Water chestnut English antibacterial preservative film as well as preparation method and application thereof

Abstract

The invention discloses an antibacterial preservative film containing chuatin as well as a preparation method and application of the antibacterial preservative film, and belongs to the technical field of preservative materials. The preparation method comprises the following steps: crushing eleocharin peel, extracting with an ethanol solution at 40-50 DEG C to obtain an eleocharin crude extract, concentrating, washing with water until no alcohol smell exists, freeze-drying, carrying out superfine grinding to obtain eleocharin superfine powder, adding ethanol to dissolve, adding an iron salt aqueous solution and an amino acid aqueous solution, stirring to react, filtering after the reaction is finished, and evaporating the filtrate to remove a solvent to obtain an eleocharin-amino acid reactant; the preparation method comprises the following steps: uniformly mixing the churiin-amino acid reactant, pullulan, konjac glucomannan, glycerol and water, homogenizing at high pressure, heating to 40-50 DEG C, keeping the temperature to be uniform and transparent, carrying out ultrasonic degassing, paving a film on a glass plate, pre-drying at 50-60 DEG C for 15-20 minutes, carrying out vacuum drying for 24-36 hours to form a film, softening, and uncovering the film to obtain the churiin antibacterial preservative film. The water chestnut extract is treated and can be dissolved in water, and the prepared preservative film is good in antibacterial effect and mechanical performance and has good application in the field of food preservation.

Description

Technical Field

[0001] The invention belongs to the technical field of fresh-keeping materials, and particularly relates to an echinocarpus antibacterial fresh-keeping film and a preparation method and application thereof. Background Art

[0002] With the continuous improvement of living standards and increasing attention to health issues, people have put forward higher requirements on the safety of food additives such as preservatives. Consumers tend to choose natural products as preservatives and antibacterial agents, and scientific and technological workers are also cautious about the use of chemical synthetic preservatives.

[0003] Water chestnut is a typical food raw material with pharmacological effects. It has the effect of medicinal and dietary homology and is highly safe. Patients with upper gastrointestinal infections have good results by eating some raw water chestnuts. In the epidemic seasons of influenza and whooping cough, eating more water chestnuts can not only prevent them, but also play an auxiliary therapeutic role. Many people peel water chestnuts very cleanly when eating them, leaving only the innermost white meat. Water chestnut skin is a waste product in the processing process. Most of it is used as feed in life in industrial production, and its utilization value is low. Little do people know that this "overly clean" step leads to the waste of water chestnut. The "Chinese Medicine Dictionary" believes that water chestnut is the main active substance in water chestnut, also known as horse hoof yellow, which refers to the yellow part between the water chestnut skin and the flesh, and has antibacterial effects. Studies have shown that water chestnut extract has an inhibitory effect on Escherichia coli, Staphylococcus aureus, Micrococcus luteus, Bacillus subtilis, etc., among which the inhibitory effect on Staphylococcus aureus is the strongest and more sustainable. Water chestnut extract can effectively prevent the decay of colored fruit tomatoes caused by Rhizopus and Alternaria during storage. 3+ The antibacterial activity of the crude extract of water chestnut treated with Na + , K + , Ca 2+ The antibacterial activity of the crude extract of water chestnut treated with , remained basically unchanged.

[0004] Through research, it was found that when water chestnut extract is directly used as an auxiliary material for plastic wrap, the compatibility of water chestnut extract with other ingredients in the plastic wrap is poor. The prepared plastic wrap containing water chestnut extract has poor antibacterial effect, and water chestnut will fall off during use or processing, affecting its antibacterial properties. In addition, the mechanical properties (tensile strength) of the plastic wrap are poor, and it is easily damaged by external forces. Summary of the invention

[0005] In view of the problems in the prior art that water chestnut peels are seriously wasted, and the prepared cling film has poor antibacterial effect and low tensile strength, the present invention provides a water chestnut antibacterial cling film and a preparation method and application thereof. The water chestnut extract is processed so that the water chestnut extract can be dissolved in water. The prepared cling film has good antibacterial effect and good mechanical properties, and has good application in the field of food preservation.

[0006] The present invention is achieved through the following technical solutions: A method for preparing an antibacterial fresh-keeping film made of water chestnut, comprising the following steps: (1) Crush the water chestnut peel, extract it with ethanol solution at 40-50°C to obtain a crude extract of water chestnut, concentrate it, wash it with water until there is no alcohol taste, freeze-dry it, and ultrafine grind it to obtain water chestnut powder; (2) Dissolve the water chestnut syrup powder in step (1) in ethanol, add an aqueous solution of iron salt and an aqueous solution of amino acids, and stir to react for 0.5 to 2 hours. After the reaction is completed, filter and evaporate the filtrate to remove the solvent to obtain a water chestnut syrup-amino acid reactant; (3) mixing the water chestnut-amino acid reactant in step (2), pullulan, konjac gum, glycerin, and water, mixing well, and homogenizing under high pressure for 3-5 times to obtain a mixed solution; (4) The mixed solution after high pressure homogenization in step (3) is heated to 40-50°C and kept warm for 10-15 minutes until it becomes homogeneous and transparent; (5) Degassing: ultrasonic degassing; (6) Pre-drying: Spread the degassed mixture on a glass plate and pre-dry at 50-60°C for 15-20 minutes; (7) Drying: vacuum drying for 24 to 36 hours to form a film; (8) Softening: After softening, remove the film to obtain the water chestnut antibacterial preservative film.

[0007] Furthermore, the ethanol in step (1) is 95% ethanol, and the water chestnut superfine powder is an ultrafine powder passed through a 120-mesh sieve.

[0008] Furthermore, the iron salt in step (2) is ferric chloride or ferric nitrate, the amino acid is glycine, the mass ratio of water chestnut superfine powder to amino acid is 1:0.2-0.5, and the molar ratio of amino acid to iron salt is 1:0.5-1.

[0009] Furthermore, in step (2), the ratio of ethanol to water is 1:1-2, and the concentration of the aqueous solution of iron salt is 0.5-1 mol / L.

[0010] Furthermore, the mixed solution in step (3) is composed of the following raw materials in parts by weight: 10-20 parts of water chestnut-amino acid reactant, 3-5 parts of pullulan, 1-2 parts of konjac gum, 3-5 parts of glycerol, and 60-70 parts of water.

[0011] Furthermore, in step (5), the ultrasonic degassing time is 2 to 3 hours.

[0012] Furthermore, the thickness of the film in step (6) is 0.3-0.6 mm.

[0013] Furthermore, the softening temperature in step (7) is 25-30°C.

[0014] In the present invention, the water chestnut antibacterial fresh-keeping film prepared by the preparation method is obtained.

[0015] In the present invention, the water chestnut antibacterial fresh-keeping film is used in food preservation.

[0016] In the present invention, water chestnut, iron ions and amino acids form a chelate: (1) metal ions and water chestnut extracts themselves have certain antibacterial activity; (2) after the metal ions, amino acids and water chestnut are chelated, the antibacterial activity is enhanced; (3) after the amino acids and water chestnut extract are chelated, the water solubility of water chestnut is enhanced, and it can be fully integrated with other components in the plastic wrap, thereby enhancing its antibacterial activity, and enhancing the mechanical properties of the plastic wrap, and enhancing the tensile strength.

[0017] Beneficial Effects The present invention extracts water chestnut from water chestnut peel, and after water chestnut is chelated with iron ions and amino acids, its water solubility is increased, and its antibacterial effect is significantly enhanced. Moreover, by being fully integrated with other components in the cling film, the antibacterial activity of the cling film is strengthened, and the mechanical properties and tensile strength of the cling film are enhanced, so the cling film has good application in the field of food preservation. DETAILED DESCRIPTION

[0018] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention.

[0019] Example 1 (1) Crush the water chestnut peel, extract with ethanol solution at 45°C to obtain a crude extract of water chestnut, concentrate, wash with water until there is no alcohol taste, freeze-dry, ultrafine grind, and pass through a 120-mesh sieve to obtain water chestnut superfine powder; (2) Dissolve the water chestnut powder in step (1) in ethanol (add 15 mL of ethanol to each gram of water chestnut powder), add 0.5 mol / L ferric chloride aqueous solution and amino acid aqueous solution (the volume ratio of ethanol to water is 1:1), the mass ratio of water chestnut powder to amino acid is 2:1, and the molar ratio of amino acid to iron salt is 2:1, stir and react for 2 hours, filter after the reaction is completed, and evaporate the filtrate to remove the solvent to obtain water chestnut-amino acid reactant; (3) Mix 15 parts of the water chestnut-amino acid reactant in step (2), 4 parts of pullulan, 2 parts of konjac gum, 4 parts of glycerol, and 65 parts of water, mix well, and homogenize under high pressure for 3 times to obtain a mixed solution; (4) The mixed solution after high pressure homogenization in step (3) is heated to 45°C and kept warm for 12 minutes until it becomes homogeneous and transparent; (5) Degassing: Ultrasonic degassing for 3 hours; (6) Pre-drying: Spread a 0.5 mm film on a glass plate after degassing and pre-dry at 55 °C for 15 min. (7) Drying: vacuum drying for 30 hours to form a film; (8) Softening: After softening at 25-30℃, remove the film to obtain the water chestnut antibacterial preservative film.

[0020] Example 2 (1) Crush the water chestnut peel, extract with ethanol solution at 45°C to obtain a crude extract of water chestnut, concentrate, wash with water until there is no alcohol taste, freeze-dry, ultrafine grind, and pass through a 120-mesh sieve to obtain water chestnut superfine powder; (2) Dissolve the water chestnut powder in step (1) in ethanol (add 15 mL of ethanol to each gram of water chestnut powder), add 0.5 mol / L ferric chloride aqueous solution and amino acid aqueous solution (the volume ratio of ethanol to water is 1:1), the mass ratio of water chestnut powder to amino acid is 2:1, and the molar ratio of amino acid to iron salt is 2:1, stir and react for 2 hours, filter after the reaction is completed, and evaporate the filtrate to remove the solvent to obtain water chestnut-amino acid reactant; (3) mixing 10 parts of the water chestnut-amino acid reactant in step (2), 3 parts of pullulan, 2 parts of konjac gum, 3 parts of glycerol, and 60 parts of water, mixing well, and homogenizing under high pressure for 5 times to obtain a mixed solution; (4) The mixed solution after high pressure homogenization in step (3) is heated to 40-50°C and kept warm for 10-15 minutes until it becomes homogeneous and transparent; (5) Degassing: Ultrasonic degassing for 2.5 hours; (6) Pre-drying: Spread a 0.5 mm film on a glass plate after degassing and pre-dry at 60 °C for 15 min. (7) Drying: vacuum drying for 36 hours to form a film; (8) Softening: After softening at 25-30℃, remove the film to obtain the water chestnut antibacterial preservative film.

[0021] Example 3 (1) Crush the water chestnut peel, extract with ethanol solution at 45°C to obtain a crude extract of water chestnut, concentrate, wash with water until there is no alcohol taste, freeze-dry, ultrafine grind, and pass through a 120-mesh sieve to obtain water chestnut superfine powder; (2) Dissolve the water chestnut powder in step (1) in ethanol (add 15 mL of ethanol to each gram of water chestnut powder), add 0.5 mol / L ferric chloride aqueous solution and amino acid aqueous solution (the volume ratio of ethanol to water is 1:1), the mass ratio of water chestnut powder to amino acid is 2:1, and the molar ratio of amino acid to iron salt is 2:1, stir and react for 2 hours, filter after the reaction is completed, and evaporate the filtrate to remove the solvent to obtain water chestnut-amino acid reactant; (3) Mix 20 parts of the water chestnut-amino acid reactant in step (2), 5 parts of pullulan, 2 parts of konjac gum, 5 parts of glycerol, and 70 parts of water, mix well, and homogenize under high pressure for 3 times to obtain a mixed solution; (4) The mixed solution after high pressure homogenization in step (3) is heated to 40-50°C and kept warm for 10-15 minutes until it becomes homogeneous and transparent; (5) Degassing: Ultrasonic degassing for 3 hours; (6) Pre-drying: Spread a 0.5 mm film on a glass plate after degassing and pre-dry at 50 °C for 20 min. (7) Drying: vacuum drying for 30 hours to form a film; (8) Softening: After softening at 25-30℃, remove the film to obtain the water chestnut antibacterial preservative film.

[0022] Example 4 (1) Crush the water chestnut peel, extract with ethanol solution at 45°C to obtain a crude extract of water chestnut, concentrate, wash with water until there is no alcohol taste, freeze-dry, ultrafine grind, and pass through a 120-mesh sieve to obtain water chestnut superfine powder; (2) Dissolve the water chestnut powder in step (1) in ethanol (add 15 mL of ethanol to each gram of water chestnut powder), add 0.5 mol / L ferric nitrate aqueous solution and amino acid aqueous solution (the volume ratio of ethanol to water is 1:2), the mass ratio of water chestnut powder to amino acid is 5:1, and the molar ratio of amino acid to iron salt is 2:1, stir and react for 2 hours, filter after the reaction is completed, and evaporate the filtrate to remove the solvent to obtain water chestnut-amino acid reactant; (3) Mix 15 parts of the water chestnut-amino acid reactant in step (2), 4 parts of pullulan, 2 parts of konjac gum, 4 parts of glycerol, and 65 parts of water, mix well, and homogenize under high pressure for 3 times to obtain a mixed solution; (4) The mixed solution after high pressure homogenization in step (3) is heated to 45°C and kept warm for 15 minutes until it becomes homogeneous and transparent; (5) Degassing: Ultrasonic degassing for 2 hours; (6) Pre-drying: The degassed mixture is spread on a glass plate with a 0.5 mm film and pre-dried at 60 °C for 20 min. (7) Drying: vacuum drying for 24 hours to form a film; (8) Softening: After softening at 25-30℃, remove the film to obtain the water chestnut antibacterial preservative film.

[0023] Comparative Example 1 Different from Example 1, step (2) is omitted in Comparative Example 1, and the water chestnut glycoside powder is directly used to replace the water chestnut glycoside-amino acid reactant in step (3). The other steps are the same as those in Example 1 to prepare the water chestnut glycoside antibacterial preservative film.

[0024] Comparative Example 2 Different from Example 1, step (2) of Comparative Example 2 is: (2) Dissolve the water chestnut syrup powder in step (1) in ethanol (add 15 mL of ethanol to each gram of water chestnut syrup powder), add an equal amount of the iron salt solution in step (1) (the volume ratio of ethanol to water is 1:1), stir and react for 0.5 to 2 hours, filter after the reaction is completed, and evaporate the filtrate to remove the solvent to obtain the water chestnut syrup-iron reactant; The water chestnut-iron reactant in the comparative example replaces the water chestnut-amino acid reactant in step (3) of Example 1, and the other steps are the same as those in Example 1 to prepare the water chestnut-antibacterial preservative film.

[0025] Performance testing: (1) Antibacterial activity test of water chestnut antibacterial cling film: The water chestnut antibacterial cling film prepared in the examples and comparative examples was processed into a 6 mm diameter disc, placed in a culture dish containing bacteria (the bacterial species were Staphylococcus aureus, Bacillus subtilis, and Escherichia coli), and cultured at 37° C. for 12 h. The diameter of the antibacterial circle was measured. The results are shown in Table 1 below: (2) Mechanical property test of water chestnut antibacterial cling film: The tensile strength (MPa) of water chestnut antibacterial cling film was tested. The results are shown in Table 1 below: Table 1 Antibacterial activity and tensile strength test table of water chestnut antibacterial plastic wrap

Claims

1. A method for preparing an antibacterial fresh-keeping film made of water chestnut, characterized in that: The following steps are involved: (1) Crush the water chestnut peel, extract it with ethanol solution at 40-50°C to obtain a crude extract of water chestnut, concentrate it, wash it with water until there is no alcohol taste, freeze-dry it, and ultrafine grind it to obtain water chestnut powder; (2) Dissolve the water chestnut syrup powder in step (1) in ethanol, add an aqueous solution of iron salt and an aqueous solution of amino acids, and stir to react for 0.5 to 2 hours. After the reaction is completed, filter and evaporate the filtrate to remove the solvent to obtain a water chestnut syrup-amino acid reactant; (3) mixing the water chestnut-amino acid reactant in step (2), pullulan, konjac gum, glycerin, and water, mixing well, and homogenizing under high pressure for 3-5 times to obtain a mixed solution; (4) The mixed solution after high pressure homogenization in step (3) is heated to 40-50°C and kept warm for 10-15 minutes until it becomes homogeneous and transparent; (5) Degassing: ultrasonic degassing; (6) Pre-drying: Spread the degassed mixed solution on a glass plate and pre-dry at 50-60°C for 15-20 minutes; (7) Drying: vacuum drying for 24 to 36 hours to form a film; (8) Softening: After softening, remove the film to obtain the water chestnut antibacterial preservative film.

2. The method for preparing the water chestnut antibacterial fresh-keeping film according to claim 1, characterized in that: The ethanol in step (1) is 95% ethanol, and the water chestnut superfine powder is ultrafine powder passed through a 120-mesh sieve.

3. The method for preparing the water chestnut antibacterial fresh-keeping film according to claim 1, characterized in that: The iron salt in step (2) is ferric chloride or ferric nitrate, the amino acid is glycine, the mass ratio of water chestnut superfine powder to amino acid is 1:0.2-0.5, and the molar ratio of amino acid to iron salt is 1:0.5-1.

4. The method for preparing the water chestnut antibacterial fresh-keeping film according to claim 1, characterized in that: In step (2), the ratio of ethanol to water is 1:1-2, and the concentration of the iron salt aqueous solution is 0.5-1 mol / L.

5. The method for preparing the water chestnut antibacterial fresh-keeping film according to claim 1, characterized in that: The mixed solution in step (3) is composed of the following raw materials in parts by weight: 10-20 parts of water chestnut-amino acid reactant, 3-5 parts of pullulan, 1-2 parts of konjac gum, 3-5 parts of glycerol, and 60-70 parts of water.

6. The method for preparing the water chestnut antibacterial fresh-keeping film according to claim 1, characterized in that: The ultrasonic degassing time in step (5) is 2 to 3 hours.

7. The method for preparing the water chestnut antibacterial fresh-keeping film according to claim 1, characterized in that: The thickness of the film in step (6) is 0.3~0.6mm.

8. The method for preparing the water chestnut antibacterial fresh-keeping film according to claim 1, characterized in that: The softening temperature in step (7) is 25-30°C.

9. An antibacterial fresh-keeping film made from water chestnut extract by the preparation method according to any one of claims 1 to 8.

10. Use of the water chestnut antibacterial preservative film according to claim 9 in food preservation.

Images