An oat protein-based edible preservative film and a method of preparing the same

Abstract

The application discloses an oat protein-based edible preservative film and a preparation method thereof. The edible preservative film is prepared from the following raw materials: oat protein aggregates, carboxymethyl cellulose, water, glycerol and bioactive glass. The preparation method comprises the following steps: oat protein aggregates are added into water and stirred uniformly to obtain a first mixed solution; carboxymethyl cellulose is added into water and stirred uniformly to obtain a second mixed solution; the first mixed solution and the second mixed solution are mixed, then glycerol and copper-doped mesoporous bioactive glass are added in sequence, and stirred for a period of time to obtain a film-forming solution; the film-forming solution is poured into a plane substrate, and then dried to obtain the oat protein-based edible preservative film. The oat protein is modified by heat treatment to obtain oat protein aggregates, the obtained oat protein aggregates are used for film preparation, a composite film is obtained, and the transparency, flexibility and barrier property of the composite film are significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to an edible preservative film and a preparation method thereof, in particular to an edible preservative film based on oat protein and a preparation method thereof, and belongs to the technical field of edible protein films. BACKGROUND

[0002] Oat contains relatively high protein, which is a low-cost, resource-rich renewable resource. In-depth study of its functional properties will help to develop high-value-added products. Studies have shown that oat protein has excellent gelation capacity, emulsifying properties, water and fat binding capacity, and foaming properties. Oat protein can also be used to prepare biodegradable films. The film developed from oat protein alone has relatively weak barrier and mechanical properties, and oat protein will form aggregates after heat treatment, which can significantly change the barrier and flexibility of the film as a film-forming material.

[0003] Based on the complementarity and synergy between multiple components, multi-component films have advantages over single-component films. Polysaccharides have abundant groups that can be combined with paper-based materials to improve mechanical strength and appropriate gas barrier properties while maintaining biodegradability and recyclability. Carboxymethyl cellulose (CMC) has good affinity due to its good film-forming properties and can be used as an effective carrier for antibacterial substances. Bioactive glass, as a biologically active, biodegradable and antibacterial ingredient, is a good candidate for biological composites and has been widely used in medicine, but there are few reports in the field of food preservation. SUMMARY

[0004] The purpose of the present application is to provide an edible preservative film based on oat protein with good transparency, high flexibility and good barrier properties. Another purpose of the present application is to provide a preparation method of an edible preservative film based on oat protein.

[0005] Technical solution: The edible preservative film based on oat protein of the present application is prepared from the following raw materials: oat protein aggregates, carboxymethyl cellulose, water, glycerol and bioactive glass.

[0006] Preferably, the bioactive glass is copper-doped mesoporous bioactive glass.

[0007] On the other hand, the present application provides a preparation method of an edible preservative film based on oat protein, which comprises the following steps:

[0008] (1) Add oat protein aggregates to water and stir until uniform to obtain a first mixed solution;

[0009] (2) Add carboxymethyl cellulose to water and stir until uniform to obtain a second mixed solution;

[0010] (3) mixing the first mixed solution and the second mixed solution, then adding glycerol and copper-doped mesoporous bioactive glass in sequence, stirring for a period of time at a temperature of 60-65°C to obtain a film-forming solution;

[0011] (4) pouring the film-forming solution into a flat substrate, and then drying to obtain the oat protein-based edible preservative film.

[0012] Further, in step (1), the preparation method of the oat protein aggregate is as follows:

[0013] Take 100 g of oat protein and add 600 mL of water, stir for 10 h to fully dissolve, then centrifuge (10000 r, 10 min) and discard the precipitate, and then dialyze the supernatant for 24 h. Adjust the pH of the dialyzed liquid to 8, heat at 90-95°C for 4 h, then cool rapidly to obtain oat protein aggregates, and then freeze-dry for later use.

[0014] Further, the mass ratio of the oat protein aggregate to carboxymethyl cellulose is 2:1.

[0015] Further, in step (3), the preparation method of the copper-doped mesoporous bioactive glass is as follows:

[0016] The copper-doped mesoporous bioactive glass is synthesized by a microemulsion sol-gel method, and the specific method is as follows: 0.56 g of CTAB is dissolved in 26.00 mL of deionized water, and after complete dissolution, 8.00 mL of C4H8O2, 5.6 mL of NH3·H2O, 3.00 mL of tetraethyl orthosilicate, 0.29 mL of triethyl phosphate, 0.40 g of Ca(NO3)2·4H2O, and 0.14 g of CuCl2·H2O are added, and after thorough stirring, further reaction is carried out for 4 h. The obtained powder is washed by centrifugation with ethanol and deionized water for 3 times, and then dried at 60°C for 12 h. The powder is calcined in a muffle furnace at a heating rate of 2°C / min, and the temperature is raised to 700°C and maintained for 4 h to obtain the copper-doped mesoporous bioactive glass powder, which is used for later testing.

[0017] Further, in step (3), the amount of glycerol added accounts for 1.5-2.0% of the mass percentage of the third mixed solution.

[0018] Further, in step (3), the amount of copper-doped mesoporous bioactive glass added accounts for 0.1-1% of the mass percentage of the third mixed solution.

[0019] Further, in step (1), and / or step (2), and / or step (3), the stirring is magnetic stirring, the stirring time is 1-2 h, and the stirring speed is 300-800 rpm.

[0020] Beneficial effects: Compared with the prior art, the present application has the following remarkable advantages: the present application modifies oat protein to obtain oat protein aggregates by heat treatment, uses the obtained oat protein aggregates to perform film making, obtains a composite film, and significantly improves the transparency, flexibility and barrier property of the composite film, and the antibacterial property of the composite film is improved by adding bioactive glass. In addition, the obtained modified oat protein solution is freeze-dried to obtain solid oat protein aggregates, which are convenient to store and transport, and can be directly used as raw materials, applied to the preparation of modified oat protein film after reconstitution, which is beneficial to large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The apparent picture of the oat protein film and the oat protein aggregate film;

[0022] Figure 2 The apparent picture of the copper-doped mesoporous bioactive glass with different contents;

[0023] Figure 3 The influence of the addition amount of copper-doped mesoporous bioactive glass on the oxygen permeability of the composite film;

[0024] Figure 4 The elongation results of the oat protein film and the oat protein aggregate film;

[0025] Figure 5 The influence of the addition amount of copper-doped mesoporous bioactive glass on the elongation of the composite film;

[0026] Figure 6 The influence of the addition amount of copper-doped mesoporous bioactive glass on the antibacterial property of the composite film. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be further described below in combination with the drawings.

[0028] The copper-doped mesoporous bioactive glass in the present embodiment is prepared by the following method:

[0029] The copper-doped mesoporous bioactive glass is synthesized by a microemulsion sol-gel method, and the specific method is as follows: 0.56g of CTAB is dissolved in 26.00mL of deionized water, and after complete dissolution, 8.00mL of C4H8O2, 5.6mL of NH3·H2O, 3.00mL of tetraethyl orthosilicate, 0.29mL of triethyl phosphate, 0.40g of Ca(NO3)2·4H2O and 0.14g of CuCl2·H2O are added, and after thorough stirring, further reaction is performed for 4h. The obtained powder is washed by centrifugation with ethanol and deionized water for 3 times, dried at 60℃ for 12h, and calcined in a muffle furnace at a temperature increasing rate of 2℃ / min, the temperature is increased to 700℃, and the temperature is kept for 4h, to obtain copper-doped mesoporous bioactive glass powder, which is used for later testing.

[0030] The oat protein aggregate in this example was prepared by the following method:

[0031] Take 100 g of oat protein and add 600 mL of water. Stir for 10 h to fully dissolve, then centrifuge (10000 r, 10 min) and discard the precipitate. Dialyze the liquid for 24 h. Adjust the pH of the dialyzed liquid to 8, heat at 90°C for 4 h, then cool rapidly to obtain the oat protein aggregate, and then freeze-dry for later use.

[0032] In this example, the stirring speed of the magnetic stirrer was 300-800 rpm, and the stirring time was 1-2 h.

[0033] Example 1

[0034] A method for preparing a modified oat protein-based edible preservative film, comprising the following steps:

[0035] (1) Preparation of protein solution: weigh 2 g of oat protein aggregate and add 50 mL of deionized water. Stir magnetically for 1 h to make the solution uniform, obtaining an oat protein aggregate solution;

[0036] (2) Preparation of CMC solution: weigh 1 g of carboxymethyl cellulose and add 50 mL of deionized water. Stir magnetically for 1 h to make it uniformly distributed, obtaining a CMC solution;

[0037] (3) Preparation of film-forming solution: mix the systems in steps 1 and 2 in equal amounts, add 2% glycerol, and add 0.25% Cu-MBG. Stir magnetically for 30 min, then stir at 60°C for 30 min to make it uniform, obtaining a film-forming solution;

[0038] (4) Film formation: take an appropriate amount of film-forming solution and pour it onto a flat substrate. Place it in an oven at 60°C and dry for 24 h to obtain an oat protein aggregate composite film.

[0039] Example 2

[0040] The difference between this example and Example 1 is that the amount of Cu-MBG added in step (3) is different. In this example, the amount of Cu-MBG added is 0.1% of the total solution.

[0041] A method for preparing a modified oat protein-based edible preservative film, comprising the following steps:

[0042] (1) Preparation of protein solution: weigh 2 g of oat protein aggregate and add 50 mL of deionized water. Stir magnetically for 1 h to make the solution uniform, obtaining an oat protein aggregate solution;

[0043] (2) Preparation of CMC solution: 1 g of carboxymethyl cellulose was weighed into 50 mL of deionized water, and magnetically stirred for 1 h to make it uniformly distributed, to obtain a CMC solution;

[0044] (3) Preparation of film-forming solution: the systems in steps 1 and 2 were mixed in equal amounts, 2% glycerol was added, 0.25% Cu-MBG was added, magnetically stirred for 30 min, and then stirred at 60°C for 30 min to make it uniform, to obtain a film-forming solution;

[0045] (4) Film formation: an appropriate amount of film-forming solution was poured into a flat substrate, placed in an oven at 60°C and dried for 24 h, to obtain an oat protein aggregate composite film.

[0046] Example 3

[0047] The difference between this example and Example 1 is that the amount of Cu-MBG added in step (3) is different, and in this example, the amount of Cu-MBG added accounts for 0.5% of the total solution.

[0048] A preparation method of a modified oat protein-based edible preservative film, comprising the following steps:

[0049] (1) Preparation of protein solution: 2 g of oat protein aggregate was weighed into 50 mL of deionized water, and magnetically stirred for 1 h to make the solution uniform, to obtain an oat protein aggregate solution;

[0050] (2) Preparation of CMC solution: 1 g of carboxymethyl cellulose was weighed into 50 mL of deionized water, and magnetically stirred for 1 h to make it uniformly distributed, to obtain a CMC solution;

[0051] (3) Preparation of film-forming solution: the systems in steps 1 and 2 were mixed in equal amounts, 2% glycerol was added, 0.5% Cu-MBG was added, magnetically stirred for 30 min, and then stirred at 60°C for 30 min to make it uniform, to obtain a film-forming solution;

[0052] (4) Film formation: an appropriate amount of film-forming solution was poured into a flat substrate, placed in an oven at 60°C and dried for 24 h, to obtain an oat protein aggregate composite film.

[0053] Example 4

[0054] The difference between this example and Example 1 is that the amount of Cu-MBG added in step (3) is different, and in this example, the amount of Cu-MBG added accounts for 1.0% of the total solution.

[0055] A preparation method of a modified oat protein-based edible preservative film, comprising the following steps:

[0056] (1) Protein solution preparation: 2 g of oat protein aggregate was weighed and added to 50 mL of deionized water, and magnetically stirred for 1 h to make the solution uniform, to obtain an oat protein aggregate solution;

[0057] (2) CMC solution preparation: 1 g of carboxymethyl cellulose was weighed and added to 50 mL of deionized water, and magnetically stirred for 1 h to make it uniformly distributed, to obtain a CMC solution;

[0058] (3) Film forming solution preparation: the systems in steps 1 and 2 were mixed in equal amounts, 2% glycerol was added, 1.0% Cu-MBG was added, magnetically stirred for 30 min, and then stirred at 60°C for 30 min to make it uniform, to obtain a film forming solution;

[0059] (4) Film forming: an appropriate amount of film forming solution was poured into a flat substrate, and placed in an oven at 60°C for drying for 24 h, to obtain an oat protein aggregate composite film.

[0060] Example 5

[0061] The difference between this example and Example 1 is that the stirring temperature in step (3) is different.

[0062] A preparation method of a modified oat protein-based edible preservative film, comprising the following steps:

[0063] (1) Protein solution preparation: 2 g of oat protein aggregate was weighed and added to 50 mL of deionized water, and magnetically stirred for 1 h to make the solution uniform, to obtain an oat protein aggregate solution;

[0064] (2) CMC solution preparation: 1 g of carboxymethyl cellulose was weighed and added to 50 mL of deionized water, and magnetically stirred for 1 h to make it uniformly distributed, to obtain a CMC solution;

[0065] (3) Film forming solution preparation: the systems in steps 1 and 2 were mixed in equal amounts, 2% glycerol was added, 0.25% Cu-MBG was added, magnetically stirred for 30 min, and then stirred at 65°C for 30 min to make it uniform, to obtain a film forming solution;

[0066] (4) Film forming: an appropriate amount of film forming solution was poured into a flat substrate, and placed in an oven at 60°C for drying for 24 h, to obtain an oat protein aggregate composite film.

[0067] Example 6

[0068] The difference between this example and Example 1 is that the stirring time in step (2) is different, and the stirring time of the CMC solution in this example is 1.5 h.

[0069] A preparation method of a modified oat protein-based edible preservative film, comprising the following steps:

[0070] (1) Protein solution preparation: 2 g of oat protein aggregate was weighed into 50 mL of deionized water, and magnetic stirring was performed for 1 h to make the solution uniform, to obtain an oat protein aggregate solution;

[0071] (2) CMC solution preparation: 1 g of carboxymethyl cellulose was weighed into 50 mL of deionized water, and magnetic stirring was performed for 1.5 h to make it uniformly distributed, to obtain a CMC solution;

[0072] (3) Film-forming solution preparation: the systems in steps 1 and 2 were mixed in equal amounts, 2% of glycerol was added, 0.25% of Cu-MBG was added, magnetic stirring was performed for 30 min, and then 60°C stirring was performed for 30 min to make it uniform, to obtain a film-forming solution;

[0073] (4) Film formation: an appropriate amount of film-forming solution was poured into a flat substrate, and placed in an oven at 60°C for drying for 24 h, to obtain an oat protein aggregate composite film.

[0074] Example 7

[0075] The difference between this example and Example 1 is that the stirring time in step (2) is different, and the stirring time of the CMC solution in this example is 2 h.

[0076] A preparation method of a modified oat protein-based edible preservative film, comprising the following steps:

[0077] (1) Protein solution preparation: 2 g of oat protein aggregate was weighed into 50 mL of deionized water, and magnetic stirring was performed for 1 h to make the solution uniform, to obtain an oat protein aggregate solution;

[0078] (2) CMC solution preparation: 1 g of carboxymethyl cellulose was weighed into 50 mL of deionized water, and magnetic stirring was performed for 2 h to make it uniformly distributed, to obtain a CMC solution;

[0079] (3) Film-forming solution preparation: the systems in steps 1 and 2 were mixed in equal amounts, 2% of glycerol was added, 0.25% of Cu-MBG was added, magnetic stirring was performed for 30 min, and then 60°C stirring was performed for 30 min to make it uniform, to obtain a film-forming solution;

[0080] (4) Film formation: an appropriate amount of film-forming solution was poured into a flat substrate, and placed in an oven at 60°C for drying for 24 h, to obtain an oat protein aggregate composite film.

[0081] The purpose of stirring is to accelerate the dissolution of carboxymethyl cellulose, and it can be seen from Examples 1, 6 and 7 that stirring for 1 h can achieve the dissolution of carboxymethyl cellulose.

[0082] Comparative Example 1

[0083] The difference between this comparative example and Example 1 is that no Cu-MBG is added in step (3).

[0084] A preparation method of an edible preservative film, comprising the following steps:

[0085] (1) Preparation of protein solution: weigh 2 g of oat protein aggregate and add it to 50 mL of deionized water, and magnetically stir for 1 h to make the solution uniform, to obtain an oat protein aggregate solution;

[0086] (2) Preparation of CMC solution: weigh 1 g of carboxymethyl cellulose and add it to 50 mL of deionized water, and magnetically stir for 1 h to make it uniformly distributed, to obtain a CMC solution;

[0087] (3) Preparation of film-forming solution: mix the systems in steps 1 and 2 in equal amounts, add 2% glycerol, magnetically stir for 30 min, and then stir at 60°C for 30 min to make it uniform, to obtain a film-forming solution;

[0088] (4) Film formation: take an appropriate amount of film-forming solution and pour it into a flat substrate, and place it in an oven at 60°C for drying for 24 h, to obtain an oat protein aggregate composite film.

[0089] Comparative Example 2

[0090] The difference between this comparative example and Example 1 is that the oat protein aggregate in step (1) is replaced by oat protein.

[0091] A preparation method of an edible preservative film, comprising the following steps:

[0092] (1) Preparation of protein solution: weigh 2 g of oat protein and add it to 50 mL of deionized water, and magnetically stir for 1 h to make the solution uniform, to obtain an oat protein solution;

[0093] (2) Preparation of CMC solution: weigh 1 g of carboxymethyl cellulose and add it to 50 mL of deionized water, and magnetically stir for 1 h to make it uniformly distributed, to obtain a CMC solution;

[0094] (3) Preparation of film-forming solution: mix the systems in steps 1 and 2 in equal amounts, add 2% glycerol, and add 0.25% Cu-MBG, magnetically stir for 30 min, and then stir at 60°C for 30 min to make it uniform, to obtain a film-forming solution;

[0095] (4) Film formation: take an appropriate amount of film-forming solution and pour it into a flat substrate, and place it in an oven at 60°C for drying for 24 h, to obtain an oat protein composite film.

[0096] The test method for the oxygen permeability of the composite film is as follows: the film is first fixed at the mouth of a cup containing a deoxidizing agent and a sealed film, the initial weight of the cup is weighed, and then the cup is placed in a desiccator with RH 72% for 48 hours. The oxygen permeability is calculated by the following formula:

[0097] Oxygen permeability = Δm / (t x A)

[0098] where Δm is the weight added to the cup (g), t is the time (h), and A is the area of the mouth of the cup (m 2 ).

[0099] The composite film elongation test method is: first, cut the composite film into a square with a length of 2.5 cm and a width of 2.5 cm, set the puncture speed to 50 mm / min, and flatten the film sample in the clamp and clamp it, 5 parallel groups are tested.

[0100] The composite film antibacterial test method: E. coli and S. aureus are used as model bacteria to verify the antibacterial effect of OPA / CMC / Cu-MBG composite film. First, adjust the concentration of the cultured E. coli and S. aureus to 1x108 CFU / m L, then weigh 200 mg of the composite film, and cut it into pieces, and add it to 30 m L of E. coli and S. aureus bacterial solution, respectively, and incubate for 12 hours. The bacterial solution without adding the composite film is used as a control. Then dilute the above treated bacterial solution 1000 times, take 50 μL of the bacterial solution and evenly spread it on the plate, and incubate in an incubator for 12 h. Then use Image J software to count and calculate the antibacterial rate.

[0101] Figure 1 、 Figure 4 The photos and elongation test results of the composite films in Comparative Examples 1 and 2 are shown in the figure. It can be seen that compared with the oat protein film, the oat protein aggregate film has lighter color, higher transparency and smoother surface. The puncture strength of the oat protein aggregate film is higher than that of the two films.

[0102] Figure 2 The apparent pictures of the composite films in Examples 1-4 and Comparative Example 1 are shown. It can be seen that as the amount of Cu-MBG added increases, the color of the composite film gradually darkens and the transparency decreases.

[0103] Figure 3 The oxygen permeability test results of the composite films in Examples 1-4 and Comparative Example 1 are shown. As the amount of Cu-MBG added increases, the oxygen permeability of the composite film decreases and the barrier property improves.

[0104] Figure 5 、 Figure 6 The elongation test results and antibacterial test results of the composite films in Examples 1-4 and Comparative Example 1 are shown. As the amount of Cu-MBG added increases, the puncture strength of the composite film decreases, the composite film becomes brittle, but the antibacterial property significantly improves.

Claims

1. An edible food preservation film based on oat protein, characterized in that, The edible preservation film is made from the following raw materials: oat protein aggregates, carboxymethyl cellulose, water, glycerol, and copper-doped mesoporous bioactive glass. The mass ratio of oat protein aggregates to carboxymethyl cellulose is 2:1, the mass of glycerol accounts for 1.5-2.0% of the total mass of oat protein aggregates, carboxymethyl cellulose, and water, and the mass of copper-doped mesoporous bioactive glass accounts for 0.1-1% of the total mass of oat protein aggregates, carboxymethyl cellulose, and water.

2. A method for preparing an edible food preservation film based on oat protein, characterized in that, The preparation method includes the following steps: (1) Add oat protein aggregates to water and stir well to obtain the first mixed solution; (2) Add carboxymethyl cellulose to water and stir well to obtain a second mixed solution. The mass ratio of oat protein aggregates to carboxymethyl cellulose is 2:

1. (3) The first and second mixed solutions are mixed, and then glycerol and copper-doped mesoporous bioactive glass are added sequentially. The mixture is stirred for a period of time at a temperature of 60℃-65℃ to obtain a film-forming solution. The mass of glycerol accounts for 1.5-2.0% of the total mass of oat protein aggregates, carboxymethyl cellulose and water, and the mass of copper-doped mesoporous bioactive glass accounts for 0.1-1% of the total mass of oat protein aggregates, carboxymethyl cellulose and water. (4) Pour the above film-forming solution into a planar matrix and then dry it to obtain an edible preservation film based on oat protein.

3. The method for preparing an edible food preservation film based on oat protein according to claim 2, characterized in that, In step (1), the method for preparing oat protein aggregates is as follows: Add water to oat protein and stir for a period of time to fully dissolve it. Then centrifuge to remove the precipitate and dialyze the supernatant for a period of time. Adjust the pH of the dialyzed liquid to weakly alkaline, heat it at 90-95℃ for a period of time, and then cool it rapidly to obtain oat protein aggregates, which are then freeze-dried for later use.

4. The method for preparing an edible food preservation film based on oat protein according to claim 2, characterized in that, In step (3), copper-doped mesoporous bioactive glass is synthesized using the microemulsion sol-gel method.

5. The method for preparing the oat protein-based edible preservation film according to claim 2, characterized in that, In step (1), the stirring is done by magnetic stirring, the stirring time is 1-2 hours, and the stirring speed is 300-800 rpm.

6. The method for preparing the oat protein-based edible preservation film according to claim 2, characterized in that, In step (2), the stirring is done by magnetic stirring, the stirring time is 1-2 hours, and the stirring speed is 300-800 rpm.

7. The method for preparing the oat protein-based edible preservation film according to claim 2, characterized in that, In step (3), the stirring is done by magnetic stirring, the stirring time is 1-2 hours, and the stirring speed is 300-800 rpm.

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