Method for bidirectionally regulating and controlling light transmittance and oxygen permeability of microporous edible film

Abstract

The invention provides a method for bidirectionally regulating and controlling the light transmittance and the oxygen permeability of a microporous edible film, and belongs to the field of materials.The method comprises the steps that an oil-soluble component, namely starch nanoparticles, is added into a microporous film forming material to prepare the edible film, and the light transmittance and the oxygen permeability of the edible film are regulated and controlled by controlling the content of direct-connected starch in starch; when the content of amylose in the starch is 50% or above, the light transmittance of the edible film is reduced, and the oxygen permeation rate is increased; when the content of amylose in the starch is below 50%, the light transmittance of the edible film is increased, and the oxygen permeation rate is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials, and specifically relates to a method for bidirectionally regulating the light transmittance and oxygen permeability of a microporous edible film. Background Art

[0002] Edible films are mainly made of edible natural polymer raw materials such as starch, protein, and cellulose. The microporous property is an inherent property of a few edible films. For example, the original hydroxypropyl methylcellulose film has been observed to have a nano-scale microporous structure. In addition, a microporous structure can also be imparted to the edible film by mixing other components through a certain blending method. For example, some researchers have prepared hydroxypropyl methylcellulose porous films by adding sodium citrate through a phase inversion method. Edible microporous films can be used as coating materials for fresh fruits and vegetables. By adjusting the gas permeability and moisture permeability of the film material, the respiration of the food can be controlled, thereby maintaining the freshness and taste of the food. It can replace traditional plastic polymer materials. In the case of increasingly serious "white pollution", edible microporous films are a good alternative to petroleum-based plastic materials.

[0003] Microporous films can be used as coating materials for fresh fruits and vegetables and have certain properties such as oxygen barrier, water vapor barrier, light barrier, and bacteria barrier, which are expected to protect fruits and vegetables. If the oxygen barrier property of the microporous film material is weak and the oxygen permeability is too high, the respiration of fruits and vegetables cannot be effectively inhibited during storage, and the senescence of fruits and vegetables cannot be effectively delayed to maintain their fresh quality. However, if the oxygen barrier property of the film material is too strong and the oxygen permeability is too low, the fruits will also rot more easily because under low oxygen conditions, cells will perform anaerobic respiration, and alcohol will be produced during the anaerobic respiration process of cells, and alcohol will cause damage to plant cells, leading to fruit rot and flavor change. Microporous films also have good light-blocking properties. In the storage and preservation of some functional foods, their light-blocking properties can prevent the photolysis of effective components in foods, such as the oxidation and rancidity of oils, the discoloration of pigments, and the destruction of functional components such as vitamin C, playing a better protective role for foods. However, in some cases, we need the film to have a certain light transmittance so that consumers can directly observe and feel the appearance characteristics of the food. Therefore, bidirectionally and flexibly regulating the oxygen permeability and light transmittance of microporous films has important practical economic significance in the field of storage and preservation of fruits, vegetables, and foods.

[0004] The addition of nanoparticles and emulsions will affect the light transmittance and oxygen permeability of the film-forming materials. The addition of citral nanoemulsion to sodium alginate to prepare a milk film for coating satsuma mandarin fruits improves the oxygen barrier effect of the film-forming material; adding a Pickering emulsion of cinnamon essential oil stabilized by zein / carboxymethyl Luozi gum to the HPMC matrix to make a film, the light-blocking performance of the film-forming material is significantly enhanced after adding the emulsion. Adding chitosan / tripolyphosphate nanoparticles to HPMC, the chitosan nanoparticles may fill the pores of the HPMC film, promoting the improvement of the mechanical properties and barrier properties of the film. And so on. These studies all show that nanoparticles and emulsions can improve the light-blocking and oxygen-barrier properties of the film-forming materials, but they cannot achieve two-way flexible regulation of the optical properties and oxygen permeability of the film-forming materials. And most of the studies focus on ordinary film-forming materials, and there are few reports on the regulation of these properties of microporous films. Summary of the Invention

[0005] Aiming at the problem that it is difficult to two-way flexibly regulate the light transmittance and oxygen permeability of the film-forming material in the prior art, the present invention proposes a method for two-way regulating the light transmittance and oxygen permeability of a microporous edible film. The present invention prepares different oil-soluble component-starch nanoparticles and mixes them with a microporous film-forming material to prepare a microporous edible film.

[0006] Technical solution: A method for two-way regulating the light transmittance and oxygen permeability of a microporous edible film, adding oil-soluble component-starch nanoparticles to a microporous film-forming material to prepare an edible film, and regulating the light transmittance and oxygen permeability of the edible film by controlling the content of amylose in the starch. Comparing with the edible film prepared without adding oil-soluble component-starch nanoparticles: when the content of amylose in the starch is 50% or more, the light transmittance of the edible film decreases and the oxygen permeability increases; when the content of amylose in the starch is less than 50%, the light transmittance of the edible film increases and the oxygen permeability decreases.

[0007] The specific preparation steps of the edible film preparation method are as follows:

[0008] Step 1. Prepare oil-soluble component-starch nanoparticles;

[0009] Step 1.1. Add NaOH solution and deionized water to starch to obtain a starch solution, and adjust the pH to 7.0 with HCl solution; put the starch solution into an autoclave for gelatinization to obtain a starch paste, cool it to 60 °C, and keep the temperature unchanged;

[0010] Step 1.2. Dissolve the oil-soluble component in ethanol to prepare an oil-soluble component ethanol solution;

[0011] Step 1.3. Under the conditions of 60 °C water bath insulation and stirring, add the oil-soluble component ethanol solution prepared in Step 1.2 to the starch paste prepared from the starch solution in Step 1.1, react the mixture at 60 °C for 3 h, and cool it to 25 °C for overnight reaction;

[0012] Step 1.4: After centrifuging the mixture, pour off the supernatant. Freeze-dry and grind the product to obtain unwashed oil-soluble component - starch nanoparticles.

[0013] Step Two: Preparation of the membrane solution;

[0014] Step 2.1: Mix the microporous membrane-forming polymer material and the auxiliary material, add deionized water at a temperature of 85°C - 95°C, continuously stir for 30 minutes, and then cool to room temperature to prepare Solution A.

[0015] Step 2.2: Disperse the oil-soluble component - starch nanoparticles in deionized water to obtain Solution B.

[0016] Step 2.3: Add Solution B to Solution A and mix well to obtain the required membrane solution.

[0017] Step Three: Prepare an edible film using the membrane solution.

[0018] Take a clean circular polystyrene plate with a diameter of 9 cm, pour 25 g of the membrane solution into the plate, avoid generating bubbles, and dry it in an oven at 37°C for 48 h. Solution A without adding oil-soluble component - starch nanoparticles is used as the blank control group.

[0019] Preferably, in Step 1.4, after centrifuging the mixture obtained in Step 1.3 and pouring off the supernatant, first elute the oil-soluble components on the surface of the product, dehydrate the product and centrifuge again, and then freeze-dry and grind the product to obtain washed oil-soluble component - starch nanoparticles.

[0020] Preferably, in Step 1.1, in the starch solution, the concentration of starch is 10 - 30 g / L, and the concentration of NaOH is 0.05 mol / L; in Step 1.2, in the oil-soluble component ethanol solution, the concentration of the oil-soluble component is 100 - 700 g / L;

[0021] In Step 1.3, the volume ratio of the oil-soluble component ethanol solution to the starch solution is 1:100.

[0022] Preferably, in the membrane solution prepared in Step 2.3, the microporous membrane-forming material accounts for 0.1 - 18% by mass of the membrane solution, and the mass ratio of the microporous membrane-forming material, the microporous membrane auxiliary material, and the oil-soluble component - starch nanoparticles is 100:(1 - 10):(1 - 15).

[0023] Preferably, the starch is any one of wheat, corn, and cassava; the starch is divided into high amylose starch and non-high amylose starch according to the amylose content; the high amylose starch is starch with an amylose content of 50% or more, and the non-high amylose starch is starch with an amylose content of less than 50%.

[0024] The non-high amylose starch is any one of native starch, octenyl succinic anhydride modified starch, phosphate ester modified starch, hydroxypropyl modified starch, acetate modified starch, carboxymethyl modified starch, and phosphate ester cross-linked modified starch;

[0025] The high amylose starch is any one of native high amylose starch, octenyl succinic anhydride modified high amylose starch, phosphate ester high amylose starch, hydroxypropyl high amylose starch, acetate high amylose starch, carboxymethyl high amylose starch, and phosphate ester cross-linked high amylose starch.

[0026] The oil-soluble component is any one of palmitic acid, myristic acid, lauric acid, stearic acid, glycerol monopalmitate, glycerol monomyristate, glycerol monolaurate, glycerol monostearate, tea polyphenol palmitate, tea polyphenol myristate, tea polyphenol laurate, and tea polyphenol stearate.

[0027] The film-forming polymer material of the microporous membrane is any one or a combination of several of these materials: methyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, and starch.

[0028] The auxiliary material of the microporous membrane is any one or a combination of several of potassium bicarbonate, potassium citrate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium lactate, sodium bicarbonate, sodium citrate (SC), sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium lactate, sodium hexametaphosphate, and sodium acid pyrophosphate.

[0029] Beneficial effects:

[0030] 1) The present invention provides a method for preparing a membrane material that can simply and bidirectionally regulate the light transmittance and oxygen permeability of a microporous membrane material. By controlling the amylose content of starch nanoparticles in the oil-soluble component-starch nanoparticles, different light transmittance and oxygen barrier properties of the microporous membrane material can be regulated.

[0031] 2) When the amylose content in the starch of the oil-soluble component-starch nanoparticles is 50% or more, the light-shielding performance of the prepared microporous edible film can be better. When the amylose content in the starch is less than 50%, the light transmittance of the prepared microporous edible film can be enhanced. While flexibly regulating the optical properties, when the amylose content in the starch is 50% or more, the oxygen permeability of the microporous edible film can be improved, and when the amylose content in the starch is less than 50%, the oxygen permeability of the microporous membrane material can be reduced. Description of the drawings

[0032] Figure 1 is the light transmittance of the microporous membrane material prepared in Example 2 with 3% tea polyphenol palmitate-starch nanoparticles added. Specific embodiments

[0033] The technical solution of the present invention will be described in detail below through embodiments, but the protection scope of the present invention is not limited to the described embodiments.

[0034] In the following examples, tapioca starch and high amylose tapioca starch were purchased from Jiangsu Sanshu Biotechnology Co., Ltd. Sodium citrate (SC) was purchased from Sinopharm Chemical Reagent Co., Ltd. Common corn starch was purchased from Liaoning Yihai Kerry Dilros Starch Technology Co., Ltd. High amylose corn starch was purchased from Penford Corporation. Tea polyphenol palmitate was purchased from Hangzhou Prime Biotechnology Co., Ltd. Hydroxypropyl methylcellulose and methylcellulose were purchased from Huzhou Zhanwang Pharmaceutical Co., Ltd.

[0035] Octenyl succinic anhydride modified corn starch was prepared by modifying corn starch. The method was as follows: Corn starch (5.0 g) was dispersed in water (30%, w / w), stirred for 10 min to form a suspension, the pH was adjusted to 8.5 with 1 M NaOH, and a solution of octenyl succinic anhydride (diluted three times with ethanol) based on 3% of the starch mass was added dropwise. The reaction time was 4 h, and then the pH was adjusted to 6.5 with 1 M HCl solution. The mixture was washed using a suction filtration device, first washed twice with 100 mL of deionized water, then washed twice with 100 mL of absolute ethanol, dried at 40 °C for 48 h, ground through a 200-mesh sieve, and stored in a double-layer self-sealing bag to obtain octenyl succinic anhydride modified corn starch (S-N). Octenyl succinic anhydride modified high amylose corn starch (S-H) was prepared in the same method.

[0036] Example 1

[0037] Step 1: Preparation of nanoparticles:

[0038] 1) Weigh 1 g of dry weight tapioca starch (starch with amylose content below 50%), add 5 mL of 1 M NaOH, add 50 mL of deionized water, adjust the pH of the starch solution to 7.0 with 1 M HCl, and make up the volume of the starch with deionized water to 100 mL. The starch solution was put into an autoclave for gelatinization for 20 min to completely gelatinize the starch. The starch paste was cooled to 60 °C and the temperature was kept constant.

[0039] In the starch solution, the concentration of starch was 10 g / L and the concentration of NaOH was 0.05 mol / L;

[0040] 2) Weigh 0.5 g of glycerol monopalmitate into a test tube, add 1 mL of absolute ethanol for dissolution to make a glycerol monopalmitate ethanol solution. In the glycerol monopalmitate ethanol solution, the concentration of glycerol monopalmitate was 500 g / L.

[0041] 3) Keep warm in a 60 °C water bath, 250 r min -1Under stirring conditions, add the glycerol monopalmitate ethanol solution to the starch paste. The mixed system reacts at 60 °C for 3 h and then cools to 25 °C and reacts overnight (12 h).

[0042] 4) Centrifuge the mixture at 4000 g for 15 min, pour off the supernatant, freeze-dry the product, grind it through a 200-mesh sieve, and store it in a double-layer self-sealing bag to obtain the unwashed glycerol monopalmitate-cassava starch nanoparticles (P-T). After pouring off the supernatant, elute the glycerol monopalmitate on the surface of the product twice with 40 mL of ethanol, dehydrate the product at the same time, and centrifuge again. Freeze-dry the product, grind it through a 200-mesh sieve, and store it in a double-layer self-sealing bag to obtain the washed palmitate-cassava starch nanoparticles (C-T).

[0043] Replace the cassava starch in the above steps with high amylose cassava starch (starch with an amylose content of 50% or more), and prepare the unwashed palmitate-high amylose cassava starch nanoparticles (P-HT) and the washed palmitate-high amylose cassava starch nanoparticles (C-HT) in the same method. A total of 4 kinds of nanoparticles are prepared in step one.

[0044] Step Two: Preparation of the membrane:

[0045] 1) Weigh methylcellulose (MC) powder and mix it with SC, add deionized water at 85 °C and continuously stir for 30 minutes, then cool to room temperature to obtain solution A;

[0046] 2) Take the four kinds of nanoparticles prepared in step one and disperse them in deionized water respectively, and ultrasonicate at 400 W to disperse the starch nanoparticles. Preparation method: Disperse the nanoparticles (based on the weight of MC) in deionized water and ultrasonicate at 400 W to disperse the starch nanoparticles to obtain solution B.

[0047] 3) Add the 4 kinds of solution B to 4 portions of solution A respectively, mix well, and the rotation speed is 100 r min -1 , and the required membrane solution is obtained.

[0048] In the 4 kinds of membrane solutions prepared, the mass percentage of methylcellulose (MC) powder in the total mass of the membrane solution is 8%, and the mass ratio of MC powder, SC, and nanoparticles is 100:3:5.

[0049] 4) Take a clean circular polystyrene plate with a diameter of 9 cm, pour 25 g of the membrane solution (4 kinds) and the solution A without adding glycerol monopalmitate-starch nanoparticles into the plate respectively, avoid generating bubbles, and dry in an oven at 37 °C for 48 h. The solution A without adding glycerol monopalmitate-starch nanoparticles is the blank control group.

[0050] 5) Remove the membrane prepared in Step 2, write a label on it, separate the membrane material from the rest of the items with a clean filter paper, and place it in a desiccator containing saturated NaBr solution. The storage condition is 59% RH at room temperature.

[0051] Example 2

[0052] Step 1. Preparation of nanoparticles:

[0053] 1) Weigh 1 g of dry weight of octenyl succinic anhydride corn starch (starch with amylose content below 50%), add 5 mL of 1 M NaOH, add 50 mL of deionized water, adjust the pH of the starch solution to 7.0 with 1 M HCl, and make up the volume of the starch with deionized water to 100 mL. Put the starch solution into an autoclave for gelatinization for 20 min to completely gelatinize the starch. Cool the starch paste to 60 °C and keep the temperature constant.

[0054] In the starch solution, the concentration of starch is 10 g / L and the concentration of NaOH is 0.05 mol / L;

[0055] 2) Weigh 0.5 g of tea polyphenol palmitate glycerol ester into a test tube, add 1 mL of absolute ethanol for dissolution to prepare a tea polyphenol palmitate ethanol solution. Under the conditions of water bath insulation at 60 °C and stirring at 250 r min -1 Add the tea polyphenol palmitate ethanol solution to the starch paste. The mixed system reacts at 60 °C for 3 h, cools to 25 °C, and reacts overnight.

[0056] 3) Centrifuge the mixture at 4000 g for 15 min, pour off the supernatant, freeze-dry the product, grind it through a 200-mesh sieve, and store it in a double-layer self-sealing bag to obtain unwashed tea polyphenol palmitate-corn starch nanoparticles (L-N).

[0057] After pouring off the supernatant, wash the surface of the product with 40 mL of ethanol in two portions to elute the tea polyphenol palmitate on the surface of the product, dehydrate the product at the same time, and centrifuge again. Freeze-dry the product, grind it through a 200-mesh sieve, and store it in a double-layer self-sealing bag to obtain washed tea polyphenol palmitate-corn starch nanoparticles (C-N).

[0058] Replace the octenyl succinic anhydride corn starch in the above steps with high amylose corn starch (starch with amylose content above 50%), and prepare unwashed tea polyphenol palmitate-high amylose corn starch nanoparticles (L-H) and washed tea polyphenol palmitate-high amylose corn starch nanoparticles (C-H) in the same method. A total of 4 kinds of nanoparticles are prepared in Step 1.

[0059] Step 2. Preparation of the membrane:

[0060] 1) Weigh the hydroxypropyl methylcellulose (HPMC) powder and mix it with SC. Add deionized water at 85 °C and continuously stir for 30 minutes, then cool to room temperature to obtain Solution A.

[0061] 2) Separately, disperse the tea polyphenol palmitate-starch nanoparticles in deionized water and use ultrasonic waves at 400 W to disperse the starch nanoparticles to obtain the tea polyphenol palmitate-starch nanoparticle solution, denoted as Solution B.

[0062] 3) Add Solution B to Solution A, mix well, and the rotation speed is 100 r min -1 , then the required membrane solution is obtained.

[0063] In the prepared membrane solution, the mass percentage of the hydroxypropyl methylcellulose (HPMC) powder in the total mass of the membrane solution is 10%, and the mass ratio of HPMC, SC, and nanoparticles is 100:4:3.

[0064] 4) Take a clean circular polystyrene plate with a diameter of 9 cm, pour 25 g of the membrane solution (4 kinds) and Solution A without adding tea polyphenol palmitate-starch nanoparticles into the plate respectively, avoid generating bubbles, and dry in an oven at 37 °C for 48 h. Solution A without adding tea polyphenol palmitate-starch nanoparticles is the blank control group.

[0065] Step Three: Testing:

[0066] Remove the membrane prepared in Step Two, write labels on it, separate the membrane material from the rest of the items with a clean filter paper, put it into a desiccator containing saturated NaBr solution, and the storage condition is 59% RH at room temperature. After equilibration for one week, perform the light transmittance and oxygen permeability tests. For the membranes prepared from the 4 kinds of membrane solutions in Example 2, the specific labels are 15HPMC / SC / 3% L-N, 15HPMC / SC / 3% C-N, 15HPMC / SC / 3% L-H, 15HPMC / SC / 3% C-H. The membrane prepared from the polymer solution without adding tea polyphenol palmitate-starch nanoparticles is the blank control group, and the label is 15HPMC / SC. The test results are as Figure 1 shown in Table 1:

[0067] Table 1 Oxygen Permeability of Microporous Membrane Materials Added with 3% Tea Polyphenol Palmitate-Starch Nanoparticles

[0068]

[0069] Example 3

[0070] Step One: Preparation of Nanoparticles:

[0071] 1) Weigh 1 g of octenyl succinic anhydride corn starch (starch with a linear amylose content of less than 50%) with a dry weight, add 5 mL of 1 M NaOH, add 50 mL of deionized water, adjust the pH of the starch solution to 7.0 with 1 M HCl, and make up the volume of the starch to 100 mL with deionized water. Put the starch solution into an autoclave for gelatinization for 20 min to completely gelatinize the starch. Cool the starch paste to 60 °C and keep the temperature constant.

[0072] In the starch solution, the concentration of starch is 10 g / L and the concentration of NaOH is 0.05 mol / L;

[0073] 2) Weigh 0.5 g of tea polyphenol palmitate into a test tube, add 1 mL of absolute ethanol for dissolution to make a tea polyphenol palmitate ethanol solution. Under the conditions of water bath insulation at 60 °C and stirring at 250 r min -1 while stirring, add the tea polyphenol palmitate ethanol solution to the starch paste. React the mixed system at 60 °C for 3 h, cool to 25 °C, and react overnight.

[0074] 3) Centrifuge the mixture at 4000 g for 15 min, pour off the supernatant, freeze-dry the product, grind it through a 200-mesh sieve, and store it in a double-layer self-sealing bag to obtain unwashed tea polyphenol palmitate-corn starch nanoparticles (L-N).

[0075] After pouring off the supernatant, wash the surface of the product with 40 mL of ethanol in two portions to elute the tea polyphenol palmitate on the surface of the product, dehydrate the product at the same time, and centrifuge again. Freeze-dry the product, grind it through a 200-mesh sieve, and store it in a double-layer self-sealing bag to obtain washed tea polyphenol palmitate-corn starch nanoparticles (C-N).

[0076] Replace the octenyl succinic anhydride corn starch in the above steps with high amylose corn starch (starch with a linear amylose content of more than 50%), and prepare unwashed tea polyphenol palmitate-high amylose corn starch nanoparticles (L-H) and washed tea polyphenol palmitate-high amylose corn starch nanoparticles (C-H) in the same method. A total of 4 kinds of nanoparticles are prepared in step one.

[0077] Step Two: Preparation of Membrane:

[0078] 1) Weigh hydroxypropyl methylcellulose (HPMC) powder and mix it with SC, add deionized water at 85 °C and continuously stir for 30 minutes, then cool to room temperature to obtain solution A.

[0079] 2) Separately disperse the tea polyphenol palmitate-starch nanoparticles in deionized water, and ultrasonicate at 400 W to disperse the starch nanoparticles to obtain a tea polyphenol palmitate-starch nanoparticle solution, denoted as solution B;

[0080] 3) Add Solution B to Solution A and mix well at a rotation speed of 100 r / min -1 , and the required membrane solution is obtained.

[0081] In the prepared membrane solution, the mass percentage of hydroxypropyl methylcellulose (HPMC) powder in the total mass of the membrane solution is 10%, and the mass ratio of HPMC, SC, and nanoparticles is 100:4:8.

[0082] 4) Take a clean circular polystyrene plate with a diameter of 9 cm, pour 25 g of the membrane solution (4 kinds) and Solution A without adding tea polyphenol palmitate-starch nanoparticles into the plate respectively, avoid generating bubbles, and dry at 37 °C in a drying oven for 48 h. Solution A without adding tea polyphenol palmitate-starch nanoparticles is the blank control group.

[0083] Step 3: Testing

[0084] Remove the membrane prepared in Step 2, write a label, separate the membrane material from other items with a clean filter paper, put it into a desiccator containing saturated NaBr solution, and the storage condition is 59% RH at room temperature. After equilibration for one week, perform the light transmittance and oxygen permeability tests. For the membranes prepared from the 4 kinds of membrane solutions in Example 3, the labels are specifically 15HPMC / SC / 8% L-N, 15HPMC / SC / 8% C-N, 15HPMC / SC / 8% L-H, and 15HPMC / SC / 8% C-H. The membrane prepared from the polymer solution without adding tea polyphenol palmitate-starch nanoparticles is the blank control group, and the label is 15HPMC / SC. The test results are shown in Tables 2 and 3:

[0085] Table 2. Light transmittance of the microporous membrane material added with 8% tea polyphenol palmitate-starch nanoparticles at a wavelength of 500 nm

[0086]

[0087]

[0088] Table 3. Oxygen permeability of the microporous membrane added with 8% tea polyphenol palmitate-starch nanoparticles

[0089]

[0090] In summary, it can be seen that the oil-soluble component-starch nanoparticles (the amylose content in starch is less than 50%) can increase the light transmittance of the microporous membrane material and reduce the oxygen permeability of the microporous membrane material. The oil-soluble component-starch nanoparticles (the amylose content in starch is higher than 50%) can reduce the light transmittance of the microporous membrane material and increase the oxygen permeability of the microporous membrane material.

[0091] As described above, although the present invention has been shown and described with reference to particular preferred embodiments, it should not be construed as a limitation on the invention itself. Various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. A method for bidirectionally regulating light transmittance and oxygen permeability of a microporous edible film, characterized in that: An edible film is prepared by adding an oil-soluble component - starch nanoparticles to the microporous film-forming material, and the light transmittance and oxygen permeability of the edible film are regulated by controlling the content of straight-linked starch in the starch; when the content of straight-linked starch in the starch is 50% or more, the light transmittance of the edible film decreases and the oxygen permeability increases; when the content of straight-linked starch in the starch is below 50%, the light transmittance of the edible film increases and the oxygen permeability decreases.

2. The method according to claim 1, characterized in that The specific preparation steps of the edible film are as follows: Step 1, preparing oil-soluble component-starch nanoparticles; Step 1.1, adding NaOH solution and deionized water to starch to obtain a starch solution, and adjusting the pH to 7.0 with HCl solution; placing the starch solution in a high-pressure steam sterilizer for gelatinization to obtain a starch paste, cooling it to 60° C., and maintaining the temperature unchanged; Step 1.2, adding ethanol to dissolve the oil-soluble component to prepare an oil-soluble component ethanol solution; Step 1.3, under the condition of keeping warm in a water bath at 60°C and stirring, add the ethanol solution of the oil-soluble component prepared in step 1.2 to the starch paste prepared from the starch solution in step 1.1, react the mixture at 60°C for 3h, cool to 25°C and react overnight; Step 1.4, centrifuging the mixture obtained in step 1.3, discarding the supernatant, freeze-drying and grinding the product to obtain an unwashed oil-soluble component - starch nanoparticles; Step 2, membrane solution preparation; Step 2.1, mixing the microporous membrane forming material and the microporous membrane auxiliary material, adding deionized water at a temperature of 85° C. to 95° C., stirring continuously for 30 minutes, and then cooling to room temperature to prepare a solution A; Step 2.2, dispersing the oil-soluble component-starch nanoparticles in deionized water to obtain solution B; Step 2.3, add solution B into solution A and mix thoroughly to obtain the desired membrane solution; Step 3: using the film solution to prepare an edible film.

3. The method according to claim 2, characterized in that In step 1.4: centrifuge the mixture obtained in step 1.3 and discard the supernatant, first elute the oil-soluble components on the surface of the product, dehydrate the product and centrifuge it again, then freeze-dry and grind the product to obtain the cleaned oil-soluble component - starch nanoparticles.

4. The method according to claim 2, characterized in that: In step 1.1, in the starch solution, the concentration of starch is (10-30) g / L, and the concentration of NaOH is 0.05 mol / L; In step 1.2, the concentration of the oil-soluble component in the ethanol solution of the oil-soluble component is (100-700) g / L; The volume ratio of the oil-soluble component ethanol solution in step 1.2 to the starch solution prepared in step 1.1 is 1:

100.

5. The method according to claim 2, characterized in that: In step 2.3, after solution B is added to solution A, the mass percentage of microporous membrane forming material in the membrane solution is 0.1-18%, and the mass ratio of microporous membrane forming material, microporous membrane auxiliary material, and oil-soluble component-starch nanoparticles is 100:(1-10):(1-15).

6. The method according to claim 2, characterized in that In step 1.1, the starch is any one of wheat, corn, and cassava; the starch is divided into high-amylose starch and non-high-amylose starch according to the content of amylose, and the high-amylose starch refers to starch with an amylose content of 50% or more; the non-high-amylose starch refers to starch with an amylose content of less than 50%; The oil-soluble component is any one of palmitic acid, myristic acid, lauric acid, stearic acid, monopalmitoylglycerol, monomyristic acid glyceryl, monolaurate glyceryl, monostearate glyceryl, tea polyphenol palmitate, tea polyphenol myristic acid ester, tea polyphenol laurate, and tea polyphenol stearate; The microporous membrane-forming polymer material is any one or a combination of methyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose and starch; The microporous membrane auxiliary material is any one or a combination of potassium bicarbonate, potassium citrate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium lactate, sodium bicarbonate, sodium citrate, sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium lactate, sodium hexametaphosphate, and disodium dihydrogen pyrophosphate.

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