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CN-122011519-A - Preparation method of composite film for blueberry preservation

CN122011519ACN 122011519 ACN122011519 ACN 122011519ACN-122011519-A

Abstract

The invention discloses a preparation method of a composite film for blueberry fresh-keeping. According to the invention, natural chitosan is used as a base material, the active ingredients of Phellinus linteus mycelium acid polysaccharide (APFP) and glycerol plasticizer are matched, no chemical preservative is added, the residual risk brought by traditional chemical preservation is avoided from the source, the antibacterial and antioxidant properties of APFP and the blocking property of chitosan form a synergistic effect, the propagation of putrefying bacteria after blueberry picking can be effectively inhibited, the water loss and the pulp softening can be slowed down, the method is simple in steps, clear in parameters, complex precise equipment is not needed, the magnetic stirring and dissolving, standing and defoaming, constant temperature drying and other processes are easy to regulate and control in standardization, the production difficulty and cost can be reduced, the indexes such as viscosity, pH value and the like of the composite film forming solution are stable, the mechanical strength and blocking property of the prepared composite film reach the standard, the batch consistency is good, the bottleneck that the mechanical strength of the traditional biological base composite film is insufficient and the process is difficult to scale is overcome, and the invention and the industrialization price are considered.

Inventors

  • ZHANG LIHONG
  • WANG JINGXUAN
  • LIU YONGKANG
  • LI MINGCHEN
  • United States, Japan, Ayi Ai Zaiti

Assignees

  • 长春大学

Dates

Publication Date
20260512
Application Date
20260313

Claims (10)

  1. 1. The preparation method of the composite film for blueberry preservation is characterized by comprising the following steps of: (1) The preparation of chitosan solution, namely accurately weighing 3g of chitosan, dissolving the chitosan in 200mL of citric acid solution with mass fraction of 2%, stirring the solution by adopting a magnetic stirrer with model number of 81-2 at the temperature of 60 ℃ and the rotating speed of 3000 r/min until the chitosan is completely dissolved to prepare chitosan solution with mass fraction of 1.5%, and simultaneously adding glycerol with mass fraction of 30% of chitosan into the solution; (2) The preparation of the composite film forming solution comprises the steps of mixing 0.25 percent, 0.5 percent, 0.75 percent and 1 percent of Phellinus linteus mycelium acidic polysaccharide (APFP) aqueous solution with the chitosan solution prepared in the step (1) according to the equal volume ratio, and uniformly stirring to prepare APFP-CS composite film forming solution; (3) The defoaming treatment, namely pouring 25 milliliters of the composite film-forming solution into a plastic culture dish with the diameter of 90mm, and standing for 1 hour to remove bubbles in the solution; (4) And (3) film forming and drying, namely placing the culture dish subjected to the defoaming treatment in a constant temperature drying oven with the model of GF-9030A, and drying for 8 hours at 50 ℃ to form the composite film.
  2. 2. The method for preparing the blueberry fresh-keeping composite film according to claim 1, wherein the Phellinus linteus mycelium acidic polysaccharide (APFP) in the step (2) is prepared by the following method: (1) Crude polysaccharide extraction, namely weighing Phellinus linteus mycelium powder, mixing with distilled water according to a solid-to-liquid ratio of 1:90 (w/v, g/mL), extracting for 3 hours in hot water at 90 ℃, centrifuging the extracting solution at 3500rpm for 15 minutes after the extraction is completed, and collecting supernatant; (2) Ethanol precipitation, namely adding ethanol with the volume fraction of 95% into the supernatant according to the volume ratio of the ethanol to the supernatant of 4:1, precipitating for 12 hours at the temperature of 4 ℃, centrifuging again under the same centrifuging condition, and collecting precipitate as crude polysaccharide (PFP); (3) 2g of crude polysaccharide (PFP) is weighed and dissolved in 100mL of distilled water, the solution is centrifuged for 15 minutes at a rotating speed of 4000rpm, supernatant is taken and added into a DEAE-52 cellulose column (35 mm multiplied by 40 cm), and after the sample completely penetrates through a cellulose matrix, the acidic polysaccharide component is eluted by 0.2mol/L sodium chloride solution at a flow rate of 1.5 mL/min; (4) And (3) dialyzing and drying, namely transferring the collected eluent into a dialysis bag with a molecular weight cut-off value of 3500Da, dialyzing with distilled water for 48 hours, concentrating the dialysate by rotary evaporation, and freeze-drying to obtain the Phellinus linteus mycelium acidic polysaccharide (APFP).
  3. 3. The composite film for blueberry fresh-keeping obtained by the preparation method according to claim 1 or 2, which is characterized in that chitosan is used as a base material, phellinus linteus mycelium acidic polysaccharide (APFP) is used as an active ingredient, glycerol is used as a plasticizer, wherein the mass fraction of Phellinus linteus mycelium acidic polysaccharide (APFP) in the composite film-forming solution is 0.25% -1%, and the addition amount of the glycerol is 30% of the mass of the chitosan.
  4. 4. The composite film for blueberry fresh-keeping according to claim 3, wherein the composite film has a mechanical strength of 20-35MPa, an elongation at break of 35% -55%, an oxygen transmission rate of 5.0cm 3/(m2.multidot.d atm), and a moisture transmission rate of 8.0 g/(m2.multidot.d).
  5. 5. The application of the composite film in postharvest preservation of blueberries, which is characterized in that the application mode is that the composite film is made into a packaging material to wrap and pack the blueberries, or is prepared into a film forming liquid to coat and dry the blueberries.
  6. 6. The method according to claim 5, wherein the thickness of the coating film is 0.05-0.15mm, the air-drying temperature is 55 ℃ and the air-drying time is 8 hours when the coating film treatment mode is adopted.
  7. 7. The blueberry preservation method is characterized by adopting the composite film according to claim 3 to carry out preservation treatment on blueberries, and specifically comprises the following steps: (1) The blueberry pretreatment, namely selecting fresh blueberries with consistent maturity, no damage and no plant diseases and insect pests, washing the fresh blueberries with clear water, and airing the surface moisture at the temperature of 25-30 ℃; (2) The pretreated blueberries are wrapped and packaged by the composite film according to the claim 3, or are immersed in the composite film forming solution according to the claim 1 for 10-20 seconds and then taken out, and are dried for 1-2 hours at 25-30 ℃; (3) And (3) storing, namely storing the blueberry subjected to the preservation treatment in an environment with the temperature of 0-4 ℃ and the relative humidity of 85-90%.
  8. 8. The blueberry fresh-keeping method according to claim 7, wherein the blueberry fresh-keeping method is characterized in that the weight loss rate is less than or equal to 18%, the decay rate is less than or equal to 16% and the pulp hardness is more than or equal to 20kg/cm < 2 > when the blueberry fresh-keeping method is stored for 15 days.
  9. 9. The composite film forming solution for preparing the blueberry preservative composite film is characterized by comprising a chitosan solution, a Phellinus linteus mycelium acidic polysaccharide (APFP) aqueous solution and glycerin, wherein the chitosan solution is a citric acid chitosan solution with the mass fraction of 1.5%, the mass fraction of the Phellinus linteus mycelium acidic polysaccharide (APFP) aqueous solution is 0.25% -1%, the volume ratio of the chitosan solution to the Phellinus linteus mycelium acidic polysaccharide (APFP) aqueous solution is 1:1, and the addition amount of the glycerin is 30% of the mass of the chitosan.
  10. 10. The composite film-forming solution according to claim 9, wherein the viscosity of the composite film-forming solution is 50-150 mPa-s (25 ℃) and the pH value is 4.0-5.5, the inhibition rate of the composite film-forming solution on common putrefying bacteria after blueberry harvest is more than or equal to 80%, and the DPPH free radical removal rate is more than or equal to 65%.

Description

Preparation method of composite film for blueberry preservation Technical Field The invention relates to the technical field of food fresh-keeping packaging materials, in particular to a preparation method of a composite film for blueberry fresh keeping. Background Blueberry is rich in nutrition, easy to soften, lose water and be infected by microorganisms after being picked, quality deterioration is fast, market circulation is severely restricted, and the efficient fresh-keeping technology is a key for the development of blueberry industry. The traditional blueberry preservation method mainly comprises low-temperature storage and chemical preservative, has the problems of high energy consumption, corrosion resistance residue and the like, and does not meet the requirements of green consumption. In recent years, blueberry preservative film research focuses on natural polysaccharide-based composite films. By introducing active ingredients such as polysaccharide, an antibacterial and antioxidant multifunctional composite film is constructed, and the preservation effect is improved to be the main stream direction. The existing bio-based composite membrane has the bottlenecks of insufficient mechanical strength, easy volatilization of active ingredients, difficult scale of preparation process and the like. Disclosure of Invention The invention aims to provide a preparation method of a composite film for blueberry preservation, which aims to solve the problems in the background technology. In order to achieve the aim, the invention provides the following technical scheme that the preparation method of the composite film for blueberry fresh-keeping comprises the following steps: (1) The preparation of chitosan solution, namely accurately weighing 3g of chitosan, dissolving the chitosan in 200mL of citric acid solution with mass fraction of 2%, stirring the solution by adopting a magnetic stirrer with model number of 81-2 at the temperature of 60 ℃ and the rotating speed of 3000 r/min until the chitosan is completely dissolved to prepare chitosan solution with mass fraction of 1.5%, and simultaneously adding glycerol with mass fraction of 30% of chitosan into the solution; (2) The preparation of the composite film forming solution comprises the steps of mixing 0.25 percent, 0.5 percent, 0.75 percent and 1 percent of Phellinus linteus mycelium acidic polysaccharide (APFP) aqueous solution with the chitosan solution prepared in the step (1) according to the equal volume ratio, and uniformly stirring to prepare APFP-CS composite film forming solution; (3) The defoaming treatment, namely pouring 25 milliliters of the composite film-forming solution into a plastic culture dish with the diameter of 90mm, and standing for 1 hour to remove bubbles in the solution; (4) And (3) film forming and drying, namely placing the culture dish subjected to the defoaming treatment in a constant temperature drying oven with the model of GF-9030A, and drying for 8 hours at 50 ℃ to form the composite film. As a preferable mode of the invention, the Phellinus linteus mycelium acidic polysaccharide (APFP) in the step (2) is prepared by the following method: (1) Crude polysaccharide extraction, namely weighing Phellinus linteus mycelium powder, mixing with distilled water according to a solid-to-liquid ratio of 1:90 (w/v, g/mL), extracting for 3 hours in hot water at 90 ℃, centrifuging the extracting solution at 3500rpm for 15 minutes after the extraction is completed, and collecting supernatant; (2) Ethanol precipitation, namely adding ethanol with the volume fraction of 95% into the supernatant according to the volume ratio of the ethanol to the supernatant of 4:1, precipitating for 12 hours at the temperature of 4 ℃, centrifuging again under the same centrifuging condition, and collecting precipitate as crude polysaccharide (PFP); (3) 2g of crude polysaccharide (PFP) is weighed and dissolved in 100mL of distilled water, the solution is centrifuged for 15 minutes at a rotating speed of 4000rpm, supernatant is taken and added into a DEAE-52 cellulose column (35 mm multiplied by 40 cm), and after the sample completely penetrates through a cellulose matrix, the acidic polysaccharide component is eluted by 0.2mol/L sodium chloride solution at a flow rate of 1.5 mL/min; (4) And (3) dialyzing and drying, namely transferring the collected eluent into a dialysis bag with a molecular weight cut-off value of 3500Da, dialyzing with distilled water for 48 hours, concentrating the dialysate by rotary evaporation, and freeze-drying to obtain the Phellinus linteus mycelium acidic polysaccharide (APFP). As a preferable mode of the invention, the composite membrane takes chitosan as a base material, phellinus linteus mycelium acidic polysaccharide (APFP) as an active ingredient and glycerin as a plasticizer, wherein the mass fraction of Phellinus linteus mycelium acidic polysaccharide (APFP) in the composite membrane forming solution is 0.25% -1%, and the