Biomass material for absorbing and decomposing ethylene and preparation method thereof, and fresh-keeping film and preparation method thereof

Abstract

The present invention provides a biomass material capable of absorbing and decomposing ethylene and a preparation method thereof, and a cling film and a preparation method thereof, which belong to the technical field of food preservation. The biomass material capable of absorbing and decomposing ethylene provided by the present invention comprises a porous nanocarrier, which can not only provide abundant attachment sites for an ethylene adsorbent, but also play a role in physically adsorbing ethylene; the biomass material capable of absorbing and decomposing ethylene provided by the present invention comprises an ethylene adsorbent loaded on the porous nanocarrier, the ethylene adsorbent comprises a biocatalyst and / or chitosan loaded with a biocatalyst, and the ethylene adsorbent has abundant ethylene oxidase, which can not only convert ethylene enriched in the porous nanocarrier into carbon dioxide and water, but also has a green and safe effect compared with a chemical adsorbent, and can make the cling film prepared from the biomass material capable of absorbing and decomposing ethylene directly contact with food.

Description

Technical Field

[0001] The invention relates to the technical field of food preservation, and in particular to a biomass material capable of absorbing and decomposing ethylene and a preparation method thereof, and a fresh-keeping film and a preparation method thereof. Background Art

[0002] As people's living standards continue to improve, consumers not only have an increasing demand for fruits and vegetables, but also have higher requirements for the freshness of fruits and vegetables. In order to facilitate the transportation and preservation of fruits and vegetables, fresh fruits and vegetables are often packaged with plastic wrap. However, a natural metabolite, ethylene, is produced in specific parts of fruits and vegetables. Ethylene is also known as plant ripening hormone. The accumulation of ethylene in the packaging of fresh fruits and vegetables will accelerate the respiration rate of fruits and vegetables, causing the fruits and vegetables to ripen and decay, resulting in a shortened storage time of fruits and vegetables, which is not conducive to the storage and transportation of fruits and vegetables. Therefore, the concentration of ethylene gas should be strictly controlled in the preservation of fruits and vegetables to extend the shelf life of fruits and vegetables.

[0003] At present, the main methods for adsorbing ethylene gas are physical adsorption and chemical adsorption. Physical adsorption mainly uses materials with porous structures such as activated carbon, minerals and synthetic resins to adsorb ethylene. This method has limited adsorption capacity for ethylene and the regeneration method is relatively complicated. Chemical adsorption uses the adsorbent to form a chemical bond with ethylene to achieve the purpose of ethylene adsorption. Currently, commonly used chemical adsorbents include Ag(I) and potassium permanganate. The chemical residues produced by this method will have toxic side effects on the human body and environmental pollution, thereby limiting its application.

[0004] Therefore, there is an urgent need to provide a green and environmentally friendly biomass material for absorbing and decomposing ethylene to solve the problems of limited ethylene adsorption capacity and chemical residues in existing ethylene gas adsorption. Summary of the invention

[0005] The purpose of the present invention is to provide a biomass material for absorbing and decomposing ethylene and a preparation method thereof, and a fresh-keeping film and a preparation method thereof. The biomass material for absorbing and decomposing ethylene provided by the present invention is green and environmentally friendly and has a strong ability to absorb ethylene.

[0006] The invention provides a biomass material for absorbing and decomposing ethylene, comprising a porous nano-carrier and an ethylene adsorbent loaded on the porous nano-carrier, wherein the ethylene adsorbent comprises a biocatalyst and / or chitosan loaded with the biocatalyst; the mass of the ethylene adsorbent accounts for 0.1 to 10% of the mass of the carrier.

[0007] Preferably, the porous nanocarrier comprises one or more of silica, amorphous starch particles, alumina and zeolite.

[0008] Preferably, the specific surface area of ​​the porous nanocarrier is 100 to 500 m3 / g.

[0009] Preferably, the biocatalyst comprises raw bamboo extract and / or pine needle extract.

[0010] Preferably, in the chitosan loaded with biocatalyst, the mass ratio of biocatalyst to chitosan is (1-5):2.

[0011] The present invention also provides a method for preparing the biomass material for absorbing and decomposing ethylene described in the above technical solution, comprising the following steps: impregnating the ethylene adsorbent dispersion and the porous nanocarrier in equal volumes, and then drying to obtain the biomass material for absorbing and decomposing ethylene.

[0012] The present invention also provides a fresh-keeping film, which is prepared from raw materials including the following components in parts by weight:

[0013]

[0014] The biomass material for absorbing and decomposing ethylene is the biomass material for absorbing and decomposing ethylene described in the above technical solution or the biomass material for absorbing and decomposing ethylene prepared by the preparation method described in the above technical solution.

[0015] Preferably, the antibacterial agent comprises one or more of curcumin, camphor oil and curcumin.

[0016] Preferably, the filler includes one or more of talc powder, mica powder, wollastonite and calcium carbonate.

[0017] The present invention also provides a method for preparing the cling film described in the above technical solution, comprising: mixing polylactic acid, biodegradable polyester, biomass material that absorbs and decomposes ethylene, antibacterial agent, toughening agent and filler, and melt-extruding to obtain a mixture; and blowing the mixture into a film to obtain the cling film.

[0018] The present invention provides a biomass material for absorbing and decomposing ethylene, comprising a porous nanocarrier and an ethylene adsorbent loaded on the porous nanocarrier, wherein the ethylene adsorbent comprises a biocatalyst and / or chitosan loaded with a biocatalyst; the mass of the ethylene adsorbent accounts for 0.1 to 10% of the mass of the carrier. The biomass material for absorbing and decomposing ethylene provided by the present invention comprises a porous nanocarrier, and the porous structure of the porous nanocarrier can not only provide abundant attachment sites for the ethylene adsorbent, but also play a role in physical adsorption of ethylene; the biomass material for absorbing and decomposing ethylene provided by the present invention comprises an ethylene adsorbent loaded on the porous nanocarrier, and the ethylene adsorbent comprises a biocatalyst and / or chitosan loaded with a biocatalyst, and the ethylene adsorbent has abundant ethylene oxidase, which can not only convert the ethylene enriched in the porous nanocarrier into carbon dioxide and water, but also has a strong ability to remove ethylene, and at the same time, compared with chemical adsorbents, has a green and safe effect, and can make the prepared cling film directly contact with food. The results of the embodiment show that the cling film prepared by the biomass material for absorbing and decomposing ethylene provided by the present invention has an excellent removal effect on ethylene, and can greatly extend the shelf life of fresh fruits and vegetables. DETAILED DESCRIPTION

[0019] The invention provides a biomass material for absorbing and decomposing ethylene, comprising a porous nano-carrier and an ethylene adsorbent loaded on the porous nano-carrier, wherein the ethylene adsorbent comprises a biocatalyst and / or chitosan loaded with the biocatalyst; the mass of the ethylene adsorbent accounts for 0.1 to 10% of the mass of the carrier.

[0020] In the present invention, unless otherwise specified, the raw materials used in the present invention can be commercially available products known in the art.

[0021] The biomass material for absorbing and decomposing ethylene provided by the present invention comprises a porous nano-carrier.

[0022] In the present invention, the porous nano-carrier preferably includes one or more of silicon dioxide, amorphous starch particles, alumina and zeolite, and more preferably silicon dioxide or amorphous starch particles. The porous nano-carrier used in the present invention has a porous structure, which can provide abundant attachment sites for the ethylene adsorbent, and is more conducive to the adsorption and dispersion of the ethylene adsorbent; and the porous structure can also achieve the adsorption of ethylene, which is more conducive to the enrichment of ethylene.

[0023] In the present invention, the method for preparing the amorphous starch granules preferably comprises:

[0024] Mixing starch with ethanol aqueous solution to obtain starch slurry;

[0025] The NaOH solution is dropped into the starch slurry to mix, and then centrifuged, washed and dried in sequence to obtain amorphous starch particles.

[0026] The present invention preferably mixes starch with ethanol aqueous solution to obtain starch slurry.

[0027] In the present invention, the starch is preferably corn starch. The present invention has no special limitation on the source of the corn starch, and any conventional commercial product can be used.

[0028] In the present invention, the volume percentage of ethanol in the ethanol aqueous solution is preferably 30-50%, more preferably 40%. The present invention uses ethanol aqueous solution as the reaction solvent.

[0029] The volume of the ethanol aqueous solution is not particularly limited in the present invention, and can be adjusted according to the amount of starch used to make the mass concentration of the starch slurry preferably 10-15%, more preferably 12-14%. The present invention is more conducive to fully modifying the starch by controlling the mass concentration of the starch slurry to be within the above range.

[0030] The present invention has no particular limitation on the method of mixing the starch with the ethanol aqueous solution, as long as the starch can be fully dispersed in the ethanol aqueous solution. In the present invention, the mixing method is preferably stirring.

[0031] After obtaining the starch slurry, the present invention preferably drips a NaOH solution into the starch slurry to mix, and then centrifuges, washes and dries in sequence to obtain amorphous starch granules.

[0032] In the present invention, the concentration of the NaOH solution is preferably 1-5 mol / L, more preferably 2-3 mol / L. In the present invention, when the mass concentration of the starch slurry is 10-15% and the concentration of the NaOH solution is 1-5 mol / L, the volume ratio of the starch slurry to the NaOH solution is preferably 1:5. The present invention controls the amount of the two within the above range, which is more conducive to fully modifying the starch.

[0033] The present invention has no special limitation on the rate of dripping the NaOH solution, and the NaOH solution can be dripped drop by drop. The present invention can prevent the product from agglomerating due to too fast addition of the NaOH solution by dripping drop by drop.

[0034] In the present invention, the mixing temperature is preferably 30-35°C, more preferably 32-35°C; the mixing time is preferably 20-60min, more preferably 30-50min. In the present invention, the mixing is preferably carried out under stirring. The present invention does not specifically limit the rotation speed of the stirring, and it can be adjusted as needed. The present invention allows the sodium hydroxide solution to fully modify the starch slurry through mixing, and forms a pore structure inside the starch granules.

[0035] The present invention has no special limitation on the operation methods of the centrifugation, washing and drying, and conventional centrifugation, washing and drying methods can be used. The present invention can fully remove impurities in amorphous starch particles through centrifugation, washing and drying. In an embodiment of the present invention, the washing reagent can be an ethanol aqueous solution, and the mass concentration of ethanol in the ethanol aqueous solution can be 30%; the number of washing times can be 3 times; the drying temperature can be 60°C, and the drying time can be 6 hours.

[0036] In the present invention, the specific surface area of ​​the porous nanocarrier is preferably 100 to 500 m 3 / g, more preferably 400 to 500 m 3 / g; the particle size of the porous nano-carrier is preferably 100-500nm, more preferably 200-300nm. The porous nano-carrier of the above size is more conducive to improving the adsorption and removal effect of ethylene.

[0037] The biomass material for absorbing and decomposing ethylene provided by the present invention also includes an ethylene adsorbent loaded on the porous nano-carrier.

[0038] In the present invention, the ethylene adsorbent comprises a biocatalyst and / or chitosan loaded with a biocatalyst, preferably a biocatalyst or chitosan loaded with a biocatalyst.

[0039] In the present invention, the biocatalyst preferably includes raw bamboo extract and / or pine needle extract, more preferably raw bamboo extract or pine needle extract. In the present invention, raw bamboo extract and / or pine needle extract contain a large amount of ethylene oxidase, and using them as biocatalysts is more conducive to fully improving the removal effect of ethylene.

[0040] In the present invention, the preparation method of the raw bamboo extract and / or pine needle extract preferably includes dry distillation or alcohol extraction.

[0041] In the present invention, the dry distillation method preferably comprises: dry distilling raw bamboo powder or pine needle powder to obtain raw bamboo extract or pine needle extract.

[0042] In the present invention, the particle size of the raw bamboo powder or pine needle powder is preferably 50 to 300 meshes, more preferably 100 to 200 meshes. The present invention controls the particle size of the raw bamboo powder or pine needle powder within the above range, which is more conducive to extracting the raw bamboo extract or pine needle extract from the raw bamboo powder or pine needle powder.

[0043] In the present invention, the temperature of the dry distillation is preferably 100-300°C, more preferably 200-300°C; the pressure of the dry distillation is preferably 0.3-0.5MPa, more preferably 0.4-0.5MPa. The present invention has no particular limitation on the dry distillation time, as long as the extract can be fully obtained.

[0044] In the present invention, the alcohol extraction method preferably comprises: extracting raw bamboo powder or pine needle powder in ethanol, and volatilizing ethanol to obtain raw bamboo extract or pine needle extract. The present invention has no special limitation on the extraction method, and conventional alcohol extraction methods can be used for extraction.

[0045] In the present invention, the mass ratio of the biocatalyst to the chitosan in the biocatalyst-loaded chitosan is preferably (1-5): 2, more preferably (1-3): 2. The present invention can utilize the synergistic effect of the biocatalyst and chitosan to improve the oxidation capacity of ethylene by loading the biocatalyst on chitosan.

[0046] In the present invention, the method for preparing the biocatalyst-loaded chitosan preferably comprises: dissolving quaternary ammonium salt chitosan in water to obtain a chitosan aqueous solution, mixing the chitosan aqueous solution with the biocatalyst aqueous solution, stirring, centrifuging and drying to obtain the biocatalyst-loaded chitosan.

[0047] In the present invention, the mass concentration of the chitosan aqueous solution is preferably 3-15%, more preferably 5-10%.

[0048] In the present invention, the mass concentration of the biocatalyst aqueous solution is preferably 15-25%, more preferably 10-20%.

[0049] The volume ratio of the chitosan aqueous solution to the biocatalyst aqueous solution is not particularly limited in the present invention, as long as the mass ratio of the biocatalyst to the chitosan in the obtained biocatalyst-loaded chitosan is (1-5):2.

[0050] In the present invention, the stirring time is preferably 1 to 1.5 hours, more preferably 1.5 hours. The present invention is more conducive to the full combination of the biocatalyst and chitosan through stirring.

[0051] The present invention has no special limitation on the operation method of the centrifugation and drying, and conventional centrifugation and drying methods can be used. In an embodiment of the present invention, the drying temperature can be 60° C., and the drying time can be 120 min.

[0052] In the present invention, the mass of the ethylene adsorbent accounts for 0.1-10% of the mass of the carrier, preferably 1-5%. The present invention controls the amount of the ethylene adsorbent within the above range, which can make the biomass material have excellent effects of absorbing and decomposing ethylene.

[0053] The porous nanocarrier in the biomass material for absorbing and decomposing ethylene provided by the present invention can provide abundant attachment sites for the ethylene adsorbent and can also play a role in physically adsorbing ethylene; the ethylene adsorbent loaded on the porous nanocarrier includes a biocatalyst and / or chitosan loaded with a biocatalyst, and the ethylene adsorbent has abundant ethylene oxidase, which can not only convert the ethylene enriched in the porous nanocarrier into carbon dioxide and water, but also has a green and safe effect compared with chemical adsorbents, and can enable the cling film prepared from the biomass material for absorbing and decomposing ethylene to directly contact with food.

[0054] The present invention also provides a method for preparing the biomass material for absorbing and decomposing ethylene described in the above technical solution, comprising the following steps: impregnating the ethylene adsorbent dispersion and the porous nanocarrier in equal volumes, and then drying to obtain the biomass material for absorbing and decomposing ethylene.

[0055] In the present invention, the mass concentration of the ethylene adsorbent dispersion is preferably 5-10%, more preferably 6-8%. The present invention controls the mass concentration of the ethylene adsorbent dispersion within the above range, which is more conducive to the ethylene adsorbent being fully dispersed in the porous nanocarrier. The present invention does not specifically limit the solvent of the ethylene adsorbent dispersion, and can be selected according to the extraction reagent.

[0056] The present invention has no special limitation on the operation method of the equal volume impregnation, and the conventional equal volume impregnation method can be used.

[0057] The present invention also provides a fresh-keeping film, which is prepared from raw materials including the following components in parts by weight:

[0058]

[0059] By weight, the raw materials for preparing the cling film of the present invention include 10 to 90 parts of polylactic acid, preferably 20 to 80 parts, more preferably 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts or 80 parts. In the present invention, the number average molecular weight Mn of the polylactic acid is preferably 100,000 to 300,000, more preferably 200,000 to 300,000. The present invention adopts the above polylactic acid, which can make the obtained cling film have good mechanical strength and can also be degraded, so that the cling film has good environmental protection.

[0060] Based on 10 to 90 parts by weight of polylactic acid, the raw materials for preparing the cling film of the present invention include 10 to 90 parts of biodegradable polyester, preferably 20 to 80 parts, and more preferably 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts or 80 parts. In an embodiment of the present invention, the model of the biodegradable polyester can be Total LX575 of Thailand. The addition of biodegradable polyester in the present invention is more conducive to improving the physical properties of the cling film, has good high temperature resistance, and is easy to degrade after use, so that the cling film has good environmental protection.

[0061] Based on 10 to 90 parts by weight of polylactic acid, the raw materials for preparing the cling film of the present invention include 0.1 to 10 parts of biomass material that absorbs and decomposes ethylene, preferably 1 to 8 parts, and more preferably 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts. In the present invention, the biomass material that absorbs and decomposes ethylene is the biomass material that absorbs and decomposes ethylene described in the above technical solution or the biomass material that absorbs and decomposes ethylene prepared by the preparation method described in the above technical solution. The present invention uses the above biomass material that absorbs and decomposes ethylene to enable the cling film to have the ability to absorb ethylene and convert ethylene into carbon dioxide and water, thereby extending the shelf life of fruits and vegetables.

[0062] Based on 10 to 90 parts by weight of polylactic acid, the raw materials for preparing the preservative film of the present invention include 0.1 to 5 parts of antibacterial agent, preferably 0.5 to 4 parts, and more preferably 1 part, 2 parts, 3 parts or 4 parts. In the present invention, the antibacterial agent preferably includes one or more of curcuminol, camphor oil and curcumin, and more preferably curcuminol and / or curcumin. The present invention adds the above antibacterial agent to the preservative film, which has an inhibitory effect on bacteria, thereby reducing the corruption of fruits and vegetables and extending the shelf life of fruits and vegetables.

[0063] Based on 10 to 90 parts by weight of polylactic acid, the raw materials for preparing the cling film of the present invention include 1 to 5 parts of a toughening agent, preferably 1 to 4 parts, and more preferably 1 part, 2 parts, 3 parts or 4 parts. In the present invention, the toughening agent preferably includes an MBS toughening agent, and the model of the MBS toughening agent is preferably M51 or M61. The use of the above-mentioned toughening agent in the present invention is more conducive to improving the flexibility of the cling film.

[0064] Based on 10 to 90 parts by weight of polylactic acid, the raw materials for preparing the cling film of the present invention include 1 to 10 parts of filler, preferably 2 to 8 parts, and more preferably 2, 3, 4, 5, 6, 7 or 8 parts. In the present invention, the filler preferably includes one or more of talc, mica powder, wollastonite and calcium carbonate, and more preferably one or more of talc, mica powder and wollastonite. In the present invention, the particle size of the filler is preferably 200 to 800 mesh, and more preferably 200 mesh, 325 mesh, 500 mesh, 600 mesh or 800 mesh. In the present invention, the talc and mica powder are flaky inorganic fillers, which can significantly reduce the oxygen permeability and water vapor penetration rate of the cling film; the granular calcium carbonate and wollastonite can improve the mechanical properties, thermal stability and anti-fogging properties of the cling film, and can promote the degradation of the cling film. At the same time, the present invention utilizes flaky talc powder or mica powder in combination with granular calcium carbonate and wollastonite to further improve the barrier properties, inhibit transpiration and extend the freshness-keeping effect.

[0065] The present invention also provides a method for preparing the cling film described in the above technical solution, comprising: mixing polylactic acid, biodegradable polyester, biomass material that absorbs and decomposes ethylene, antibacterial agent, toughening agent and filler, and melt-extruding to obtain a mixture; and blowing the mixture into a film to obtain the cling film.

[0066] The invention mixes polylactic acid, biodegradable polyester, biomass material capable of absorbing and decomposing ethylene, antibacterial agent, toughening agent and filler, and then melts and extrude the mixture to obtain a mixed material.

[0067] The present invention has no particular limitation on the method of mixing the polylactic acid, biodegradable polyester, biomass material that absorbs and decomposes ethylene, antimicrobial agent, toughening agent and filler, and conventional mixing methods can be used to uniformly mix the components. In an embodiment of the present invention, the mixing is preferably performed in a high-speed mixer.

[0068] In the present invention, the temperature of the melt extrusion is preferably 100-200°C, more preferably 130-180°C. The present invention has no special limitation on the device for the melt extrusion, and any conventional melt extrusion device can be used. In an embodiment of the present invention, the melt extrusion device can be a twin-screw extruder. The present invention obtains a mixture of the above-mentioned materials by melt extrusion.

[0069] After the mixed material is obtained, the present invention blows the mixed material into a film to obtain a fresh-keeping film.

[0070] The present invention has no special limitation on the device and parameters of the film blowing. Conventional film blowing devices and parameters can be used to adjust the mixed material to form a fresh-keeping film with uniform thickness. In an embodiment of the present invention, the film blowing device can be a single-screw extruder film blowing machine; the film blowing temperature can be 150-200°C, or 160-180°C.

[0071] The preparation method provided by the present invention is simple to operate. By adding biomass materials that absorb and decompose ethylene into the raw materials, the cling film can have the functions of absorbing and decomposing ethylene. In addition, the raw materials for preparing the cling film are green adsorbents, so that the cling film can be in direct contact with fruits and vegetables and is easy to degrade after use, thereby making the cling film more environmentally friendly.

[0072] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0073] Example 1

[0074] A biomass material for absorbing and decomposing ethylene, comprising a porous nano-carrier and an ethylene adsorbent loaded on the porous nano-carrier, wherein the ethylene adsorbent is a raw bamboo extract; the mass of the ethylene adsorbent accounts for 2% of the mass of the carrier; the porous nano-carrier is silicon dioxide (with a specific surface area of ​​400 m 3 / g, particle size is 200-300nm);

[0075] The preparation method of the raw bamboo extract comprises: performing dry distillation on raw bamboo powder at 200° C. and a pressure of 0.5 MPa, and condensing to obtain the raw bamboo extract;

[0076] The preparation method of the biomass material for absorbing and decomposing ethylene comprises: impregnating silicon dioxide and a raw bamboo extract aqueous solution with a mass concentration of 6% by volume in equal volumes, and drying to obtain the biomass material for absorbing and decomposing ethylene.

[0077] Example 2

[0078] A biomass material for absorbing and decomposing ethylene, comprising a porous nano-carrier and an ethylene adsorbent loaded on the porous nano-carrier, wherein the ethylene adsorbent is a raw bamboo extract; the mass of the ethylene adsorbent accounts for 4% of the mass of the carrier; the porous nano-carrier is silicon dioxide (with a specific surface area of ​​400 m 3 / g, particle size is 200-300nm);

[0079] The preparation method of the raw bamboo extract is the same as that of Example 1;

[0080] The preparation method of the biomass material for absorbing and decomposing ethylene is the same as that in Example 1.

[0081] Example 3

[0082] A biomass material for absorbing and decomposing ethylene, comprising a porous nano-carrier and an ethylene adsorbent loaded on the porous nano-carrier, wherein the ethylene adsorbent is a pine needle extract; the mass of the ethylene adsorbent accounts for 4% of the mass of the carrier; the porous nano-carrier is silicon dioxide (with a specific surface area of ​​400 m 3 / g, particle size is 200-300nm);

[0083] The preparation method of the pine needle extract comprises: dry distilling pine needle powder at 200° C. and a pressure of 0.5 MPa, and condensing to obtain the pine needle extract;

[0084] The preparation method of the biomass material for absorbing and decomposing ethylene is the same as that in Example 1.

[0085] Example 4

[0086] A biomass material for absorbing and decomposing ethylene, comprising a porous nano-carrier and an ethylene adsorbent loaded on the porous nano-carrier; the porous nano-carrier is silicon dioxide (with a specific surface area of ​​400 m 3 / g, particle size of 200-300nm); the ethylene adsorbent is chitosan loaded with raw bamboo extract; the mass of the ethylene adsorbent accounts for 4% of the mass of the carrier; the mass ratio of raw bamboo extract to chitosan in the chitosan loaded with raw bamboo extract is 3:2;

[0087] The preparation method of the chitosan loaded with raw bamboo extract is as follows: dissolving quaternary ammonium salt chitosan in water to obtain a chitosan aqueous solution with a mass concentration of 5%, mixing it with a raw bamboo extract aqueous solution with a mass concentration of 15%, stirring for 1.5 hours, centrifuging and drying to obtain chitosan loaded with raw bamboo extract;

[0088] The preparation method of the biomass material for absorbing and decomposing ethylene is the same as that in Example 1.

[0089] Example 5

[0090] A biomass material for absorbing and decomposing ethylene, comprising a porous nano-carrier and an ethylene adsorbent loaded on the porous nano-carrier, wherein the ethylene adsorbent is a raw bamboo extract; the mass of the ethylene adsorbent accounts for 4% of the mass of the carrier; the porous nano-carrier is an amorphous starch particle (with a specific surface area of ​​200 m 3 / g, particle size is 200-300nm);

[0091] The preparation method of the amorphous starch granules is as follows: corn starch and ethanol aqueous solution (40% by volume) are stirred and mixed evenly to obtain a starch slurry with a mass concentration of 12%;

[0092] Under stirring, a 2 mol / L NaOH solution is dropped into the starch slurry (the volume ratio of the starch slurry to the NaOH solution is 1:5), and the stirring is continued at 32° C. for 50 min, and then centrifuged, and the obtained solid is washed with an ethanol aqueous solution (the mass concentration of ethanol is 30%), and dried at 60° C. for 6 h to obtain amorphous starch granules;

[0093] The preparation method of the biomass material for absorbing and decomposing ethylene is the same as that in Example 1.

[0094] Example 6

[0095] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 5 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 1, 3 parts of an antibacterial agent (curcumin), 3 parts of a toughening agent (M51), and 6 parts of a filler (mica powder 200 mesh);

[0096] The preparation method of the fresh-keeping film comprises the following steps: uniformly mixing polylactic acid, biodegradable polyester, biomass material capable of absorbing and decomposing ethylene, antibacterial agent, toughening agent and filler in a high-speed mixer, and then melt-extruding the mixture in a twin-screw extruder at 160° C. to obtain a mixture; and blowing the mixture into a film in a single-screw extrusion film blowing machine at a temperature of 170° C. to obtain the fresh-keeping film.

[0097] Example 7

[0098] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 5 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 2, 3 parts of an antibacterial agent (curcumin), 3 parts of a toughening agent (M51), and 6 parts of a filler (mica powder 200 mesh);

[0099] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0100] Example 8

[0101] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 5 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 3, 3 parts of an antibacterial agent (curcumin), 3 parts of a toughening agent (M51), and 6 parts of a filler (mica powder 200 mesh);

[0102] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0103] Example 9

[0104] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 5 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 4, 3 parts of an antibacterial agent (curcumin), 3 parts of a toughening agent (M51), and 6 parts of a filler (mica powder 200 mesh);

[0105] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0106] Example 10

[0107] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 5 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 5, 3 parts of an antibacterial agent (curcumin), 3 parts of a toughening agent (M51), and 6 parts of a filler (mica powder 200 mesh);

[0108] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0109] Embodiment 11

[0110] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 8 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 1, 3 parts of an antibacterial agent (curcumin), 3 parts of a toughening agent (M51), and 6 parts of a filler (mica powder 500 mesh);

[0111] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0112] Example 12

[0113] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 1 part of the biomass material for absorbing and decomposing ethylene prepared in Example 1, 3 parts of an antibacterial agent (curcumin), 3 parts of a toughening agent (M51), and 6 parts of a filler (mica powder 500 mesh);

[0114] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0115] Example 13

[0116] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 8 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 1, 3 parts of an antibacterial agent (camphor oil), 3 parts of a toughening agent (M51), and 6 parts of a filler (mica powder 200 mesh);

[0117] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0118] Embodiment 14

[0119] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 8 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 1, 3 parts of an antibacterial agent (camphor oil), 3 parts of a toughening agent (M51), 3 parts of filler mica powder (200 meshes), and 3 parts of calcium carbonate (500 meshes);

[0120] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0121] Comparative Example 1

[0122] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 3 parts of antibacterial agent (camphor oil), 3 parts of toughening agent (M51) and 6 parts of filler (mica powder 200 mesh);

[0123] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0124] Comparative Example 2

[0125] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 5 parts of silicon dioxide used in Example 1, 3 parts of antibacterial agent (camphor oil), 3 parts of toughening agent (M51) and 6 parts of filler (mica powder 200 mesh);

[0126] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0127] Comparative Example 3

[0128] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 5 parts of amorphous starch particles used in Example 5, 3 parts of antibacterial agent (camphor oil), 3 parts of toughening agent (M51) and 6 parts of filler (mica powder 200 mesh);

[0129] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0130] Comparative Example 4

[0131] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 5 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 1, 3 parts of a toughening agent (M51) and 6 parts of a filler (mica powder);

[0132] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0133] Comparative Example 5

[0134] A fresh-keeping film is prepared from the following raw materials: 50 parts of polylactic acid (Mn is 200,000), 50 parts of biodegradable polyester (Total LX575 from Thailand), 5 parts of the biomass material for absorbing and decomposing ethylene prepared in Example 1, 3 parts of a toughening agent (M51) and 3 parts of an antibacterial agent (camphor oil);

[0135] The preparation method of the fresh-keeping film is the same as that of Example 6.

[0136] Test Case

[0137] The fresh-keeping effect of the cling film prepared in Examples 6 to 14 and Comparative Examples 1 to 5 on fruits and vegetables was tested, and the method was as follows: 15 freshly picked apples, tomatoes and bananas were taken, washed and dried, and then placed in containers respectively, and the openings of the containers were sealed with the above-mentioned cling films respectively, and other conditions were kept the same, and the boxes were sealed for storage, and the changes in the fruits were observed. The effect was evaluated based on the degree of rot on the surface of the fruits, wherein normal: no rot on the surface of the fruit; mild rot: the degree of rot does not exceed 1 / 4 of the surface of the fruit; moderate rot: the degree of rot reaches 1 / 2 to 3 / 4 of the surface of the fruit; severe rot: the degree of rot exceeds 3 / 4 of the surface of the fruit. The results are shown in Table 1.

[0138] Table 1 The preservation effect of various cling films on fruits and vegetables

[0139]

[0140] It can be seen from Table 1 that after the fruits and vegetables are sealed with the cling film prepared in Examples 6 to 14, the time it takes for the fruits and vegetables to start to spoil is significantly longer than that of the fruits and vegetables sealed with the cling film prepared in Comparative Examples 1 to 5; this is because the cling film prepared in the present invention contains biomass materials that absorb and decompose ethylene, and the porous nano-carriers therein can absorb and enrich the ethylene produced by the fruits and vegetables, and use the ethylene adsorbent to convert the ethylene into carbon dioxide and water, and the generated carbon dioxide can inhibit transpiration, thereby extending the shelf life of the fruits and vegetables. The fruits and vegetables covered with the cling film prepared in Comparative Example 1 first showed signs of corruption, which was because after the cling film sealed the container, the concentration of ethylene produced in the fruits and vegetables gradually increased, thereby accelerating the ripening and corruption of the fruits and vegetables; the cling films prepared in Comparative Examples 2 and 3 also showed signs of corruption, which was because the removal effect of ethylene by simple physical adsorption was limited, so although the preservation effect was extended compared with Comparative Example 1, the preservation effect was lower than that of the cling film prepared in the embodiment of the present invention; it can be seen from Example 14 that the cling film has a good preservation effect, which is because the flaky mica powder and the granular calcium carbonate are mixed and have good barrier properties; the preservation effects in Comparative Examples 4 and 5 are better than those in Comparative Examples 1 to 3, but lower than those in the cling film prepared in the embodiment of the present invention, which is because the antibacterial agent can inhibit the growth of bacteria and thus delay the preservation effect; the filler can reduce the air permeability of the film and has good barrier properties, so it can extend the preservation effect by inhibiting transpiration.

[0141] It can be seen from the above results that the cling film prepared from the biomass material that absorbs and decomposes ethylene provided by the present invention can significantly prolong the preservation effect on fruits and vegetables, and the biomass material that absorbs and decomposes ethylene has no chemical residues, can be in direct contact with food, and is relatively green and safe; at the same time, the cling film is degradable and has good environmental protection.

[0142] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A biomass material for absorbing and decomposing ethylene, comprising a porous nano-carrier and an ethylene adsorbent loaded on the porous nano-carrier, wherein the ethylene adsorbent comprises a biocatalyst and / or chitosan loaded with a biocatalyst; the mass of the ethylene adsorbent accounts for 0.1 to 10% of the mass of the carrier.

2. The biomass material for absorbing and decomposing ethylene according to claim 1, characterized in that: The porous nanocarrier comprises one or more of silica, amorphous starch particles, alumina and zeolite.

3. The biomass material for absorbing and decomposing ethylene according to claim 1 or 2, characterized in that: The specific surface area of ​​the porous nanocarrier is 100 to 500 m 3 / g.

4. The biomass material for absorbing and decomposing ethylene according to claim 1, characterized in that: The biocatalyst includes raw bamboo extract and / or pine needle extract.

5. The biomass material for absorbing and decomposing ethylene according to claim 1, characterized in that: In the chitosan loaded with biocatalyst, the mass ratio of biocatalyst to chitosan is (1-5):

2.

6. The method for preparing the biomass material capable of absorbing and decomposing ethylene according to any one of claims 1 to 5, comprising the following steps: The ethylene adsorbent dispersion liquid and the porous nano-carrier are impregnated in equal volumes and then dried to obtain a biomass material that absorbs and decomposes ethylene.

7. A fresh-keeping film, prepared from the following raw materials in parts by weight: The biomass material for absorbing and decomposing ethylene is the biomass material for absorbing and decomposing ethylene according to any one of claims 1 to 5 or the biomass material for absorbing and decomposing ethylene prepared by the preparation method according to claim 6.

8. The cling film according to claim 7, characterized in that: The antibacterial agent comprises one or more of curcumin, camphor oil and curcumin.

9. The cling film according to claim 7, characterized in that: The filler includes one or more of talc powder, mica powder, wollastonite and calcium carbonate.

10. The method for preparing the fresh-keeping film according to any one of claims 7 to 9, comprising: Polylactic acid, biodegradable polyester, biomass material that absorbs and decomposes ethylene, antimicrobial agent, toughening agent and filler are mixed and melt-extruded to obtain a mixture; The mixed material is blown into a film to obtain a fresh-keeping film.

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