Preparation and application of glutenin-based multi-component composite agglomerate

Abstract

The invention discloses preparation and application of a glutenin-based multi-component composite aggregate, and belongs to the field of food packaging. According to the invention, glutenin and epsilon-polylysine form a composite agglomerate for packaging tannic acid to form a multi-component composite agglomerate, and the composite agglomerate has the properties of efficient sterilization, oxidation resistance and good stability; the multi-component composite coacervate is used as an edible coating, compared with glutenin, the multi-component composite coacervate has better water vapor and oxygen barrier capacity, the antibacterial activity and antioxidant activity of a glutenin coating can be incubated, and the food preservation period is prolonged. In a word, the invention designs a novel multifunctional substance packaging strategy, and further broadens the application of glutenin.

Description

Technical Field

[0001] The invention relates to the preparation and application of a multi-component complex coacervate based on glutenin, and belongs to the field of food packaging. Background Art

[0002] Microbial contamination is the main cause of food quality deterioration. How to inhibit or slow down microbial growth and metabolic activities during food preservation is a hot topic of research at home and abroad. Unlike traditional food packaging materials, edible coatings or films are thin layers wrapped or wrapped on the surface of food, aiming to prevent the migration of moisture, gas and solutes between food and the environment. Compared with polysaccharide or lipid-based coatings and films, protein-based edible coatings have attracted increasing attention due to their low cost, wide availability, high nutritional properties, better gas barrier and mechanical properties. Therefore, the development of new protein-based edible coatings is of great significance.

[0003] At present, the research at home and abroad is more about using polysaccharides to preserve food coatings, while protein-based coatings have the characteristics of high nutritional value, good taste, and low permeability, so it is necessary to develop new protein-based edible coatings. The main raw materials that are studied more include gelatin, soy protein, zein, whey protein, etc. Different protein coatings have different film-forming properties and gas barrier properties. In addition, problems such as color, taste, and allergens will also limit consumers' desire to buy, so it is necessary to study other different types of proteins.

[0004] Gluten is a protein rich in wheat gluten (about 30%-40%). It is composed of polypeptide chains connected by intermolecular disulfide bonds. The molecules are fibrous, slender and have a large surface area. They have rich active groups and are easy to interact with other molecules. The amino acid composition of gluten shows that its central repeating region is hydrophilic, while the N-terminal and C-terminal regions are hydrophobic. This amphiphilic molecular feature enables gluten to assemble with other molecules into nanostructures. Compared with other proteins, gluten has the characteristics of wide sources, no odor, low allergy risk, strong film-forming ability, and good uniformity. It is suitable as a substrate for edible coatings. However, gluten edible coatings have a single functional property and low gas barrier performance, which is limited in practical applications. Edible coatings focus on antibacterial effects, antioxidant properties, gas barrier properties, and physical properties (thickness, transparency, uniformity) in food preservation. Therefore, it is necessary to add other substances to the gluten coating to give it new functions while improving the basic performance and improving the preservation effect. Complex coacervate is one of the most effective encapsulation technologies, known for its simplicity of functional components, low cost, scalability, and reproducibility, but it has been less studied for glutenin.

[0005] Therefore, the preparation of an edible coating with good antibacterial, gas barrier and antioxidant properties based on the film-forming property of glutenin combined with the composite gel method has high practical and economic value. Summary of the invention

[0006] In order to solve at least one of the above-mentioned problems and improve the effectiveness of glutenin in practical applications, this patent proposes a method for forming a complex coacervate based on glutenin, ε-polylysine (ε-PL) and tannic acid, which can effectively retain the antibacterial activity of ε-PL and the antioxidant activity of tannic acid, and can improve the water permeability and air permeability of the glutenin coating, so as to improve the performance of packaging materials and extend the shelf life of food.

[0007] In view of the defects existing in the above-mentioned prior art, the present invention first forms a complex coagulant with glutenin and ε-PL, and then adds tannic acid thereto to obtain a multi-component complex coagulant of glutenin / ε-PL / tannic acid. By analyzing the bactericidal and antioxidant properties of the multi-component complex coagulants of glutenin / ε-PL / tannic acid at different mass ratios, a complex coagulant that can retain the biological activity of ε-PL and tannic acid and has good bactericidal and antioxidant properties is obtained. After the complex coagulant is naturally dried, an edible coating can be formed on the surface of the substrate. By analyzing the water vapor permeability and oxygen permeability of the edible coating, it is found that the coating prepared by the multi-component complex coagulant of glutenin / ε-PL / tannic acid can significantly improve the water vapor and oxygen barrier properties of the single glutenin coating. The present invention is simple to operate, has cheap raw materials, outstanding effects, and is widely applicable, further broadening the application of edible coatings of glutenin.

[0008] The first object of the present invention is to provide a multi-component complex coacervate coating based on glutenin, wherein the preparation method of the multi-component complex coacervate coating based on glutenin is:

[0009] The substrate is immersed in a glutenin / ε-polylysine / tannic acid multi-component complex coacervate solution to prepare a glutenin-based multi-component complex coacervate coating on the surface of the substrate;

[0010] The method for preparing the glutenin / ε-polylysine / tannic acid multi-component complex coacervate solution comprises the following steps:

[0011] (1) mixing a glutenin solution and an ε-polylysine solution to obtain a glutenin / ε-PL two-component complex coacervate solution; wherein the mass ratio of glutenin to ε-polylysine is 1 to 5:1;

[0012] (2) Take a glutenin / ε-PL two-component complex coacervate solution, add a tannic acid solution under stirring conditions of 300 to 400 rpm, and prepare a glutenin / ε-polylysine / tannic acid multi-component complex coacervate solution; wherein the mass ratio of tannic acid to ε-polylysine is 1:9 to 47.

[0013] In one embodiment, the substrate includes, but is not limited to, common solid or semi-solid materials such as films, plastics, metals, and stones.

[0014] In one embodiment, the substrate is immersed in the glutenin / ε-polylysine / tannic acid multi-component complex coacervate solution for at least 20 minutes.

[0015] In one embodiment, the method for preparing a glutenin solution comprises:

[0016] According to the dosage ratio of 0.4-1g:50mL, glutenin is dissolved in 0.01-0.05M NaOH solution, and stirred at 400-600rpm for 20-40min; an equal volume of PBS buffer is added, and stirring is continued for 1-3h; after stirring, centrifuge at 4000-5000rpm for 10-20min, and the supernatant is taken to prepare a glutenin solution.

[0017] In one embodiment, the pH of the glutenin solution is 7-9.

[0018] In one embodiment, the pH of the ε-polylysine solution is 6-8.

[0019] In one embodiment, the pH of the tannic acid solution is 6-7.

[0020] In one embodiment, the mass ratio of glutenin to ε-PL is 1 to 5, wherein the final concentration of glutenin is 1 to 20 mg / mL, and the final concentration of ε-PL is 1 to 10 mg / mL.

[0021] In one embodiment, the method of adding tannic acid comprises dropwise addition, stirring, and mixing, wherein the final concentration of tannic acid is 0.085-0.425 mg / mL.

[0022] In one embodiment, the preparation method comprises the following steps:

[0023] (1) Preparation of glutenin, ε-PL and tannic acid solution:

[0024] 0.4 g of glutenin was added to 50 mL of NaOH solution (0.01 M) and stirred at 500 rpm for 30 min, then 50 mL of PBS buffer (0.1 mM, pH 7.4) was added and stirred for 1 h. After stirring, the mixture was centrifuged at 5000 rpm for 10 min, and the supernatant was taken out to obtain the glutenin solution and stored in a refrigerator at 4 °C for later use.

[0025] The ε-PL solid powder was dissolved in deionized water to obtain an ε-PL solution of a certain concentration, which was filtered and stored in a refrigerator at 4°C for later use.

[0026] The solid powder of tannic acid is dissolved in deionized water to obtain a tannic acid solution of a certain concentration, which is ready for use.

[0027] (2) Preparation of glutenin / ε-PL / tannic acid multicomponent complex coacervates

[0028] First, the ε-PL solution and the glutenin solution were mixed in a volume ratio of 1:1 to obtain a glutenin / ε-PL two-component complex coacervate, and a certain concentration of tannic acid solution was added thereto to obtain a glutenin / ε-PL / tannic acid multi-component complex coacervate solution.

[0029] In one embodiment, the mass ratio of glutenin to ε-PL in the complex coacervate of step (1) is 1 to 4;

[0030] In one embodiment, the mass ratio of glutenin, ε-PL and tannic acid in the glutenin / ε-PL / tannic acid multi-component complex coacervate of step (1) is 20:5:0.425.

[0031] The second object of the present invention is to provide a multi-component complex coacervate based on glutenin, wherein the multi-component complex coacervate based on glutenin is prepared from glutenin, ε-polylysine and tannic acid, and the preparation method comprises:

[0032] (1) mixing a glutenin solution and an ε-polylysine solution to obtain a glutenin / ε-PL two-component complex coacervate solution; wherein the mass ratio of glutenin to ε-polylysine is 1 to 5:1;

[0033] (2) Take a glutenin / ε-PL two-component complex coacervate solution, add a tannic acid solution under stirring conditions of 300-400 rpm, and prepare a multi-component complex coacervate based on glutenin; wherein the mass ratio of tannic acid to ε-polylysine is 1:9-47.

[0034] In one embodiment, the method for preparing a glutenin solution comprises:

[0035] According to the dosage ratio of 0.4g:50mL, glutenin was dissolved in 0.01-0.05M NaOH solution, and stirred at 400-600rpm for 20-40min; an equal volume of PBS buffer was added, and stirring was continued for 1-3h; after stirring, centrifuged at 4000-5000rpm for 10-20min, and the supernatant was taken to prepare a glutenin solution.

[0036] In one embodiment, the pH of the glutenin solution is 7-9.

[0037] In one embodiment, the pH of the ε-polylysine solution is 6-8.

[0038] In one embodiment, the pH of the tannic acid solution is 6-7.

[0039] In one embodiment, the mass ratio of glutenin to ε-PL is 1 to 5, wherein the final concentration of glutenin is 1 to 20 mg / mL, and the final concentration of ε-PL is 1 to 10 mg / mL.

[0040] In one embodiment, the method of adding tannic acid comprises dropwise addition, stirring, and mixing, wherein the final concentration of tannic acid is 0.085-0.425 mg / mL.

[0041] In one embodiment, the preparation method comprises the following steps:

[0042] (1) Preparation of glutenin, ε-PL and tannic acid solution:

[0043] 0.4 g of glutenin was added to 50 mL of NaOH solution (0.01 M) and stirred at 500 rpm for 30 min, then 50 mL of PBS buffer (0.1 mM, pH 7.4) was added and stirred for 1 h. After stirring, the mixture was centrifuged at 5000 rpm for 10 min, and the supernatant was taken out to obtain the glutenin solution and stored in a refrigerator at 4 °C for later use.

[0044] The ε-PL solid powder was dissolved in deionized water to obtain an ε-PL solution of a certain concentration, which was filtered and stored in a refrigerator at 4°C for later use.

[0045] The solid powder of tannic acid is dissolved in deionized water to obtain a tannic acid solution of a certain concentration, which is ready for use.

[0046] (2) Preparation of glutenin / ε-PL / tannic acid multicomponent complex coacervates

[0047] First, the ε-PL solution and the glutenin solution were mixed in a volume ratio of 1:1 to obtain a glutenin / ε-PL two-component complex coacervate, and a certain concentration of tannic acid solution was added thereto to obtain a glutenin / ε-PL / tannic acid multi-component complex coacervate solution.

[0048] In one embodiment, the mass ratio of glutenin to ε-PL in the complex coacervate of step (1) is 1-4;

[0049] In one embodiment, the mass ratio of glutenin, ε-PL and tannic acid in the glutenin / ε-PL / tannic acid multi-component complex coacervate of step (1) is 20:5:0.425;

[0050] The third object of the present invention is to provide a product, which contains any one of the above-mentioned glutenin-based multi-component complex coacervate coatings or one or more of any one of the above-mentioned glutenin-based multi-component complex coacervates; the product includes a chemical product, a packaging material or a food preservation product.

[0051] In one embodiment, the chemical products include: paints, fuels, coatings, pigments, reagents, additives, adhesives, etc.

[0052] In one embodiment, the packaging material includes: polyethylene terephthalate, polystyrene, polyethylene, polyvinyl chloride, phenol formaldehyde, urea formaldehyde, epoxy, polyester, polyurethane, polymethyl methacrylate, etc.

[0053] The fourth object of the present invention is to provide the use of any of the above-mentioned glutenin-based multi-component complex coacervate coatings or any of the above-mentioned glutenin-based multi-component complex coacervate in the preparation of products; the products include chemical products, packaging materials or food preservation products.

[0054] In one embodiment, the chemical products include: paints, fuels, coatings, pigments, reagents, additives, adhesives; packaging materials include: polyethylene terephthalate, polystyrene, polyethylene, polyvinyl chloride, phenolic formaldehyde, urea formaldehyde, epoxy, polyester, polyurethane, polymethyl methacrylate, etc.

[0055] In one embodiment, the glutenin-based multi-component complex coacervate coating can be used to prepare food preservative materials or packaged foods; the food includes any one of meat, eggs, fruits, fresh-cut fruits, etc.

[0056] Beneficial effects of the present invention:

[0057] The present invention mixes glutenin, ε-PL and tannic acid, and by controlling the mass ratio and the order of addition, a multi-component complex coacervate can be obtained, which extremely well retains the antibacterial property of ε-PL and the antioxidant property of tannic acid, and delays the time for tannic acid to be oxidized by air; on this basis, the complex coacervate can form an edible coating on the surface of packaging materials and foods, and compared with a single glutenin coating, the barrier water vapor and oxygen permeation ability thereof is significantly improved; the present invention fills the application gap of glutenin, and further broadens the application of glutenin, ε-PL and tannic acid in the food industry;

[0058] Specific:

[0059] (1) The glutenin / ε-PL / tannic acid multi-component complex coacervate of the present invention has a significant antioxidant effect;

[0060] (2) The glutenin / ε-PL / tannic acid multi-component complex coacervate of the present invention has excellent antibacterial effect and can maintain a 100% bactericidal rate for 8 hours;

[0061] (3) After the glutenin / ε-PL / tannic acid multi-component complex coacervate of the present invention is prepared as a coating, it can significantly improve the water vapor and oxygen permeability, which are increased by 21.13% and 8.45% respectively compared with the PET film. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 Figure 2 is a picture of glutenin / ε-PL complex coacervate at different mass ratios (MR refers to the mass ratio of glutenin:ε-PL, and the lower right corner is the ratio value; MR0-MR5 corresponds to Example 1; MR 5.5 ~MR 20 Corresponding proportion 1);

[0063] Figure 2 is the turbidity of glutenin / ε-PL complex coacervate at different mass ratios (MR refers to the mass ratio of glutenin:ε-PL, and the lower right corner is the ratio value; MR0~MR5 corresponds to Example 1; MR 5.5 ~MR 20 Corresponding proportion 1);

[0064] Figure 3 This is a picture of the glutenin / tannic acid composite system of comparative example 2 after standing at 23°C for 5 minutes (MR refers to the mass ratio of glutenin: tannic acid, and the lower right corner mark is the ratio value);

[0065] Figure 4 This is a picture of the glutenin / tannic acid / ε-PL composite system of comparative example 2 after standing at 23°C for 5 minutes (MR is the mass ratio; glutenin:ε-PL), and the final concentration of tannic acid is fixed to 0.425 mg / mL;

[0066] Figure 5 The glutenin / ε-PL / tannic acid complex coacervate of Example 1, wherein the final concentration of glutenin is 20 mg / mL; the final concentration of ε-PL is 4 mg / mL; and the final concentration of tannic acid is 0.425 mg / mL;

[0067] Figure 6 The results of the antibacterial and bactericidal experiments of glutenin / ε-PL / tannic acid complex coacervates in Example 1; wherein, (A) the total number of colonies of Escherichia coli after being treated with glutenin / ε-PL complex coacervates; (B) the total number of colonies of Staphylococcus aureus after being treated with glutenin / ε-PL complex coacervates; (C) the bactericidal rates of glutenin / ε-PL / tannic acid complex coacervates against Escherichia coli and Staphylococcus aureus (the final concentration of ε-PL was fixed at 4 mg / mL);

[0068] Figure 7 is the DPPH radical scavenging rate of the glutenin / ε-PL / tannic acid complex coacervate and tannic acid in Example 1 (MR is the mass ratio; glutenin: tannic acid, wherein the final concentration of fixed glutenin is 20 mg / mL);

[0069] Figure 8 Water vapor and oxygen permeability of glutenin / ε-PL / tannic acid complex coacervate coatings prepared by different methods, where the final concentration of glutenin was 20 mg / mL; the final concentration of ε-PL was 5 mg / mL; and the final concentration of tannic acid was 0.425 mg / mL. DETAILED DESCRIPTION

[0070] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0071] The instruments involved in the present invention are:

[0072] UV-visible spectrophotometer (Model T 9, Beijing Puxi General Instrument Co., Ltd.); Controllable constant temperature and humidity test chamber (Dongguan Huitai Machinery Co., Ltd.); Handheld digital micrometer (Spain Mitutoyo); Gas permeation test system C130H (Jinan Languang Electromechanical Technology Co., Ltd.)

[0073] Source of raw materials:

[0074] ε-PL was purchased from Zhangshu Lion Biotechnology Co., Ltd.; tannic acid and glutenin were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; PET film was purchased from Dongguan Jubang Plastic Material Co., Ltd.

[0075] The test methods involved in the embodiments and comparative examples of the present invention are as follows:

[0076] 1. Effect of different mass ratios on complex coacervate system:

[0077] The UV spectrophotometer (OD 600 ) The turbidity of the complex coacervates formed by glutenin and ε-PL was compared, and the measurements were performed three times in parallel to obtain the average value; the stability of the complex coacervates was analyzed by comparing the turbidity before and after standing for 30 minutes.

[0078] 2. Determination of minimum bactericidal concentration (MBC):

[0079] First, 100 μL of LB broth medium was added to each well of the 96-well plate, and then 100 μL of the prepared ε-PL or glutenin / ε-PL complex coacervate of different concentrations was added to the first well of each row, and then 100 μL of it was pipetted and added to the second well. The above steps were repeated to well 11, and 100 μL was pipetted and discarded. Each group of samples was repeated three times, and well 12 was used as a blank control group. 100 μL of the diluted bacterial suspension (concentration of 10 6 CFU / mL). The 96-well plate was placed in a constant temperature incubator (37°C) and cultured for 24 hours. After the incubation was completed, 100 μL of the bacterial suspension was inoculated on the plate count agar with a pipette, spread evenly, and cultured in a constant temperature incubator for 16 hours. If no colony growth appeared in the culture medium, it means that the antibacterial agent at this concentration has a bactericidal effect on the microorganisms, otherwise it means that the antibacterial agent at this concentration has only an inhibitory effect on the microorganisms.

[0080] 3. Determination of bactericidal kinetics:

[0081] Bacteria (Escherichia coli and Staphylococcus aureus) in the logarithmic growth phase were resuspended twice with PBS (0.1 mM) and then diluted to 10 with PBS buffer. 6 CFU / mL. The diluted bacterial suspension was mixed with an equal volume of the complex coacervate, and the diluted bacterial suspension was mixed with an equal volume of ε-PL as a control, wherein the final concentration of ε-PL was fixed at 1 mg / mL, the mass ratio of glutenin to ε-PL in the complex coacervate was 0 mg / mL, 0.5 mg / mL, 2 mg / mL, 5 mg / mL, 10 mg / mL and 20 mg / mL, and sterile PBS buffer was used as a control group. Subsequently, the test tube was placed in a microbial shaker (37°C, 150 rpm) for shaking culture, and the total number of colonies was measured at regular time points to draw a bactericidal kinetic curve.

[0082] 4. DPPH free radical scavenging experiment:

[0083] Combine 2 mL of DPPH solution (prepared with 0.1 mM ethanol) with 2 mL of water to make A cDilute the sample to be tested 50 times to obtain a sample solution, take 2 mL of DPPH solution and combine it with 2 mL of sample solution to form A t Combine 2 mL of sample solution with 2 mL of water to form A b After standing for 30 minutes at 25°C in the dark, the absorbance was measured at 517 nm. The free radical scavenging rate was calculated as follows:

[0084]

[0085] 5. Preparation of PET film with coating:

[0086] PET (thickness 0.07 mm) was soaked in acetone, ethanol and deionized water in turn, and ultrasonically treated for 20 min, and then dried naturally to obtain a cleaned PET film. Three types of PET films were prepared, namely: PET films were soaked in glutenin (20 mg / mL), PET films were soaked in glutenin / ε-PL (glutenin was 20 mg / mL, ε-PL was 4 mg / mL) two-component complex coacervates, and PET films were soaked in glutenin / ε-PL / tannic acid multi-component complex coacervates coating (glutenin was 20 mg / mL, ε-PL was 4 mg / mL, tannic acid was 0.425 mg / mL) for 30 min, taken out and dried naturally, and then stored in a desiccator.

[0087] 6. Determination of water vapor transmission rate:

[0088] The water vapor permeation rate was measured by the gravimetric method. A permeable cup (30 mm × 50 mm weighing bottle) filled with 10 mL of deionized water was sealed with the coated PET film treated in step 5, and the initial weight was recorded and placed in a desiccator. The weight of the permeable cup was measured every 12 hours for a total of 6 days.

[0089] 7. Determination of oxygen permeability:

[0090] In an environment of 23° C. and 50% humidity, the oxygen transmission rate of the coated PET film treated in step 5 is measured by a gas permeation test system.

[0091] Example 1: Preparation of glutenin / ε-PL / tannic acid complex coacervates

[0092] 1. Preparation of glutenin / ε-PL two-component complex coacervates

[0093] (1) Take 0.4g of glutenin in 50mL of NaOH solution (0.01M) and stir at 500rpm for 30min, then add 50mL of PBS buffer (0.1mM, pH 7.4) and continue stirring for 1h. After stirring, centrifuge at 5000rpm for 10min, take out the supernatant to obtain the glutenin solution and store it in a refrigerator at 4℃ for later use. ε-PL solid powder is dissolved in PBS buffer to obtain a 10mg / mL ε-PL solution, which is filtered and stored in a refrigerator at 4℃ for later use. Tannic acid powder is dissolved in deionized water to obtain a 0.85mg / mL tannic acid solution.

[0094] (2) The glutenin solution prepared in step (1) and the ε-PL solution were mixed at a mass ratio of 1 to 20 (glutenin:ε-PL, wherein the ε-PL concentration was fixed at 250 μg / mL) to prepare a glutenin / ε-PL two-component complex coacervate solution.

[0095] 2. Detection of antibacterial properties of glutenin / ε-PL two-component complex coacervate solution

[0096] The minimum bactericidal concentration (MBC) of the glutenin / ε-PL two-component complex coacervate solution was tested, and the results are shown in Table 1.

[0097] The results showed that the minimum bactericidal concentration of glutenin / ε-PL two-component complex coacervate solution against Escherichia coli and Staphylococcus aureus was 1000 μg / mL.

[0098] Table 1 Minimum bactericidal concentration (MBC)

[0099] Escherichia coli Staphylococcus aureus MBC (μg / mL) MBC (μg / mL) ε-PL 1000 1000 <![CDATA[MR1]]> 1000 1000 <![CDATA[MR2]]> 1000 1000 <![CDATA[MR5]]> 1000 1000 <![CDATA[MR 10 ]]> 1000 1000 <![CDATA[MR 20 ]]> 1000 1000

[0100] 3. A multi-component complex coacervate based on glutenin, comprising the following steps:

[0101] (1) Take 0.4g of glutenin in 50mL of NaOH solution (0.01M) and stir at 500rpm for 30min, then add 50mL of PBS buffer (0.1mM, pH 7.4) and continue stirring for 1h. After stirring, centrifuge at 5000rpm for 10min, take out the supernatant to obtain the glutenin solution and store it in a refrigerator at 4℃ for later use. ε-PL solid powder is dissolved in PBS buffer to obtain a 10mg / mL ε-PL solution, which is filtered and stored in a refrigerator at 4℃ for later use. Tannic acid powder is dissolved in deionized water to obtain a 0.85mg / mL tannic acid solution.

[0102] (2) mixing the glutenin solution prepared in step (1) with the ε-PL solution at a mass ratio (glutenin:ε-PL, wherein the ε-PL concentration is fixed at 4 mg / mL) of 1 to 5 to obtain a glutenin / ε-PL two-component complex coacervate solution;

[0103] (3) Take the glutenin / ε-PL two-component complex coacervate prepared in step (2), add tannic acid solution under stirring at 300 rpm to make the final concentration of tannic acid 0.425 mg / mL, and prepare a glutenin / ε-PL / tannic acid multi-component complex coacervate solution.

[0104] 4. Performance testing

[0105] (1) Turbidity detection of glutenin / ε-PL two-component complex coacervate solution

[0106] The glutenin / ε-PL two-component complex coacervate solutions of different mass ratios (MR0-MR5) prepared above were taken and allowed to stand at 23°C for 30 min. The turbidity of the solution was observed with the naked eye and measured. If there was no obvious decrease, it was considered to be a stable system.

[0107] The turbidity results of glutenin / ε-PL two-component complex coacervate solution are as follows Figure 1 As shown in (MR0-MR5, MR represents the mass ratio of glutenin to ε-PL); OD of glutenin / ε-PL two-component complex coacervate 600 (MR0~MR5, MR represents the mass ratio of glutenin to ε-PL) Figure 2 shown.

[0108] Depend on Figure 1 and Figure 2 It can be seen that within the range of 1 to 5 mass ratios of glutenin and ε-PL, no obvious precipitation was observed by naked eye and the OD 600 The turbidity did not decrease, indicating that stable complex coacervates could be formed.

[0109] (2) Detection of tannic acid oxidation relief by glutenin / ε-PL / tannic acid multi-component complex coacervate solution

[0110] The glutenin / ε-PL / tannic acid multi-component complex coacervate solution prepared by the above method (the final concentration of glutenin was 20 mg / mL; the final concentration of ε-PL was 5 mg / mL; the final concentration of tannic acid was 0.425 mg / mL) was allowed to stand at 23°C for 30 min without stratification. The results are as follows Figure 5 As shown, there is no obvious change in the color of the solution, indicating that the complex coacervate can effectively slow down the oxidation of tannic acid by air.

[0111] (3) Antibacterial property test of glutenin / ε-PL two-component complex coacervate solution Glutenin / ε-PL complex coacervate (mass ratio of glutenin to ε-PL was 0.5-20; ε-PL concentration was 4 mg / mL) was prepared according to the method 1, and its bactericidal kinetics (Escherichia coli and Staphylococcus aureus) was tested, with ε-PL (concentration of 4 mg / mL) as the control. The results are as follows: Figure 6 As shown in A, 6B, Table 2 and Table 3.

[0112] The results showed that glutenin / ε-PL complex coacervates had effective bactericidal properties, and the antibacterial properties of ε-PL in the complex coacervates would not be reduced when the treatment time exceeded 8 h.

[0113] (4) Antibacterial property test of glutenin / ε-PL / tannic acid complex

[0114] According to the method of 1, glutenin / ε-PL / tannic acid complex coacervates (glutenin: tannic acid mass ratio of 47-235; ε-PL concentration was fixed at 4 mg / mL) were prepared, and their bactericidal kinetics (Escherichia coli, Staphylococcus aureus) were detected, with ε-PL (concentration of 4 mg / mL) and glutenin / ε-PL complex coacervates (glutenin 20 mg / mL; ε-PL 4 mg / mL) as controls. The results are as follows: Figure 6 C. As shown in Table 4.

[0115] The results showed that the glutenin / ε-PL / tannic acid complex coacervate could still maintain the good bactericidal properties of the glutenin / ε-PL / tannic acid multi-component complex coacervate after the addition of tannic acid, and could still maintain a 100% bactericidal rate after 8 hours of treatment of the bacterial solution.

[0116] Table 2 Escherichia coli inhibition effect of glutenin / ε-PL two-component complex coacervate solution

[0117]

[0118]

[0119] Table 3 Inhibitory effect of glutenin / ε-PL two-component complex coacervate solution on Staphylococcus aureus

[0120]

[0121] Table 4 Antibacterial effect of glutenin / ε-PL / tannic acid multi-component complex coacervates

[0122]

[0123] (5) Antioxidant activity of glutenin / ε-PL / tannic acid complex

[0124] According to the method of 1, glutenin / ε-PL / tannic acid complex coacervates (glutenin: tannic acid mass ratio of 47-235; final glutenin concentration of 20 mg / mL) were prepared, and glutenin alone (20 mg / mL) and glutenin / ε-PL complex coacervates (glutenin 20 mg / mL; ε-PL 1 mg / mL) were used as controls. The results are shown in Figure 7 shown.

[0125] The results showed that glutenin and ε-PL did not have the ability to scavenge DPPH free radicals, but after forming glutenin / ε-PL / tannic acid multi-component complex coacervates, the DPPH free radical scavenging effect of tannic acid itself was almost retained.

[0126] In summary, the glutenin / ε-PL / tannic acid multi-component complex coacervate can generally retain the antibacterial properties of ε-PL and the antioxidant properties of tannic acid, and delay the oxidation of tannic acid by air.

[0127] Comparative Example 1: Changing the dosage of ε-PL

[0128] On the basis of Example 1 (other steps and parameters are consistent with Example 1), the mass ratio of glutenin to ε-PL in step (2) (glutenin: ε-PL, wherein the final concentration of ε-PL is fixed at 1 mg / mL) is adjusted to 6 to 20, and glutenin / ε-PL complex coacervates and glutenin / ε-PL / tannic acid multi-component complex coacervates are prepared, respectively.

[0129] The results are as follows Figure 1 and Figure 2 As shown in the results, the glutenin / ε-PL complex coacervate (the mass ratio of glutenin to ε-PL was 6-20) showed obvious stratification after standing at 23°C for 30 min, as shown in Figure 1 and Figure 2 As shown, and OD 600 The turbidity was significantly reduced, indicating that the glutenin / ε-PL / tannic acid multi-component complex coacervate system was unstable.

[0130] Comparative Example 2: Changing the preparation order

[0131] On the basis of Example 1 (other steps and parameters not mentioned are consistent with those of Example 1), the order of adding the raw materials is adjusted, that is, the glutenin solution and the tannic acid solution are mixed first, and then the ε-PL solution is added. Specifically, the steps are as follows:

[0132] The glutenin solution and the tannic acid solution were mixed (the final concentration of glutenin was 20 mg / mL, and the final concentration of tannic acid ranged from 0.085 to 0.425 mg / mL) to form a glutenin / tannic acid composite system.

[0133] The results are as follows Figure 3 As shown, the composite system was stratified after standing at 23°C for 30 min and tannic acid was oxidized to yellow, which indicated that tannic acid could not form a stable composite system with glutenin.

[0134] Considering that ε-PL may have an impact on the system, ε-PL solution was then added to the glutenin / tannic acid composite system (tannic acid concentration was fixed at 0.425 mg / mL and glutenin was 20 mg / mL) (so that the mass ratio of glutenin to ε-PL was 4-20), and under stirring at 300 rpm, a glutenin / tannic acid / ε-PL multi-component composite system with a tannic acid concentration of 0.425 mg / mL and different ratios of glutenin to ε-PL was obtained.

[0135] The results are as follows Figure 4 As shown in the figure, the multi-component composite system showed obvious stratification after standing for 30 minutes at 23°C, which indicates that the post-addition of ε-PL cannot improve the stability of the glutenin / tannic acid composite system.

[0136] Example 2: Preparation of glutenin / ε-PL / tannic acid complex coacervate coating

[0137] A preparation method of a multi-component complex coacervate edible coating based on glutenin is as follows:

[0138] (1) Based on Example 1, a multi-component complex coacervate of glutenin / ε-PL / tannic acid was prepared (wherein the concentrations were: glutenin concentration was 20 mg / mL; ε-PL concentration was 4 mg / mL; tannic acid concentration was 0.425 mg / mL);

[0139] (2) PET (thickness 0.07 mm) was sequentially soaked in acetone, ethanol and deionized water, and ultrasonically treated for 20 min, and then naturally dried to obtain a cleaned PET film. The PET film was then soaked in the above-mentioned glutenin / ε-PL / tannic acid multi-component complex coacervate for 30 min, taken out and naturally dried to obtain a PET film with a multi-component complex coacervate coating.

[0140] The effect on water vapor and oxygen permeability was tested. The results are as follows Figure 8As shown (the horizontal axis "PET" represents the untreated PET film; the horizontal axis "glutenin" represents the PET film directly immersed in a 20 mg / mL glutenin solution for 30 min, taken out and naturally dried to obtain a PET film with a single glutenin coating; the horizontal axis "glutenin / ε-PL" represents the PET film directly immersed in a glutenin / ε-PL two-component complex coacervate for 30 min (wherein the glutenin concentration is 20 mg / mL and the ε-PL concentration is 4 mg / mL), taken out and naturally dried to obtain to a PET film with a coating of glutenin / ε-PL two-component complex coacervate; the horizontal axis "glutenin / ε-PL / tannic acid" represents directly immersing the above-mentioned PET film in a glutenin / ε-PL / tannic acid multi-component complex coacervate for 30 minutes (wherein the glutenin concentration is 20 mg / mL, the ε-PL concentration is 4 mg / mL, and the tannic acid concentration is 0.425 mg / mL), taking it out and naturally drying it to obtain a PET film with a coating of glutenin / ε-PL / tannic acid multi-component complex coacervate).

[0141] The results showed that the coating formed by glutenin in PET film can improve the resistance of PET film to water vapor and oxygen permeation; the water vapor permeability of glutenin / ε-PL two-component complex coacervate coating increased from 25.94 g / (m 2 ·24h) increased to 25.07g / (m 2 ·24h), compared with PET film, it increased by 21.13%; oxygen permeability compared with glutenin coating increased from 18.56cm 3 / (m 2 ·24h·0.1MPa) increased to 18.20cm 3 / (m 2 ·24h·0.1MPa), which is 8.45% higher than that of PET film.

[0142] The glutenin / ε-PL / tannic acid multi-component complex coacervate coating was 23.31 g / (m 2 ·24h), which is 29.12% higher than that of PET film, and the oxygen permeability is 16.06cm 3 / (m 2 ·24h·0.1MPa), which is 19.21% higher than that of PET film.

[0143] In summary, the glutenin / ε-PL / tannic acid multi-component complex coacervate coating can effectively improve the coating's ability to resist water vapor and oxygen penetration, and greatly improve the food preservation performance.

[0144] Comparative Example 3: Coatings with different preparation processes

[0145] (1) Reduce the amount of ε-PL

[0146] Based on Comparative Example 1, a glutenin / ε-PL / tannic acid multi-component complex coacervate was prepared (glutenin concentration was 20 mg / mL; ε-PL concentration was 1 mg / mL; tannic acid concentration was 0.425 mg / mL), and its water vapor permeability and oxygen permeability were tested according to the method of Example 2.

[0147] The results showed that precipitation occurred in the glutenin / ε-PL / tannic acid multi-component complex coacervate system, and the PET film contained a very small amount of glutenin coating, with water vapor and oxygen permeation rates of 31.29 g / (m 2 24h) and 19.64cm 3 / (m 2 ·24h·0.1MPa), there is no significant difference between the performance of PET film itself.

[0148] (2) Change the preparation order

[0149] On the basis of Comparative Example 2, a glutenin / tannic acid / ε-PL multi-component complex coacervate was obtained (the final concentration of glutenin was 20 mg / mL; the final concentration of tannic acid was 0.425 mg / mL; the final concentration of ε-PL was 4 mg / mL). According to the method of Example 2, its water vapor permeability and oxygen permeability were tested.

[0150] The results showed that stratification occurred in the glutenin / tannic acid / ε-PL multi-component complex coacervate system, and the PET film contained a small amount of glutenin / ε-PL coating. The water vapor and oxygen permeation results were as follows Figure 8 The water vapor and oxygen permeability of the glutenin / tannic acid / ε-PL group were 26.29 g / (m 2 24h) and 19.01cm 3 / (m 2 ·24h·0.1MPa), although the performance is improved compared with PET film, it is similar to the effect of using only glutenin and glutenin / ε-PL two-component complex coacervate coating.

[0151] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A multi-component complex coacervate coating based on glutenin, characterized in that: The preparation method of the multi-component complex coacervate coating based on glutenin is as follows: The substrate is immersed in a glutenin / ε-polylysine / tannic acid multi-component complex coacervate solution to prepare a glutenin-based multi-component complex coacervate coating on the surface of the substrate; The method for preparing the glutenin / ε-polylysine / tannic acid multi-component complex coacervate solution comprises the following steps: (1) mixing a glutenin solution and an ε-polylysine solution to obtain a glutenin / ε-polylysine two-component complex coacervate solution; wherein the mass ratio of glutenin to ε-polylysine is 1 to 5:1; (2) A glutenin / ε-polylysine two-component complex coacervate solution was taken, and a tannic acid solution was added under stirring conditions of 300 to 400 rpm to prepare a glutenin / ε-polylysine / tannic acid multi-component complex coacervate solution; wherein the mass ratio of tannic acid to ε-polylysine was 1:9 to 47.

2. The glutenin-based multi-component complex coacervate coating according to claim 1, characterized in that: The method for preparing the glutenin solution comprises: According to the dosage ratio of 0.4-1g:50mL, glutenin is dissolved in 0.01-0.05M NaOH solution, and stirred at 400-600rpm for 20-40min; an equal volume of PBS buffer is added, and stirring is continued for 1-3h; after stirring, centrifuge at 4000-5000rpm for 10-20min, and the supernatant is taken to prepare a glutenin solution.

3. The glutenin-based multi-component complex coacervate coating according to claim 1, characterized in that: The pH of the glutenin solution is 7-9; the pH of the ε-polylysine solution is 6-8; and the pH of the tannic acid solution is 6-7.

4. A multi-component complex coacervate based on glutenin, characterized in that: The multi-component complex coacervate based on glutenin is prepared from glutenin, ε-polylysine and tannic acid, and the preparation method comprises: (1) mixing a glutenin solution and an ε-polylysine solution to obtain a glutenin / ε-polylysine two-component complex coacervate solution; wherein the mass ratio of glutenin to ε-polylysine is 1 to 5:1; (2) A glutenin / ε-polylysine two-component complex coacervate solution was taken, and a tannic acid solution was added under stirring conditions of 300 to 400 rpm to prepare a multi-component complex coacervate based on glutenin; wherein the mass ratio of tannic acid to ε-polylysine was 1:9 to 47.

5. The multi-component complex coacervate based on glutenin according to claim 4, characterized in that: The method for preparing the glutenin solution comprises: According to the dosage ratio of 0.4-1g:50mL, glutenin is dissolved in 0.01-0.05M NaOH solution, and stirred at 400-600rpm for 20-40min; an equal volume of PBS buffer is added, and stirring is continued for 1-3h; after stirring, centrifuge at 4000-5000rpm for 10-20min, and the supernatant is taken to prepare a glutenin solution.

6. A product, characterized in that The product contains one or more of the glutenin-based multi-component complex coacervate coating described in any one of claims 1 to 3 or the glutenin-based multi-component complex coacervate described in any one of claims 4 to 5; the product includes a chemical product, a packaging material or a food preservation product.

7. The product according to claim 6, characterized in that The chemical products include: paints, fuels, coatings, pigments, reagents, additives, and adhesives.

8. The product according to claim 6, characterized in that The packaging materials include: polyethylene terephthalate, polystyrene, polyethylene, polyvinyl chloride, phenolic acid, urea-formaldehyde, epoxy, polyester, polyurethane, and polymethyl methacrylate.

9. Use of the glutenin-based multi-component complex coacervate coating according to any one of claims 1 to 3 or the glutenin-based multi-component complex coacervate according to any one of claims 4 to 5 in the preparation of products; the products include chemical products, packaging materials or food preservation products.

10. The use according to claim 9, characterized in that: The chemical products include: paints, fuels, coatings, pigments, reagents, additives, adhesives; packaging materials include: polyethylene terephthalate, polystyrene, polyethylene, polyvinyl chloride, phenolic formaldehyde, urea formaldehyde, epoxy, polyester, polyurethane, polymethyl methacrylate.

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