Method for preparing preservative film from ginger essential oil

Abstract

The invention discloses a method for preparing a preservative film from ginger essential oil. The method comprises the following steps: mixing a chitosan solution with a polylactic acid degradation solution, fresh ginger essential oil and glycerol, casting to form a film, and drying to obtain the preservative film. The chitosan solution, the polylactic acid degradation liquid and the ginger essential oil are compounded, so that resource recovery of waste polylactic acid is realized, white pollution is effectively reduced, and the preservative film is endowed with excellent biocompatibility; the introduction of the ginger essential oil enhances the antibacterial performance of the film material, prolongs the shelf life of food, improves the safety and functionality of the packaging material, and has significant environmental benefits and application prospects.

Description

Technical Field

[0001] This invention relates to the field of food preservation technology, specifically to a method for making a preservation film using ginger essential oil. Background Technology

[0002] Polylactic acid (PLA) is a renewable plant resource with good biocompatibility, processability, and mechanical properties, and it has been widely used in packaging, fiber, and medical fields. However, with the large-scale use of PLA products, the amount of waste PLA is also increasing. Currently, the main methods for disposing of waste PLA include landfill, incineration, and recycling. Landfill occupies a large amount of land resources, and PLA degrades slowly in landfill environments, still causing long-term environmental impacts. Incineration, while reducing volume, produces greenhouse gases such as carbon dioxide, exacerbating global warming. Therefore, recycling waste PLA has become a key approach to solving its environmental problems.

[0003] Ginger (Zingiber officinale Roscoe) is a common plant used for both medicinal and culinary purposes. Its underground stems contain abundant volatile oil, known as ginger essential oil. The main components of ginger essential oil include gingerene, gingerol, phellandrene, and citral, which give it its unique aroma and various biological activities. Studies have shown that ginger essential oil has significant antibacterial, antioxidant, and anti-inflammatory effects. Its antibacterial properties can inhibit the growth and reproduction of various bacteria and fungi, and it has a good inhibitory effect on common food spoilage bacteria such as Escherichia coli, Staphylococcus aureus, and molds. Its antioxidant properties can scavenge free radicals in the body, delay the oxidative deterioration of food, and extend its shelf life. Its anti-inflammatory properties help reduce inflammatory responses, thus providing positive protection for human health.

[0004] Based on the aforementioned bioactivities of ginger essential oil, it has enormous application potential in the field of food preservation.

[0005] Therefore, adding ginger essential oil to plastic wrap can effectively inhibit the growth of microorganisms on the surface of food and prevent food spoilage by utilizing its antibacterial and antioxidant properties. On the other hand, the waste polylactic acid can be used to effectively reduce white pollution. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for making plastic wrap using ginger essential oil, which aims to use the secondary metabolites or medicinal components (essential oil) of plants in biological preservation and to recycle and reuse waste polylactic acid to reduce white pollution.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for making plastic wrap using ginger essential oil includes the following steps: mixing chitosan solution with polylactic acid degradation solution and ginger essential oil, casting the mixture into a film, and drying it to obtain plastic wrap.

[0009] Preferably, the polylactic acid degradation solution is prepared by dissolving waste polylactic acid under high temperature with NaOH and then neutralizing it.

[0010] Preferably, the ginger essential oil is an essential oil obtained by steam distillation of ginger rhizomes.

[0011] Preferably, the above method further includes the step of adding a plasticizer.

[0012] Preferably, the plasticizer is glycerol.

[0013] Preferably, the above method includes the following steps: take 2.5 g of chitosan, dissolve it in 100 mL of 1% acetic acid solution at 50°C, and stir for 1 h; add 0.5 mL of glycerol and stir for 30 min; then add polylactic acid degradation solution and ginger essential oil, mix well to obtain film-forming solution, pour the film-forming solution into a mold, dry it, and obtain plastic wrap.

[0014] Preferably, the final concentration of the polylactic acid degradation solution in the film-forming solution is 5% by mass / volume.

[0015] Preferably, the final concentration of ginger essential oil in the film-forming solution is 15% by volume.

[0016] On the other hand, the present invention also provides a food preservation film prepared according to the above method.

[0017] On the other hand, the present invention also provides the application of the plastic wrap in food preservation.

[0018] This invention provides a method for making food preservation film using ginger essential oil. Its beneficial effects are as follows: by combining chitosan solution with polylactic acid degradation liquid and ginger essential oil, not only is the resource recycling of waste polylactic acid achieved, effectively reducing white pollution, but the food preservation film is also endowed with excellent biocompatibility. The introduction of ginger essential oil enhances the antibacterial properties of the film material, extends the shelf life of food, and improves the safety and functionality of packaging materials, thus having significant environmental benefits and application prospects. Attached Figure Description

[0019] Figure 1 Image showing the antibacterial effect of ginger essential oil-polylactic acid (PLA) plastic wrap. CK indicates bacterial growth without the film; +1 / 4MIC indicates chitosan plastic wrap containing 1 / 4MIC PLA alkaline degradation solution; +1 / 4MIC+ginger essential oil indicates chitosan plastic wrap containing 15% ginger essential oil and 1 / 4MIC PLA alkaline degradation solution. Detailed Implementation

[0020] The following embodiments are further illustrations of the present invention, but not limitations thereof.

[0021] Example 1

[0022] 1. Preparation of ginger essential oil

[0023] The essential oil extracted from ginger rhizomes using the steam extraction method includes the following steps: Fresh ginger rhizomes are washed, sliced, and dried in an oven at 55℃ to constant weight. The dried ginger powder is then pulverized and passed through a 40-mesh sieve. The dried ginger powder and deionized water are added to a distillation vessel at a ratio of 1 g: 10 mL, soaked for 30 min, heated to a gentle boil, and continuously distilled for 4 h. The steam carries the essential oil through a condenser, and the distillate is collected. The upper oil phase is separated using a separatory funnel, and anhydrous sodium sulfate is added and dried overnight. The desiccant is filtered off to obtain ginger essential oil, which is then stored in a sealed container at 4℃ away from light.

[0024] 2. Preparation of PLA degradation solution

[0025] Waste PLA was washed, dried, and cut into fragments ≤5 mm × 5 mm. The fragments were added to a 0.5 mol / L NaOH solution at a solid-liquid ratio of 1 g: 10 mL and stirred at 180℃ for 2 h until completely dissolved. The solution was filtered while hot to remove insoluble impurities, yielding a clear PLA alkaline hydrolysis solution. After cooling to room temperature in an ice-water bath, 1 mol / L HCl was added dropwise while stirring to adjust the pH to 6.5-7.0, thus obtaining the PLA degradation solution. The solution was sealed and stored at 4℃ for later use.

[0026] 3. Determination of the minimum inhibitory concentration (MIC) of PLA degradation solution

[0027] 10 μL of Staphylococcus aureus and Escherichia coli suspension (OD) 600 =1) Add to a 96-well plate containing PLA degradation solution of different concentrations diluted by the double-soup method, and incubate at 37°C for 24 h. The minimum inhibitory concentration (MIC) is the concentration at which no visible bacterial growth is observed.

[0028] The results showed that the minimum inhibitory concentration (MIC) of PLA degradation solution against Staphylococcus aureus and Escherichia coli was 20% (200 mg / mL).

[0029] 4. Preparation of plastic wrap

[0030] (1) Preparation of chitosan + ginger essential oil - polylactic acid plastic wrap

[0031] 2.5 g of chitosan was dissolved in 100 mL of 1% (w / v) acetic acid solution at 50 °C and stirred thoroughly for 1 h. Then, 0.5 mL of glycerol was added and stirred for 30 min. A certain amount of PLA degradation solution and ginger essential oil were added and mixed well to obtain a film-forming solution. 20 mL of the film-forming solution was poured into a film-forming mold and placed in an oven at 45 °C for 48 h to obtain a plastic wrap. The final concentration of PLA degradation solution in the film-forming solution was 1 / 4 MIC (i.e., 5% or 50 mg / mL), and the final concentration of ginger essential oil in the film-forming solution was 15% (v / v).

[0032] (2) Preparation of chitosan preservation film containing +1 / 4MIC PLA alkaline degradation solution

[0033] Take 2.5 g of chitosan and dissolve it in 100 mL of 1% (mass fraction) acetic acid solution at 50℃, and stir thoroughly for 1 h. Then add 0.5 mL of glycerol and stir for 30 min. Add a certain amount of PLA degradation solution and mix well to obtain the film-forming solution. Take 20 mL of the film-forming solution and pour it into a film-forming container, and place it in an oven at 45℃ for 48 h to obtain the plastic wrap. The final concentration of PLA degradation solution in the film-forming solution is 1 / 4 MIC concentration (i.e., 5% or 50 mg / mL).

[0034] 5. Biofilm antibacterial verification

[0035] The membrane was sterilized under ultraviolet light for 1 hour, and 0.8 g of the membrane was added to a solution containing 10 mL of OD. 600 In a 0.3% concentration of either *E. coli* or *Staphylococcus aureus* bacterial suspension, the bacterial solution without biological preservation film served as the control (CK). The mixture was incubated with shaking at 37°C for 4 hours, and then diluted 10⁻⁶ times. 4 Then, 50 μL was placed on an LB agar plate and incubated at 37°C for 24 h to observe the colony density.

[0036] Figure 1 The figure shows the antibacterial effect of ginger essential oil-polylactic acid (PLA) plastic wrap. As can be seen from the figure, the chitosan plastic wrap containing both 15% ginger essential oil and 1 / 4 MIC PLA alkaline degradation solution has the best antibacterial effect, which is significantly better than the chitosan plastic wrap containing only +1 / 4 MIC PLA alkaline degradation solution. This result indicates that ginger essential oil can significantly improve the antibacterial effect of plastic wrap.

[0037] The above detailed description is a specific description of the embodiments of the present invention. These embodiments are not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included in the patent scope of this case.

Claims

1. A method for making plastic wrap using ginger essential oil, characterized in that, Includes the following steps: Chitosan solution was mixed with polylactic acid degradation solution and ginger essential oil, and then cast into a film and dried to obtain a plastic wrap.

2. The method according to claim 1, characterized in that, The polylactic acid degradation solution is prepared by dissolving waste polylactic acid under high temperature with NaOH and then neutralizing it.

3. The method according to claim 1, characterized in that, The ginger essential oil is obtained by extracting ginger rhizomes using steam distillation.

4. The method according to claim 1, characterized in that, It also includes the step of adding plasticizers.

5. The method according to claim 4, characterized in that, The plasticizer is glycerol.

6. The method according to claim 5, characterized in that, The process includes the following steps: Take 2.5 g of chitosan, dissolve it in 100 mL of 1% acetic acid solution at 50℃, and stir for 1 h; add 0.5 mL of glycerol and stir for 30 min; then add polylactic acid degradation solution and ginger essential oil, mix well to obtain film-forming solution, pour the film-forming solution into a mold, dry it, and obtain plastic wrap.

7. The method according to claim 6, characterized in that, The final concentration of the polylactic acid degradation solution in the film-forming solution is 5% by mass / volume.

8. The method according to claim 6, characterized in that, The final concentration of ginger essential oil in the film-forming solution is 15% by volume.

9. The food preservation film prepared by the method according to any one of claims 1-8.

10. The application of the plastic wrap according to claim 9 in food preservation.

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