Biomass-based aerogel for fruit cushion packaging and method of making the same

Abstract

This invention discloses a biomass-based aerogel for fruit cushioning packaging and its preparation method, belonging to the technical field of food packaging materials. The preparation steps are as follows: chitosan solution and gelatin solution are mixed, and vanillin is added to carry out a cross-linking reaction to obtain a cross-linked mixture; the cross-linked mixture is subjected to low-temperature pre-freezing treatment, followed by freeze-drying to obtain the biomass-based aerogel for fruit cushioning packaging. The aerogel preparation method provided by this invention is simple, the raw materials are natural and renewable, and the acquisition cost is low. The obtained aerogel possesses excellent mechanical properties and cushioning effect, which is of great significance for the cushioning and storage of fruits during transportation.

Description

Technical Field

[0001] This invention belongs to the field of food packaging materials technology, and more specifically relates to a biomass-based aerogel for fruit cushioning packaging and its preparation method. Background Technology

[0002] Fresh fruits and vegetables, such as grapes, strawberries, blueberries, cherry tomatoes, and bell peppers, continue to undergo vigorous respiration and transpiration after harvesting. They are also susceptible to mechanical damage from external factors like vibration and compression during transportation and storage, leading to spoilage and significant economic losses. Mechanical damage to fruits and vegetables primarily stems from various factors during actual transportation, including the type of transport vehicle, road conditions, temperature, and humidity.

[0003] Traditional cushioning packaging materials for fruits and vegetables are mostly petroleum-based plastics such as expanded polyethylene and expanded polystyrene. While these materials have good cushioning properties, their non-degradability leads to serious white pollution problems and poses an environmental burden.

[0004] Aerogels are three-dimensional porous materials with gas as the dispersion medium, possessing unique properties such as low density and high porosity. Biomass-based aerogels prepared by freeze-drying technology can completely retain the three-dimensional network structure in solution, forming a porous framework with excellent buffering and adsorption properties, and have broad application prospects in the field of cushioning packaging.

[0005] While existing packaging materials based on natural polymers offer advantages such as wide availability and suitability for green packaging development, single-component or simple compound systems still suffer from limitations in mechanical strength, moisture stability, and structural controllability. Previous research has shown that cross-linking modification based on Schiff base reactions can improve the strength and water stability of amino-enriched biopolymers; however, for fruit cushioning packaging applications, achieving a balance between material molding quality, mechanical properties, wet structural stability, and pore structure control requires further optimization. Therefore, developing a biomass-based aerogel material suitable for fruit cushioning packaging has significant practical application value.

[0006] Based on this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a biomass-based aerogel for fruit cushioning packaging and its preparation method, so as to solve the problems existing in the prior art.

[0008] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is to provide a method for preparing biomass-based aerogels for fruit cushioning packaging, comprising the following steps: Chitosan solution and gelatin solution were mixed, and vanillin was added to carry out a cross-linking reaction to obtain a cross-linked mixture. The crosslinked mixture is pre-frozen to obtain a frozen solid; The frozen solid was freeze-dried to obtain the biomass-based aerogel used for fruit cushioning packaging.

[0009] Preferably, the chitosan solution is prepared by dissolving chitosan in acetic acid solution to obtain chitosan solution.

[0010] Preferably, the concentration of the acetic acid solution is 0.5-1.5 wt%; the concentration of the chitosan solution is 1-3 wt%; and the concentration of the gelatin solution is 1-3 wt%.

[0011] Preferably, the mass ratio of chitosan to gelatin is 1:5 to 5:1.

[0012] Preferably, the amount of vanillin added is 0.2 to 1.2 wt% of the total mass of chitosan and gelatin.

[0013] Preferably, the crosslinking reaction is carried out at a temperature of 60°C for a time of 45-90 minutes.

[0014] Preferably, the pre-freezing treatment is performed at a temperature of -40 to -20°C for 12 to 24 hours.

[0015] Preferably, the parameters of the freeze-drying process include: vacuum degree below 20 Pa, cold trap temperature below -60°C, and drying time of 36~48 h.

[0016] The second technical solution of the present invention provides a biomass-based aerogel for fruit cushioning packaging prepared by the above preparation method.

[0017] The third technical solution of the present invention provides the application of the above-mentioned biomass-based aerogel for fruit cushioning packaging in the field of food cushioning packaging materials.

[0018] Preferably, the field of food cushioning packaging materials mainly refers to cushioning packaging materials used in the transportation of fruits.

[0019] The technical principle of this invention is as follows: Chitosan is an alkaline polysaccharide prepared by deacetylation of chitin extracted from crustacean shells. Its molecular chain contains numerous amino and hydroxyl groups, giving it excellent antibacterial activity and biocompatibility. However, pure chitosan materials are brittle and lack flexibility, making it difficult to meet the mechanical performance requirements of cushioning packaging when used alone. Gelatin, a natural biomaterial obtained from the partial hydrolysis of animal collagen, possesses excellent gelling properties and biodegradability, and is widely used in food and packaging materials. However, gelatin materials have low mechanical strength and poor stability at room temperature. Composite materials prepared by mixing chitosan and gelatin can form hydrogen bonds and electrostatic interactions between the two molecules, effectively improving the water resistance of gelatin and the brittleness of chitosan, thus enhancing the overall performance of the material.

[0020] Based on this, the present invention introduces vanillin, a natural crosslinking agent. The aldehyde groups in vanillin molecules can react with the amino groups on the chitosan molecular chain to form a Schiff base reaction, thereby forming a chemical crosslinking network and further enhancing the structural stability and mechanical strength of the composite material.

[0021] Specifically, this invention further introduces vanillin, a natural cross-linking agent. The aldehyde group (-CHO) in the vanillin molecule can undergo a Schiff base reaction with the amino group (-NH2) on the chitosan molecular chain to generate an imine bond (-C=N-), thereby forming a stable chemical cross-linking network between chitosan and gelatin molecules. This chemical cross-linking, synergistically with physical cross-linking such as hydrogen bonding and electrostatic interactions between chitosan and gelatin molecules, significantly enhances the network structure stability and mechanical strength of the composite material. Simultaneously, vanillin, as a natural plant-derived compound, possesses good biocompatibility and antioxidant activity, meeting the requirements for green food packaging materials. The aerogel provided by this invention possesses excellent pore structure and mechanical properties, meeting the comprehensive performance requirements of cushioning materials during fruit transportation.

[0022] The present invention discloses the following technical effects: (1) The aerogel provided by the present invention uses natural biomass materials chitosan and gelatin as the base material. No petroleum-based raw materials or toxic chemical reagents are used in the whole process. The resulting aerogel has good biodegradability and meets the development requirements of green packaging.

[0023] (2) The aerogel provided by this invention uses vanillin as a natural cross-linking agent; a three-dimensional network structure is formed through Schiff base reaction, and a porous aerogel is prepared by unidirectional freezing pre-freezing and freeze-drying. The preparation method is simple, the raw materials are natural and renewable, and the acquisition cost is low. The obtained aerogel has the following properties: density 0.032~0.045 g / cm³. 3Porosity 45.83~75.84%, hardness 100.47~162.80 N, compressive modulus 0.78~1.67 MPa, compressive toughness 99.06~176.31 kJ / m 3 The aerogel has an average pore size of 146 μm, with a more concentrated distribution of smaller pore sizes. The aerogel provided by this invention is of great significance for the buffering and storage of fruits during transportation. Attached Figure Description

[0024] Figure 1 The images show the appearance of the biomass-based aerogels prepared in Examples 1-6 and Comparative Examples 1-5. Figure 2 These are structural stability test diagrams of the biomass-based aerogels prepared in Examples 1-6 and Comparative Examples 1-3; Figure 3 The figures show the compressive stress-strain diagrams of the biomass-based aerogels prepared in Examples 1-6 and Comparative Examples 1-3. Figure 4 Fourier transform infrared spectra of the biomass-based aerogels prepared in Example 5 and Comparative Examples 1-3; Figure 5 The images show the microstructure of the biomass-based aerogels prepared in Example 5 and Comparative Examples 1-3. Figure 6 The pore size distribution diagrams are for the biomass-based aerogels prepared in Example 5 and Comparative Examples 1-3. Detailed Implementation

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0027] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0028] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0029] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0030] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0031] Unless otherwise specified, all raw materials used in the following embodiments and comparative examples of this invention are commercially available products, and the source of these commercially available products does not affect the technical effect of this invention.

[0032] Example 1 This embodiment provides a method for preparing biomass-based aerogels, including the following steps: (1) Add 1 mL of glacial acetic acid to a 100 mL volumetric flask and dilute to the mark to prepare a 1 wt% acetic acid solution. Dissolve 1.5 g of chitosan completely in 100 mL of acetic acid solution using magnetic stirring to obtain a 1.5 wt% acidic chitosan solution. Dissolve 1.5 g of gelatin completely in 100 mL of distilled water at 50 °C using magnetic stirring to obtain a 1.5 wt% gelatin aqueous solution.

[0033] (2) Take 30 mL of the acidic chitosan solution and 10 mL of the gelatin aqueous solution (chitosan:gelatin mass ratio is 3:1) from (1) and add them to a beaker for mixing. Add vanillin, which accounts for 0.5% of the total mass of chitosan and gelatin, to the mixture and stir magnetically at 60℃ for 60 min to obtain a cross-linked mixture.

[0034] (3) Inject the cross-linked mixture into the mold and pre-freeze it in a -30℃ refrigerator for 18 hours to obtain a frozen solid.

[0035] (4) The frozen solid was placed in a freeze dryer and dried for 48 hours under conditions of vacuum degree below 20 Pa and cold trap temperature of -80 °C to obtain biomass-based aerogel, denoted as C3G1V0.5.

[0036] Example 2 The difference from Example 1 is that in step (2), the mass ratio of chitosan to gelatin is 3:1, and the amount of vanillin added accounts for 1% of the total mass of chitosan and gelatin. The remaining steps are the same as in Example 1, denoted as C3G1V1.

[0037] Example 3 The difference from Example 1 is that in step (2), the mass ratio of chitosan to gelatin is 1:3, the amount of vanillin added accounts for 0.5% of the total mass of chitosan and gelatin, and the remaining steps are the same as in Example 1, denoted as C1G3V0.5.

[0038] Example 4 The difference from Example 1 is that in step (2), the mass ratio of chitosan to gelatin is 1:3, the amount of vanillin added accounts for 1% of the total mass of chitosan and gelatin, and the remaining steps are the same as in Example 1, denoted as C1G3V1.

[0039] Example 5 The difference from Example 1 is that in step (2), the mass ratio of chitosan to gelatin is 1:1, the amount of vanillin added accounts for 0.5% of the total mass of chitosan and gelatin, and the remaining steps are the same as in Example 1, denoted as C1G1V0.5.

[0040] Example 6 The difference from Example 1 is that in step (2), the mass ratio of chitosan to gelatin is 1:1, the amount of vanillin added accounts for 1% of the total mass of chitosan and gelatin, and the remaining steps are the same as in Example 1, denoted as C1G1V1.

[0041] Comparative Example 1 This comparative example provides a method for preparing a chitosan / gelatin physically mixed aerogel, comprising the following steps: Prepare a 1.5 wt% acidic chitosan solution and a 1.5 wt% aqueous gelatin solution. Mix 20 mL of chitosan solution and 20 mL of gelatin solution (mass ratio 1:1), stir evenly, and without adding vanillin, directly inject into a mold. Perform pre-freezing treatment and freeze-drying under the same conditions as in Example 1 to obtain pure chitosan aerogel, denoted as CS / GEL (CG).

[0042] Comparative Example 2 This comparative example provides a method for preparing pure chitosan aerogel, comprising the following steps: Prepare 40 mL of a 1.5 wt% acidic chitosan solution, inject it into a mold, and perform pre-freezing and freeze-drying under the same conditions as in Example 1 to obtain pure chitosan aerogel, denoted as CS.

[0043] Comparative Example 3 This comparative example provides a method for preparing pure gelatin aerogel, comprising the following steps: Prepare 40 mL of a 1.5 wt% gelatin aqueous solution, inject it into a mold, and perform pre-freezing and freeze-drying under the same conditions as in Example 1 to obtain pure gelatin aerogel, denoted as GEL.

[0044] Comparative Example 4 This comparative example provides a method for preparing biomass-based aerogels, comprising the following steps: The difference from Example 1 is that in step (2), the mass ratio of chitosan to gelatin is 1:7, the amount of vanillin added accounts for 0.5% of the total mass of chitosan and gelatin, and the remaining steps are the same as in Example 1, denoted as C1G7V0.5.

[0045] Comparative Example 5 This comparative example provides a method for preparing biomass-based aerogels, comprising the following steps: The difference from Example 1 is that in step (2), the mass ratio of chitosan to gelatin is 1:1, the amount of vanillin added accounts for 0.05% of the total mass of chitosan and gelatin, and the remaining steps are the same as in Example 1, denoted as C1G1V0.05.

[0046] Figure 1 The images show the appearance of the biomass-based aerogels prepared in Examples 1-6 and Comparative Examples 1-5.

[0047] Depend on Figure 1It can be seen that the aerogel samples obtained in the examples can form relatively complete block / columnar structures. Some of the sample surfaces are relatively smooth and the edges are relatively complete, showing good molding quality. Although the comparative examples can also form aerogel samples, they are generally inferior to the sample samples in terms of surface smoothness, structural integrity, and macroscopic morphology. Furthermore, Comparative Examples 4 and 5 show that when the CS / GEL ratio or the amount of crosslinking agent added exceeds the limit, although the obtained samples can still form lyophilized materials, their macroscopic appearance integrity decreases, manifested as an overall collapsed appearance, irregular edges, local depressions, or increased shrinkage. This indicates that when the CS / GEL ratio or the amount of crosslinking agent exceeds the limit, it is difficult to fully exert the chemical crosslinking effect, which is not conducive to the formation of a stable and relatively dense three-dimensional network structure, making it unsuitable for subsequent index determination and compression testing. Therefore, it is shown that by controlling the CS / GEL ratio and the amount of vanillin added within a suitable range, biomass-based aerogel materials with better molding quality, more complete appearance, and more complete structure can be obtained. The parameter range defined in this invention is of great significance for obtaining biomass-based aerogels with relatively complete structures.

[0048] Test Example 1 Density and porosity Density: The density of the aerogel was determined by measuring its weight and dimensions using an analytical balance and a digital vernier caliper, with the measurement performed using a precision balance with an accuracy of 0.1 mg.

[0049] ; In the formula: ρ represents the density of the aerogel (g / cm³) 3 ), m represents the weight of the aerogel (g), R represents the radius of the aerogel (cm), and H represents the height of the aerogel (cm). Porosity: The porosity of the aerogel was determined using a liquid displacement method. The dried aerogel sample was immersed in anhydrous ethanol to achieve adsorption saturation, and then removed. Excess ethanol was wiped off with filter paper, and the moistened aerogel was reweighed.

[0050] ; In the formula: m2 represents the weight (g) of the wet aerogel after immersion in ethanol, and m1 represents the weight (g) of the dry aerogel. C represents the density of ethanol (0.785 g / cm³). 3 V represents the volume of the dried aerogel (cm³). 3 ).

[0051] The densities and porosities of the aerogels obtained in Examples 1-6 and Comparative Examples 1-3 are shown in Table 1.

[0052] Table 1 Aerogel density and porosity As shown in Table 1, the cross-linked aerogel structure is more compact, and the density range of the aerogels prepared in the examples is 0.032~0.045 g / cm³. 3 The porosity ranges from 45.83% to 75.84%, all exhibiting low density and high porosity, meeting the requirements for lightweight porous materials. Cross-linking reactions facilitate the formation of a more developed porous framework; the aerogel in Example 5 (C1G1V0.5) has a density of 0.039 g / cm³. 3 With a porosity of 75.84%, it maintains a low density while exhibiting high porosity, resulting in superior overall performance compared to other embodiments. Combined with... Figure 1 It is understood that by adjusting the chitosan / gelatin ratio and the amount of vanillin, this invention can obtain an aerogel material with both low density and suitable porosity, thus meeting the needs of fruit cushioning packaging.

[0053] Test Example 2 Mechanical performance testing The mechanical properties of the aerogels were determined using a texture analyzer with a cylindrical probe. The testing conditions were: pre-test speed 5.0 mm / s, mid-test speed 1.0 mm / s, post-test speed 5.0 mm / s, aerogel deformation compression percentage of 70%, and a trigger force of 5 g. The hardness (N) and stress-strain curves of each aerogel were obtained through analysis. The compressive modulus (MPa) was calculated from the slope of the initial linear segment of the stress-strain curve, and the compressive toughness (kJ / m²) was also determined. 3 The results are obtained by area integration under the stress-strain curve, and are shown in Table 2.

[0054] Table 2 Mechanical properties of aerogels As shown in Table 2, the aerogels prepared according to the embodiments of the invention have a hardness range of 100.47~162.80 N, a compressive modulus range of 0.78~1.67 MPa, and a compressive toughness range of 99.06~176.31 kJ / m. 3 All samples exhibited good mechanical strength, meeting the material's compression resistance requirements for fruit cushioning packaging. Compared to the comparative example, the mechanical properties of the examples were comprehensively improved. Taking Example 5 (C1G1V0.5) as an example, its hardness (162.80 N) was approximately 4.2 times that of Comparative Example 1 (CS / GEL, 38.74 N), its compressive modulus (1.42 MPa) was 4.3 times that of Comparative Example 1 (0.33 MPa), and its compressive toughness was approximately 2 to 4 times that of the comparative example. This indicates that the chemical network structure formed by vanillin cross-linking effectively enhances the mechanical stability of the material.

[0055] Test Example 3 Structural stability test The structural stability of the aerogel was evaluated by observing its physical state in water and a nonpolar oil phase (soybean oil). A 12-well culture plate was immersed in the aerogel, and its physical state was monitored and observed at predetermined intervals (0h, 2h, 12h, and 24h), and the results were recorded using photographs. The results are shown below. Figure 2 As shown.

[0056] Figure 2 The diagrams show the structural stability test results of the biomass-based aerogels prepared in Examples 1-6 and Comparative Examples 1-3.

[0057] Depend on Figure 2 It can be seen that all aerogel samples maintained good structural stability in the nonpolar oil phase system. In the aqueous phase system, some pure component aerogels gradually showed blurred sample boundaries and decreased structural integrity after contact with water, eventually leading to disintegration. CS / GEL aerogels, due to their own hydrogen bonding, did not disintegrate but exhibited a certain degree of swelling. The cross-linked aerogels prepared in the examples, due to the presence of covalent bond networks formed by Schiff base reactions, exhibited relatively stable structures and did not show structural collapse, disintegration, or other structural instability phenomena. The cross-linked aerogels absorbed more water than oil, which is related to the abundant hydroxyl / amino functional groups inherent in the material, increasing its hydrophilicity.

[0058] Test Example 4 Compressive stress and strain The compressive stress and strain of the aerogels were obtained using a texture analyzer with a cylindrical probe. The testing conditions were: pre-test velocity 5.0 mm / s, test velocity 1.0 mm / s, post-test velocity 5.0 mm / s, aerogel deformation compression percentage of 70%, and a trigger force of 5 g. The stress-strain curves for each aerogel were obtained through analysis, and the results are as follows: Figure 3 As shown.

[0059] Figure 3 The figures show the compressive stress-strain diagrams of the biomass-based aerogels prepared in Examples 1-6 and Comparative Examples 1-3.

[0060] In the context of packaging fragile fruits, aerogels used as cushioning materials must possess both softness and sufficient flexibility. Analysis of compression stress-strain curves revealed three distinct stages in all samples: first, an elastic deformation stage (5-15%), characterized by an initial linear region; second, permanent deformation (15-50%), characterized by a plastic region; and third, a dense region (50-70%), which can form a more compact structure. This demonstrates that the aerogels prepared in the examples possess both softness and sufficient flexibility. The stress-strain behavior in these three stages is closely related to the microporous structure of the aerogel. In the examples, vanillin crosslinking creates a more uniform and denser three-dimensional network structure, enabling the aerogel to exhibit better load-bearing and deformation coordination during compression. This results in a more stable plateau stress and a longer plateau region during the plastic deformation stage, thus more effectively absorbing impact energy and preventing premature stress peaks that could damage the fruit.

[0061] Test Example 5 Fourier transform infrared spectroscopy analysis The prepared aerogels were analyzed using a Fourier transform infrared spectroscopy (ATR) instrument in ATR mode from 4000 to 6000 cm⁻¹. -1 The scan was performed within the range, and the results are as follows: Figure 4 As shown.

[0062] Figure 4 Fourier transform infrared spectra of the biomass-based aerogels prepared in Example 5 and Comparative Examples 1-3.

[0063] Infrared analysis revealed characteristic absorption peaks in both CS and GEL aerogels, indicating their respective chemical structures. The peak corresponding to the superposition of NH and OH bonds in the CS / GEL aerogel shifted to 3301 m. -1 The presence of hydrogen bonds indicates that the two only have hydrogen bonding. In the spectrum of Example 5 (CS / GEL / VAN), the introduction of the vanillin phenolic hydroxyl group causes the NH and OH superposition peaks to shift to 3239 cm⁻¹. -1 This indicates that the introduction of vanillin enhanced the hydrogen bonding, resulting in a more compact structure, 1639 cm⁻¹. -1 C=N stretching vibration and 1662cm -1 The absence of an aldehyde peak indicates that vanillin successfully reacted with chitosan and gelatin to form a Schiff base.

[0064] Test Example 6 Micromorphology After gold sputtering and liquid nitrogen fracturing, the cross-sectional morphology of the prepared aerogels was observed using scanning electron microscopy to examine their porous structure and pore size distribution. The results are as follows: Figure 5 and Figure 6 As shown.

[0065] Figure 5 The images show the microstructure of the biomass-based aerogels prepared in Example 5 and Comparative Examples 1-3.

[0066] Figure 6 The pore size distribution diagrams are for the biomass-based aerogels prepared in Example 5 and Comparative Examples 1-3.

[0067] Microscopic morphology reveals that the pore structure integrity and pore size distribution of CS and GEL aerogels are weaker than those of CS / GEL aerogels and the aerogel of Example 5 (CS / GEL / VAN). This is because CS and GEL aerogels can form a denser network structure through hydrogen bonding, while the self-crosslinking of CS and GEL aerogels is weaker, resulting in larger pore sizes and a tendency for structural collapse. For CS / GEL / VAN aerogels, imine bonds are generated through Schiff base reactions, supplemented by physical hydrogen bonding. Under the synergistic effect, smaller pores with more uniform pore size are formed, significantly reducing the pore size and further enhancing the stability of the network structure. Figure 5 Histograms of pore size distribution for each sample show that CS, GEL, and CS / GEL aerogels exhibit larger pore sizes and wider distribution. Due to hydrogen bonding, the maximum pore size of CS / GEL decreased from 427 μm to 296 μm. The average pore size of the aerogel in Example 5 (CS / GEL / VAN) further decreased from 178 μm to 146 μm, the smallest among the four samples, with a reduced peak value and a significantly decreased proportion of large pores. Figure 6 The above results indicate that vanillin crosslinking modification can effectively regulate the micropore structure of biomass-based aerogels, transforming them from macropores with a wide distribution to micropores with a narrow distribution. This results in aerogel materials with both good mechanical properties and structural stability, meeting the requirements of fruit cushioning packaging for material microstructure.

[0068] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0069] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a biomass-based aerogel for fruit cushioning packaging, characterized in that, Includes the following steps: Chitosan solution and gelatin solution were mixed, and vanillin was added to carry out a cross-linking reaction to obtain a cross-linked mixture. The crosslinked mixture is pre-frozen to obtain a frozen solid; The frozen solid was freeze-dried to obtain the biomass-based aerogel used for fruit cushioning packaging.

2. The preparation method according to claim 1, characterized in that, The preparation steps of the chitosan solution are as follows: dissolve chitosan in acetic acid solution to obtain chitosan solution.

3. The preparation method according to claim 2, characterized in that, The concentration of the acetic acid solution is 0.5~1.5wt%; the concentration of the chitosan solution is 1~3wt%; and the concentration of the gelatin solution is 1~3wt%.

4. The preparation method according to claim 1, characterized in that, The mass ratio of chitosan to gelatin is 1:5 to 5:

1.

5. The preparation method according to claim 1, characterized in that, The amount of vanillin added is 0.2 to 1.2 wt% of the total mass of chitosan and gelatin.

6. The preparation method according to claim 1, characterized in that, The cross-linking reaction was carried out at a temperature of 60°C for 45-90 minutes.

7. The preparation method according to claim 1, characterized in that, The pre-freezing treatment is performed at a temperature of -40 to -20°C for 12 to 24 hours.

8. The preparation method according to claim 1, characterized in that, The parameters for the freeze-drying process include: vacuum degree below 20 Pa, cold trap temperature below -60℃, and drying time of 36~48 h.

9. The biomass-based aerogel for fruit cushioning packaging prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the biomass-based aerogel for fruit cushioning packaging as described in claim 9 in the field of food cushioning packaging materials.

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