (5) Refer to GB 4789.3-2016 National Food Safety Standard - Microbiological Examination of Foods for the enumeration of coliforms. Refer to GB 4789.4-2016 National Food Safety Standard - Microbiological Examination of Foods for the examination of Salmonella. Refer to GB 4789.5-2012 National Food Safety Standard - Microbiological Examination of Foods for the examination of Shigella. Refer to GB 4789.10-2016 National Food Safety Standard - Microbiological Examination of Foods for the examination of Staphylococcus aureus. Refer to GB 4789.11-2014 National Food Safety Standard - Microbiological Examination of Foods for the examination of β-hemolytic streptococci. The test results were as follows: coliforms negative, and no pathogenic bacteria (Salmonella, Shigella, Staphylococcus aureus, hemolytic streptococci) were detected.

[0088] Detection of mycotoxins such as aflatoxins (B1, B2, G1, and G2), fumonisin B1, deoxynivalenol, and ochratoxin A. Refer to the method of Wang Lu et al. (Wang Lu; Yang Hua; Xie Guoxiang; Jia Wei, Detection of Mycotoxins in Pu-erh Tea, Black Tea, and Green Tea. China Journal of Chinese Materia Medica 2017, 42(24), 4801-4806.). The test results showed that no mycotoxins such as aflatoxins (B1, B2, G1, and G2), fumonisin B1, deoxynivalenol, and ochratoxin A were detected.

[0089] Example 5

[0090] Preparation of corn silk Pu-erh tea beverage

[0091] Based on 1000 parts by weight, 2.6 parts of the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety prepared in Example 1, 1.2 parts of mulberry leaves, and the balance is pure water. The mulberry leaves are picked after frost and dried in a cool place.

[0092] Preheat the pure water and perform hot extraction at 90°C - 95°C. Each extraction uses a portion of the pure water, and the extraction time is 30 minutes. Perform secondary filtration, extract 3 times, combine the filtrates, and after high-temperature instantaneous sterilization, perform hot filling, followed by spray cooling, lamp inspection, and other processes to prepare the tea beverage. The tea beverage has a brownish-red and bright color, a pure taste, and no bitter or astringent taste.

[0093] Example 6

[0094] Detection of the main chemical components and hygienic indicators of the tea beverage prepared in Example 5. The specific detection methods are as follows:

[0095] (1) Determination of the contents of tea polyphenols and caffeine. Refer to GB / T 21733-2008 and GB / T 5009.139-2014 respectively, the detection methods of tea polyphenols and caffeine in tea beverages. The content of tea polyphenols is determined by the ferrous tartrate colorimetric method, and the content of caffeine is determined by the HPLC method.

[0096] (2) Determination of the total flavonoid content. Determined by the aluminum trichloride colorimetric method

[0097] (3) Determination of proteins and fats. Refer to GB / T 5009.5-2016 (the first method) and GB / T 5009.6-2016 (the first method) respectively.

[0098] (4) Determination of the total sugar content. Using the sulfuric acid-phenol method.

[0099] (5) Detection of total arsenic, lead and copper. The detection was carried out with reference to the methods specified in GB / T 5009.11-2014 (the first method), GB / T 5009.12-2017 (the first method) and GB / T 5009.13-2017 (the third method).

[0100] (6) Detection of total number of colonies, coliforms, molds, yeasts and pathogenic bacteria. The detection was carried out with reference to the methods specified in GB / T 4789.2-2022, GB / T 4789.3-2016 (the second method), GB / T 4789.15-2016 (the first method), GB4789.4-2016, GB 4789.5-2012 and GB 4789.10-2016.

[0101] The test results of the above (1)-(4) are shown in Table 3:

[0102] Table 3 Main components of tea beverages (mg / Kg)

[0103] Tea polyphenols Caffeine Total flavonoids Total sugar Protein Fat Example 5 158.50±3.52 118.00±2.63 17.59±1.31 226.00±7.07 - -

[0104] Note: "-" means not detected

[0105] The test result of the above (5) is as follows: the concentration of total arsenic is less than 0.002 mg / L (the national standard requires less than 0.2 mg / L), and the concentrations of lead and copper are both less than 0.02 mg / L (the national standard requires lead less than 0.3 mg / L and copper less than 5 mg / L).

[0106] The test result of the above (6) is as follows: the total number of colonies is less than 100 cfu / mL, coliforms are negative, molds and yeasts are not detected, and pathogenic bacteria (Salmonella, Shigella, Staphylococcus aureus) are not detected.

[0107] Example 7

[0108] The specific method for detecting the antioxidant activity of the tea beverage prepared in Example 5 is as follows:

[0109] (1) Determination of hydroxyl radical scavenging ability. The salicylic acid method was adopted. In a 96-well microplate, 100 μL of 9 mmol / L FeSO4, 40 μL of 9 mmol / L salicylic acid-ethanol solution were successively added. 40 μL, 20 μL, 10 μL, 5 μL and 2.5 μL of tea beverages were respectively taken and 0 μL, 20 μL, 30 μL, 35 μL and 37.5 μL of pure water were respectively added. Finally, 40 μL of 8.8 mmol / L H2O2 was added and then mixed well. The reaction system was 220 μL. After water bath at 37 °C for 30 min, the absorbance value A2 of the reaction solution at a wavelength of 510 nm was measured using a Safire2 microplate reader (Tecan); 40 μL of pure water was used to replace the tea beverage as the absorbance value A0 of the blank control; 40 μL of pure water was added to replace H2O2 as the absorbance value A1 without the color developing agent H2O2. Trolox was used as the positive control. The calculation formula for the hydroxyl radical scavenging rate is as follows:

[0110]

[0111] (2) Determination of oxygen radical absorbance capacity. The ORAC method was adopted. The specific operation steps were as follows. 20 μL, 10 μL, 5 μL, 2.5 μL and 1.25 μL of tea beverages were respectively added to a 96-well microplate, and 0 μL, 10 μL, 15 μL, 17.5 μL and 18.75 μL of pure water were respectively added. Then 80 μL of fluorescein sodium (FL) solution was added. After preheating at 37 °C for 5 min, 100 μL of AAPH (200 mmol / L) was added immediately for reaction. The reaction system was 200 μL, and the reaction temperature was 37 °C. Using a Safire2 microplate reader (Tecan), the excitation wavelength was 485 nm and the emission wavelength was 538 nm. In the kinetic mode, the fluorescence intensity of each well was measured every 6 min for 120 min continuously, and the fluorescence decay showed a baseline. The reaction was set with a fluorescence natural decay control without AAPH (-AAPH) and a fluorescence decay solely by AAPH without antioxidant as the blank control (+AAPH). Trolox was used as the positive control. The samples were repeated 3 times, and the area under the fluorescence decay curve (AUC) was calculated using the approximate integral method. The experimental results were expressed as the relative ORAC value of the tea beverage. The unit of the relative ORAC value was expressed in TE equivalents (μmol TE / mL), that is, how many micromoles of Trolox antioxidant capacity was represented by the antioxidant capacity of each milliliter of tea beverage. The calculation formula is as follows:

[0112]

[0113] In the formula, AUC 样品 , AUC Trolox and AUC 空白 respectively represent the area under the fluorescence decay curves of the sample, Trolox and the blank.

[0114] (3) Determination of total reducing power: The potassium ferricyanide method was used. Precisely measure 500 μL, 250 μL, 125 μL, 62.5 μL, and 31.3 μL of the tea beverage respectively, add 0 μL, 250 μL, 375 μL, 437.5 μL, and 468.7 μL respectively, then successively add 1 mL of 0.2 mol / L phosphate buffer (pH 6.8) and 1 mL of 1% potassium ferricyanide solution, mix evenly. The reaction system is 2.5 mL, keep it warm in a water bath at 50 °C for 20 min, and then add 1 mL of 10% trichloroacetic acid. After mixing evenly, precisely measure 1 mL, add 1 mL of pure water and 0.5 mL of 0.1% FeCl3. The reaction system is 2.5 mL. After mixing evenly, perform colorimetry at 700 nm, and use A 700 to represent the total reducing power of the tea beverage. Use Trolox as the positive control.

[0115] (4) Determination of ABTS cation radical scavenging ability. The ABTS method was used. Add 40 μL, 20 μL, 10 μL, 5 μL, and 2.5 μL of the tea beverage respectively into a 96-well microplate, add 0 μL, 20 μL, 30 μL, 55 μL, and 37.5 μL of pure water respectively, and then add 160 μL of ABTS working solution (A 734 = 0.80 ± 0.1) and mix. The reaction system is 200 μL. React in the dark at room temperature. Use a Safire2 microplate reader (Tecan) to measure the absorbance value of the reaction solution at 734 nm. The reaction time is 5 min. Take the absorbance value measured at the fifth minute of the reaction to calculate the scavenging rate of ABTS cation radicals. Use 50 mmol / L Tris-HCl (pH 7.4) buffer as the blank control and Trolox as the positive control. The calculation formula for the scavenging rate of ABTS cation radicals is as follows:

[0116] Scavenging rate of ABTS cation radicals (%) = [(A blank - A sample ) / A blank × 100%

[0117] where A sample and A blank are the absorbances at 734 nm after the reaction of the sample solution and the blank control solution respectively.

[0118] In the above Example 7(1), the hydroxyl radical scavenging ability of the tea beverage was detected, and the detection results are as Figure 2As shown, the hydroxyl radical scavenging rate of 2.5 μL of the tea beverage was 18.42 ± 0.98%, and that of 40 μL of the tea beverage was 36.62 ± 2.44%. In the reaction system for the determination of the hydroxyl radical scavenging rate, as the volume of the tea beverage increased, the hydroxyl radical scavenging rate gradually increased, indicating that the tea beverage has the ability to scavenge hydroxyl radicals.

[0119] In Example 7(2) above, the oxygen radical absorbance capacity of the tea beverage was detected, and the detection results are as Figure 3 shown. The area under the fluorescence decay curve (AUC 样品 ) of 1.25 μL - 20 μL of the tea beverage increased from 5.24 to 21.71. In the reaction system for the determination of the oxygen radical absorbance capacity, as the volume of the tea beverage increased, the oxygen radical absorbance capacity increased, indicating that the tea beverage has the ability to scavenge oxygen radicals. The relative ORAC value of the tea beverage was 1.59 ± 0.04 μmol TE / mL.

[0120] In Example 7(3) above, the total reducing power of the tea beverage was detected, and the detection results are as Figure 4 shown. The total reducing power A 700 of 31.3 μL of the tea beverage was 0.14, and the total reducing power A 700 of 500 μL of the tea beverage was 0.89. In the reaction system for the determination of the total reducing power, as the volume of the tea beverage increased, the total reducing power increased, indicating that the tea beverage has good reducing power activity.

[0121] In Example 7(4) above, the ABTS cation radical scavenging rate of the tea beverage was detected, and the detection results are as Figure 5 shown. The ABTS cation radical scavenging rate of 2.5 μL of the tea beverage was 44.00 ± 2.13%, and the ABTS cation radical scavenging rate reached the maximum of 93.70 ± 0.11% at 10 μL of the tea beverage. Between 10 μL - 40 μL of the tea beverage, the ABTS cation radical scavenging rate no longer increased. In the reaction system for the determination of the ABTS cation radical scavenging rate, as the volume of the tea beverage increased, the ABTS cation radical scavenging ability increased, indicating that the tea beverage has the ability to scavenge ABTS cation radicals.

[0122] In summary, detection methods such as hydroxyl radical scavenging ability, oxygen radical absorbance capacity, total reducing power, and ABTS cation radical scavenging ability are all important indicators for measuring the antioxidant ability of substances. The above results indicate that the tea beverage prepared in Example 5 has good antioxidant activity.

[0123] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A beverage of corn silk Pu-erh tea, characterized in that: The tea beverage is prepared from the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety, and mulberry leaves as raw materials.

2. The corn silk pu-erh tea beverage according to claim 1, wherein: Based on 1000 parts by weight, the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety is 1.5 - 5 parts, and mulberry leaves are 0.8 - 1.5 parts, with the balance being pure water.

3. The corn silk Pu-erh tea beverage according to claim 1 or 2, characterized in that: The co-fermentation product of corn silk and sun-dried green tea of large-leaf variety is prepared by the following method: Weigh dry corn silk, add pure water 12 - 20 times the weight of dry corn silk, perform vacuum reflux extraction at an extraction temperature of 100 °C and an extraction time of 20 - 30 min, filter the extract, under the condition of 80 °C, perform vacuum concentration, and finally spray-dry the concentrated solution to obtain powdered water extract of corn silk. Prepare a spore suspension of Thermomyces lanuginosus PE-3 with the preservation number CGMCC No.21065. According to the weight ratio of raw materials: 0.05 - 0.3 parts of aqueous extract of corn silk, 4 parts of sun-dried green tea of large-leaf variety. Mix the aqueous extract of corn silk and sun-dried green tea of large-leaf variety, add the spore suspension of Thermomyces lanuginosus PE-3, control the moisture content of the raw materials to be 35% - 40%, and inoculate 2.0×10 4 -2×10 6 individuals per 1 kg of dry weight of raw materials; Load it into a stainless-steel container, cover it with a wet gauze on top, cover the container lid, and place it in a fermentation chamber. The fermentation temperature is 55 ± 2 °C, the relative humidity is 30% - 40%, and after 22 - 30 days of fermentation, the fermentation ends. Perform ventilation and drying, and conduct re-screening and picking.

4. The corn silk Pu-erh tea beverage according to claim 3, wherein During the fermentation process, open the stainless-steel container and turn the fermented material 3 - 5 times.

5. The corn silk Pu-erh tea beverage according to claim 3, characterized in that, During the fermentation process, control the water content of the raw materials to be 35% - 40% by adding water.

6. The corn silk Pu-erh tea beverage according to claim 3, characterized in that, The specific preparation method of the spore suspension is as follows: Inoculate Thermomyces lanuginosus PE-3 with the preservation number CGMCC No.21065 onto a potato agar medium, place it in a constant-temperature incubator at 55 ± 2 °C for 3 - 5 days, transfer it 2 - 3 times. When the mycelium grows well and forms abundant mature spores, add sterile pure water, scrape off the spores with an inoculation loop to obtain a spore suspension, transfer this spore suspension into a sterilized Erlenmeyer flask containing glass beads and shake it well, and count using a hemocytometer for standby.

7. The corn silk Pu-erh tea beverage according to claim 1 or 2, characterized in that: The mulberry leaves are the mulberry leaves picked after the Frost's Descent.

8. A preparation method of the corn silk Pu-erh tea beverage according to any one of claims 1-7, characterized in that, This method includes using the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety, and mulberry leaves as raw materials, and through extraction, filtration, sterilization, and hot filling treatments to obtain the corn silk Pu-erh tea beverage.

9. The preparation method according to claim 8, wherein This method includes: Weigh the co-fermentation product of corn silk and sun-dried green tea of large-leaf variety and mulberry leaves as raw materials, preheat the pure water, perform hot extraction on the raw materials under the condition of 90 °C - 95 °C, extract 2 - 3 times, each extraction for 25 - 35 min, filter, combine the filtrates, after sterilization, perform hot filling, and spray cooling to obtain.

10. The preparation method according to claim 8 or 9, characterized in that, The sterilization adopts high-temperature short-time sterilization.

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