Edible blueberry anthocyanin composite film and preparation method thereof
Technical Field
The invention belongs to the technical field of food packaging, and particularly relates to a blueberry anthocyanin edible composite film and a preparation method thereof.
Background
In recent years, white pollution and resource shortage are receiving more and more attention, and non-degradable plastic packages not only cause harm to the environment, but also have certain harmful influence on the quality of packaged food. The food quality safety is directly related to human health, the food safety is closely related to food packaging, the food industry is continuously developed along with the improvement of the living standard of people, and the technical requirements on food packaging are also continuously improved. In the modern society, the shelf life of the product is prolonged, the loss of nutrient components is prevented, and the original quality and freshness of the food are maintained on the basis of protecting the product. The edible composite film is a film with a compact structure formed by taking an edible biological macromolecular substance as a main matrix and an edible plasticizer as an auxiliary material through a certain treatment process. Compared with the traditional plastic packaging film, the edible packaging film is edible, safe and sanitary, does not influence the flavor of food, is biodegradable and does not pollute the environment.
At present, the main materials used for preparing edible composite films are: proteins, polysaccharides, lipids, and composite materials thereof. The edible film with single component has the defects of poor mechanical performance, poor gas barrier property and the like, and has the problems of low tensile strength, insufficient mechanical strength, low hydrophobicity of polysaccharide film and the like of the protein film. The main research on edible composite films is to modify or compound various materials to improve the tensile strength and gas barrier ability of edible composite films, but none of them is ideal. Therefore, under the policy of circular economy of promoting resource conservation and environmental protection, the novel edible film becomes a key research object of numerous scholars.
The anthocyanin is a natural water-soluble pigment commonly existing in fruits, vegetables, flowers and grains, belongs to flavonoid compounds, wherein the blueberry has the title of 'the king of the anthocyanin', has high content and various varieties of the anthocyanin, and has good oxidation resistance and bacteriostasis. Starch is a natural polysaccharide high molecular compound, has rich sources, is renewable, can be naturally degraded, and is an ideal film-forming material.
The anthocyanin edible composite film provided by the invention takes anthocyanin as a main film forming material, is combined with other proteins and polysaccharides, and forms a stable net-shaped structure film through intermolecular interaction. In order to enhance the stability and film-forming property of the film, a certain amount of connecting agent and plasticizer must be added to improve the mechanical property and cohesiveness of the composite film. Compared with a single film, the composite film can improve the performance of the film, and can be coordinated with each other to overcome the defect of the single film.
Disclosure of Invention
The edible composite film has wide raw material sources, good edibility, good mechanical property and excellent gas barrier property, is soluble in water, can prolong the shelf life of food, has good oxidation resistance and bacterial inhibition property, and can be completely biodegraded.
In order to achieve the purpose of the invention, the invention provides a blueberry anthocyanin edible composite film which is prepared by taking blueberry anthocyanin and starch as main film forming materials, then taking a bonding agent and a plasticizer as auxiliary materials to prepare a solution, and then carrying out casting film forming.
Further, the blueberry anthocyanin edible composite film comprises the following raw materials in percentage by weight: 3-25% of blueberry anthocyanin, 1-3% of starch, 1-3% of bonding agent, 0.5-2% of plasticizer and the balance of deionized water.
Further, the starch is one or more of corn starch, potato starch, cassava starch and sweet potato starch.
Further, the bonding agent is one or more of carboxymethyl cellulose, agar, gellan gum and gelatin.
Further, the plasticizer is one or more of glycerol, propylene glycol and sorbitol.
A preparation method of the blueberry anthocyanin edible composite film specifically comprises the following steps:
(1) starch gelatinization: weighing a proper amount of starch, adding the starch into deionized water, carrying out water bath gelatinization for 15-25 min at the temperature of 75-80 ℃, and stirring at the rotating speed of 350-450 r/min to prepare a gelatinization solution.
(2) And (3) adding a linking agent into the gelatinized solution prepared in the step (1), and stirring for 20-30 min to prepare a mixed solution A.
(3) And (3) adding a plasticizer into the mixed solution A prepared in the step (2), and stirring for 15-25 min to prepare a mixed solution B.
(4) And (4) adding blueberry anthocyanin powder into the mixed liquid B prepared in the step (3), and stirring for 15-25 min to prepare mixed liquid C.
(5) And (3) ultrasonically defoaming the mixed solution C, pouring 60-70 mL of defoamed mixed solution C onto a dry and clean organic glass plate with the surface area of 250cm 2-280 cm2, casting to form a film, drying in a vacuum drying oven at the temperature of 30-35 ℃ for 16-20 h, cooling, and uncovering the film to obtain the blueberry anthocyanin edible composite film.
Further, the temperature of the gelatinized solution in the step (2) during stirring is 50-55 ℃, and the stirring speed is 700-800 r/min.
Further, the temperature of the mixed solution A in the step (3) during stirring is 50-55 ℃, and the stirring speed is 700-800 r/min.
Further, the temperature of the mixed liquid B in the step (4) during stirring is 20-25 ℃, and the stirring speed is 700-800 r/min.
The invention achieves the following beneficial effects:
1. the blueberry anthocyanin edible composite film prepared by the invention is a red film in appearance, the tensile strength is 7.92-37.72 MPa, the elongation at break is 5.15-39.22%, and the water vapor transmission rate is 2.06 x 10 < -4 > to 3.63 x 10 < -4 > [ (g.mm)/(m) <2·h·Pa)]The water content is 16.77-28.62%, and the DPPH free radical clearance rate is 66.98-90.14%.
2. According to the invention, the binding agent is added, so that the mechanical property of the blueberry anthocyanin edible composite film is improved, and the stability of the edible composite film and the compatibility of each raw material component are also improved, so that the blueberry anthocyanin edible composite film has a flat and smooth surface and a uniform structure. The addition of the plasticizer improves the toughness and plasticity of the edible composite film.
3. The blueberry anthocyanin, the starch, the binding agent and other raw materials are all edible substances, wherein the blueberry anthocyanin is wide in source and belongs to renewable resources, and the starch is a natural polysaccharide high-molecular compound and is non-toxic and harmless to the environment and human bodies, so that the blueberry anthocyanin edible composite film is soluble in water and is an environment-friendly edible composite film which can be completely biodegraded.
4. The blueberry anthocyanin edible composite film prepared by the invention has excellent oxidation resistance and antibacterial activity, and can prolong the shelf life of food. The blueberry anthocyanin edible composite film can be used as an inner package of food, and an inner coating of packaging materials such as plastics, paper and the like, is suitable for packaging of food such as fruits, milk, meat, aquatic products and the like, and plays a role in keeping the food packaged in the food fresh and preserved while protecting the environment.
5. The production method of the invention is safe, simple in process flow, low in production cost, capable of being widely popularized in the market and good in market prospect.
Drawings
FIG. 1 is a schematic diagram of tensile strength and elongation at break of an edible composite film according to the present invention when different blueberry anthocyanidin addition amounts are adopted;
FIG. 2 is a schematic diagram of DPPH free radical scavenging rate of the edible composite film when different blueberry anthocyanidin addition amounts are adopted.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the preparation process, an electric stirrer is adopted for operation during stirring, and the electric stirrer adopts a JB-200-S digital display rotating speed electric stirrer manufactured by Shanghai specimen model factory; the stirring reaction is carried out in a water bath kettle which is a DK-S22 electric heating constant temperature water bath kettle manufactured by Shanghai Jing Macro experimental equipment Limited company.
The mechanical property measurement of the invention is carried out by adopting a UTM5205X type microcomputer controlled electronic universal tester manufactured by Shenzhen Sansi longitudinal and transverse science and technology Limited; the DPPH radical clearance was measured by using a UV-1800 UV-visible spectrophotometer manufactured by Shimadzu corporation, Japan.
The blueberry anthocyanin edible composite film of the invention is further explained by combining specific examples.
Example 1
The blueberry anthocyanin edible composite film is composed of the following raw materials in percentage by weight:
sample 1: 3% of blueberry anthocyanin, 2% of corn starch, 2% of carboxymethyl cellulose, 1% of glycerol and 92% of deionized water.
Sample 2: 6% of blueberry anthocyanin, 2% of corn starch, 2% of carboxymethyl cellulose, 1% of glycerol and 89% of deionized water.
Sample 3: 12% of blueberry anthocyanin, 2% of corn starch, 2% of carboxymethyl cellulose, 1% of glycerol and 83% of deionized water.
Sample 4: 18% of blueberry anthocyanin, 2% of corn starch, 2% of carboxymethyl cellulose, 1% of glycerol and 77% of deionized water.
Sample 5: 25% of blueberry anthocyanin, 2% of corn starch, 2% of carboxymethyl cellulose, 1% of glycerol and 70% of deionized water.
The preparation method of the blueberry anthocyanin edible composite film of the samples 1-5 comprises the following steps: adding deionized water into the corn starch in the proportion, setting the stirring speed to be 350-450 r/min, carrying out water bath gelatinization at 75 ℃, and stirring for 20min to prepare a gelatinization solution; then cooling the gelatinization temperature to 55 ℃, adding carboxymethyl cellulose, setting the stirring speed to 700-800 r/min, and stirring in a water bath for 25min to obtain a mixed solution A; adding glycerol into the mixed solution A and continuously stirring for 15min under the conditions that the temperature is 55 ℃ and the stirring speed is 700-800 r/min to prepare mixed solution B; cooling the mixed solution B to 20 ℃, adding blueberry anthocyanin powder under the condition that the stirring speed is 700-800 r/min, and stirring for 20min after constant volume to obtain mixed solution C; and (3) ultrasonically defoaming the mixed solution C, carrying out tape casting on an organic glass plate to form a film, drying in a vacuum drying oven at 35 ℃ for 16-20 h, and removing the film after cooling to obtain the blueberry anthocyanin edible composite film.
The casting film forming method of the embodiment is as follows: pouring 60-70 mL of defoamed mixed liquid C into a container with the area of 250cm2~280cm2The surface of the organic glass plate is dry and clean, and a film is formed by casting.
As shown in fig. 1, the tensile strength and elongation at break of the products 1 to 5 obtained above. As shown in fig. 2, the DPPH radical clearance of the products 1-5 obtained above. Analysis shows that when the addition amount of the blueberry anthocyanin is 6%, the performance of the sample 2 is good, and the blueberry anthocyanin has excellent mechanical performance, water vapor barrier property and antibacterial and antioxidant properties, and the performance is as follows: tensile strength26.93MPa, elongation at break 20.84%, water vapor transmission rate 2.22X 10-4/[(g·mm)/(m2·h·Pa)]The water content is 17.63%, and the DPPH free radical clearance rate is 80.22%.
Example 2
The blueberry anthocyanin edible composite film is composed of the following raw materials in percentage by weight: 12% of blueberry anthocyanin, 1% of potato starch, 2% of carboxymethyl cellulose, 1.5% of glycerol and 83.5% of deionized water.
The preparation method of the blueberry anthocyanin edible composite film comprises the following steps: adding deionized water into potato starch according to the proportion, gelatinizing in a 75 ℃ water bath for 15min, cooling to 50 ℃, adding carboxymethyl cellulose, stirring in the water bath for 25min, adding glycerol, continuously stirring for 15min, cooling to 25 ℃, finally adding blueberry anthocyanin powder, stirring for 15min after constant volume, defoaming, casting on an organic glass plate to form a film, drying at 30 ℃, cooling and uncovering the film to obtain the blueberry anthocyanin edible composite film.
The blueberry anthocyanin edible composite film prepared in the embodiment has the following properties: tensile strength of 19.33MPa, elongation at break of 24.35 percent and water vapor transmission rate of 3.05 multiplied by 10-4[(g·mm)/(m2·h·Pa)]The water content is 20.51 percent, and the DPPH free radical clearance rate is 83.63 percent.
Example 3
The blueberry anthocyanin edible composite film is composed of the following raw materials in percentage by weight: : 18% of blueberry anthocyanin, 3% of corn starch, 2% of carboxymethyl cellulose, 1% of glycerol and 76% of deionized water.
The preparation method of the blueberry anthocyanin edible composite film comprises the following steps: adding deionized water into the corn starch according to the proportion, gelatinizing the corn starch in a water bath at the temperature of 75 ℃ for 20min, cooling the corn starch to the temperature of 55 ℃, adding carboxymethyl cellulose, stirring the mixture in the water bath for 30min, adding glycerol, continuously stirring the mixture for 15min, cooling the mixture to the temperature of 25 ℃, finally adding blueberry anthocyanin powder, stirring the mixture for 20min after constant volume, defoaming the mixture, casting the mixture on an organic glass plate to form a film, drying the film at the temperature of 35 ℃, cooling and uncovering the film to obtain the blueberry anthocyanin edible composite film.
The blueberry anthocyanin edible composite film prepared in the embodiment has the following properties: resist againstTensile strength 23.94MPa, elongation at break 14.85%, water vapor transmission rate 3.27X 10-4[(g·mm)/(m2·h·Pa)]The water content is 18.93 percent, and the DPPH free radical clearance rate is 87.08 percent.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.