A composite aerogel for controlling Nisin release, its preparation method and its application

Abstract

This application discloses a composite aerogel for controlling Nisin release, its preparation method, and its application, relating to the field of food engineering technology. By selecting chitosan nanoparticles and nanocellulose as two loading materials, Nisin is dual-loaded to improve the Nisin loading rate. The composite aerogel obtained by freeze-drying has a three-dimensional porous network structure inside, which can provide channels for Nisin delivery and release, prolong the Nisin release cycle, and realize the sustained and controlled release of Nisin.

Description

Technical Field

[0001] This application belongs to the field of food engineering technology, specifically relating to a composite aerogel for controlling Nisin release, its preparation method, and its application. Background Technology

[0002] Nisin is a polypeptide-based natural antimicrobial agent produced by lactic acid bacteria fermentation. It possesses excellent antibacterial effects and, due to its natural and non-toxic nature, is the only antimicrobial peptide suitable for food preservation, making it widely used in this field. However, nisin undergoes burst release during use, resulting in a short duration of antimicrobial activity and limited protection for food, thus restricting its application. Therefore, it is necessary to improve the antimicrobial activity of nisin and develop suitable delivery systems to achieve sustained-release nisin.

[0003] Among the published patents retrieved so far, patent CN109173946B utilizes sodium alginate and chitosan to encapsulate Nisin and polylysine into microcapsules, which can improve the antibacterial activity and stability of Nisin, but it does not study the release behavior of Nisin from the microcapsules. Patent CN106432774B first modifies the surface of a PE / PET film, then coats the modified film surface with a chitosan / Nisin solution to prepare a chitosan / Nisin antibacterial film, which is used for pork preservation, but it also does not involve the release behavior of Nisin.

[0004] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to address the limitations of current Nisin applications by providing a composite aerogel for controlling Nisin release, its preparation method, and its application, thereby improving the sustained release of Nisin, extending the release period of Nisin, controlling the release of Nisin, and promoting the application of Nisin in food antibacterial and preservation applications.

[0006] To achieve the above-mentioned objectives, this application provides the following technical solution:

[0007] A method for preparing a composite aerogel with controlled Nisin release includes the following steps:

[0008] (1) Preparation of chitosan nanoparticle emulsion: Prepare a 1-5 wt% chitosan acetate aqueous solution, add sodium tripolyphosphate to it, control the mass ratio of sodium tripolyphosphate to chitosan to be 1:20-40, and stir evenly;

[0009] (2) Preparation of Nisin / chitosan nanoparticle emulsion: Nisin is added to the chitosan nanoparticle emulsion prepared in step (1), wherein the mass ratio of Nisin to chitosan is 1:1 to 5, and the mixture is stirred evenly.

[0010] (3) Preparation of Nisin / chitosan / nanocellulose mixture: Add nanocellulose to the Nisin / chitosan nanoparticle emulsion obtained in step (2), with the mass ratio of nanocellulose to Nisin being 1:0.5-2, and stir until homogeneous;

[0011] (4) Preparation of Nisin / chitosan / nanocellulose composite aerogel: The mixture obtained in step (4) is centrifuged to remove the unloaded Nisin in the supernatant, the lower part is dialyzed to remove excess acetic acid, and then freeze-dried.

[0012] In some embodiments of this application, the mixing in steps (1), (2), and (3) specifically involves magnetic stirring at 45°C.

[0013] In some embodiments of this application, the nanocellulose in step (3) is cellulose nanocrystals or cellulose nanofibers.

[0014] In some embodiments of this application, the centrifugation process in step (4) is specifically centrifugation at 8000-10000 r / min for 5-10 min.

[0015] In some embodiments of this application, the freeze-drying is performed at -50°C in a freeze dryer for 48 hours.

[0016] In another embodiment of this application, a composite aerogel for controlling Nisin release is also provided. Chitosan nanoparticles and nanocellulose are selected as two loading materials to dual-load Nisin, thereby increasing the loading rate of Nisin. The composite aerogel obtained by freeze-drying has a three-dimensional porous network structure inside, which can provide channels for the delivery and release of Nisin, prolong the release cycle of Nisin, and realize the sustained and controlled release of Nisin.

[0017] In some embodiments of this application, the in vitro cumulative release curve of Nisin in the composite aerogel is divided into three processes: burst release, sustained release, and balanced release. At 4, 10, 20, and 40 hours, the cumulative release amount of the aerogel is 46.3%, 65.4%, 66.7%, and 68.5% of the total Nisin, respectively.

[0018] In some embodiments of this application, the cumulative release of aerogel at 4, 10, 20, and 40 hours is 67.5%, 74.2%, 76.5%, and 79.3% of the total Nisin, respectively.

[0019] In some embodiments of this application, the composite aerogel has a Nisin loading rate of 60.5%-65%.

[0020] In other embodiments of this application, the application of the above-described composite aerogel with controlled Nisin release in food antibacterial preservation is also provided.

[0021] Compared with the prior art, this application has at least the following beneficial effects:

[0022] 1) This application uses two loading materials, chitosan nanoparticles and nanocellulose, to dual-load Nisin. The porous network structure of nanocellulose aerogel provides loading sites for Nisin and chitosan nanoparticles, further improving the loading rate of Nisin.

[0023] 2) The porous network structure of the composite aerogel in this application can serve as a channel for the release and transport of Nisin, prolonging the release cycle of Nisin and controlling the release of Nisin.

[0024] 3) The composite aerogel prepared in this application has a Nisin loading rate of 65%, and the in vitro cumulative release curve of Nisin is divided into three processes: burst release, sustained release and equilibrium release, which can better control the release of Nisin.

[0025] 4) The composite aerogel prepared in this application can improve the thermal stability of Nisin. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 These are morphology images of the composite aerogels in Examples 1, 2, and 3;

[0028] Figure 2 This refers to the Nisin loading rate of the composite aerogel in Examples 1, 2, and 3;

[0029] Figure 3 These are the in vitro release curves of the composite aerogel Nisin in Examples 1, 2, and 3;

[0030] Figure 4 These are the thermal stability curves of the composite aerogels in Examples 1 and 3; Detailed Implementation

[0031] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of this application, but not all embodiments, and are only used to illustrate this application, and should not be regarded as limiting the scope of this application.

[0032] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0033] The following examples further illustrate the above-mentioned content of this application, but it should not be construed as limiting the scope of the above-mentioned subject matter of this application to the following examples. All technologies implemented based on the above-mentioned content of this application fall within the scope of this application.

[0034] Example 1

[0035] Prepare a 2 wt% chitosan acetate aqueous solution, add sodium tripolyphosphate to it so that the mass ratio of sodium tripolyphosphate to chitosan is 1:30, and stir magnetically at 45°C to obtain a chitosan nanoparticle emulsion.

[0036] Then Nisin was added to make the mass ratio of Nisin to chitosan 1:5, and the mixture was magnetically stirred at 45°C to obtain a Nisn / chitosan nanoparticle emulsion.

[0037] The mixture was centrifuged at 10000 r / min for 10 min to remove unloaded Nisin from the supernatant. The lower fraction was dialyzed to remove excess acetic acid, and then freeze-dried to obtain Nisin / chitosan / aerogel. This example serves as a control group, using only chitosan nanoparticles as the loading material to prepare Nisin / chitosan aerogel. Figure 1 As shown in (a), the product morphology is characterized by large agglomerates and wrinkles with inconspicuous void structures. The loading rate of Nisin on the aerogel is 51.5%, and the cumulative release of Nisin only reaches about 50% after 40 hours.

[0038] Example 2

[0039] A 2 wt% chitosan acetate aqueous solution was prepared, and sodium tripolyphosphate was added to it to make the mass ratio of sodium tripolyphosphate to chitosan 1:25. The mixture was magnetically stirred at 45°C to obtain a chitosan nanoparticle emulsion.

[0040] Then, Nisin was added to achieve a Nisin to chitosan mass ratio of 1:5, and the mixture was magnetically stirred at 45℃ until homogeneous. Next, nanocellulose was added to achieve a nanocellulose to Nisin mass ratio of 1:1, and the mixture was magnetically stirred at 45℃ until homogeneous, resulting in a Nisin / chitosan / nanocellulose mixture. The mixture was centrifuged at 10000 r / min for 10 min to remove unloaded Nisin from the supernatant. The lower fraction was dialyzed to remove excess acetic acid, and then freeze-dried to obtain a Nisin / chitosan / nanocellulose composite aerogel. Test results: The Nisin loading rate of this composite aerogel was 60.5%. The in vitro release curve showed that the release rate and amount of Nisin were relatively fast from 0 to 4 h, slowed down from 4 to 10 h, continued to slow down from 10 to 20 h, and stabilized after 20 h. At 4, 10, 20, and 40 hours, the cumulative release of aerogel was 46.3%, 65.4%, 66.7%, and 68.5% of the total Nisin, respectively. The morphology of the aerogel is as follows: Figure 1 As shown in (b), the load factor is as follows Figure 2 As shown, the release curve is as follows Figure 3 As shown.

[0041] Example 3

[0042] Prepare a 2 wt% chitosan acetate aqueous solution, add sodium tripolyphosphate to it so that the mass ratio of sodium tripolyphosphate to chitosan is 1:30, and stir magnetically at 45°C to obtain a chitosan nanoparticle emulsion.

[0043] Then Nisin was added to make the mass ratio of Nisin to chitosan 1:5. The mixture was magnetically stirred at 45°C until homogeneous. Then nanocellulose was added to make the mass ratio of nanocellulose to Nisin 1:0.5. The mixture was magnetically stirred at 45°C until homogeneous, and finally a Nisn / chitosan / nanocellulose mixture was obtained.

[0044] The mixture was centrifuged at 10000 r / min for 10 min to remove unloaded Nisin from the supernatant. The lower part was dialyzed to remove excess acetic acid, and then freeze-dried to obtain Nisin / chitosan / nanocellulose composite aerogel.

[0045] Test results: The composite aerogel had a Nisin loading rate of 65%. In vitro release curves showed that the release rate and amount of Nisin were rapid from 0 to 4 hours, slowed down from 4 to 10 hours, continued to slow down from 10 to 20 hours, and stabilized after 20 hours. At 4, 10, 20, and 40 hours, the cumulative release of the aerogel was 67.5%, 74.2%, 76.5%, and 79.3% of the total Nisin, respectively. The morphology of the aerogel is shown below. Figure 1 As shown in (c), the load factor is as follows: Figure 2 As shown, the release curve is as follows Figure 3 As shown, the thermal stability curve is as follows Figure 4 As shown.

[0046] When only chitosan is used as the loading material, the morphology is characterized by large agglomerates and wrinkles, with indistinct pores. After adding nanocellulose, a distinct fibrous network emerges; the more nanocellulose added, the more pronounced the three-dimensional network structure. Nanocellulose provides more loading sites for Nisin, increasing the Nisin loading rate. Furthermore, the three-dimensional network structure is more conducive to Nisin release, resulting in a greater release amount.

[0047] The thermogravimetric analysis (TGA) curves show that, after adding nanocellulose, the weight loss rate of the aerogel in Example 3 was significantly lower than that in Example 1 before reaching 300℃. The weight loss between 0 and 80℃ was mainly due to the gradual evaporation of moisture as the temperature gradually increased; subsequently, as the temperature rose (80–200℃), Nisin gradually decomposed, and the weight loss in Example 3 was not significant, with a stable curve. In contrast, Example 1 showed significant weight loss, with a noticeable decrease in the curve. This indicates that the addition of nanocellulose can effectively load Nisin, thereby protecting it and improving its thermal stability. The hydrogen bonding between Nisin and chitosan further stabilizes the conformation of Nisin, resulting in better protection. Simultaneously, the intermolecular interactions between chitosan and nanocellulose form a stable composite aerogel system, effectively prolonging the release period of Nisin and controlling its release.

[0048] The above embodiments describe the basic principles, main features and advantages of this application. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of this application. Various changes and improvements can be made to this application without departing from the scope of the principles of this application, and all such changes and improvements fall within the protection scope of this application.

Claims

1. A method for the preparation of a composite aerogel for controlled release of Nisin, characterized in that, It comprises the following steps: (1) preparation of chitosan nanoparticle emulsion: prepare 1-5wt% chitosan acetic acid aqueous solution, add sodium tripolyphosphate thereto, control the mass ratio of sodium tripolyphosphate to chitosan to be 1:20-40, and stir uniformly; (2) preparation of Nisin / chitosan nanoparticle emulsion: add Nisin to the chitosan nanoparticle emulsion prepared in step (1), the mass ratio of Nisin to chitosan being 1:1-5, and stir uniformly; (3) preparation of Nisin / chitosan / nano-cellulose mixed solution: add nano-cellulose to the Nisin / chitosan nanoparticle emulsion obtained in step (2), the mass ratio of nano-cellulose to Nisin being 1:0.5-2, and stir uniformly; (4) preparation of Nisin / chitosan / nano-cellulose composite aerogel: centrifuge the mixed solution obtained in step (4) to remove the unloaded Nisin in the supernatant, dialyze the lower part to remove excess acetic acid, and freeze-dry; the nano-cellulose in step (3) is cellulose nanocrystal or cellulose nanofiber.

2. A method of preparing a composite aerogel for controlled release of Nisin as claimed in claim 1, wherein, The stirring uniformly in steps (1), (2), and (3) is specifically magnetic stirring at 45°C.

3. A method of preparing a composite aerogel for controlled release of Nisin as claimed in claim 1, wherein, The centrifugation in step (4) is specifically centrifugation at 8000-10000r / min for 5-10min.

4. A method of preparing a composite aerogel for controlled release of Nisin as claimed in claim 1, wherein, The freeze-drying is freeze-drying at-50°C in a freeze-drying machine for 48h.

5. A composite aerogel for controlled release of Nisin, characterized in that, The preparation method according to any one of claims 1-4 is used to prepare a composite aerogel by selecting chitosan nanoparticles and nano-cellulose as two kinds of loading materials to double load Nisin, thereby improving the loading rate of Nisin; freeze-drying to obtain a composite aerogel with a three-dimensional porous network structure inside, which can provide channels for the transmission and release of Nisin, prolong the release period of Nisin, and realize the sustained release and controlled release of Nisin.

6. The composite aerogel for controlling the release of Nisin according to claim 5, wherein, The cumulative release curve of Nisin in the composite aerogel is divided into three processes: burst release, sustained release, and equilibrium release; at 4h, 10h, 20h, and 40h, the cumulative release amount of the aerogel is 46.3%, 65.4%, 66.7%, and 68.5% of the total amount of Nisin, respectively.

7. The composite aerogel for controlling the release of Nisin according to claim 5, wherein At 4h, 10h, 20h, and 40h, the cumulative release amount of the composite aerogel is 67.5%, 74.2%, 76.5%, and 79.3% of the total amount of Nisin, respectively.

8. The composite aerogel for controlling the release of Nisin according to claim 5, wherein The loading rate of the composite aerogel for Nisin is 60.5%-65%.

9. The use of a composite aerogel for controlling the release of Nisin in the preservation of foodstuffs, characterized in that, The composite aerogel is the controlled Nisin release composite aerogel according to any one of claims 5-8.

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