Natural anthocyanin indicating film and modification preparation method thereof

Abstract

The invention relates to a natural anthocyanin indicating film and a modification preparation method thereof. The method comprises the steps of preparing amur grape pomace anthocyanin, preparing a soybean protein isolate solution, preparing a chitosan solution, preparing a film solution, modifying the film solution, preparing the anthocyanin indicating film and the like. According to the indicating film, the color development characteristic and the oxidation resistance of anthocyanin in the amur grape pomace are fully utilized, meanwhile, the ultrasonic wave, microwave and ultraviolet light modification technologies are combined, so that the compatibility among various film forming matrixes is improved, and the mechanical property, the heat stability, the light resistance and the oxidation resistance of the indicating film are improved. In addition, the color change of the anthocyanin indicating film can intuitively reflect the change of the freshness of the food, so that an effective detection method is provided for food safety.

Description

Technical Field

[0001] The invention relates to a method for preparing an edible film, in particular to a natural anthocyanin indicator film and a modified preparation method thereof. Background Art

[0002] Wild grape anthocyanin is a natural water-soluble flavonoid pigment formed by the combination of anthocyanin and sugar. In the winemaking process of wild grapes, a large amount of grape pomace is produced. The main components of these pomace include polyphenols, proanthocyanidins, resveratrol, grape seed oil, dietary fiber and protein. These components not only have a significant effect on color expression, but also show good health functions. However, my country's wild grape wine companies produce millions of tons of grape pomace every year after winemaking, but these by-products rich in beneficial ingredients are often not fully utilized, resulting in serious waste of resources.

[0003] As a new type of packaging material, edible film has the characteristics of hygiene, safety, pollution-free and biodegradability. This film is made by taking edible biomacromolecules and their derivatives (such as polysaccharides, proteins and lipids) as raw materials, adding edible plasticizers, and undergoing a series of processes such as dissolution, mixing and drying. It has certain engineering properties and selective permeability. With the progress of research, anthocyanin smart indicator film has gradually become a research hotspot for smart food packaging materials. The film can sense changes in food quality by embedding natural pigments (such as carotenoids, curcumin and anthocyanins), and intuitively reflects the freshness of food through the color changes of these natural pigments.

[0004] The indicator film prepared by directly mixing anthocyanins with film-forming matrix by the traditional method has several defects: (1) the compatibility between anthocyanins and traditional film-forming materials is poor, which will have a negative impact on the mechanical properties and barrier properties of the film; (2) anthocyanins have low stability and are very sensitive to external environmental conditions such as light and heat. They are easily degraded and lose their color-changing function. These problems seriously limit the further development and practical application of indicator edible films. Summary of the invention

[0005] The present invention aims to overcome the deficiencies in the prior art and provide a natural anthocyanin indicator film and a modified preparation method thereof. Specifically, it is a method for preparing an anthocyanin indicator film of wild grape skin residue by synergistic modification using ultrasound, microwaves, and ultraviolet light. The anthocyanin indicator film prepared by the method has a smooth surface and good gloss, which improves its mechanical properties, light-blocking properties, and thermal stability, and effectively solves the deficiencies of the edible film prepared by the traditional single casting method in terms of mechanical strength and sensory state. This indicator film can not only be widely used in the preservation of fruits and vegetables and prolonging the shelf life, but also can enable consumers to judge the freshness of fruits and vegetables by the color change of the film through the color reaction between anthocyanins and metabolites released by fruits and vegetables during storage. In addition, the present invention protects the environment while reducing the waste of wild grape skin residue resources, and improves the economic and social benefits of wild grapes.

[0006] The technical solution of the present invention is: a natural anthocyanin indicator membrane and a modified preparation method thereof, characterized by the following steps (the concentration of the following prepared solution is in mass percentage): (1) Preparation of anthocyanins from wild grape skin residue: Place the wild grape skin residue in a drying oven at 50-80℃ for 6-12h, crush it and pass it through a 40-60 mesh sieve. Add the wild grape skin residue powder to a 30-70% ethanol solution at a mass ratio of 5-20%, extract it at a temperature of 30-70℃ for 10-50 min under ultrasonic extraction, and then centrifuge it for 10-20min to obtain the wild grape skin residue anthocyanin extract for later use.

[0007] (2) Preparation of soy protein isolate solution: dissolve soy protein isolate in 50-80°C distilled water at a mass ratio of 5-20%, and stir magnetically for 30-60 minutes to obtain a soy protein isolate solution.

[0008] (3) Preparation of chitosan solution: Dissolve chitosan at a mass ratio of 5-20% in 0.5-2% glacial acetic acid solution, and stir magnetically at 40-60°C for 2-5 hours to obtain a chitosan solution.

[0009] (4) preparing a membrane solution: the soy protein isolate solution prepared in step (2) and the chitosan solution prepared in step (3) are mixed in a mass ratio of 3:0.5-3:4, 0.1-2% of the total mass of the anthocyanin extract prepared in step (1) is added, 1% hydrochloric acid solution is added to adjust the pH to 3, 0.5-2 g of glycerol is added, and the total mass of the membrane solution is 100 g. Homogenize at 3000-15000 r / min for 5-30 min.

[0010] (5) Membrane solution modification treatment: The mixed membrane solution prepared in step (4) is subjected to ultrasonic, microwave, ultraviolet light and their synergistic modification treatment at an ultrasonic power of 0-720 W, a microwave power of 0-300 W, and an ultraviolet light power of 0-200 W, and is vacuum degassed at -0.01-0.09 MPa for 5-120 min.

[0011] (6) Preparation of anthocyanin indicator film: The modified film solution in step (5) is uniformly poured into a film former, dried at 40-80°C for 3-15 hours, and after removing the film, placed in a constant temperature and humidity chamber at 25°C and 50% humidity for 12-48 hours to obtain an anthocyanin indicator film.

[0012] Preferably: a natural anthocyanin indicator membrane and a modified preparation method thereof, wherein the steps are as follows (the concentration of the following solution is in mass percentage): (1) Preparation of anthocyanins from wild grape skin residue: Place the wild grape skin residue in a drying oven at 50℃ and dry for 10 hours, then grind it and pass it through a 40-mesh sieve. Add the wild grape skin residue powder to a 60% ethanol solution at a mass ratio of 6%, extract it at an ultrasonic extraction temperature of 40℃ for 20 minutes, and then centrifuge it for 15 minutes to obtain the wild grape skin residue anthocyanin extract for later use.

[0013] (2) Preparation of soy protein isolate solution: dissolve soy protein isolate in 80°C distilled water at a mass ratio of 5%, and stir magnetically for 50 min to obtain a soy protein isolate solution.

[0014] (3) Preparation of chitosan solution: Dissolve chitosan at a mass ratio of 5% in 2% glacial acetic acid solution and stir under magnetic stirring at 60°C for 4 h to obtain a chitosan solution.

[0015] (4) Preparation of membrane solution: The soy protein isolate solution prepared in step (2) and the chitosan solution prepared in step (3) were mixed in a mass ratio of 3:2, 1% of the total mass of the anthocyanin extract prepared in step (1) was added, 1% hydrochloric acid solution was added to adjust the pH to 3, 1.5 g of glycerol was added, and the total mass of the membrane solution was 100 g. Homogenization was carried out at 10,000 r / min for 10 min.

[0016] (5) Membrane solution modification treatment: The mixed membrane solution prepared in step (4) was subjected to ultrasonic, microwave and ultraviolet light synergistic modification treatment at an ultrasonic power of 720 W, a microwave power of 300 W and an ultraviolet light power of 200 W, and then vacuum degassed at -0.08 MPa for 30 min.

[0017] (6) Preparation of anthocyanin indicator film: The modified film solution in step (5) was evenly poured into a film former, dried at 50°C for 12 h, and after removing the film, placed in a constant temperature and humidity chamber at 25°C and 50% for equilibration for 24 h to obtain an anthocyanin indicator film.

[0018] The advantages of the present invention are: 1. The anthocyanin used in the present invention is extracted from wild grape skin residue, which can effectively utilize the by-products and wastes of wild grape wine production and reduce production costs.

[0019] 2. The film-forming matrix of the anthocyanin indicator film prepared by the present invention, the anthocyanin from grape skin residue and chitosan, can produce a synergistic antioxidant effect, thus giving the anthocyanin indicator film functionality.

[0020] 3. The anthocyanin indicator membrane mixed liquid is modified and treated with ultrasonic, microwave and ultraviolet light to make it fully mixed and emulsified, forming a dense network structure and a membrane liquid with a more stable tissue state, enhancing the intermolecular force, improving the compatibility between the matrices, improving the appearance of the anthocyanin indicator membrane, enhancing the transmittance and thermal stability of the membrane, and improving the application performance and application range of the anthocyanin indicator membrane.

[0021] 4. Compared with the prior art, the present invention has simple process, low cost, easy promotion and is suitable for industrial production. The prepared anthocyanin indicator film is degradable, which improves the economic and social benefits of wild grape wine byproducts on the basis of reducing the waste of wild grape skin residue resources and promoting environmental protection.

[0022] The embodiments of the present invention will be described in further detail below with reference to examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the picture of the film of the present invention.

[0024] Figure 2 is a picture of the thermal properties of the membrane of the present invention.

[0025] Figure 3 It is a picture of the ultraviolet and visible light transmittance of the film of the present invention. DETAILED DESCRIPTION Example

[0026] A natural anthocyanin indicator membrane and a modified preparation method thereof, the steps are as follows (the concentration of the following prepared solution is in mass percentage): (1) Preparation of anthocyanins from wild grape skin residue: Place the wild grape skin residue in a drying oven at 50℃ and dry for 10 hours, then grind it and pass it through a 40-mesh sieve. Add the wild grape skin residue powder to a 60% ethanol solution at a mass ratio of 6%, extract it at an ultrasonic extraction temperature of 40℃ for 20 minutes, and then centrifuge it for 15 minutes to obtain the wild grape skin residue anthocyanin extract for later use.

[0027] (2) Preparation of soy protein isolate solution: dissolve soy protein isolate in 80°C distilled water at a mass ratio of 5%, and stir magnetically for 50 min to obtain a soy protein isolate solution.

[0028] (3) Preparation of chitosan solution: Dissolve chitosan at a mass ratio of 5% in 2% glacial acetic acid solution and stir under magnetic stirring at 60°C for 4 h to obtain a chitosan solution.

[0029] (4) Preparation of membrane solution: The soy protein isolate solution prepared in step (2) and the chitosan solution prepared in step (3) were mixed in a mass ratio of 3:2, 1% of the total mass of the anthocyanin extract prepared in step (1) was added, 1% hydrochloric acid solution was added to adjust the pH to 3, 1.5 g of glycerol was added, and the total mass of the membrane solution was 100 g. Homogenization was carried out at 10,000 r / min for 10 min.

[0030] (5) Membrane solution modification treatment: The mixed membrane solution prepared in step (4) was subjected to ultrasonic, microwave and ultraviolet light synergistic modification treatment at an ultrasonic power of 720 W, a microwave power of 300 W and an ultraviolet light power of 200 W, and then vacuum degassed at -0.08 MPa for 30 min.

[0031] (6) Preparation of anthocyanin indicator film: The modified film solution in step (5) was evenly poured into a film former, dried at 50°C for 12 h, and after removing the film, placed in a constant temperature and humidity chamber at 25°C and 50% for equilibration for 24 h to obtain an anthocyanin indicator film. Example

[0032] A natural anthocyanin indicator membrane and a modified preparation method thereof, the steps are as follows (the concentration of the following prepared solution is in mass percentage): (1) Preparation of anthocyanins from wild grape skin residue: Place the wild grape skin residue in a drying oven at 50℃ and dry for 10 hours, then grind it and pass it through a 40-mesh sieve. Add the wild grape skin residue powder to a 60% ethanol solution at a mass ratio of 6%, extract it at an ultrasonic extraction temperature of 40℃ for 20 minutes, and then centrifuge it for 15 minutes to obtain the wild grape skin residue anthocyanin extract for later use.

[0033] (2) Preparation of soy protein isolate solution: dissolve soy protein isolate in 80°C distilled water at a mass ratio of 5%, and stir magnetically for 50 min to obtain a soy protein isolate solution.

[0034] (3) Preparation of chitosan solution: Dissolve chitosan at a mass ratio of 5% in 2% glacial acetic acid solution and stir under magnetic stirring at 60°C for 4 h to obtain a chitosan solution.

[0035] (4) Preparation of membrane solution: The soy protein isolate solution prepared in step (2) and the chitosan solution prepared in step (3) were mixed in a mass ratio of 3:2, 1% of the total mass of the anthocyanin extract prepared in step (1) was added, 1% hydrochloric acid solution was added to adjust the pH to 3, 1.5 g of glycerol was added, and the total mass of the membrane solution was 100 g. Homogenization was carried out at 10,000 r / min for 10 min.

[0036] (5) Membrane solution modification treatment: The mixed membrane solution prepared in step (4) was subjected to microwave and ultraviolet light synergistic modification treatment at a microwave power of 300 W and an ultraviolet light power of 200 W, and then vacuum degassed at -0.08 MPa for 30 min.

[0037] (6) Preparation of anthocyanin indicator film: The modified film solution in step (5) was evenly poured into a film former, dried at 50°C for 12 h, and after removing the film, placed in a constant temperature and humidity chamber at 25°C and 50% for equilibration for 24 h to obtain an anthocyanin indicator film. Example

[0038] A natural anthocyanin indicator membrane and a modified preparation method thereof, the steps are as follows (the concentration of the following prepared solution is in mass percentage): (1) Preparation of anthocyanins from wild grape skin residue: Place the wild grape skin residue in a drying oven at 50℃ and dry for 10 hours, then grind it and pass it through a 40-mesh sieve. Add the wild grape skin residue powder to a 60% ethanol solution at a mass ratio of 6%, extract it at an ultrasonic extraction temperature of 40℃ for 20 minutes, and then centrifuge it for 15 minutes to obtain the wild grape skin residue anthocyanin extract for later use.

[0039] (2) Preparation of soy protein isolate solution: dissolve soy protein isolate in 80°C distilled water at a mass ratio of 5%, and stir magnetically for 50 min to obtain a soy protein isolate solution.

[0040] (3) Preparation of chitosan solution: Dissolve chitosan at a mass ratio of 5% in 2% glacial acetic acid solution and stir under magnetic stirring at 60°C for 4 h to obtain a chitosan solution.

[0041] (4) Preparation of membrane solution: The soy protein isolate solution prepared in step (2) and the chitosan solution prepared in step (3) were mixed in a mass ratio of 3:2, 1% of the total mass of the anthocyanin extract prepared in step (1) was added, 1% hydrochloric acid solution was added to adjust the pH to 3, 1.5 g of glycerol was added, and the total mass of the membrane solution was 100 g. Homogenization was carried out at 10,000 r / min for 10 min.

[0042] (5) Membrane solution modification treatment: The mixed membrane solution prepared in step (4) was subjected to ultrasonic and ultraviolet light synergistic modification treatment at an ultrasonic power of 720 W and an ultraviolet light of 200 W, and then vacuum degassed at -0.08 MPa for 30 min.

[0043] (6) Preparation of anthocyanin indicator film: The modified film solution in step (5) was evenly poured into a film former, dried at 50°C for 12 h, and after removing the film, placed in a constant temperature and humidity chamber at 25°C and 50% for equilibration for 24 h to obtain an anthocyanin indicator film.

[0044] The preparation method of the edible film without adding anthocyanins from wild grape skin residues comprises the following steps (the concentration of the following prepared solution is in mass percentage): (1) Preparation of soy protein isolate solution: dissolve soy protein isolate in 80°C distilled water at a mass ratio of 5%, and stir magnetically for 50 min to obtain a soy protein isolate solution.

[0045] (2) Preparation of chitosan solution: Dissolve chitosan at a mass ratio of 5% in 2% glacial acetic acid solution and stir under magnetic stirring at 60°C for 4 h to obtain a chitosan solution.

[0046] (3) Preparation of membrane solution: The soy protein isolate solution prepared in step (1) and the chitosan solution prepared in step (2) were mixed in a mass ratio of 3:2, 1.5 g of glycerol was added, and the total mass of the membrane solution was 100 g. Homogenization was performed at 10,000 r / min for 10 min.

[0047] (4) Preparation of edible film: The film solution prepared in step (3) is evenly poured into a film former, dried at 50°C for 12 h, and after removing the film, placed in a constant temperature and humidity chamber at 25°C and 50% for equilibration for 24 h to obtain an anthocyanin indicator film. Figure 1 From left to right in the figure are the membrane pictures of Examples 1-3 and the comparative example.

[0048] Membrane performance test: The DPPH removal rate, tensile strength, elongation at break, contact angle, and surface color parameter a value of the membranes prepared in Example 1, Example 2, Example 3, and the control example are shown in Table 1. Figure 2 As shown, the ultraviolet and visible light transmittance is Figure 3As shown ( Figure 3 From left to right in the figure are the control example and the curves of Examples 1-3, it can be seen that the performance indicators such as DPPH removal rate, tensile strength and elongation at break of the wild grape skin residue anthocyanin indicator film prepared in Examples 1, 2 and 3 are improved compared with the control example. The surface color of the wild grape anthocyanin indicator film is purple-red, the appearance is smooth and flat, the texture is uniform, and the thermal stability and light-blocking performance are enhanced.

[0049] Table 1 Comparison of relevant performance tests .

Claims

1. A method for preparing a modified natural anthocyanin indicator membrane, characterized in that Here are the steps: (1) Preparation of anthocyanins from wild grape skin residue: Place the wild grape skin residue in a drying oven at 50-80°C for 6-12 hours, grind it and pass it through a 40-60 mesh sieve; add the wild grape skin residue powder to a 30-70% ethanol solution at a mass ratio of 5-20%, extract it at a temperature of 30-70°C for 10-50 minutes under ultrasonic extraction, and then centrifuge it for 10-20 minutes to obtain a wild grape skin residue anthocyanin extract for later use; (2) preparing a soy protein isolate solution: dissolving the soy protein isolate in 50-80° C. distilled water at a mass ratio of 5-20%, and stirring with a magnetic stirrer for 30-60 min to obtain a soy protein isolate solution; (3) preparing chitosan solution: dissolving chitosan at a mass ratio of 5-20% in 0.5-2% glacial acetic acid solution, and magnetically stirring at 40-60° C. for 2-5 h to obtain a chitosan solution; (4) preparing a membrane solution: mixing the soy protein isolate solution prepared in step (2) and the chitosan solution prepared in step (3) in a mass ratio of 3:0.5-3:4, adding 0.1-2% of the total mass of the anthocyanin extract prepared in step (1), adding 1% hydrochloric acid solution to adjust the pH to 3, adding 0.5-2 g of glycerol, the total mass of the membrane solution is 100 g, and homogenizing at 3000-15000 r / min for 5-30 min; (5) Membrane solution modification treatment: the mixed membrane solution prepared in step (4) is subjected to ultrasonic, microwave, ultraviolet light and their synergistic modification treatment at an ultrasonic power of 0-720 W, a microwave power of 0-300 W, and an ultraviolet light power of 0-200 W, and is vacuum degassed at -0.01-0.09 MPa for 5-120 min; (6) Preparation of anthocyanin indicator film: The modified film solution in step (5) is uniformly poured into a film former, dried at 40-80°C for 3-15 hours, and after removing the film, placed in a constant temperature and humidity chamber at 25°C and 50% humidity for 12-48 hours to obtain an anthocyanin indicator film.

2. The method for preparing a modified natural anthocyanin indicator membrane according to claim 1, characterized in that In step (1), the preparation of anthocyanins from wild grape skin residues is as follows: the wild grape skin residues are placed in a drying oven at 50-80° C. and dried for 6-12 hours, and then crushed and sieved through a 40-60 mesh sieve; the wild grape skin residue powder is added to a 30-70% ethanol solution by volume fraction at a mass ratio of 5-20%, and the extraction is performed at a temperature of 30-70° C. for 10-50 minutes under ultrasonic extraction, followed by centrifugation for 10-20 minutes to obtain a wild grape skin residue anthocyanin extract for later use.

3. The method for preparing a modified natural anthocyanin indicator membrane according to claim 1, characterized in that In step (4), a membrane solution is prepared: the soy protein isolate solution prepared in step (2) and the chitosan solution prepared in step (3) are mixed in a mass ratio of 3:0.5-3:4, 0.1-2% of the total mass of the anthocyanin extract prepared in step (1) is added, 1% hydrochloric acid solution is added to adjust the pH to 3, 0.5-2 g of glycerol is added, the total mass of the membrane solution is 100 g, and homogenization is carried out at 3000-15000 r / min for 5-30 min.

4. The method for preparing a modified natural anthocyanin indicator membrane according to claim 1, characterized in that In step (5), the membrane solution is modified: the mixed membrane solution prepared in step (4) is subjected to ultrasonic, microwave, ultraviolet light and their synergistic modification treatments at ultrasonic power of 0-720 W, microwave power of 0-300 W, and ultraviolet light power of 0-200 W, and then vacuum degassed at -0.01-0.09 MPa for 5-120 min.

5. The method for preparing a modified natural anthocyanin indicator membrane according to claim 1, characterized in that Here are the steps: (1) Preparation of anthocyanins from wild grape skin residue: Place the wild grape skin residue in a drying oven at 50°C for 10 hours, grind it and pass it through a 40-mesh sieve; add the wild grape skin residue powder at a mass ratio of 6% to a 60% ethanol solution, extract it at an ultrasonic extraction temperature of 40°C for 20 minutes, and then centrifuge it for 15 minutes to obtain a wild grape skin residue anthocyanin extract for later use; (2) Preparation of soy protein isolate solution: dissolve soy protein isolate in 80°C distilled water at a mass ratio of 5%, and stir magnetically for 50 min to obtain a soy protein isolate solution; (3) Preparation of chitosan solution: Dissolve chitosan at a mass ratio of 5% in 2% glacial acetic acid solution, and stir the mixture under magnetic stirring at 60°C for 4 h to obtain a chitosan solution; (4) preparing a membrane solution: mixing the soy protein isolate solution prepared in step (2) and the chitosan solution prepared in step (3) at a mass ratio of 3:2, adding 1% of the total mass of the anthocyanin extract prepared in step (1), adding 1% hydrochloric acid solution to adjust the pH to 3, adding 1.5 g of glycerol, the total mass of the membrane solution is 100 g, and homogenizing at 10,000 r / min for 10 min; (5) Membrane solution modification treatment: The mixed membrane solution prepared in step (4) was subjected to ultrasonic, microwave and ultraviolet light synergistic modification treatment at an ultrasonic power of 720 W, a microwave power of 300 W and an ultraviolet light power of 200 W, and then vacuum degassed at -0.08 MPa for 30 min; (6) Preparation of anthocyanin indicator film: The modified film solution in step (5) was evenly poured into a film former, dried at 50°C for 12 h, and after removing the film, placed in a constant temperature and humidity chamber at 25°C and 50% for equilibration for 24 h to obtain an anthocyanin indicator film.

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