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CN-122011234-A - Chitosan for food packaging and preparation method thereof, and preparation method of food packaging film

CN122011234ACN 122011234 ACN122011234 ACN 122011234ACN-122011234-A

Abstract

The invention provides chitosan for food packaging, a preparation method and a preparation method of a food packaging film, and belongs to the field of food engineering; dissolving chitosan in glacial acetic acid aqueous solution, fully swelling to form transparent solution, dropwise adding pigment solution into the transparent solution at room temperature, stirring and mixing to obtain a mixture, adding sufficient formaldehyde solution into the mixture until the reaction is complete, dropwise adding sodium hydroxide solution to form a precipitate, collecting the precipitate, washing and freeze-drying to obtain chitosan powder, wherein the natural pigment comprises curcumin and alizarin. The chitosan prepared by the method can improve the dispersibility of the natural pigment in the film, improve the pigment fixing mode, avoid migration loss, improve the photo-thermal stability of the natural pigment, improve the structural stability and mechanical property of the film, and realize the dual functions of fresh keeping and indication.

Inventors

  • FENG YAOZE
  • ZHOU MINGRUI
  • LIU WENJING
  • WANG YIJIAN
  • Wei Duxian
  • ZHU MING

Assignees

  • 华中农业大学

Dates

Publication Date
20260512
Application Date
20260206

Claims (10)

  1. 1. A method for preparing chitosan for food packaging, which is characterized by comprising the following steps: Adding natural pigment into N, N-dimethylformamide, and stirring until the natural pigment is completely dissolved to obtain pigment solution; Dissolving chitosan in glacial acetic acid aqueous solution, fully swelling and forming transparent solution; adding the pigment solution into the transparent solution in a dropwise manner at room temperature, and uniformly stirring and mixing to obtain a mixture; Adding a sufficient amount of formaldehyde solution into the mixture until the reaction is completed, dripping sodium hydroxide solution to form a product into a precipitate, collecting the precipitate, washing and freeze-drying to obtain chitosan powder; Wherein the natural pigment comprises curcumin and alizarin.
  2. 2. The method for producing chitosan for food packaging according to claim 1, wherein when the natural pigment is curcumin, the ratio of curcumin, chitosan and N, N-dimethylformamide comprises 934mg:1.0g:50ml; When the natural pigment is alizarin, the ratio of alizarin, chitosan and N, N-dimethylformamide comprises 634mg:1.0g:50mL.
  3. 3. The method for producing chitosan for food packaging according to claim 1, wherein the formaldehyde solution is 53mL of a 37% mass fraction formaldehyde solution.
  4. 4. The method of preparing chitosan for food packaging according to claim 1, wherein said adding a sufficient amount of formaldehyde solution to said mixture until the reaction is complete comprises: after a sufficient amount of formaldehyde solution was added to the mixture, the reaction system was kept stirring at 500rpm for 24 hours at 60 ℃.
  5. 5. The method for producing chitosan for food packaging according to claim 1, wherein collecting the precipitate comprises centrifuging the precipitate at 6000 rpm for 10 minutes.
  6. 6. The method for producing chitosan for food packaging according to claim 1, wherein the concentration of the sodium hydroxide solution comprises 0.5mol/L.
  7. 7. A chitosan for food packaging, characterized by being prepared based on the method for preparing chitosan for food packaging according to any one of claims 1 to 6.
  8. 8. A method of preparing a food packaging film comprising: Adding gelatin into deionized water, heating and stirring until the gelatin is completely dissolved, and cooling; Adding the chitosan solution prepared from the chitosan for food packaging according to claim 7 into the gelatin solution, uniformly stirring and mixing, and adding glycerol into the mixed solution, and continuously stirring until the glycerol is fully dispersed; Adding calcium chloride and stirring uniformly to obtain film-forming precursor liquid; Slowly pouring the film-forming precursor liquid into a culture dish, uniformly spreading the film-forming precursor liquid at the bottom of the dish, and drying to remove the solvent to form a solid film.
  9. 9. The method of claim 8, wherein the gelatin to deionized water ratio comprises 300 mg/5 ml.
  10. 10. The method of preparing a food packaging film according to claim 8, wherein the chitosan solution concentration comprises 20mg/mL.

Description

Chitosan for food packaging and preparation method thereof, and preparation method of food packaging film Technical Field The invention relates to the field of food engineering, in particular to chitosan for food packaging, a preparation method of chitosan and a preparation method of a food packaging film. Background Natural pigments have been widely used in the field of food packaging, such as in packaging films for performing freshness-retaining functions and the like. The existing natural pigment has poor dispersibility in hydrophilic biological base film, the fixing mode of the natural pigment in the film is lack of effective control, migration or loss is easy to occur, the photo-thermal stability of the natural pigment is insufficient, and the color is easy to decay when the natural pigment is used for a long time. In addition, the lack of molecular-level bonding between the pigment and the matrix limits the improvement of the film structure and performance, and the prior art is mostly focused on antibacterial or functional release, and lacks the synergy of freshness preservation and indication dual functions. Disclosure of Invention Aiming at the problems existing in the prior art, the invention provides chitosan for food packaging, a preparation method thereof and a preparation method of a food packaging film. The invention provides a preparation method of chitosan for food packaging, which comprises the steps of adding natural pigment into N, N-Dimethylformamide (DMF), stirring until the natural pigment is completely dissolved to obtain pigment solution, dissolving chitosan into glacial acetic acid aqueous solution, fully swelling the chitosan to form transparent solution, adding the pigment solution into the transparent solution in a dropwise manner at room temperature, stirring and uniformly mixing the transparent solution to obtain a mixture, adding sufficient formaldehyde solution into the mixture until the reaction is complete, dropwise adding sodium hydroxide solution to enable a product to form precipitate, collecting precipitate, washing and freeze-drying the precipitate to obtain chitosan powder, wherein the natural pigment comprises Curcumin (CUR) and Alizarin (AL). According to the preparation method of the chitosan for food packaging, when the natural pigment is curcumin, the ratio of curcumin to chitosan to N, N-dimethylformamide comprises 934mg to 1.0g to 50mL, and when the natural pigment is alizarin, the ratio of alizarin to chitosan to N, N-dimethylformamide comprises 634mg to 1.0g to 50mL. According to the preparation method of the chitosan for food packaging provided by the invention, the formaldehyde solution is 53mL of 37% formaldehyde solution in mass fraction. According to the preparation method of chitosan for food packaging, provided by the invention, a sufficient amount of formaldehyde solution is added to the mixture until the reaction is complete, and the reaction system is kept stirring at 500rpm for 24 hours at 60 ℃ after the sufficient amount of formaldehyde solution is added to the mixture. The preparation method of the chitosan for food packaging provided by the invention comprises the step of centrifugally collecting the precipitate under the conditions of 6000 rpm and 10min. The invention also provides the chitosan for food packaging, which is prepared based on the preparation method of the chitosan for food packaging. The invention also provides a preparation method of the food packaging film, which comprises the steps of adding gelatin into deionized water, heating and stirring until the gelatin is completely dissolved, cooling, adding chitosan solution prepared from the chitosan for food packaging into gelatin solution, stirring and uniformly mixing, adding glycerol into the mixed solution, continuously stirring until the glycerol is fully dispersed, adding calcium chloride and stirring uniformly to obtain film-forming precursor liquid, slowly pouring the film-forming precursor liquid into a culture dish, uniformly spreading the film-forming precursor liquid at the bottom of the dish, and drying to remove the solvent to form a solid film. According to the preparation method of the food packaging film provided by the invention, the proportion of the gelatin to the deionized water comprises 300 mg/5 mL. According to the preparation method of the food packaging film provided by the invention, the concentration of the chitosan solution is 20 mg/mL. The chitosan for food packaging, the preparation method and the preparation method of the food packaging film provided by the invention can improve the dispersibility of the natural pigment in the film, improve the fixation mode of the pigment, avoid migration loss, improve the photo-thermal stability of the natural pigment, improve the structural stability and mechanical property of the film and realize the dual functions of fresh keeping and indication. Drawings In order to more clearly illustrate the invention or the t