A packaging film for aquatic products and its preparation method

Abstract

The present invention belongs to the field of membrane materials, and specifically relates to a packaging film for aquatic products and a preparation method thereof, including a membrane matrix, liposomes loaded on the membrane matrix, and oxides of titanium and zinc contained in the liposomes. The packaging film for aquatic products of the present invention can synergistically catalyze and decompose a large amount of water vapor generated by aquatic products slowly, destroy the high-humidity environment for the growth of germs, and simultaneously generate antibacterial hydrogen to extend the storage time of aquatic products.

Description

Technical Field

[0001] The invention belongs to the field of film materials, and in particular relates to a packaging film for aquatic products and a preparation method thereof. Background Art

[0002] Aquatic products are rich in unsaturated fatty acids and other substances, and have high nutritional value. However, highly unsaturated fatty acids are very easy to oxidize and cause rancidity. In addition, environments suitable for microbial growth such as high moisture content and neutral pH values ​​are also very easy to cause microbial corruption of aquatic products, reducing nutritional quality and causing food waste. Lipid oxidation and microbial reproduction are important reasons for the deterioration of the quality of aquatic products during refrigeration. Therefore, based on active packaging, the development of environmentally friendly aquatic product preservation technology that is both effective and safe has become a current research hotspot. Many studies have confirmed that hydrogen can improve the antioxidant capacity of organisms through different mechanisms of action, effectively reduce the deterioration and degree of corruption of the sensory quality of aquatic products, maintain their storage color, flavor, and nutritional quality, and has potential application value in improving food safety. How to effectively use hydrogen in actual aquatic product preservation requires further research. Summary of the invention

[0003] The present invention mainly provides a packaging film for aquatic products that can utilize the high water content of aquatic products to produce hydrogen and maintain the storage quality of aquatic products. The technical solution is as follows:

[0004] A method for preparing a packaging film for aquatic products comprises the following steps:

[0005] a. Mix titanium dioxide and zinc acetate, add triethanolamine at room temperature, grind until the triethanolamine is completely melted and continue grinding for 5 to 20 minutes; then disperse them in anhydrous ethanol, heat to 60 to 80°C, let stand for 12 to 20 hours, evaporate the ethanol, and roast at 400 to 550°C for 1 to 3 hours to obtain titanium and zinc oxides;

[0006] b. Mixing titanium and zinc oxides with triethanolamine; dissolving lecithin, cholesterol and ethyl butyrate in ethanol, and then adding titanium and zinc oxides mixed with triethanolamine to fully disperse to obtain a dispersion; evaporating the ethanol in the dispersion under reduced pressure, adding water to hydrate; and obtaining a liposome liquid after ultrasonication;

[0007] c. When preparing the membrane matrix, add liposome liquid and obtain the packaging film after drying.

[0008] Furthermore, the mass ratio of titanium dioxide to zinc acetate in step a is 1:2-5; the mass ratio of triethanolamine to zinc acetate in step a is 1:1.5-2.5; and the concentration of zinc acetate in anhydrous ethanol in step a is 0.02-0.1 g / mL.

[0009] Furthermore, the mass ratio of cholesterol to lecithin described in step b is 1:4 - 6; the mass ratio of ethyl butyrate to lecithin is 1:15 - 20; the mass ratio of titanium and zinc oxides to lecithin is 1:8 - 12; the mass ratio of triethanolamine to titanium and zinc oxides described in step b is 1:5 - 8.

[0010] Furthermore, the steps of distilling off ethanol from the dispersion under reduced pressure and adding water for hydration are as follows: distill off ethanol under reduced pressure at 40 - 60°C, then add water to restore the original volume of the dispersion, and perform normal-pressure rotary hydration for 0.3 - 1 h.

[0011] Furthermore, the drying in step c is carried out until the mass no longer changes, and then continue drying at 80 - 90°C for 0.5 - 2 h.

[0012] Furthermore, the steps of preparing the film matrix in step c include: placing gelatin and chitosan in the lipid body fluid, fully mixing at 60 - 80°C to obtain the film matrix body fluid; subjecting the film matrix body fluid to ultrasonic degassing, then pouring it into a mold, drying at 40 - 50°C for 3 - 5 h, and then raising the temperature to 80 - 90°C and continuing to dry for 10 - 30 min.

[0013] Furthermore, the mass ratio of gelatin to chitosan is 1:0.5 - 2; the concentration of gelatin in the film matrix body fluid is 0.05 - 0.1 g / mL.

[0014] Furthermore, the time for full mixing is 15 - 30 min.

[0015] A packaging film for aquatic products prepared by the above preparation method, comprising a film matrix, liposomes loaded on the film matrix, and titanium and zinc oxides contained in the liposomes.

[0016] Furthermore, the components of the film matrix include one or more of polylactic acid, gelatin, chitosan, dextran, polyvinyl alcohol, or sodium alginate.

[0017] Adopting the above scheme, the method of the present invention has the following advantages:

[0018] 1. Under light conditions, the titanium and zinc oxides in the packaging film of the present invention can synergistically catalyze and decompose a large amount of water vapor generated by aquatic products slowly, destroy the high-humidity environment for the growth of germs, and at the same time generate antibacterial hydrogen, and the concentration increases with the increase of storage time and light intensity under closed conditions, adapting to the antibacterial intensity requirements of different storage conditions.

[0019] 2. The present invention grinds titanium dioxide and zinc acetate together. Utilizing the large polarity of titanium dioxide, it cooperates with moisture-absorbing zinc acetate to generate surface hydroxyl groups, so that titanium dioxide and zinc acetate are fully and evenly dispersed and combined during the grinding process.

[0020] 3. The present invention utilizes the melting point of triethanolamine close to room temperature to promote the particle size refinement of zinc acetate and titanium dioxide in the solid state, and also promotes the full mixing of the two; during the grinding process, triethanolamine gradually becomes liquid, realizing the change of the triethanolamine concentration in the system from low to high, enabling triethanolamine to form a uniform coating with the dispersed titanium dioxide, and making the contact with zinc acetate more sufficient, reducing the dosage of ethanol, shortening the gelation time, and saving costs.

[0021] 4. After the liposome is loaded on the membrane matrix, the removal of ethyl butyrate can be completed by extending the drying time, thereby causing the liposome to have a break, facilitating the contact of zinc and titanium oxides with the outside world, and forming channels for hydrogen production and release.

[0022] 5. The triethanolamine of the present invention can be used for the dispersion of titanium dioxide and the decomposition of zinc acetate. When preparing liposomes, it can be used for the full dispersion of titanium and zinc oxides, and can also be used as an emulsifier during film formation, achieving multiple uses of one substance, greatly reducing costs, and the single raw material also avoids the introduction of impurities and separation costs.

[0023] 6. The oxides of titanium and zinc of the present invention are firmly locked on the membrane, evenly dispersed and not easy to fall off, solving the problem of easy agglomeration of titanium dioxide in the system, and ensuring the stability of the antibacterial effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a photo of the packaging film sample of Example 1;

[0025] Figure 2 It is a photo of the packaging film sample of Example 2;

[0026] Figure 3 It is a comparison chart of the antibacterial effects of each example and the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] Example 1:

[0029] (1) Take 1 g of titanium dioxide and 5 g of zinc acetate and mix them. Add 1.5 g of triethanolamine at room temperature, grind until all the triethanolamine melts and then continue grinding for 10 min; then place it in 100 mL of absolute ethanol for full dispersion, heat up to 70 °C, stand for 16 h, evaporate the ethanol, and calcine at 500 °C for 12 h to obtain titanium and zinc oxides;

[0030] (2) Mix 0.5 g of titanium and zinc oxides with 0.1 g of triethanolamine; dissolve 5 g of egg yolk lecithin, 1 g of cholesterol, and 0.25 g of ethyl butyrate in ethanol, then add the mixture of titanium and zinc oxides mixed with triethanolamine and disperse it thoroughly to obtain a dispersion; evaporate ethanol under reduced pressure at 40 - 60 °C, then add water to restore the original volume of the dispersion, and perform normal-pressure rotary hydration for 0.5 h; after ultrasonic treatment, lipid body fluid is obtained.

[0031] (3) Place 2 g of gelatin and 1 g of chitosan in 20 mL of lipid body fluid, mix thoroughly at 70 °C to obtain a membrane-based body fluid; perform ultrasonic degassing on the membrane-based body fluid, then take 16 mL and pour it into a 13 cm × 13 cm square mold, dry it at 400 °C for 3 h, and then raise the temperature to 90 °C and continue to dry for 10 min. Figure 1 It can be seen that the obtained membrane sample has a smooth, dense, and uniform surface, and its relatively high zinc content makes it light yellow.

[0032] Example 2:

[0033] (1) Take 1 g of titanium dioxide and 2 g of zinc acetate, add 1.5 g of triethanolamine at room temperature, grind until all the triethanolamine melts and then continue to grind for 10 min; then disperse it thoroughly in 100 mL of absolute ethanol, raise the temperature to 70 °C, let it stand for 16 h, evaporate the ethanol, and then calcine it at 500 °C for 12 h to obtain titanium and zinc oxides.

[0034] (2) Mix 0.5 g of titanium and zinc oxides with 0.1 g of triethanolamine; dissolve 5 g of egg yolk lecithin, 1 g of cholesterol, and 0.25 g of ethyl butyrate in ethanol, then add the mixture of titanium and zinc oxides mixed with triethanolamine and disperse it thoroughly to obtain a dispersion; evaporate ethanol under reduced pressure at 40 - 60 °C, then add water to restore the original volume of the dispersion, and perform normal-pressure rotary hydration for 0.5 h; after ultrasonic treatment, lipid body fluid is obtained.

[0035] (3) Place 2 g of gelatin and 1 g of chitosan in 20 mL of lipid body fluid, mix thoroughly at 70 °C to obtain a membrane-based body fluid; perform ultrasonic degassing on the membrane-based body fluid, then take 16 mL and pour it into a 13 cm × 13 cm square mold, dry it at 400 °C for 3 h, and then raise the temperature to 90 °C and continue to dry for 10 min. Figure 2 It can be seen that the obtained membrane sample has a smooth, dense, and uniform surface, and is permeable.

[0036] Example 3:

[0037] (1) Mix 1 g of titanium dioxide and 5 g of zinc acetate, add 1.5 g of triethanolamine at room temperature, grind until all the triethanolamine melts and then continue grinding for 10 min; then place it in 100 mL of absolute ethanol for sufficient dispersion, heat up to 70 °C, stand for 16 h, evaporate the ethanol, and calcine at 500 °C for 12 h to obtain the oxides of titanium and zinc;

[0038] (2) Mix 0.5 g of the oxides of titanium and zinc with 0.06 g of triethanolamine; dissolve 5 g of egg yolk lecithin, 1 g of cholesterol, and 0.25 g of ethyl butyrate in ethanol, then add the oxides of titanium and zinc mixed with triethanolamine for sufficient dispersion to obtain a dispersion; evaporate the ethanol under reduced pressure at 40 - 60 °C, then add water to restore the original volume of the dispersion, and rotate and hydrate at normal pressure for 0.5 h; after ultrasonic treatment, the lipid body fluid is obtained;

[0039] (3) Place 2 g of gelatin and 1 g of chitosan in 20 mL of the lipid body fluid, mix well at 70 °C to obtain the membrane-based body fluid; perform ultrasonic degassing on the membrane-based body fluid, then take 16 mL and pour it into a 13 cm × 13 cm square mold, dry at 400 °C for 3 h, and then heat up to 90 °C and continue drying for 10 min.

[0040] Example 4:

[0041] (1) Mix 1 g of titanium dioxide and 5 g of zinc acetate, add 1.5 g of triethanolamine at room temperature, grind until all the triethanolamine melts and then continue grinding for 10 min; then place it in 100 mL of absolute ethanol for sufficient dispersion, heat up to 70 °C, stand for 16 h, evaporate the ethanol, and calcine at 500 °C for 12 h to obtain the oxides of titanium and zinc;

[0042] (2) Mix 0.5 g of the oxides of titanium and zinc with 0.1 g of triethanolamine; dissolve 5 g of egg yolk lecithin, 1 g of cholesterol, and 0.34 g of ethyl butyrate in ethanol, then add the oxides of titanium and zinc mixed with triethanolamine for sufficient dispersion to obtain a dispersion; evaporate the ethanol under reduced pressure at 40 - 60 °C, then add water to restore the original volume of the dispersion, and rotate and hydrate at normal pressure for 0.5 h; after ultrasonic treatment, the lipid body fluid is obtained;

[0043] (3) Place 2 g of gelatin and 1 g of chitosan in 20 mL of the lipid body fluid, mix well at 70 °C to obtain the membrane-based body fluid; perform ultrasonic degassing on the membrane-based body fluid, then take 16 mL and pour it into a 13 cm × 13 cm square mold, dry at 400 °C for 3 h, and then heat up to 90 °C and continue drying for 10 min.

[0044] Example 5:

[0045] (1) Mix 1 g of titanium dioxide and 5 g of zinc acetate, add 1.5 g of triethanolamine at room temperature, grind until the triethanolamine is completely melted and then continue grinding for 10 min; then place it in 100 mL of absolute ethanol for sufficient dispersion, heat up to 70 °C, let it stand for 16 h, evaporate the ethanol, and calcine at 500 °C for 12 h to obtain the oxides of titanium and zinc;

[0046] (2) Mix 0.5 g of the oxides of titanium and zinc with 0.1 g of triethanolamine; dissolve 5 g of egg yolk lecithin, 1 g of cholesterol, and 0.25 g of ethyl butyrate in ethanol, then add the oxides of titanium and zinc mixed with triethanolamine for sufficient dispersion to obtain a dispersion; evaporate the ethanol under reduced pressure at 40 - 60 °C, then add water to restore the original volume of the dispersion, and perform normal pressure rotary hydration for 0.5 h; after ultrasonic treatment, the lipid body fluid is obtained;

[0047] (3) Place 2 g of gelatin and 4 g of chitosan in 20 mL of the lipid body fluid, mix well at 70 °C to obtain the film - based body fluid; perform ultrasonic degassing on the film - based body fluid, then take 16 mL and pour it into a 13 cm × 13 cm square mold, dry at 400 °C for 3 h, and then heat up to 90 °C and continue drying for 10 min.

[0048] Example 6:

[0049] (1) Mix 1 g of titanium dioxide and 5 g of zinc acetate, add 1.5 g of triethanolamine at room temperature, grind until the triethanolamine is completely melted and then continue grinding for 10 min; then place it in 100 mL of absolute ethanol for sufficient dispersion, heat up to 70 °C, let it stand for 16 h, evaporate the ethanol, and calcine at 500 °C for 12 h to obtain the oxides of titanium and zinc;

[0050] (2) Mix 0.5 g of the oxides of titanium and zinc with 0.1 g of triethanolamine; dissolve 5 g of egg yolk lecithin, 1 g of cholesterol, and 0.25 g of ethyl butyrate in ethanol, then add the oxides of titanium and zinc mixed with triethanolamine for sufficient dispersion to obtain a dispersion; evaporate the ethanol under reduced pressure at 40 - 60 °C, then add water to restore the original volume of the dispersion, and perform normal pressure rotary hydration for 0.5 h; after ultrasonic treatment, the lipid body fluid is obtained;

[0051] (3) Place 2 g of gelatin and 1 g of chitosan in 40 mL of the lipid body fluid, mix well at 70 °C to obtain the film - based body fluid; perform ultrasonic degassing on the film - based body fluid, then take 16 mL and pour it into a 13 cm × 13 cm square mold, dry at 400 °C for 3 h, and then heat up to 90 °C and continue drying for 10 min.

[0052] Example 7:

[0053] (1) Mix 1 g of titanium dioxide and 5 g of zinc acetate, add 1.5 g of triethanolamine at room temperature, grind until triethanolamine is completely melted and then continue grinding for 10 min; then disperse it fully in 100 mL of absolute ethanol, heat up to 70 °C, let it stand for 16 h, after evaporating the ethanol, calcine it at 500 °C for 12 h to obtain the oxides of titanium and zinc;

[0054] (2) Mix 0.5 g of the oxides of titanium and zinc with 0.1 g of triethanolamine; dissolve 5 g of egg yolk lecithin, 1 g of cholesterol, and 0.25 g of ethyl butyrate in ethanol, then add the oxides of titanium and zinc mixed with triethanolamine and disperse them fully to obtain a dispersion; evaporate ethanol under reduced pressure at 40 - 60 °C, then add water to restore the original volume of the dispersion, and carry out normal-pressure rotary hydration for 0.5 h; after ultrasonic treatment, the lipid body fluid is obtained;

[0055] (3) Put 2 g of gelatin and 1 g of chitosan into 20 mL of lipid body fluid, mix them fully at 70 °C to obtain the film-based body fluid; carry out ultrasonic degassing on the film-based body fluid, then take 16 mL and pour it into a 13 cm × 13 cm square mold, dry it at 400 °C for 3 h, and then heat up to 90 °C and continue drying for 30 min.

[0056] Comparative Example 1:

[0057] Put 2 g of gelatin and 4 g of chitosan into 20 mL of water, mix them fully at 70 °C to obtain the film-based body fluid; carry out ultrasonic degassing on the film-based body fluid, then take 16 mL and pour it into a 13 cm × 13 cm square mold, dry it at 400 °C for 3 h, and then heat up to 90 °C and continue drying for 10 min.

[0058] Preparation and testing of the example samples:

[0059] Take out the scallop adductor muscle from the shell completely, and the average mass of the adductor muscle is (14.8 ± 0.9) g. Randomly divide the adductor muscles into 8 groups according to each example and comparative example, with 15 adductor muscles in each group, and wrap each group with the packaging film of each example and comparative example. Store each group at 4 °C, irradiate with xenon lamp to simulate visible light for 4 h every day, collect samples on the 0th, 3rd, 6th, 9th, and 12th days and conduct index detection. Randomly select 6 adductor muscles from each group. Determine the total number of colonies of the samples according to GB 4789.2—2022 "National Food Safety Standard Food Microbiology Examination Determination of Total Number of Colonies". Add 5.0 g of minced sample and 45 mL of sterile 0.85% NaCl solution into a sterile homogenization bag, homogenize and beat at a speed of 8 times / s for 90 s to obtain an extract. Continuously dilute the extract 10 times with sterile 0.85% NaCl solution, then inoculate 1 mL of the diluted solution into plate count agar, and calculate the total number of colonies after incubating at 30 °C for 72 h.

[0060] The results are as follows:

[0061]

[0062] Combined with the above table Figure 3 It can be seen that the total number of colonies in the control group of Example 1 without loaded liposomes increased significantly, reaching 5.92 lg(CFU / g) on the 6th day, exceeding the total number of colonies in each of the Examples at 12 days. However, the number of colonies of the scallops wrapped with the packaging film of the present invention was still lower than the limit value of 7.0 lg(CFU / g) at 12 days, indicating that the packaging film of the present invention can significantly extend the storage period of aquatic products. The growth rate of the total number of colonies in Example 1 with more zinc acetate was slower than that in Example 2, but the degree of mitigation was not as great as the increase in the zinc acetate content, indicating that zinc and titanium oxides can synergistically promote hydrogen production, and only increasing zinc cannot effectively improve the antibacterial ability of the packaging film. The antibacterial effect of Example 3 was not as good as that of Example 1, probably because less triethanolamine was not conducive to the full dispersion of zinc and titanium oxides, affecting the antibacterial effect of the packaging film. Compared with Example 1, Example 4 added more ethyl butyrate, but the growth rate of the total number of colonies was faster than that in Example 1, probably because too much ethyl butyrate easily affected the integrity of the liposomes, and after volatilization in the later stage of film drying, it affected the integrity of the film. The growth rate of the total number of colonies in Example 5 was not as fast as that in Example 1, indicating that more chitosan can improve the antibacterial ability of the film and the water vapor barrier performance of gelatin. The amount of liposome solution added in Example 6 was increased to 40 mL, but its antibacterial effect was not as expected, probably because too many liposomes easily affected the strength of the film and the water vapor permeability. The increased amount of zinc and titanium oxides increased the hydrogen production rate, but the reduction of water was not conducive to hydrogen production. The drying time of Example 7 was longer than that of Example 1, and the total number of colonies decreased at 12 days.

[0063] For those skilled in the art, according to the technical solutions and concepts described above, various corresponding changes and deformations can be made, and all these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a packaging film for aquatic products, characterized in that: The following steps are involved: Mix titanium dioxide and zinc acetate, add triethanolamine at room temperature, grind until the triethanolamine is completely melted, and then continue grinding for 5-20 minutes; then fully disperse in anhydrous ethanol, heat to 60-80°C, stand for 12-20 hours, evaporate the ethanol, and roast at 400-550°C for 1-3 hours to obtain titanium and zinc oxides; the mass ratio of titanium dioxide to zinc acetate is 1:2-5; the mass ratio of triethanolamine to zinc acetate is 1:1.5-2.5; the concentration of zinc acetate in anhydrous ethanol is 0.02-0.1 g / mL; The oxides of titanium and zinc are mixed with triethanolamine; lecithin, cholesterol and ethyl butyrate are dissolved in ethanol, and then the oxides of titanium and zinc mixed with triethanolamine are added and fully dispersed to obtain a dispersion; the ethanol in the dispersion is evaporated under reduced pressure, and water is added for hydration; and a liposome liquid is obtained after ultrasonic treatment; When preparing the membrane matrix, the liposome liquid is added and the packaging membrane is obtained after drying.

2. The method for preparing a packaging film for aquatic products according to claim 1, characterized in that: The mass ratio of cholesterol to lecithin in step b is 1:4-6; the mass ratio of ethyl butyrate to lecithin is 1:15-20; the mass ratio of titanium and zinc oxides to lecithin is 1:8-12; the mass ratio of triethanolamine to titanium and zinc oxides in step b is 1:5-8.

3. The method for preparing a packaging film for aquatic products according to claim 1, characterized in that: The steps of removing ethanol from the dispersion under reduced pressure and adding water for hydration are: removing ethanol under reduced pressure at 40-60° C., then adding water to restore the dispersion to its original volume, and rotating at normal pressure for 0.3-1 h.

4. The method for preparing a packaging film for aquatic products according to claim 1, characterized in that: The drying in step c is to dry until the mass no longer changes, and then control the temperature at 80-90° C. to continue drying for 0.5-2 hours.

5. The method for preparing a packaging film for aquatic products according to claim 1, characterized in that: The step of preparing the membrane matrix in step c comprises: placing gelatin and chitosan in a liposome liquid, and fully mixing them at 60-80° C. to obtain a membrane matrix liquid; ultrasonically degassing the membrane matrix liquid, and then pouring it into a mold, drying it at 40-50° C. for 3-5 hours, and then heating it to 80-90° C. and continuing to dry it for 10-30 minutes.

6. The method for preparing a packaging film for aquatic products according to claim 5, characterized in that: The mass ratio of gelatin to chitosan is 1:0.5-2; the concentration of gelatin in the membrane matrix fluid is 0.05-0.1 g / mL.

7. The method for preparing a packaging film for aquatic products according to claim 5, characterized in that: The time for the thorough mixing is 15 to 30 minutes.

8. A packaging film for aquatic products prepared by the preparation method according to claim 1, characterized in that: The invention comprises a membrane matrix, a liposome loaded on the membrane matrix, and titanium and zinc oxides contained in the liposome.

9. The packaging film for aquatic products according to claim 8, characterized in that: The components of the membrane matrix include one or more of polylactic acid, gelatin, chitosan, dextran, polyvinyl alcohol or sodium alginate.

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