Medicinal and edible mulberry leaf drink substitute tea and processing method thereof

Abstract

The invention discloses medicinal and edible mulberry leaf drink substitute tea and a processing method thereof, and belongs to the technical field of mulberry leaf tea drink production. The processing method comprises the following steps: picking mulberry leaves, rinsing with ice water, carrying out synergistic fixation with ginger juice and steam, rolling and forming, dipping with a mulberry polysaccharide-iron compound solution in combination with a low-frequency electromagnetic field, and then treating with a staged oxygen-controlled fermentation process. Wherein the ginger juice steam enzyme deactivation system accelerates enzyme deactivation through the synergistic effect of ginger volatile oil and high-temperature steam under the conditions that the temperature is 105-110 DEG C and the pressure is 0.10-0.25 MPa; the mulberry polysaccharide-iron compound permeates into mulberry leaf cells under the assistance of a low-frequency electromagnetic field, and synthesis of gamma-aminobutyric acid is promoted; in the primary fermentation stage, eurotium cristatum is utilized to carry out anaerobic metabolism under mediation of Fe < 3 + >, and in the secondary fermentation, a metabolic pathway is optimized through combination of lactobacillus plantarum and bacillus subtilis. The prepared tea substitute is rich in GABA (gamma-aminobutyric acid), flavonoid substances and alkaloid substance DNJ, has the physiological effects of reducing blood sugar and blood fat, and can relieve pancreas burden.

Description

Technical Field

[0001] The present invention belongs to the technical field of mulberry leaf tea production, and particularly relates to a mulberry leaf substitute tea with both medicinal and edible properties and its processing method. Background Art

[0002] The mulberry tree, also known as Jing Sang, Sang Shen Shu, Huang Sang Ye, etc., is a deciduous perennial woody plant of the Moraceae family and the Morus genus. Mulberry leaves contain very rich nutrients such as sugar, protein, cellulose, and trace elements, and have the effects of nourishing yin and enriching blood, benefiting the liver and promoting qi flow, dispersing wind and heat, reducing blood pressure and diuresis, antibacterial and antivirus. As a medicine, mulberry leaves have a long history in China, dating back to "Shennong Ben Cao Jing" and "Chinese Medicine Dictionary", both of which record that mulberry is a "plant with both medicinal and edible properties". Mulberry leaves have functions such as reducing blood sugar, blood pressure, and blood lipids, anti-aging, anti-cancer, anti-tumor, antiviral, antibacterial and anti-inflammatory, spasmolysis, anti-ulcer, improving intestinal function, as well as beauty care and fat reduction.

[0003] As a typical resource of "plants with both medicinal and edible properties", mulberry leaves are rich in various bioactive components, including: 1-deoxynojirimycin (DNJ), a natural α-glucosidase inhibitor that can significantly inhibit the rise of postprandial blood sugar; γ-aminobutyric acid (GABA), which reduces blood pressure by regulating neurotransmitter activity; and flavonoids (such as rutin, isoquercitrin), polysaccharides, and trace elements, etc., which have effects such as antioxidant, anti-inflammatory, and immune regulation. However, the traditional processing technology of mulberry leaf substitute tea has obvious limitations: for example, high-temperature fixation is easy to cause the degradation of heat-sensitive components such as DNJ and GABA (the thermal decomposition temperature of DNJ is about 80°C), and the inactivation of polyphenol oxidase is not thorough, and polyphenols are easily oxidized to quinones during subsequent fermentation, reducing the functional activity; the metabolic pathway of single-strain fermentation is limited, and the accumulation of metabolic by-products caused by fluctuations in oxygen content affects the flavor. Therefore, it is urgent to develop a new processing technology that can synergistically retain active components and optimize fermentation metabolism to break through the existing bottlenecks and meet the market demand for functional substitute tea. Summary of the Invention

[0004] In view of the above situation, to overcome the defects of the prior art, the present invention provides a ginger juice steam synergistic fixation system, a mulberry polysaccharide-iron complex impregnation technology assisted by low-frequency electromagnetic fields, and a stepwise oxygen-controlled fermentation process, realizing the efficient retention of mulberry leaf active components and the directional conversion of functional metabolites.

[0005] To achieve the above object, the following technical solutions are adopted: The present invention provides a mulberry leaf substitute tea with both medicinal and edible properties and its processing method, and the mulberry leaf substitute tea with both medicinal and edible properties is prepared by the preparation method. The mulberry leaf substitute tea with both medicinal and edible properties and its processing method include the following steps: (1) Picking: Select young leaves with intact leaf veins and no pests and diseases, and pick fresh mulberry leaves at 5-8 am in the morning; (2)Rinsing: Rinse the mulberry leaves 3 times with ice water at 4°C for 3 minutes each time. Then add the rinsed mulberry leaves to a 0.1% sodium bicarbonate solution and soak for 2 minutes to remove pesticide residues. Then wash with clean water until neutral, and then centrifuge to dehydrate; (3)Ginger juice steam fixation: Break fresh raw ginger into ginger juice according to the mass ratio of ginger: water = 1:5. Then put the ginger juice into a partitioned container and connect it to a steam generator. Put the rinsed mulberry leaves on the upper layer of the ginger juice partitioned container and input steam for fixation; (4)Rolling and shaping: Pour the fixed mulberry leaves into a rolling machine for rolling; (5)Primary fermentation: Prepare a mulberry polysaccharide-iron complex solution with a mass fraction of 0.3 - 0.5%. Immerse the rolled and shaped mulberry leaves according to the mass ratio of material to liquid of 1:8, oscillate in a 45°C water bath for 2 hours, and apply a 50Hz low-frequency electromagnetic field at the same time. Then let the immersed mulberry leaves air-dry naturally for 1 - 2 hours, and inoculate Eurotium cristatum for primary fermentation; (6)Pressing and shaping: Put the fermentation product into a mold, press it into a fixed shape, demold after shaping, and air-dry naturally for 1 - 2 hours; (7)Secondary fermentation: Inoculate the pressed mulberry leaves with Lactobacillus plantarum and Bacillus subtilis for secondary fermentation; (8)Drying: Put the secondarily fermented mulberry leaves into a drying room for drying; (9)Storage in warehouse: Package and store the dried mulberry leaves in the warehouse to obtain the mulberry leaf substitute tea for both medicine and food, and store it in the dark.

[0006] Furthermore, the mulberry polysaccharide-iron complex is prepared through the following steps: Remove the stalks from mature mulberries and make them into pulp. Add deionized water according to the material-liquid ratio of 1:10 - 20. Then add 0.5% cellulose enzyme to the mixture, and perform ultrasonic-assisted extraction at 50°C and 200W for 30 minutes. Then centrifuge at 4000rpm for 15 minutes, take the supernatant, concentrate it to one-fourth of the volume, and then add 3 times the volume of absolute ethanol to precipitate the polysaccharide. Let it stand at 4°C for 12 hours to collect the precipitate. Dissolve the precipitate in deionized water, add a chloroform and n-butanol mixed solution accounting for 15 - 25% of the total volume of the precipitate and deionized water, where the volume ratio of chloroform to n-butanol is 4:1, and oscillate to remove proteins 3 times to remove the interfacial protein layer. Dialyze through an 8kDa filter membrane for 48 hours and freeze-dry to obtain mulberry polysaccharide. Dissolve the mulberry polysaccharide and ferric chloride in deionized water according to the mass ratio of 2:1, adjust the pH to 9 with 0.1mol / L sodium hydroxide solution, then centrifuge at 4000rpm for 15 minutes, take the supernatant, and freeze-dry to obtain the mulberry polysaccharide-iron complex.

[0007] Furthermore, the centrifugal dehydration speed is 4000 - 5000rpm, and centrifuge for 5 - 8 minutes.

[0008] Further, during steam fixation, the steam has a temperature of 105 - 110°C, a pressure of 0.10 - 0.25 MPa, and the fixation time is 3 - 5 min.

[0009] Further, during the rolling process, the rotational speed of the rolling machine is 40 - 50 rpm, and the rolling time is 20 - 30 min.

[0010] Further, the inoculation amount of Eurotium cristatum is 10 6 CFU / g. During the primary fermentation, vacuum is pumped to -0.08 MPa, nitrogen is filled to maintain O2 < 0.5%, the temperature is 25 - 35°C, the fermentation time is 6 - 8 h, and it is turned over every 8 - 12 h.

[0011] Further, the inoculation amount of Lactobacillus plantarum is 10 7 CFU / g, the inoculation amount of Bacillus subtilis is 10 7 CFU / g. During the secondary fermentation, the temperature is 28 - 32°C, the humidity is 60 - 70%, and the fermentation time is 12 - 24 h.

[0012] Further, the following procedure is adopted during the drying process: hot air circulation at 60°C for 3 h to make the water content of mulberry leaves < 30%, and then cold air drying at 40°C for 12 h to make the water content of mulberry leaves ≤ 6%.

[0013] The beneficial effects of the present invention are as follows: (1) In the present invention, a partitioned container is used to enable the steam to carry the volatile oil components (such as zingiberene and gingerol) in ginger juice, forming a composite fixation system of ginger juice and steam. The terpenoid substances in ginger juice and high-temperature steam act synergistically, not only effectively inactivating polyphenol oxidase, but also promoting the expansion of the stomata on the mulberry leaf epidermis, accelerating water evaporation, shortening the fixation time, and effectively retaining heat-sensitive components such as DNJ in mulberry leaves; (2) The present invention uses a mulberry polysaccharide-iron complex solution to impregnate mulberry leaves and combines it with low-frequency electromagnetic field treatment. The low-frequency electromagnetic field increases the permeability of the mulberry leaf cell membrane, promotes the penetration of the polysaccharide-iron complex, and the nano-scale colloidal particles formed by the mulberry polysaccharide-iron complex can penetrate the cell wall. As an electron acceptor, iron elements can activate the glutamate decarboxylase system, improving the conversion efficiency of γ-aminobutyric acid; (3) At the primary fermentation stage, Eurotium cristatum completes electron transfer with the assistance of Fe 3+ Fe 3+ acts as an electron acceptor to participate in the respiratory chain transfer of Eurotium cristatum, improving the conversion rate of polyphenolic substances, avoiding the excessive generation of quinone substances caused by oxygen fluctuations in traditional fermentation, and reducing metabolic by-products; (4)The mulberry leaf tea substitute prepared by the present invention contains rich GABA, flavonoids and alkaloid DNJ. Flavonoids have the effects of lowering blood sugar, blood lipids and blood pressure, and GABA and DNJ can also assist in reducing blood sugar. Therefore, the tea substitute prepared by the present invention has the physiological effects of lowering blood sugar and blood lipids and reducing the burden on the pancreas. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the detection result of GABA content in the mulberry leaf tea substitute prepared in each example and comparative example of the present invention; Figure 2 It is the detection result of DNJ content in the mulberry leaf tea substitute prepared in each example and comparative example of the present invention; Figure 3 It is the detection result of fasting blood glucose of mice in the evaluation of the influence of the mulberry leaf tea substitute prepared in each example and comparative example of the present invention on blood sugar and blood lipids; Figure 4 It is the detection result of four blood lipid items of mice in the evaluation of the influence of the mulberry leaf tea substitute prepared in each example and comparative example of the present invention on blood sugar and blood lipids; Figure 5 It is the detection result of insulin level of mice in the evaluation of the influence of the mulberry leaf tea substitute prepared in each example and comparative example of the present invention on blood sugar and blood lipids.

[0015] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0017] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are only for demonstration purposes, but cannot limit the content of this application.

[0018] The experimental methods in the following embodiments are all conventional methods unless otherwise specified. The test materials used in the following embodiments are all obtained from commercial channels unless otherwise specified. Example 1

[0019] A mulberry leaf substitute tea with both medicinal and edible properties and its processing method. The mulberry leaf substitute tea with both medicinal and edible properties is prepared by the said preparation method. The mulberry leaf substitute tea with both medicinal and edible properties and its processing method include the following steps: (1) Picking: Select young leaves with intact leaf veins and no pests or diseases, and pick fresh mulberry leaves at 5:00 in the morning. (2) Rinsing: Rinse the mulberry leaves 3 times with 4°C ice water for 3 minutes each time. Then add the rinsed mulberry leaves to a 0.1% sodium bicarbonate solution and soak for 2 minutes to remove pesticide residues. Then wash with clean water until neutral, and then perform centrifugal dehydration. (3) Ginger juice steam fixation: Break fresh raw ginger into ginger juice according to the mass ratio of ginger: water = 1:5. Then put the ginger juice into a partitioned container and connect a steam generator. Put the rinsed mulberry leaves on the upper layer of the ginger juice partitioned container and input steam for fixation. (4) Rolling and forming: Pour the fixed mulberry leaves into a rolling machine for rolling. (5) Primary fermentation: Prepare a mulberry polysaccharide-iron complex solution with a mass fraction of 0.3%. Immerse the rolled mulberry leaves according to the mass ratio of material to liquid of 1:8, oscillate in a 45°C water bath for 2 hours, and apply a 50Hz low-frequency electromagnetic field at the same time. Then let the immersed mulberry leaves air-dry for 1 hour, and inoculate Eurotium cristatum for primary fermentation. (6) Compacting and forming: Put the fermentation product into a mold, press it into a fixed shape, demold after shaping, and air-dry for 1 hour. (7) Secondary fermentation: Inoculate Lactobacillus plantarum and Bacillus subtilis into the compacted mulberry leaves for secondary fermentation. (8) Drying: Put the secondarily fermented mulberry leaves into a drying room for drying. (9) Storage in warehouse: Package the dried mulberry leaves and store them in the warehouse to obtain the mulberry leaf substitute tea with both medicinal and edible properties, and store them in the dark. The mulberry polysaccharide-iron complex is prepared by the following steps: Remove the stalks from mature mulberries and make a pulp. Add deionized water according to the material-liquid ratio of 1:10. Then add 0.5% cellulase by mass to the mixture, and perform ultrasonic-assisted extraction at 50°C and 200W for 30 minutes. Then centrifuge at 4000rpm for 15 minutes, take the supernatant, concentrate it to one-fourth of the volume, and then add 3 times the volume of anhydrous ethanol to precipitate the polysaccharide. Let it stand at 4°C for 12 hours to collect the precipitate. Dissolve the precipitate in deionized water, add a chloroform and n-butanol mixed solution accounting for 15% of the total volume of the precipitate and deionized water, where the volume ratio of chloroform to n-butanol is 4:1, and oscillate to remove protein 3 times to remove the interfacial protein layer. Dialyze through an 8kDa filter membrane for 48 hours and lyophilize to obtain mulberry polysaccharide. Dissolve the mulberry polysaccharide and ferric chloride in deionized water according to the mass ratio of 2:1, adjust the pH = 9 with 0.1mol / L sodium hydroxide solution, then centrifuge at 4000rpm for 15 minutes, take the supernatant, and lyophilize to obtain the mulberry polysaccharide-iron complex. The centrifugal dehydration speed is 4000 rpm, and centrifugation is carried out for 5 min. During steam fixation, the steam temperature is 105 °C, the pressure is 0.10 MPa, and the fixation time is 3 min. During the rolling process, the rotation speed of the rolling machine is 40 rpm, and rolling is carried out for 20 min. The inoculation amount of Eurotium cristatum is 10 6 CFU / g. During the primary fermentation, vacuum is drawn to -0.08 MPa, nitrogen is filled to maintain O2 < 0.5%, the temperature is 25 °C, the fermentation time is 6 h, and it is turned over every 8 h. The inoculation amount of Lactobacillus plantarum is 10 7 CFU / g, the inoculation amount of Bacillus subtilis is 10 7 CFU / g. During the secondary fermentation, the temperature is 28 °C, the humidity is 60%, and the fermentation is carried out for 12 h. During the drying process, the following procedure is adopted: hot air circulation at 60 °C for 3 h to make the water content of mulberry leaves < 30%, and then cold air drying at 40 °C for 12 h to make the water content of mulberry leaves ≤ 6%. Example 2

[0020] A medicinal and edible mulberry leaf substitute tea and its processing method. The medicinal and edible mulberry leaf substitute tea is prepared by the preparation method. The medicinal and edible mulberry leaf substitute tea and its processing method include the following steps: (1) Picking: Select young leaves with intact leaf veins and no pests and diseases, and pick fresh mulberry leaves at 8 am in the morning; (2) Rinsing: Rinse the mulberry leaves 3 times with 4 °C ice water for 3 min each time. Then add the rinsed mulberry leaves to a 0.1% sodium bicarbonate solution and soak for 2 min to remove pesticide residues. Then wash with clean water until neutral, and then carry out centrifugal dehydration; (3) Ginger juice steam fixation: Break fresh raw ginger into ginger juice according to the mass ratio of ginger: water = 1:5. Then put the ginger juice into a partition container and connect a steam generator. Put the rinsed clean mulberry leaves on the upper layer of the ginger juice partition container and input steam for fixation; (4) Rolling and forming: Pour the fixed mulberry leaves into a rolling machine for rolling; (5) Primary fermentation: Prepare a mulberry polysaccharide-iron complex solution with a mass fraction of 0.5%, impregnate the rolled and formed mulberry leaves according to the mass ratio of material to liquid of 1:8, oscillate in a 45 °C water bath for 2 h, and apply a 50 Hz low-frequency electromagnetic field at the same time. Then let the impregnated mulberry leaves air-dry naturally for 2 h, and inoculate Eurotium cristatum for primary fermentation; (6) Compacting and forming: Put the fermentation product into a mold, press it into a fixed shape, demold after shaping, and air-dry naturally for 2 h; (7) Secondary fermentation: inoculate Lactobacillus plantarum and Bacillus subtilis into the compacted mulberry leaves for secondary fermentation; (8) Drying: put the mulberry leaves after secondary fermentation into a drying room for drying; (9) Storage in warehouse: pack and store the dried mulberry leaves in a warehouse to obtain the mulberry leaf substitute tea with both medicinal and edible properties, and store it in the dark. The mulberry polysaccharide-iron complex is prepared by the following steps: remove the stalks from mature mulberries and make them into pulp, add deionized water according to the ratio of material to liquid of 1:20, then add 0.5% by mass of cellulase to the mixture, perform ultrasonic-assisted extraction at 50 °C and 200 W for 30 min, then centrifuge at 4000 rpm for 15 min, take the supernatant, concentrate it to one-fourth of the volume, add 3 times the volume of absolute ethanol to precipitate polysaccharides, let it stand at 4 °C for 12 h to collect the precipitate, dissolve the precipitate in deionized water, add a chloroform and n-butanol mixed solution accounting for 25% of the total volume of the precipitate and deionized water, where the volume ratio of chloroform to n-butanol is 4:1, shake it to remove proteins 3 times, remove the interfacial protein layer, dialyze through an 8 kDa filter membrane for 48 h, and freeze-dry to obtain mulberry polysaccharide. Dissolve the mulberry polysaccharide and ferric chloride in deionized water according to the mass ratio of 2:1, adjust the pH = 9 with 0.1 mol / L sodium hydroxide solution, then centrifuge at 4000 rpm for 15 min, take the supernatant, and freeze-dry to obtain the mulberry polysaccharide-iron complex. The centrifugal dehydration speed is 5000 rpm and the centrifugation time is 8 min. During steam fixation, the steam temperature is 110 °C, the pressure is 0.25 MPa, and the fixation time is 5 min. During the rolling process, the rotation speed of the rolling machine is 50 rpm and the rolling time is 30 min. The inoculation amount of Eurotium cristatum is 10 6 CFU / g. During the primary fermentation, evacuate to -0.08 MPa, fill with nitrogen to maintain O2 < 0.5%, the temperature is 35 °C, the fermentation time is 8 h, and turn it over every 12 h. The inoculation amount of Lactobacillus plantarum is 10 7 CFU / g, the inoculation amount of Bacillus subtilis is 10 7 CFU / g. The temperature of the secondary fermentation is 32 °C, the humidity is 70%, and the fermentation time is 24 h. The following program is adopted during the drying process: hot air circulation at 60 °C for 3 h to make the water content of mulberry leaves < 30%, and then cool air drying at 40 °C for 12 h to make the water content of mulberry leaves ≤ 6%. Example 3

[0021] A mulberry leaf substitute tea with both medicinal and edible properties and its processing method. The mulberry leaf substitute tea with both medicinal and edible properties is prepared by the said preparation method. The mulberry leaf substitute tea with both medicinal and edible properties and its processing method include the following steps: (1)Picking: Select young leaves with intact leaf veins and no pests or diseases, and pick fresh mulberry leaves at 6:00 in the morning. (2)Rinsing: Rinse the mulberry leaves 3 times with 4°C ice water for 3 minutes each time. Then add the rinsed mulberry leaves to a 0.1% sodium bicarbonate solution and soak for 2 minutes to remove pesticide residues. Then wash with clean water until neutral, and then perform centrifugal dehydration. (3)Ginger juice steam fixation: Crush fresh raw ginger according to a mass ratio of ginger: water = 1:5 to obtain ginger juice. Then put the ginger juice into a partitioned container and connect it to a steam generator. Put the rinsed mulberry leaves on the upper layer of the ginger juice partitioned container and input steam for fixation. (4)Rolling and shaping: Pour the fixed mulberry leaves into a rolling machine for rolling. (5)Primary fermentation: Prepare a 0.4% polysaccharide-iron complex solution of mulberry fruit. Immerse the rolled and shaped mulberry leaves according to a material-liquid mass ratio of 1:8, oscillate in a 45°C water bath for 2 hours, and apply a 50Hz low-frequency electromagnetic field at the same time. Then let the immersed mulberry leaves air-dry for 1.5 hours and inoculate Eurotium cristatum for primary fermentation. (6)Pressing and shaping: Put the fermentation product into a mold, press it into a fixed shape, demold after shaping, and air-dry for 1.5 hours. (7)Secondary fermentation: Inoculate Lactobacillus plantarum and Bacillus subtilis into the pressed mulberry leaves for secondary fermentation. (8)Drying: Put the secondarily fermented mulberry leaves into a drying room for drying. (9)Storage in warehouse: Package and store the dried mulberry leaves in a warehouse to obtain the mulberry leaf substitute tea with both medicinal and edible properties, and store it in the dark. The polysaccharide-iron complex of mulberry fruit is prepared by the following steps: Remove the stalks from mature mulberry fruit and make a pulp. Add deionized water according to a material-liquid ratio of 1:15, and then add 0.5% cellulase by mass to the mixture. Assist extraction with ultrasonic waves at 50°C and 200W for 30 minutes, then centrifuge at 4000rpm for 15 minutes, take the supernatant, concentrate it to one-fourth of the volume, and then add 3 times the volume of absolute ethanol to precipitate the polysaccharide. Let it stand at 4°C for 12 hours to collect the precipitate. Dissolve the precipitate in deionized water, add a chloroform and n-butanol mixed solution accounting for 20% of the total volume of the precipitate and deionized water, where the volume ratio of chloroform to n-butanol is 4:1, oscillate to remove protein 3 times, remove the interfacial protein layer, dialyze through an 8kDa filter membrane for 48 hours, and lyophilize to obtain mulberry polysaccharide. Dissolve the mulberry polysaccharide and ferric chloride in deionized water according to a mass ratio of 2:1, adjust the pH = 9 with 0.1mol / L sodium hydroxide solution, then centrifuge at 4000rpm for 15 minutes, take the supernatant, and lyophilize to obtain the polysaccharide-iron complex of mulberry fruit. The rotation speed of the centrifugal dehydration is 4500rpm, and the centrifugation time is 6.5 minutes. During steam fixation, the steam temperature is 107°C, the pressure is 0.18 MPa, and the fixation time is 4 min. During the rolling process, the rotation speed of the rolling machine is 45 rpm, and the rolling time is 25 min. The inoculation amount of Eurotium cristatum is 10 6 CFU / g. During the primary fermentation, vacuum is drawn to -0.08 MPa, nitrogen is filled to maintain O2 < 0.5%, the temperature is 30°C, the fermentation time is 7 h, and it is turned over every 10 h. The inoculation amount of Lactobacillus plantarum is 10 7 CFU / g, the inoculation amount of Bacillus subtilis is 10 7 CFU / g. During the secondary fermentation, the temperature is 30°C, the humidity is 65%, and the fermentation time is 18 h. During the drying process, the following procedure is adopted: hot air circulation at 60°C for 3 h to make the water content of mulberry leaves < 30%, and then cold air drying at 40°C for 12 h to make the water content of mulberry leaves ≤ 6%.

[0022] Comparative Example 1 In this comparative example, steam generated directly by a steam generator is used to fix the rinsed mulberry leaves, and ginger juice steam fixation is not adopted. The rest are the same as in Example 3.

[0023] Comparative Example 2 In this comparative example, the mulberry leaves are not impregnated with a mulberry polysaccharide-iron complex solution, and a 50 Hz low-frequency electromagnetic field is not applied. The rolled mulberry leaves are directly air-dried for 1 h and then inoculated with Eurotium cristatum for primary fermentation. The rest are the same as in Example 3.

[0024] Comparative Example 3 In this comparative example, a mulberry polysaccharide-iron complex solution with a mass fraction of 0.4% (without adding an iron complex) is prepared to replace the mulberry polysaccharide-iron complex solution for impregnating the mulberry leaves. The rest are the same as in Example 3.

[0025] Test Example 1 GABA content detection Experimental equipment: high performance liquid chromatograph (Agilent 1260), fluorescence detector (λex = 335 nm, λem = 420 nm); Standard: GABA standard (purity ≥ 99%, Shanghai Macklin Biochemical Co., Ltd.); Sample treatment: Take 5 g of the mulberry leaf substitute tea samples prepared in each example and comparative example, add 50 mL of an ethanol solution with a mass fraction of 80%, perform ultrasonic-assisted extraction for 30 min (power 200 W, temperature 50°C), centrifuge at 4000 rpm for 15 min, and take the supernatant to pass through a 0.45 μm filter membrane; Chromatographic conditions: C18 chromatographic column (4.6×250 mm, 5 μm); mobile phase: 0.05 mol / L potassium dihydrogen phosphate buffer (pH 6.0) - acetonitrile (85:15, v / v); flow rate 1.0 mL / min; column temperature 35 °C.

[0026] The above detection results of GABA content are shown in Figure 1 .

[0027] Through Figure 1 It can be seen that the content of GABA in the examples is significantly higher than that in the comparative examples. Thanks to the dual effects of ginger juice steam greening and mulberry polysaccharide-iron complex, the ginger juice volatile oil accelerates water evaporation by expanding the pores of mulberry leaves, shortens the heat exposure time, and reduces the thermal decomposition of GABA; while the mulberry polysaccharide-iron complex acts as an electron acceptor, activates the glutamate decarboxylase system, and promotes the efficient conversion of glutamate to GABA.

[0028] Test Example 2 Determination of DNJ content Experimental equipment: high performance liquid chromatograph (Agilent 1260), evaporative light scattering detector; Standard: DNJ standard (purity ≥ 98%, Shanghai Yuanye Bio-Technology Co., Ltd.) Sample preparation: Take 5 g of the mulberry leaf substitute tea samples prepared in each example and comparative example, add 50 mL of 0.1 mol / L hydrochloric acid solution, hydrolyze in a boiling water bath for 2 h, cool, adjust to neutral with 1 mol / L NaOH solution, centrifuge at 4000 rpm for 15 min, and filter the supernatant through a 0.45 μm filter membrane; Chromatographic conditions: amino column (4.6×250 mm, 5 μm); mobile phase: acetonitrile - water (75:25, v / v); flow rate 1.0 mL / min; column temperature 30 °C; ELSD drift tube temperature 80 °C, carrier gas flow rate 2.5 L / min.

[0029] The above detection results of DNJ content are shown in Figure 2 .

[0030] Figure 2 Among them, the DNJ content in each example is higher. What is achieved by ginger juice steam temperature-controlled greening (rapid inactivation of polyphenol oxidase, reduction of DNJ degradation, provision of interlayer steam penetration to shorten the treatment time, and improvement of DNJ retention rate).

[0031] Test Example 3 Evaluation of the effects of mulberry leaf substitute tea on blood glucose and blood lipids Experimental animals: Take 90 SPF-grade KM (Kunming) mice, 7 - 8 months old, half male and half female, provided by Beijing Vital River Laboratory Animal Technology Co., Ltd.

[0032] Feeding conditions: Feeding temperature: 22±2°C, relative humidity: 55 - 75%, 12h light-dark cycle, free access to standard rodent feed and sterilized water.

[0033] Animal adaptation and model establishment: After the mice were purchased, they were adaptively fed for 14 days, during which the basic physiological indicators were observed and recorded. Randomly select 10 as the normal control group, and the remaining 80 were used to induce type 2 diabetes model by STZ / NA combined modeling method, as the negative control group, positive control group, example group and comparative example group. The modeling method is as follows: Fast for 12h before modeling without water restriction; Intraperitoneally inject STZ (streptozotocin, dissolved in 0.1mol / L citric acid buffer, pH4.5) at 60mg / kg body weight for 2 consecutive days; On the 7th day after modeling, detect fasting blood glucose (FBG≥11.1mmol / L and accompanied by symptoms of excessive drinking and eating) as a successful model.

[0034] Experimental grouping: Normal control group (NC group): Gavage normal saline (0.2mL / 10g body weight) daily; Negative control group (MC group): Gavage normal saline (0.2mL / 10g body weight) daily; Positive control group (PC group): Gavage metformin hydrochloride (200mg / kg body weight) daily; Example group (E1 - E3 groups): Gavage mulberry leaf tea drink (0.3g / mL, 0.2mL / 10g body weight) daily; Comparative example group (C1 - C3 groups): Gavage mulberry leaf tea drink (0.3g / mL, 0.2mL / 10g body weight) daily.

[0035] Index observation: Record the food intake, water intake and body weight changes daily; Observe the hair color gloss, skin cleanliness and mental state of the mice weekly.

[0036] Biochemical index detection: Fasting blood glucose (FBG): After 6 weeks of the experiment, fast for 6h, collect blood from the tail vein, and provide it for detection with a blood glucose meter; Four lipid items: Collect blood from the orbital venous plexus at the 7th week of the experiment. After centrifuging to separate the serum, use an automatic biochemical analyzer to detect TG (triglyceride), CHO (total cholesterol), HDL-C (high-density lipoprotein cholesterol), LDL-C (low-density lipoprotein cholesterol); Insulin (INS): Collect blood from the orbital venous plexus at the 7th week of the experiment, and use ELISA method to detect the serum insulin level.

[0037] The above results are shown in Figures 3 - 5 .

[0038] FromFigures 3 - 5 As can be seen from the results, the mulberry leaf tea substitute prepared by the present invention has significant effects in reducing blood sugar and blood lipids, improves the average fasting blood sugar value, has a certain effect on increasing high-density lipoprotein in serum and reducing triglyceride, total cholesterol, and low-density lipoprotein in serum. At the same time, it can effectively reduce the production of insulin in the serum of type II diabetic mice and reduce the burden on the islets of type II diabetic mice.

[0039] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0040] The above describes the present invention and its implementation manners. Such a description is not restrictive. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual application is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and design similar ways and embodiments to this technical solution without creative efforts without departing from the purpose of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A method for processing mulberry leaves as tea substitute with both medicinal and edible properties, characterized in that: The following steps are involved: (1) Picking: Select young leaves with intact veins and no pests or diseases, and pick fresh mulberry leaves between 5 and 8 in the morning; (2) Rinse: Rinse the mulberry leaves with 4°C ice water for 3 times, 3 minutes each time, then add the rinsed mulberry leaves to 0.1% sodium bicarbonate solution and soak for 2 minutes to remove pesticide residues, then wash with clean water until neutral, and then centrifuge to dehydrate; (3) Steam sterilization with ginger juice: crush fresh ginger according to the mass ratio of ginger: water = 1:5 to obtain ginger juice, then put the ginger juice into a compartment container, connect it to a steam generator, put the rinsed mulberry leaves into the upper layer of the ginger juice compartment container, and input steam to sterilize the leaves; (4) Rolling and forming: pour the withered mulberry leaves into the rolling machine and roll them; (5) Primary fermentation: prepare a 0.3-0.5% mass fraction of mulberry polysaccharide-iron complex solution, soak the rolled mulberry leaves at a mass ratio of 1:8, oscillate in a 45°C water bath for 2 h, apply a 50 Hz low-frequency electromagnetic field, then let the soaked mulberry leaves air-dry for 1-2 h, and inoculate with Eurotium cristoloniferum for primary fermentation; (6) Pressing and forming: The fermented product is placed into a mold and pressed into a fixed shape. After the shape is fixed, the product is demoulded and allowed to dry naturally for 1-2 hours. (7) Secondary fermentation: The compressed mulberry leaves are inoculated with Lactobacillus plantarum and Bacillus subtilis for secondary fermentation; (8) Drying: Put the mulberry leaves after secondary fermentation into a drying room for drying; (9) Storage: The dried mulberry leaves are packaged and stored to obtain the mulberry leaf tea substitute with medicinal and edible properties, and stored away from light; The mulberry polysaccharide-iron complex is prepared by the following steps: removing the stems of mature mulberries and beating them, adding deionized water at a solid-liquid ratio of 1:10-20, adding 0.5% by weight of cellulase to the mixture, performing ultrasonic-assisted extraction at 50°C and 200W for 30 minutes, and then centrifuging at 4000rpm for 15 minutes, taking the supernatant, concentrating it to a quarter of its volume, adding 3 times the volume of anhydrous ethanol to precipitate polysaccharides, standing at 4°C for 12 hours to collect the precipitate, dissolving the precipitate in deionized water, and adding the precipitate. A mixed solution of chloroform and n-butanol with a total volume of 15-25% of the precipitate and deionized water, wherein the volume ratio of chloroform to n-butanol is 4:1, oscillate to deproteinize 3 times, remove the interface protein layer, dialyze through an 8kDa filter membrane for 48 hours, and freeze-dry to obtain mulberry polysaccharide, dissolve mulberry polysaccharide and ferric chloride in deionized water at a mass ratio of 2:1, adjust the pH to 9 with 0.1mol / L sodium hydroxide solution, centrifuge at 4000rpm for 15min, take the supernatant, and freeze-dry to obtain the mulberry polysaccharide-iron complex.

2. The method for processing a mulberry leaf tea substitute with both medicinal and edible properties according to claim 1, characterized in that: The centrifugal dehydration speed is 4000-5000 rpm, and the centrifugation is 5-8 minutes.

3. The method for processing a mulberry leaf tea substitute with both medicinal and edible properties according to claim 2, characterized in that: During the steam killing, the steam temperature is 105-110° C., the pressure is 0.10-0.25 MPa, and the killing time is 3-5 min.

4. The method for processing a mulberry leaf tea substitute with both medicinal and edible properties according to claim 3, characterized in that: During the kneading process, the rotation speed of the kneading machine is 40-50 rpm, and the kneading is performed for 20-30 minutes.

5. The method for processing a mulberry leaf tea substitute with both medicinal and edible properties according to claim 4, characterized in that: The inoculation amount of the crown-shaped spores is 10 6 CFU / g, during the initial fermentation, the vacuum is evacuated to -0.08MPa, nitrogen is inflated to maintain oxygen <0.5%, the temperature is 25-35°C, the fermentation time is 6-8h, and the fermentation is stirred every 8-12h.

6. The method for processing a mulberry leaf tea substitute with both medicinal and edible properties according to claim 5, characterized in that: The inoculation amount of the plant lactobacillus is 10 7 CFU / g, the inoculation amount of Bacillus subtilis is 10 7 CFU / g, the secondary fermentation temperature is 28-32°C, the humidity is 60-70%, and the fermentation is 12-24h.

7. The method for processing a mulberry leaf tea substitute with both medicinal and edible properties according to claim 6, characterized in that: The drying process adopts the following procedure: hot air circulation at 60°C for 3 hours to make the moisture content of the mulberry leaves less than 30%, and then cold air drying at 40°C for 12 hours to make the moisture content of the mulberry leaves ≤6%.

8. A mulberry leaf tea substitute with both medicinal and edible properties, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

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