PH intelligent response type grape seed extract, preparation method thereof and application of pH intelligent response type grape seed extract in PLA / P34HB composite spinning fiber membrane

Abstract

The invention relates to a pH intelligent response type grape seed extract, a preparation method of the pH intelligent response type grape seed extract and application of the pH intelligent response type grape seed extract in a PLA / P34HB composite spinning fiber membrane. The preparation method of the pH intelligent response type grape seed extract comprises the following steps: providing a polyacrylic acid (PAA) solution; the preparation method comprises the following steps: adding ethyl cellulose (EC) into a polyacrylic acid (PAA) solution, mixing, and adding alpha-cyclodextrin to obtain a PAA / EC / alpha-cyclodextrin compound; the preparation method comprises the following steps: dispersing a grape seed extract (GSE) and lauryl sodium sulfate in diethyl ether to obtain a GSE dispersion liquid, adding the GSE dispersion liquid into a PAA / EC / alpha-cyclodextrin compound, heating and stirring, and then adding potassium persulfate to obtain a GSE-containing PAA / EC / alpha-cyclodextrin nano compound; and separating nano-particles in the PAA / EC / alpha-cyclodextrin nano-composite containing GSE from a water phase through solid-liquid separation, and carrying out low-temperature freezing on the obtained nano-particles to obtain the pH intelligent response type grape extract. When the PLA / P34HB composite spinning fiber membrane is applied to the PLA / P34HB composite spinning fiber membrane, the electrostatic spinning fiber membrane prepared by the process has excellent oxidation resistance and pH responsiveness.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing and preservation, and in particular relates to a pH intelligent response grape seed extract, a preparation method thereof, and an application thereof in a PLA / P34HB composite spinning fiber membrane. Background Art

[0002] Grape seed extract (GSE) is a mixture of polyphenols extracted from the seeds of wine grapes and is a natural antioxidant. Domestic and foreign studies have shown that grape seed extract has biological activities such as scavenging free radicals, anti-oxidation, anti-fatigue, anti-aging, prevention of cardiovascular disease, anti-cancer and antibacterial. It also has high nutritional and medicinal value. GSE is the strongest effective oxygen free radical scavenger and lipid peroxidation inhibitor found so far, and can be used for the storage and preservation of perishable foods. Therefore, adding GSE to plastic wrap can greatly enhance the film's antioxidant and other biological activities. However, due to the high activity of GSE, it is very easy to oxidize, and the heat processing temperature is low, which will cause the melt to become sticky and break during the melt extrusion process. Therefore, it is necessary to find a carrier that effectively protects the stability of GSE and allows it to efficiently exert its antioxidant effect through a sustained release effect.

[0003] Chinese patent CN118909280A discloses a composite cling film loaded with grape seed extract, which is a technology that mixes a ternary composite Pickering emulsion of grape seed extract-soy protein isolate-xanthan gum, a blended solution of gelatin and sodium alginate, and glycerol to obtain a composite film liquid, and then dries it to obtain a composite cling film loaded with grape seed extract. However, glycerol is easily precipitated after being added, and when used as a food preservative material, there may be a problem that the plasticizer migrates to the surface of fruits and vegetables, causing food safety hazards.

[0004] Chinese patent CN116589836A discloses a green biodegradable material containing natural antioxidants such as grape seed extract, in which the natural antioxidants are stably loaded with inorganic carriers and natural polysaccharides, gelatin, zein, etc., and are used for ground film by extrusion granulation. The stable loading of grape seed extract in the film is achieved by physical blending, and the effect of the system for food preservation packaging is not explained.

[0005] In view of this, how to use grape seed extract to prepare grape seed extract plastic wrap with high antioxidant activity and good processing characteristics is a technical problem that needs to be solved at present. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a pH intelligent responsive grape seed extract and a preparation method thereof and an application thereof in a PLA / P34HB composite spinning fiber membrane.

[0007] The first object of the present invention is to provide a method for preparing a pH intelligent responsive grape seed extract, comprising the following steps:

[0008] Providing a polyacrylic acid PAA solution;

[0009] Ethyl cellulose EC is added to the polyacrylic acid PAA solution and mixed, and α-cyclodextrin is added to obtain a PAA / EC / α-cyclodextrin complex;

[0010] Grape seed extract (GSE) and an emulsifier are dispersed in ether to obtain a GSE dispersion, the GSE dispersion is added to a PAA / EC / α-cyclodextrin complex, heated and stirred, and then an initiator is added to obtain a PAA / EC / α-cyclodextrin nanocomposite containing GSE;

[0011] The nanoparticles in the PAA / EC / α-cyclodextrin nanocomposite containing GSE are separated from the aqueous phase by solid-liquid separation, the obtained nanoparticles are cryogenically frozen, and then powdered by a freeze dryer to obtain the pH intelligent responsive grape extract.

[0012] In some embodiments of the present invention, the concentration of the polyacrylic acid PAA solution is 10 wt % to 45 wt %;

[0013] The mass ratio of polyacrylic acid PAA, ethyl cellulose EC and α-cyclodextrin is (0.6-4): (0.1-1): (0.020-0.08).

[0014] In some embodiments of the present invention, the concentration of GSE in the GSE dispersion is 5-20 μg / mL;

[0015] The heating and stirring temperature is 50-70°C, and the stirring time is 10-30 minutes;

[0016] The concentration of the initiator in the PAA / EC / α-cyclodextrin nanocomposite containing GSE is 0.5-2%;

[0017] The initiator is selected from potassium persulfate;

[0018] The emulsifier is selected from sodium lauryl sulfate; the use of the emulsifier of the present invention can synergistically enhance the effect of cyclodextrin-coated ethyl cellulose.

[0019] The second object of the present invention is to provide a pH intelligent response type grape seed extract prepared by the preparation method.

[0020] The third object of the present invention is to provide a pH-intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane, comprising the pH-intelligent responsive grape seed extract.

[0021] The fourth object of the present invention is to provide a method for preparing a pH intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane, comprising the following steps:

[0022] A polylactic acid (PLA) solution treated with tetrabutyl titanate and a poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (P34HB) solution are provided and mixed to obtain a spinning solution;

[0023] Adding the pH intelligent responsive grape seed extract to the spinning solution, and mixing to obtain an electrospinning solution;

[0024] The electrospinning solution is electrospinned to obtain the pH intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane.

[0025] In some embodiments of the present invention, the mass ratio of polylactic acid to poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) is (1:3)-(3:1).

[0026] In some embodiments of the present invention, the steps of treating the polylactic acid solution and the poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) solution treated with tetrabutyl titanate are as follows: dispersing tetrabutyl titanate in an organic solvent, spraying it onto the surface of the polylactic acid, and then mixing it with the poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) after drying. The above treatment method can enhance compatibility and facilitate spinning.

[0027] Furthermore, the concentration of tetrabutyl titanate is 0.1-0.2 g / mL.

[0028] In some embodiments of the present invention, the solvent of the polylactic acid solution is selected from two or more of chloroform, dichloromethane, dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide;

[0029] The solvent of the poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) solution is selected from two or more of chloroform, dichloromethane, dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide.

[0030] In some embodiments of the present invention, the concentration of polylactic acid (PLA) in the spinning solution is 10-30wt%; the concentration of poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) in the spinning solution is 10-30wt%; and the mass fraction of the pH intelligent responsive grape seed extract is 5%-20%.

[0031] In some embodiments of the present invention, the parameters of the electrospinning are: voltage of 15-30 kV, receiving distance of 10-20 cm, and solution flow rate of 0.5-2 ml / h.

[0032] In the present invention, the electrospun fiber membrane prepared by the process of the present invention has excellent antioxidant properties and pH responsiveness (in an acidic environment, the polyacrylic acid (PAA) chain shrinks, the microcapsule wall is relatively tight, and the internal substance is released slowly; in an alkaline environment, the PAA chain stretches, the wall material pores increase, and the internal GSE release is accelerated), realizing the development of green, environmentally friendly and intelligent food packaging.

[0033] The above technical solution of the present invention has the following advantages compared with the prior art:

[0034] (1) The film contains grape seed extract (GSE), which can effectively remove oxygen free radicals in the environment inside the food packaging, inhibit the oxidation and rancidity of fats in the food, and delay the oxidation and deterioration process of the food, thereby extending the shelf life of the food.

[0035] (2) The film is pH responsive. Under different pH conditions, its internal structure will change, thereby controlling the release rate of GSE. In food packaging, when the food inside the package spoils and produces acidic or alkaline substances, such as meat spoilage producing acidic substances, the pH changes, and the film will adjust the release of GSE accordingly.

[0036] (3) Reasonable selection of the ratio of PLA and P34HB and electrospinning process parameters can adjust the flexibility of the film so that it can adapt to the packaging needs of food of different shapes and sizes, fit closely to the food surface, reduce the residual air in the package, and further improve the preservation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0038] Figure 1 The film obtained in the examples of the present invention and the comparative experiment was tested for food contact migration using 50% ethanol as a simulant and 4% acetic acid as a simulant.

[0039] Figure 2 The antioxidant properties of the spun fiber membranes obtained in the examples of the present invention and comparative example 1. DETAILED DESCRIPTION

[0040] In order to solve the technical problems pointed out in the background technology, the present invention implements the solution through the following method:

[0041] The present invention provides a method for preparing a pH intelligent responsive grape seed extract, comprising the following steps:

[0042] Providing a polyacrylic acid PAA solution;

[0043] Ethyl cellulose EC is added to the polyacrylic acid PAA solution and mixed, and α-cyclodextrin is added to obtain a PAA / EC / α-cyclodextrin complex;

[0044] Grape seed extract (GSE) and an emulsifier are dispersed in ether to obtain a GSE dispersion, the GSE dispersion is added to a PAA / EC / α-cyclodextrin complex, heated and stirred, and then an initiator is added to obtain a PAA / EC / α-cyclodextrin nanocomposite containing GSE;

[0045] The nanoparticles in the PAA / EC / α-cyclodextrin nanocomposite containing GSE are separated from the aqueous phase by solid-liquid separation, the obtained nanoparticles are cryogenically frozen, and then powdered by a freeze dryer to obtain the pH intelligent responsive grape extract.

[0046] In a specific embodiment of the present invention, the concentration of the polyacrylic acid PAA solution is 10 wt% to 45 wt%, and illustratively, it can be 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, etc., or any interval value between any two values;

[0047] The mass ratio of polyacrylic acid PAA, ethyl cellulose EC and α-cyclodextrin is (0.6-4): (0.1-1): (0.020-0.08).

[0048] In a specific embodiment of the present invention, the concentration of GSE in the GSE dispersion is 5-20 μg / mL, illustratively, it can be 5 μg / mL, 6 μg / mL, 7 μg / mL, 8 μg / mL, 9 μg / mL, 10 μg / mL, 11 μg / mL, 12 μg / mL, 13 μg / mL, 14 μg / mL, 15 μg / mL, 16 μg / mL, 17 μg / mL, 18 μg / mL, 19 μg / mL, 20 μg / mL, etc., or any interval value between any two values;

[0049] The heating and stirring temperature is 50-70°C, and the stirring time is 10-30 minutes;

[0050] The concentration of the initiator in the PAA / EC / α-cyclodextrin nanocomposite containing GSE is 0.5-2wt%, illustratively, it can be 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.8wt%, 2wt%, etc., or any interval value between any two values;

[0051] The initiator is selected from potassium persulfate;

[0052] The emulsifier is selected from sodium lauryl sulfate; the use of the emulsifier of the present invention can synergistically enhance the effect of cyclodextrin-coated ethyl cellulose.

[0053] The present invention also provides a pH intelligent response type grape seed extract, which is prepared by the preparation method.

[0054] The present invention also provides a pH intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane, comprising the pH intelligent responsive grape seed extract.

[0055] The present invention also provides a method for preparing a pH intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane, comprising the following steps:

[0056] A polylactic acid (PLA) solution treated with tetrabutyl titanate and a poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (P34HB) solution are provided and mixed to obtain a spinning solution;

[0057] Adding the pH intelligent responsive grape seed extract to the spinning solution, and mixing to obtain an electrospinning solution;

[0058] The electrospinning solution is electrospinned to obtain the pH intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane.

[0059] In a specific embodiment of the present invention, the mass ratio of polylactic acid to poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) is (1:3)-(3:1).

[0060] In a specific embodiment of the present invention, the steps of treating the polylactic acid solution and the poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) solution treated with tetrabutyl titanate are as follows: dispersing tetrabutyl titanate in an organic solvent, spraying it onto the surface of the polylactic acid, and then mixing it with the poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) after drying. The above treatment method can enhance compatibility and facilitate spinning.

[0061] Furthermore, the concentration of tetrabutyl titanate is 0.1-0.2 g / mL.

[0062] In a specific embodiment of the present invention, the solvent of the polylactic acid solution is selected from two or more of chloroform, dichloromethane, dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide;

[0063] The solvent of the poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) solution is selected from two or more of chloroform, dichloromethane, dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide.

[0064] In a specific embodiment of the present invention, the concentration of polylactic acid (PLA) in the spinning solution is 10-30wt%, which is rational and can be 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 20wt%, 25wt%, 30wt%, etc., or any interval value between any two values;

[0065] The concentration of poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) in the spinning solution is 10-30 wt %, illustratively, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %, 20 wt %, 25 wt %, 30 wt %, etc., or any interval value between any two values;

[0066] The mass fraction of the pH intelligent responsive grape seed extract is 5wt%-20wt%, illustratively, it can be 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 20wt%, etc., or any interval value between any two values;.

[0067] In a specific embodiment of the present invention, the parameters of the electrospinning are: voltage of 15-30 kV, receiving distance of 10-20 cm, and solution flow rate of 0.5-2 ml / h.

[0068] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0069] Example 1

[0070] This embodiment provides a method for preparing a pH intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane, which is as follows:

[0071] (1) Preparation of polyacrylic acid / ethyl cellulose / α-cyclodextrin complex

[0072] 4 g of polyacrylic acid (PAA) polymer was added to 150 mL of 2% (v / v) acetic acid until completely dissolved to obtain a PAA solution. Then, 0.5 g of ethyl cellulose (EC) powder was added to the PAA solution and placed in an ultrasonic bath for 10 min after complete dissolution. Subsequently, 60 mg of α-cyclodextrin was added under continuous stirring to prepare a PAA / EC / cyclodextrin complex.

[0073] (2) Grape seed extract (GSE) and sodium dodecyl sulfate were dispersed in ether to prepare a dispersion with a final GSE concentration of 15 μg / mL, and added dropwise to the PAA / EC / α-cyclodextrin complex synthesized in step (1) under continuous stirring, heated and stirred at 70°C for 30 minutes, and 0.3 g of potassium persulfate was added to finally obtain a uniform PAA / EC / α-cyclodextrin nanocomposite containing GSE. The oil phase was removed by a sampler, and the nanoparticles were separated from the aqueous phase by centrifugation (6000 rpm, 10 minutes). Finally, the sample was frozen in a -20°C refrigerator, and then powdered by a freeze dryer to obtain a stabilized grape seed extract for use.

[0074] (3) Polylactic acid / P34HB / grape seed extract electrospinning fiber membrane

[0075] Polylactic acid (PLA) and poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (P34HB) were selected as degradable fiber membrane substrates. PLA and P34HB were dissolved in a suitable binary organic solvent system (chloroform, dichloromethane) to form a uniform spinning solution with a concentration of 30%, wherein 10g of tetrabutyl titanate was dispersed in 100ml of ethanol, sprayed on the surface of polylactic acid, and then mixed with poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) solution after drying. The PLA solution treated with tetrabutyl titanate and the P34HB solution were mixed in a certain proportion (mass ratio of 1:3), and a sustained-release grape seed extract with a mass fraction of 20% obtained in step (2) was added, and stirred evenly to form an electrospinning solution. The electrospinning solution was placed in an electrospinning device, the voltage was set to 15 kV, the receiving distance was 20 cm, the solution flow rate was 1.6 ml / h, and the electrospinning operation was performed to obtain a PLA / P34HB film a loaded with sustained-release grape seed extract.

[0076] Example 2

[0077] The same as Example 1, except that the final concentration of GSE was 5 μg / mL of the dispersion, and a PLA / P34HB film b loaded with sustained-release grape seed extract was obtained.

[0078] Example 3

[0079] The same as Example 1, except that the final concentration of GSE was 10 μg / mL of the dispersion, and a PLA / P34HB film c loaded with sustained-release grape seed extract was obtained.

[0080] Example 4

[0081] The same as Example 1, except that the final concentration of GSE was 20 μg / mL of the dispersion, and a PLA / P34HB film d loaded with sustained-release grape seed extract was obtained.

[0082] Comparative Example 1

[0083] The same as Example 1, except that grape seed extract (GSE) was not added.

[0084] Performance Testing

[0085] 1. Antioxidant performance: DPPH is a free radical scavenger that can be used for phenol photometric determination. It has a fixed absorption peak at 515nm through ultraviolet spectral scanning. It absorbs free radicals and then reduces them. At this time, the absorption peak at 515nm decreases or disappears. In view of this feature, the DPPH free radical scavenging method is widely used to evaluate the free radical scavenging activity of natural antioxidants. The sample film is cut into pieces and immersed in methanol. It is left to stand at room temperature for 24 hours. The supernatant is collected and mixed with a methanol solution of DPPH in a 1:1 ratio. Finally, the resulting mixed solution is kept in a dark place for 60 minutes, and the absorption band intensity of DPPH at 515nm is measured on a UV spectrophotometer. Methanol is used as a blank, and the DPPH / methanol solution is set as a negative control. The antioxidant activity is expressed as the DPPH free radical scavenging ability (RSA). The RSA calculation formula is shown in Eq. (1):

[0086]

[0087] A sample Refers to the ultraviolet absorption of the sample at 515nm, A control Refers to the UV absorption of 25mg / mL DPPH / methanol solution at 515nm. The experimental results are shown in Figure 2 ,from Figure 2 It can be seen that the absorption peak of the GSE series films at 525nm is weaker or even disappears compared with that of Ctrl, indicating that the films have good antioxidant properties.

[0088] 2. Detection of the shelf life of food. Specific method: Buy fresh strawberries, remove diseased fruits, and select strawberries of similar size and maturity. The packaging form is a film directly coated on the surface of the strawberry. The experimental group is strawberries packaged with PBAT / PLA / grape seed extract composite film, and the control group is strawberries packaged with PBAT / PLA film. The experiment was carried out under the same refrigeration conditions (4°C). The soluble solids content of the strawberries was recorded at regular intervals, and the freshness of the strawberries was evaluated by sensory evaluation and mass loss rate. The experimental results are shown in Tables 2-3.

[0089] 3. Food contact migration test, specific test method: According to GB 31604.8-2016, the migration amount of the film when 50% ethanol and 4% acetic acid are used as food simulants is determined. Cut a film with an area of ​​50cm2, put it into 100mL food simulant solution, keep it at 60℃ for 2h, take out the film, transfer the remaining liquid to an evaporating dish with an absolute dry weight, dry it at 103℃ and weigh it, and calculate the migration amount by the difference in mass of the two absolute dry evaporating dishes. The experimental results are shown in Figure 1 ,from Figure 1 It can be seen that the GSE series films obtained in the examples meet the food contact safety requirements specified in the national standards (10 mg / dm 2 ).

[0090] 4. pH response experiment, specific method: weigh 1g of the composite film, immerse it in a conical flask containing 100mL of a series of pH = 2, 5, 7, 8 and 9 buffer solutions, then place the conical flask in an oscillator, and study the release behavior of GSE under light-proof conditions at a temperature of 37°C and a rotation speed of 120rpm. Use a 2mL quartz colorimetric cell to periodically sample the solution, and use a spectrophotometer to perform absorption detection at a wavelength of 285nm. After the detection is completed, quickly pour the release liquid in the colorimetric cell back into the original conical flask, and repeat this process until its release amount no longer changes, that is, it reaches release equilibrium. The experimental results are shown in Table 1.

[0091] Table 1 GSE release within 10 h of PLA / P34HB film obtained in Example at different pH

[0092]

[0093] From the data in Table 1, it can be seen that the release amount of GSE increases with the increase of pH at the same time. This is because in an acidic environment, the protonation of the carboxyl group tends to form a tight network structure with the hydrogen bonds of the molecular chain. In an alkaline environment, the electrostatic repulsion of the deprotonated carboxyl group increases, and the formed spatial grid becomes larger. At this time, GSE can diffuse freely, allowing GSE to be transmitted faster, resulting in an increase in the release rate and amount.

[0094] Table 2 Quality changes of strawberries during preservation

[0095]

[0096]

[0097] Table 3 Changes in soluble solids content during strawberry preservation

[0098]

[0099] It can be seen from Tables 2 and 3 that during the strawberry preservation process, the film containing GSE loses water at a slower rate, and the soluble solid content, i.e., sugar content, gradually decreases with time, among which the decreasing trend of GSE a and GSE d is more obvious.

[0100] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A method for preparing a pH intelligent responsive grape seed extract, characterized in that: The following steps are involved: Providing a polyacrylic acid PAA solution; Ethyl cellulose EC is added to the polyacrylic acid PAA solution and mixed, and α-cyclodextrin is added to obtain a PAA / EC / α-cyclodextrin complex; Grape seed extract GSE and emulsifier sodium dodecyl sulfate are dispersed in ether to obtain a grape seed extract GSE dispersion, and the grape seed extract GSE dispersion is added to a PAA / EC / α-cyclodextrin complex, heated and stirred, and then an initiator is added to obtain a PAA / EC / α-cyclodextrin nanocomposite containing grape seed extract; The nanoparticles in the PAA / EC / α-cyclodextrin nanocomposite containing grape seed extract are separated from the aqueous phase by solid-liquid separation, the obtained nanoparticles are cryogenically frozen, and then powdered by a freeze dryer to obtain the pH intelligent responsive grape seed extract.

2. The preparation method according to claim 1, characterized in that: The concentration of the polyacrylic acid PAA solution is 10wt% to 45wt%; The mass ratio of polyacrylic acid PAA, ethyl cellulose EC and α-cyclodextrin is (0.6-4): (0.1-1): (0.020-0.08).

3. The preparation method according to claim 1, characterized in that: The concentration of GSE in the GSE dispersion was 5-20 μg / mL; The heating and stirring temperature is 50-70°C, and the stirring time is 10-30 minutes; The concentration of the initiator in the PAA / EC / α-cyclodextrin nanocomposite containing GSE is 0.5-2%; The emulsifier is selected from sodium lauryl sulfate; The initiator is selected from potassium persulfate.

4. A pH intelligent response grape seed extract, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 3.

5. A pH intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane, characterized in that: The invention comprises the pH intelligent response type grape seed extract as claimed in claim 4.

6. A method for preparing a pH-intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane, characterized in that: The following steps are involved: Provide a polylactic acid solution treated with tetrabutyl titanate and a poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) solution and mix them to obtain a spinning solution; Adding the pH intelligent responsive grape seed extract of claim 4 to the spinning solution, and mixing to obtain an electrospinning solution; The electrospinning solution is electrospinned to obtain the pH intelligent responsive grape seed extract PLA / P34HB composite spinning fiber membrane.

7. The preparation method according to claim 6, characterized in that: The mass ratio of polylactic acid to poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) is (1:3)-(3:1) ； The processing steps of the polylactic acid solution and the poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) solution treated with tetrabutyl titanate are as follows: the tetrabutyl titanate is dispersed in an organic solvent, sprayed onto the surface of the polylactic acid, and then mixed with the poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) after drying.

8. The preparation method according to claim 6, characterized in that: The solvent of the polylactic acid solution is selected from two or more of chloroform, dichloromethane, dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide; the solvent of the poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) solution is selected from two or more of chloroform, dichloromethane, dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide.

9. The preparation method according to claim 6, characterized in that: The concentration of polylactic acid PLA in the spinning solution is 10-30wt%; the concentration of poly (3-hydroxybutyric acid-co-3-hydroxyvaleric acid) in the spinning solution is 10-30wt%; and the mass fraction of the pH intelligent responsive grape seed extract is 5%-20%.

10. The preparation method according to claim 6, characterized in that: The parameters of the electrospinning are: voltage of 15-30 kV, receiving distance of 10-20 cm, and solution flow rate of 0.5-2 ml / h.

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