Preparation method of functional natural polysaccharide adhesive

Abstract

The invention relates to a preparation method of a functional natural polysaccharide adhesive, which comprises the following steps: fermenting dried orange peel by using poria cocos zymophyte powder, extracting mixed polysaccharide, and cutting the mixed polysaccharide into large, medium and small molecular weight base materials through an ultrafiltration membrane; then poria cocos zymophyte powder is used for fermenting folium cortex eucommiae, raspberry tea powder is added for combined extraction of genipin and dihydromyricetin, the combined extract can improve the mechanical performance, antibacterial performance and the like of the polysaccharide adhesive, the flexibility of the polysaccharide adhesive is improved, and the brittleness of the polysaccharide adhesive is reduced; and fully mixing the polysaccharide base material with the combined extract of genipin and dihydromyricetin to prepare the functional natural polysaccharide adhesive. The functional natural polysaccharide adhesive is good in adhesive property and stability, has biocompatibility and biodegradability, is green, environment-friendly, non-toxic and harmless, further has multiple biological activity functions such as tumor resistance, oxidation resistance, inflammation resistance, bacterium resistance and immunity improvement, and can be widely applied to multiple fields such as food, cosmetics and medicine.

Description

Technical Field

[0001] The present application relates to the field of biomaterial engineering, and more specifically, to a method for preparing a functional natural polysaccharide adhesive. Background Art

[0002] As an important connecting material, adhesives play an indispensable role in daily life, industrial production and medical fields. According to the different properties of the materials, adhesives are mainly divided into two categories: chemical adhesives and biological adhesives. Chemical adhesives have long been the mainstream products on the market due to their strong bonding ability and wide range of applications. However, during use, such adhesives often release chemicals that are harmful to the human body, have potential chemical toxicity, and pose a threat to the environment and human health. In order to overcome this defect of chemical adhesives, biological adhesives came into being. Bioadhesives are made of natural polymer materials and have significant advantages such as non-toxicity, good biocompatibility and biodegradability. These characteristics make bioadhesives show great application potential in the medical field, especially in situations where high biosafety and degradability are required. In recent years, bioadhesives have become a research hotspot in the fields of materials science and biomedical engineering.

[0003] Among the many types of bioadhesives, polysaccharide adhesives have attracted much attention due to their wide source of raw materials and strong renewability. Polysaccharides are extremely widely distributed in nature and are an important renewable resource on the earth. Among them, starch, chitosan, sodium alginate, etc. are often used to develop new bioadhesives due to their unique chemical structure and biological activity. These polysaccharides are not only non-toxic and degradable, but also have good compatibility with human tissues, providing a rich selection of raw materials for the preparation of bioadhesives.

[0004] However, adhesives prepared using polysaccharides alone often have limited bonding strength and are difficult to meet certain high-strength bonding requirements. In order to improve the bonding performance of bioadhesives, researchers often use cross-linking composite methods to composite polysaccharides with other materials (such as proteins, cellulose, synthetic polymers, etc.) in order to obtain higher bonding strength and a wider range of applications.

[0005] In view of the above background, the present invention aims to provide a new type of bioadhesive, which uses polysaccharides as the main raw materials and achieves a significant improvement in bonding strength through a specific cross-linking composite technology. Summary of the invention

[0006] The invention provides a preparation method of a functional natural polysaccharide adhesive. The method comprises the following steps: using tuckahoe fermented bacteria powder to ferment tangerine peel, extracting a mixed polysaccharide containing tuckahoe mycelium polysaccharide and tangerine peel polysaccharide, cutting the mixed polysaccharide into large, medium and small molecular weight polysaccharides through an ultrafiltration membrane as a natural high molecular weight base material for the adhesive, fermenting eucommia leaves with tuckahoe fermented bacteria powder, adding berry tea powder to the eucommia leaf fermentation product to carry out joint extraction of genipin and dihydromyricetin, the joint extract serving as an additive having the functions of a cross-linking agent and a curing agent can improve the mechanical properties and antibacterial properties of the polysaccharide adhesive, increase its flexibility and reduce its brittleness, and fully mixing the large, medium and small molecular weight polysaccharide base materials with the joint extract of genipin and dihydromyricetin to prepare a functional natural polysaccharide adhesive with good bonding performance, good stability, non-toxicity, harmlessness and green environmental protection. The functional natural polysaccharide adhesive can be widely used in multiple fields such as food, cosmetics and medicine.

[0007] In order to achieve the above invention objectives, this application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a method for preparing a functional natural polysaccharide adhesive, the method comprising the following steps:

[0009] (1) fermenting tangerine peel: dissolving the fermented Poria cocos powder in distilled water and spraying the mixture on the tangerine peel, and fermenting under intermittent high temperature conditions;

[0010] (2) extracting mixed polysaccharides: drying the fermentation product of step (1) and then crushing it, adding distilled water to reflux extraction, filtering out insoluble impurities, decompressing and concentrating the filtrate, adding 95% ethanol and standing overnight to precipitate polysaccharides, suction filtering, washing the precipitate with anhydrous ethanol, and low-temperature drying to obtain a mixed polysaccharide crude product containing Poria mycelium polysaccharide and tangerine peel polysaccharide; dissolving the mixed polysaccharide crude product in distilled water, adding Sevag reagent, shaking thoroughly, standing and stratifying, discarding the lower organic phase, repeating the operation for multiple times until there is no white suspension at the interface, suction filtering the collected polysaccharide solution, freeze-drying, that is, obtaining a refined mixed polysaccharide containing Poria mycelium polysaccharide and tangerine peel polysaccharide, grinding into powder, and storing in a dry environment for later use;

[0011] (3) Preparation of polysaccharide base material: taking the mixed polysaccharide powder containing Poria mycelium polysaccharide and tangerine peel polysaccharide prepared in step (2), adding distilled water, stirring and dissolving, diluting, and then ultrafiltration using ultrafiltration membranes with different molecular weight cutoffs to cut the polysaccharides into different molecular weights, collecting the filtrate at each level, concentrating, filtering, freeze-drying, and grinding into powder, so as to obtain mixed polysaccharides of different molecular weights as a natural polymer base material for making an adhesive;

[0012] (4) Fermenting Eucommia ulmoides leaves: dissolving the Poria cocos fermented fungus powder in distilled water and spraying the mixture on the Eucommia ulmoides leaves, and fermenting under intermittent high temperature conditions;

[0013] (5) Combined extraction of genipin and dihydromyricetin: drying and crushing the fermented product of Eucommia ulmoides leaves in step (4), mixing with berry tea powder, and carrying out combined extraction, adding distilled water for reflux extraction, filtering to remove insoluble impurities, adding β-glucosidase to the filtrate for water bath enzymolysis, filtering, and boiling the filtrate to inactivate the enzyme; concentrating the filtrate under reduced pressure, filtering, freeze-drying to obtain a crude extract, recrystallizing to obtain a refined combined extract of genipin and dihydromyricetin, using the additive as both a cross-linking agent and a curing agent, freeze-drying, grinding into granular powder, and storing in a dry environment for later use;

[0014] (6) Glue preparation: The polysaccharide base prepared in step (3) is mixed with the genipin and dihydromyricetin combined extract in step (5), distilled water is added to the mixed powder, the mixture is stirred thoroughly and allowed to stand for swelling, and a natural polysaccharide adhesive is obtained.

[0015] Preferably, the specific steps of step (1) are: dissolving the Poria cocos fermentation powder with distilled water, spraying it evenly on the tangerine peel according to a 1% inoculation amount, controlling the intermittent high temperature conditions, raising the temperature to 70°C for 30 minutes every day, and then cooling it to 30°C to maintain the fermentation process. The fermentation time is 30 days.

[0016] Preferably, the specific steps of step (2) are: drying the tangerine peel fermentation product containing Poria mycelium in step (1) at 80°C and then crushing it, adding distilled water at a solid-liquid ratio of 1:10 and reflux extraction at 60°C for 2h, filtering to remove insoluble impurities, decompressing and concentrating the filtrate, adding 5 times the volume of 95% ethanol, standing at 4°C overnight to precipitate polysaccharides, filtering with suction, washing the precipitate with anhydrous ethanol, and drying at low temperature to obtain a mixed polysaccharide crude product containing Poria mycelium polysaccharide and tangerine peel polysaccharide; dissolving the mixed polysaccharide crude product in distilled water, adding Sevag reagent, shaking thoroughly, standing and stratifying, discarding the lower organic phase, continuously operating for multiple times until there is no white suspension at the interface, filtering the collected polysaccharide solution, freeze-drying, that is, obtaining a refined mixed polysaccharide containing Poria mycelium polysaccharide and tangerine peel polysaccharide, grinding it into a powder with a particle size of less than or equal to 0.2 mm, and storing it in a dry environment for standby use.

[0017] Preferably, the specific steps of step (3) are: take the mixed polysaccharide powder containing Poria mycelium polysaccharide and tangerine peel polysaccharide prepared in step (2), add distilled water, stir and dissolve thoroughly, dilute 5 times and then load into ultrafiltration equipment, under the conditions of ultrafiltration pressure 0.6MPa, ultrafiltration temperature 40°C, and ultrafiltration time 30min, use ultrafiltration membranes with cutoff molecular weights of 500kD, 300kD, 100kD, 70kD, and 5kD to perform ultrafiltration, cut the polysaccharides into different molecular weights, collect the filtrate at each level, concentrate, filter, freeze-dry, and grind into powder, so as to obtain mixed polysaccharides of different molecular weights as natural polymer base materials for making adhesives; use 5kD or less as low molecular weight polysaccharide base materials, 70kD-100kD as medium molecular weight polysaccharide base materials, and 300kD-500kD as high molecular weight polysaccharide base materials.

[0018] Preferably, the specific steps of step (4) are: dissolving the Poria cocos fermentation powder with distilled water, spraying it evenly on the Eucommia ulmoides leaves according to a 1% inoculation amount, controlling the intermittent high temperature conditions, raising the temperature to 70°C for 30 minutes every day, and then cooling it to 30°C to maintain the fermentation process. The fermentation time is 30 days.

[0019] Preferably, the specific steps of step (5) are: drying the fermentation product of Eucommia ulmoides leaves in step (4) at 80°C and then crushing it, mixing it with berry tea powder at a mass ratio of 1:(0.5-1.5), performing joint extraction, adding distilled water at a solid-liquid ratio of 1:20 and reflux extraction at 60°C for 2h, filtering to remove insoluble impurities, adding 1% β-glucosidase to the filtrate and performing enzymolysis in a 30°C water bath for 24h, filtering, and boiling the filtrate for 10min to inactivate the enzyme; using a rotary evaporator to reduce the pressure and concentrate the filtrate, suction filter, freeze-dry, and obtain a crude extract, repeatedly recrystallizing 3 times to obtain a refined genipin and dihydromyricetin joint extract, as an additive that acts as both a cross-linking agent and a curing agent, freeze-drying, grinding into a powder with a particle size of less than or equal to 0.2mm, and storing it in a dry environment for standby use.

[0020] Preferably, the specific steps of step (6) are: mixing the large, medium and small molecular weight polysaccharide bases prepared in step (3) with the combined extract of genipin and dihydromyricetin in step (5) in a mass ratio of (20-40):1, adding distilled water to the mixed powder in a mass ratio of (1-2):100, stirring well, standing and swelling for 12 to 16 hours, stirring gently 2 to 3 times during the period to ensure that the glue is fully swollen, and obtaining a natural polysaccharide adhesive.

[0021] Preferably, in step (5), the eucommia leaf fermentation product powder and the berry tea powder are evenly mixed in a mass ratio of 1:1.

[0022] Preferably, in step (6), the polysaccharide base material is mixed with the combined extract of genipin and dihydromyricetin in a mass ratio of 30:1; the mass ratio of the mixed powder to distilled water is 2:100, and the mixture is stirred at 28°C and 180 r / min for 20 min to be evenly mixed, and allowed to stand for swelling for 12 to 16 h.

[0023] In a second aspect, the present application provides a functional natural polysaccharide adhesive prepared by the preparation method described in any one of the first aspects.

[0024] Poria cocos is a fungus belonging to the Polyporaceae family. It mostly parasitizes on the roots of Pinus massoniana and Pinus koraiensis. In addition to its medicinal value of promoting diuresis and removing dampness, benefiting the spleen and stomach, nourishing the heart and calming the nerves, it also has edible value and can be processed into a variety of foods such as "Poria cocos cake" and "Poria cocos candy". The main component of Poria cocos is polysaccharide, which accounts for about 90% of the dry weight. The polysaccharide present in the Poria cocos mycelium is called intracellular polysaccharide. Poria cocos polysaccharide is β-(1→3)-glucan, which is a glucan with β-(1,3) as the main chain and β-(1,6) side chains. It has a double helix structure and can be used in many fields such as medicine, food, and cosmetics. β-(1→3)-glucan has high viscosity, water retention and emulsification stability, so it is often used as a binder, thickener, water-retaining agent, etc. in food in the food industry; β-(1→3)-glucan is a type of immune polysaccharide with anti-tumor, anti-infection, anti-radiation, and immunity enhancement functions, and has a wide range of medical value in the medical field; β-(1→3)-glucan has antioxidant, film-forming, cell proliferation, antibacterial, and water absorption properties. It can increase epidermal growth factor on aging skin and wrinkled skin and promote the production of collagen and elastin in the skin. Therefore, it can be used in the cosmetics industry to increase the skin's moisturizing properties, delay aging, remove wrinkles, and promote wound healing.

[0025] Tangerine peel contains functional ingredients such as polysaccharides, flavonoids, and volatile oils. Pectin, the main component of polysaccharides, is a polysaccharide substance that is polymerized with galacturonic acid as the structural unit through α-1,4 glycosidic bonds. Pectin has good gelling and thickening properties and can be used in the production of foods such as yogurt and jam, as well as the preparation of composite cling film. It can also increase the viscosity of cosmetics and is used in skin care products such as moisturizing water, lotions, and facial masks.

[0026] Eucommia ulmoides, also known as bakelite, is a deciduous tree. The medicinal tree is the dried bark of Eucommia ulmoides, which is a tonic herb that has the effects of nourishing the liver and kidneys, strengthening tendons and bones, and consolidating menstruation and stabilizing pregnancy. Eucommia ulmoides leaves are an ideal raw material for extracting geniposide, which is hydrolyzed by β-glucosidase to produce genipin. Genipin is an excellent natural biological cross-linking agent that can be cross-linked with proteins, gelatin, chitosan, etc. to make biomaterials such as artificial bones and hemostatic dressings. Compared with chemical cross-linking agents such as glutaraldehyde, it has low toxicity and is biodegradable, and has great application value. In addition to its cross-linking effect, genipin also has certain pharmacological properties, which can relieve the symptoms of type 2 diabetes and treat liver diseases, headaches, etc.

[0027] Berry tea mainly grows in the mountainous areas of southern my country and is widely used as a herbal tea. The main active ingredient is dihydromyricetin, which is found in very high levels in young stems and leaves. Dihydromyricetin is a dihydroflavonol flavonoid compound that contains five unstable phenolic hydroxyl groups in its structure. It has antioxidant, anti-tumor, anti-inflammatory, alcohol-detoxifying, liver-protecting, and blood sugar-lowering effects. It has become a research hotspot because of its safety, easy preparation, and wide range of pharmacological activities. The synergistic effect of flavonoids and polysaccharides is significantly better than that of monosaccharides and oligosaccharides. Flavonoids can form complexes with polysaccharides through non-covalent interactions such as hydrogen bonds, hydrophobic forces, van der Waals forces, and electrostatic forces, thereby improving the bioavailability of flavonoids.

[0028] Compared with the prior art, the beneficial effects or advantages of the present invention are mainly reflected in the following aspects:

[0029] The invention uses the previously prepared tuckahoe fermented bacteria powder to ferment tangerine peel, extracts mixed polysaccharides containing tuckahoe mycelium polysaccharides and tangerine peel polysaccharides, and cuts them into different molecular weights through an ultrafiltration membrane to serve as a natural polymer base material for making an adhesive. Extracting two polysaccharides simultaneously can simplify the extraction process and improve efficiency, and the compounding of tuckahoe mycelium polysaccharides and tangerine peel polysaccharides can also play a synergistic role and improve the mechanical properties of the adhesive.

[0030] The present invention utilizes Poria fermentation powder to ferment Eucommia leaf, and adds berry tea powder to the Eucommia leaf fermentation product to carry out the joint extraction of genipin and dihydromyricetin, because dihydromyricetin has polarity, and the hydroxyl group in the molecular structure can form hydrogen bonds with polar solvents to increase solubility, so the addition of berry tea powder can improve the extraction rate of genipin, and the simultaneous extraction of two substances also makes the operation simpler and faster. An additive having both the functions of a crosslinking agent and a curing agent is obtained by joint extraction, and is added to a polysaccharide base material to improve the mechanical properties and antibacterial properties of a polysaccharide adhesive, etc., increase its bonding strength, flexibility and reduce brittleness.

[0031] The functional natural polysaccharide adhesive prepared by the present invention has high bonding strength and good stability. Since its raw materials are all natural active ingredients extracted from plants and microorganisms and do not contain chemically synthesized ingredients, it has bioaffinity and biodegradability, is green and environmentally friendly, non-toxic and harmless, and also has multiple biological active functions such as anti-tumor, anti-oxidation, anti-inflammatory, antibacterial, and immunity enhancement.

[0032] The functional natural polysaccharide adhesive prepared by the present invention can be widely used in multiple fields such as food, cosmetics, medicine, and chemical industry. Since the molecular weight of the polysaccharide base material used is different and the bonding strength is different, large, medium, and small molecular weight natural polysaccharide adhesives can be applied to corresponding different fields. Small molecular weight natural polysaccharide adhesives can be used in the food field, such as making candies, jellies, jams, and bonding tea cakes, etc. The antibacterial properties of dihydromyricetin can also extend the shelf life of food; medium molecular weight natural polysaccharide adhesives can be used in the cosmetic field, because the adhesive components are all natural, it can reduce skin irritation and allergy risks; large molecular weight natural polysaccharide adhesives can be used in the fields of medicine and chemical industry, such as wound dressings, tissue adhesives, and paper and wood adhesives. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 : Determination of tensile strength of functional natural polysaccharide adhesives. DETAILED DESCRIPTION

[0034] The technical scheme and effects of the present application are further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention, rather than to limit the invention.

[0035] Example 1

[0036] This embodiment provides a method for preparing a functional natural polysaccharide adhesive, and the specific steps are as follows:

[0037] (1) Fermentation of dried tangerine peel: Dissolve the fermented Poria powder in an appropriate amount of distilled water, and spray it evenly on the dried tangerine peel at a 1% inoculum amount. Control the intermittent high temperature conditions, raise the temperature to 70°C for 30 minutes every day, and then cool it down to 30°C to maintain the fermentation process. The fermentation time is 30 days.

[0038] (2) Extraction of mixed polysaccharides: The dried tangerine peel fermentation product containing Poria mycelium in step (1) is dried at 80°C and then crushed, distilled water is added at a solid-liquid ratio of 1:10 and refluxed at 60°C for 2h, insoluble impurities are removed by filtration, the filtrate is concentrated under reduced pressure, 5 volumes of 95% ethanol are added, the mixture is allowed to stand overnight at 4°C to precipitate polysaccharides, suction filtered, the precipitate is washed with anhydrous ethanol, and low-temperature dried to obtain a mixed polysaccharide crude product containing Poria mycelium polysaccharide and tangerine peel polysaccharide. The mixed polysaccharide crude product is dissolved in distilled water, Sevag reagent (chloroform: n-butanol = 4:1) is added, fully shaken, allowed to stand for stratification, the lower organic phase is discarded, the operation is repeated for multiple times until there is no white suspension at the interface, the collected polysaccharide solution is suction filtered, and freeze-dried to obtain a refined mixed polysaccharide containing Poria mycelium polysaccharide and tangerine peel polysaccharide, which is ground into a powder with a particle size of less than or equal to 0.2 mm and stored in a dry environment for standby use.

[0039] (3) Take the mixed polysaccharide powder containing Poria mycelium polysaccharide and dried orange peel polysaccharide prepared in step (2), add appropriate amount of distilled water, stir and dissolve thoroughly, dilute 5 times and load into ultrafiltration equipment, under the conditions of ultrafiltration pressure 0.6MPa, ultrafiltration temperature 40°C, and ultrafiltration time 30min, use ultrafiltration membranes with molecular weight cutoff of 500, 300, 100, 70, and 5kD to perform ultrafiltration, cut the polysaccharide into different molecular weights, collect the filtrate at each level, concentrate, filter, freeze-dry, grind to make powder, and obtain mixed polysaccharides of different molecular weights as natural polymer base materials for making adhesives. Take 5kD or less as low molecular weight polysaccharide base materials, 70-100kD as medium molecular weight polysaccharide base materials, and 300-500kD as high molecular weight polysaccharide base materials.

[0040] (4) Fermentation of Eucommia ulmoides leaves: Dissolve the fermented Poria cocos powder in an appropriate amount of distilled water, and spray it evenly on the Eucommia ulmoides leaves at a 1% inoculum amount. Control the intermittent high temperature conditions, raise the temperature to 70°C for 30 minutes every day, and then cool it down to 30°C to maintain the fermentation process. The fermentation time is 30 days.

[0041] (5) Combined extraction of genipin and dihydromyricetin: The fermentation product of Eucommia ulmoides leaves in step (4) was dried at 80°C and then crushed, mixed evenly with berry tea powder at a mass ratio of 1:1, and combined extraction was performed. Distilled water was added at a solid-liquid ratio of 1:20 and refluxed at 60°C for 2h, insoluble impurities were removed by filtration, 1% β-glucosidase was added to the filtrate and enzymolyzed in a 30°C water bath for 24h, filtered, and the filtrate was boiled for 10min to inactivate the enzyme. The filtrate was concentrated under reduced pressure by a rotary evaporator, filtered, and freeze-dried to obtain a crude extract, which was recrystallized 3 times to obtain a refined genipin and dihydromyricetin combined extract, which was freeze-dried and ground into a powder with a particle size of less than or equal to 0.2mm as an additive that acts as both a cross-linking agent and a curing agent, and stored in a dry environment for standby use.

[0042] (6) Glue preparation: The high, medium and low molecular weight polysaccharide base materials prepared in step (3) are respectively mixed with the genipin and dihydromyricetin combined extract in step (5) at a mass ratio of 30:1, distilled water is added to the mixed powder at a mass ratio of 2:100, and the mixture is stirred at 28° C. and 180 r / min for 20 min to make the mixture uniform. The mixture is allowed to stand for swelling for 12 to 16 h, and gently stirred 2 to 3 times during the period to ensure that the glue is fully swollen, thereby obtaining a natural polysaccharide adhesive.

[0043] Example 2

[0044] This embodiment provides a method for preparing a functional natural polysaccharide adhesive, and the specific steps are as follows:

[0045] (1) Fermentation of dried tangerine peel: Dissolve the fermented Poria powder in an appropriate amount of distilled water, and spray it evenly on the dried tangerine peel at a 1% inoculum amount. Control the intermittent high temperature conditions, raise the temperature to 70°C for 30 minutes every day, and then cool it down to 30°C to maintain the fermentation process. The fermentation time is 30 days.

[0046] (2) Extraction of mixed polysaccharides: The dried tangerine peel fermentation product containing Poria mycelium in step (1) is dried at 80°C and then crushed, distilled water is added at a solid-liquid ratio of 1:10 and refluxed at 60°C for 2h, insoluble impurities are removed by filtration, the filtrate is concentrated under reduced pressure, 5 volumes of 95% ethanol are added, the mixture is allowed to stand overnight at 4°C to precipitate polysaccharides, suction filtered, the precipitate is washed with anhydrous ethanol, and low-temperature dried to obtain a mixed polysaccharide crude product containing Poria mycelium polysaccharide and tangerine peel polysaccharide. The mixed polysaccharide crude product is dissolved in distilled water, Sevag reagent (chloroform: n-butanol = 4:1) is added, fully shaken, allowed to stand for stratification, the lower organic phase is discarded, the operation is repeated for multiple times until there is no white suspension at the interface, the collected polysaccharide solution is suction filtered, and freeze-dried to obtain a refined mixed polysaccharide containing Poria mycelium polysaccharide and tangerine peel polysaccharide, which is ground into a powder with a particle size of less than or equal to 0.2 mm and stored in a dry environment for standby use.

[0047] (3) Take the mixed polysaccharide powder containing Poria mycelium polysaccharide and dried orange peel polysaccharide prepared in step (2), add appropriate amount of distilled water, stir and dissolve thoroughly, dilute 5 times and load into ultrafiltration equipment, under the conditions of ultrafiltration pressure 0.6MPa, ultrafiltration temperature 40°C, and ultrafiltration time 30min, use ultrafiltration membranes with molecular weight cutoff of 500, 300, 100, 70, and 5kD to perform ultrafiltration, cut the polysaccharide into different molecular weights, collect the filtrate at each level, concentrate, filter, freeze-dry, grind to make powder, and obtain mixed polysaccharides of different molecular weights as natural polymer base materials for making adhesives. Take 5kD or less as low molecular weight polysaccharide base materials, 70-100kD as medium molecular weight polysaccharide base materials, and 300-500kD as high molecular weight polysaccharide base materials.

[0048] (4) Fermentation of Eucommia ulmoides leaves: Dissolve the fermented Poria cocos powder in an appropriate amount of distilled water, and spray it evenly on the Eucommia ulmoides leaves at a 1% inoculum amount. Control the intermittent high temperature conditions, raise the temperature to 70°C for 30 minutes every day, and then cool it down to 30°C to maintain the fermentation process. The fermentation time is 30 days.

[0049] (5) Combined extraction of genipin and dihydromyricetin: The fermentation product of Eucommia ulmoides leaves in step (4) was dried at 80°C and then crushed, mixed evenly with berry tea powder at a mass ratio of 1:0.5, and combined extraction was performed. Distilled water was added at a solid-liquid ratio of 1:20 and refluxed at 60°C for 2h, insoluble impurities were removed by filtration, 1% β-glucosidase was added to the filtrate and enzymolyzed in a 30°C water bath for 24h, filtered, and the filtrate was boiled for 10min to inactivate the enzyme. The filtrate was concentrated under reduced pressure by a rotary evaporator, filtered, and freeze-dried to obtain a crude extract, which was recrystallized 3 times to obtain a refined genipin and dihydromyricetin combined extract, which was freeze-dried as an additive having both the functions of a cross-linking agent and a curing agent, ground into a powder having a particle size of less than or equal to 0.2mm, and stored in a dry environment for standby use.

[0050] (6) Glue preparation: The large, medium and small molecular weight polysaccharide base materials prepared in step (3) are respectively mixed with the genipin and dihydromyricetin combined extract in step (5) at a mass ratio of 20:1, distilled water is added to the mixed powder at a mass ratio of 1:100, and the mixture is stirred at 28° C. and 180 r / min for 20 min to make the mixture uniform. The mixture is allowed to stand for swelling for 12 to 16 h, and gently stirred 2 to 3 times during the period to ensure that the glue is fully swollen, thereby obtaining a natural polysaccharide adhesive.

[0051] Example 3

[0052] This embodiment provides a method for preparing a functional natural polysaccharide adhesive, and the specific steps are as follows:

[0053] (1) Fermentation of dried tangerine peel: Dissolve the fermented Poria powder in an appropriate amount of distilled water, and spray it evenly on the dried tangerine peel at a 1% inoculum amount. Control the intermittent high temperature conditions, raise the temperature to 70°C for 30 minutes every day, and then cool it down to 30°C to maintain the fermentation process. The fermentation time is 30 days.

[0054] (2) Extraction of mixed polysaccharides: The dried tangerine peel fermentation product containing Poria mycelium in step (1) is dried at 80°C and then crushed, distilled water is added at a solid-liquid ratio of 1:10 and refluxed at 60°C for 2h, insoluble impurities are removed by filtration, the filtrate is concentrated under reduced pressure, 5 volumes of 95% ethanol are added, the mixture is allowed to stand overnight at 4°C to precipitate polysaccharides, suction filtered, the precipitate is washed with anhydrous ethanol, and low-temperature dried to obtain a mixed polysaccharide crude product containing Poria mycelium polysaccharide and tangerine peel polysaccharide. The mixed polysaccharide crude product is dissolved in distilled water, Sevag reagent (chloroform: n-butanol = 4:1) is added, fully shaken, allowed to stand for stratification, the lower organic phase is discarded, the operation is repeated for multiple times until there is no white suspension at the interface, the collected polysaccharide solution is suction filtered, and freeze-dried to obtain a refined mixed polysaccharide containing Poria mycelium polysaccharide and tangerine peel polysaccharide, which is ground into a powder with a particle size of less than or equal to 0.2 mm and stored in a dry environment for standby use.

[0055] (3) Take the mixed polysaccharide powder containing Poria mycelium polysaccharide and dried orange peel polysaccharide prepared in step (2), add appropriate amount of distilled water, stir and dissolve thoroughly, dilute 5 times and load into ultrafiltration equipment, under the conditions of ultrafiltration pressure 0.6MPa, ultrafiltration temperature 40°C, and ultrafiltration time 30min, use ultrafiltration membranes with molecular weight cutoff of 500, 300, 100, 70, and 5kD to perform ultrafiltration, cut the polysaccharide into different molecular weights, collect the filtrate at each level, concentrate, filter, freeze-dry, grind to make powder, and obtain mixed polysaccharides of different molecular weights as natural polymer base materials for making adhesives. Take 5kD or less as low molecular weight polysaccharide base materials, 70-100kD as medium molecular weight polysaccharide base materials, and 300-500kD as high molecular weight polysaccharide base materials.

[0056] (4) Fermentation of Eucommia ulmoides leaves: Dissolve the fermented Poria cocos powder in an appropriate amount of distilled water, and spray it evenly on the Eucommia ulmoides leaves at a 1% inoculum amount. Control the intermittent high temperature conditions, raise the temperature to 70°C for 30 minutes every day, and then cool it down to 30°C to maintain the fermentation process. The fermentation time is 30 days.

[0057] (5) Combined extraction of genipin and dihydromyricetin: The fermentation product of Eucommia ulmoides leaves in step (4) was dried at 80°C and then crushed, mixed evenly with berry tea powder at a mass ratio of 1:1.5, and combined extraction was performed. Distilled water was added at a solid-liquid ratio of 1:20 and refluxed at 60°C for 2h, insoluble impurities were removed by filtration, 1% β-glucosidase was added to the filtrate and enzymolyzed in a 30°C water bath for 24h, filtered, and the filtrate was boiled for 10min to inactivate the enzyme. The filtrate was concentrated under reduced pressure by a rotary evaporator, filtered, and freeze-dried to obtain a crude extract, which was recrystallized 3 times to obtain a refined genipin and dihydromyricetin combined extract, which was freeze-dried and ground into a powder with a particle size of less than or equal to 0.2mm as an additive having both the functions of a cross-linking agent and a curing agent, and stored in a dry environment for standby use.

[0058] (6) Glue preparation: The large, medium and small molecular weight polysaccharide base materials prepared in step (3) are respectively mixed with the genipin and dihydromyricetin combined extract in step (5) at a mass ratio of 40:1, distilled water is added to the mixed powder at a mass ratio of 1.5:100, and the mixture is stirred at 28° C. and 180 r / min for 20 min to mix them evenly, and allowed to stand for swelling for 12 to 16 h, during which time the mixture is gently stirred 2 to 3 times to ensure that the glue is fully swollen, thereby obtaining a natural polysaccharide adhesive.

[0059] Comparative Example 1

[0060] In the glue making step, chitosan powder is mixed with a combined extract of genipin and dihydromyricetin in a mass ratio of 30:1, distilled water is added to the mixed powder in a mass ratio of 2:100, and the mixture is stirred at 28°C and 180 r / min for 20 min to make it evenly mixed, and allowed to stand for swelling for 15 h, during which time it is gently stirred 2 to 3 times at 80 r / min to obtain a chitosan adhesive.

[0061] Performance Testing

[0062] Test 1:

[0063] This example measures the content of genipin extracted by adding berry tea powder to the fermented product of Eucommia ulmoides leaves, and evaluates the extraction effect of the combined extraction method by extracting genipin alone without adding berry tea powder as a control. The content of genipin was detected by high performance liquid chromatography, 0.5g of sample powder was taken, 70% methanol aqueous solution was added, ultrasonic extraction was performed for 30min, centrifuged at 5000rpm / min for 5min, the supernatant was appropriately diluted and tested, phosphoric acid aqueous solution and acetonitrile were selected as the mobile phase, the flow rate was 1mL / min, the injection volume was 10μL, and the content of genipin was determined according to the standard curve at a detection wavelength of 238nm.

[0064] The test results are shown in Table 1. This test measured the content of genipin extracted by adding berry tea powder to the fermented eucommia leaves and the content of genipin extracted alone without adding berry tea powder. The results showed that the content of genipin extracted by adding berry tea powder was higher than that of genipin extracted alone, indicating that the method of adding berry tea powder to the eucommia leaf fermentation product for joint extraction adopted in the present invention is more efficient.

[0065] Table 1 Determination of genipin content in combined extraction and single extraction

[0066]

[0067] Test 2: Bond strength test

[0068] The bonding strength of natural polysaccharide adhesives was determined by overlapping part bonding shear method. Two pieces of fresh pigskin were taken, fat was removed, and they were trimmed into strips of 10mm×80mm. The natural polysaccharide adhesive was evenly coated on one piece of pigskin with a length of 20mm. The two pieces of pigskin were overlapped together with an overlapping area of ​​10×20mm2. They were irradiated under ultraviolet light for 15min to solidify. The two pieces of pigskin were pulled apart at a speed of 5mm / min at room temperature using a universal mechanical testing machine. The maximum tensile force when pulled apart was the bonding strength of the natural polysaccharide adhesive. This was repeated three times and the average value was taken. The bonding strength of chitosan adhesives was determined by the same method.

[0069] The test results are shown in Table 2. This test measured the bonding strength of the prepared low molecular weight natural polysaccharide adhesive, medium molecular weight natural polysaccharide adhesive, high molecular weight natural polysaccharide adhesive, and chitosan adhesive. The results showed that the bonding strength of polysaccharide adhesives of different molecular weights was different. The bonding strength was from large to small, which was high molecular weight polysaccharide adhesive, medium molecular weight natural polysaccharide adhesive, and low molecular weight natural polysaccharide adhesive. In addition, the bonding strength of the three natural polysaccharide adhesives prepared with Poria mycelium polysaccharide and tangerine peel polysaccharide as the base materials of the present invention was greater than that of the traditional polysaccharide adhesive prepared with chitosan as the base material, indicating that the natural polysaccharide adhesive prepared by the present invention has good bonding properties.

[0070] Table 2 Determination of bonding strength of different polysaccharide adhesives

[0071]

[0072] Test 3: Weathering test

[0073] The functional natural polysaccharide adhesive was spread flat in a petri dish, dried at 40°C to form a film, cut into two 20mm×80mm rectangular pieces, one piece was placed in the sun at 36-38°C for 20 days, and the other piece was placed in a 26°C room for 20 days, and then the tensile strength of the film was measured to evaluate the weather resistance of the functional natural polysaccharide adhesive. The tensile strength of the film was measured at a trigger force of 5g, an initial stretching distance of 20mm, and a stretching speed of 4mm / s.

[0074] The test results can be found in Figure 1 This test measured the tensile strength of a film made of a functional natural polysaccharide adhesive after being exposed to sunlight outdoors, and used this as an indicator to evaluate the weather resistance of the adhesive. The results showed that there was no significant difference in the tensile strength of the film exposed to sunlight outdoors and the film placed indoors, indicating that the functional natural polysaccharide adhesive of the present invention has good weather resistance.

[0075] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A method for preparing a functional natural polysaccharide adhesive, characterized in that: The following steps are involved: (1) fermenting tangerine peel: dissolving the fermented Poria cocos powder in distilled water and spraying the mixture on the tangerine peel, and fermenting under intermittent high temperature conditions; (2) extracting mixed polysaccharides: drying the fermentation product of step (1) and then crushing it, adding distilled water to reflux extraction, filtering out insoluble impurities, decompressing and concentrating the filtrate, adding 95% ethanol and standing overnight to precipitate polysaccharides, suction filtering, washing the precipitate with anhydrous ethanol, and low-temperature drying to obtain a mixed polysaccharide crude product containing Poria mycelium polysaccharide and tangerine peel polysaccharide; dissolving the mixed polysaccharide crude product in distilled water, adding Sevag reagent, shaking thoroughly, standing and stratifying, discarding the lower organic phase, repeating the operation for multiple times until there is no white suspension at the interface, suction filtering the collected polysaccharide solution, freeze-drying, that is, obtaining a refined mixed polysaccharide containing Poria mycelium polysaccharide and tangerine peel polysaccharide, grinding into powder, and storing in a dry environment for later use; (3) Preparation of polysaccharide base material: taking the mixed polysaccharide powder containing Poria mycelium polysaccharide and tangerine peel polysaccharide prepared in step (2), adding distilled water, stirring and dissolving, diluting, and then ultrafiltration using ultrafiltration membranes with different molecular weight cutoffs to cut the polysaccharides into different molecular weights, collecting the filtrate at each level, concentrating, filtering, freeze-drying, and grinding into powder, so as to obtain mixed polysaccharides of different molecular weights as a natural polymer base material for making an adhesive; (4) Fermenting Eucommia ulmoides leaves: dissolving the Poria cocos fermented fungus powder in distilled water and spraying the mixture on the Eucommia ulmoides leaves, and fermenting under intermittent high temperature conditions; (5) Combined extraction of genipin and dihydromyricetin: drying and crushing the fermented product of Eucommia ulmoides leaves in step (4), mixing with berry tea powder, and carrying out combined extraction, adding distilled water for reflux extraction, filtering to remove insoluble impurities, adding β-glucosidase to the filtrate for water bath enzymolysis, filtering, and boiling the filtrate to inactivate the enzyme; concentrating the filtrate under reduced pressure, filtering, freeze-drying to obtain a crude extract, recrystallizing to obtain a refined combined extract of genipin and dihydromyricetin, using the additive as both a cross-linking agent and a curing agent, freeze-drying, grinding into granular powder, and storing in a dry environment for later use; (6) Glue preparation: The polysaccharide base prepared in step (3) is mixed with the genipin and dihydromyricetin combined extract in step (5), distilled water is added to the mixed powder, the mixture is stirred thoroughly and allowed to stand for swelling, and a natural polysaccharide adhesive is obtained.

2. The preparation method according to claim 1, characterized in that: The specific steps of step (1) are: dissolving the Poria cocos fermented bacteria powder with distilled water, spraying it evenly on the tangerine peel according to a 1% inoculation amount, controlling the intermittent high temperature conditions, raising the temperature to 70° C. for 30 minutes every day, and then cooling it to 30° C. to maintain the fermentation process, and the fermentation time is 30 days.

3. The preparation method according to claim 1, characterized in that: The specific steps of step (2) are: drying the tangerine peel fermentation product containing Poria mycelium in step (1) at 80°C and then crushing it, adding distilled water at a solid-liquid ratio of 1:10 and refluxing at 60°C for extraction for 2h, filtering to remove insoluble impurities, decompressing and concentrating the filtrate, adding 5 times the volume of 95% ethanol, standing at 4°C overnight to precipitate polysaccharides, filtering with suction, washing the precipitate with anhydrous ethanol, and low-temperature drying to obtain a mixed polysaccharide crude product containing Poria mycelium polysaccharide and tangerine peel polysaccharide; dissolving the mixed polysaccharide crude product in distilled water, adding Sevag reagent, fully shaking, standing and stratifying, discarding the lower organic phase, continuously operating for multiple times until there is no white suspension at the interface, filtering the collected polysaccharide solution with suction, freeze-drying, that is, obtaining a refined mixed polysaccharide containing Poria mycelium polysaccharide and tangerine peel polysaccharide, grinding it into a powder with a particle size of less than or equal to 0.2 mm, and storing it in a dry environment for standby use.

4. The preparation method according to claim 1, characterized in that: The specific steps of step (3) are: taking the mixed polysaccharide powder containing Poria mycelium polysaccharide and tangerine peel polysaccharide prepared in step (2), adding distilled water, fully stirring and dissolving, diluting 5 times and then loading into an ultrafiltration device, under the conditions of ultrafiltration pressure 0.6MPa, ultrafiltration temperature 40°C, and ultrafiltration time 30min, ultrafiltration is performed in sequence using ultrafiltration membranes with molecular weight cutoffs of 500kD, 300kD, 100kD, 70kD, and 5kD, cutting the polysaccharide into different molecular weights, collecting the filtrate at each level, concentrating, filtering, freeze-drying, and grinding to make powder, i.e. obtaining mixed polysaccharides of different molecular weights as a natural polymer base material for making an adhesive; using 5kD or less as a low molecular weight polysaccharide base material, using 70kD-100kD as a medium molecular weight polysaccharide base material, and using 300kD-500kD as a high molecular weight polysaccharide base material.

5. The preparation method according to claim 1, characterized in that: The specific steps of step (4) are: dissolving the Poria cocos fermentation powder with distilled water, spraying it evenly on the Eucommia ulmoides leaves according to a 1% inoculation amount, controlling the intermittent high temperature conditions, raising the temperature to 70°C for 30 minutes every day, and then cooling it to 30°C to maintain the fermentation process. The fermentation time is 30 days.

6. The preparation method according to claim 1, characterized in that: The specific steps of step (5) are as follows: drying the fermentation product of Eucommia ulmoides leaves in step (4) at 80°C and then crushing it, mixing it with berry tea powder at a mass ratio of 1:(0.5-1.5), performing joint extraction, adding distilled water at a solid-liquid ratio of 1:20 and reflux extraction at 60°C for 2h, filtering to remove insoluble impurities, adding 1% β-glucosidase to the filtrate and performing enzymolysis in a 30°C water bath for 24h, filtering, and boiling the filtrate for 10min to inactivate the enzyme; using a rotary evaporator to reduce the pressure and concentrate the filtrate, suction filter, freeze-dry, and obtain a crude extract, repeatedly recrystallizing 3 times to obtain a refined genipin and dihydromyricetin joint extract, as an additive that has both the functions of a cross-linking agent and a curing agent, freeze-drying, grinding to form a powder with a particle size of less than or equal to 0.2mm, and storing it in a dry environment for standby use.

7. The preparation method according to claim 1, characterized in that: The specific steps of step (6) are: mixing the large, medium and small molecular weight polysaccharide base materials prepared in step (3) with the combined extract of genipin and dihydromyricetin in step (5) at a mass ratio of (20-40):1, adding distilled water to the mixed powder at a mass ratio of (1-2):100, stirring evenly, standing and swelling for 12 to 16 hours, stirring gently 2 to 3 times during the period to ensure that the glue is fully swollen, and obtaining a natural polysaccharide adhesive.

8. The preparation method according to claim 6, characterized in that: In step (5), the eucommia leaf fermentation product powder and the berry tea powder are evenly mixed in a mass ratio of 1:

1.

9. The preparation method according to claim 7, characterized in that: In step (6), the polysaccharide base material is mixed with the combined extract of genipin and dihydromyricetin in a mass ratio of 30:1; the mass ratio of the mixed powder to distilled water is 2:100, and the mixture is stirred at 28°C and 180r / min for 20min to be evenly mixed, and allowed to stand for swelling for 12 to 16h.

10. A functional natural polysaccharide adhesive prepared by the preparation method according to any one of claims 1 to 9.

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