A hydrogel loaded with wheat bran oligopeptide GK-8, a preparation method and application thereof
By loading gluten bran oligopeptide GK-8 into OHA/CMCS hydrogel, a ternary composite hydrogel system was constructed, which solved the problems of insufficient antibacterial properties and poor antioxidant effects of existing hydrogels, and achieved long-term preservation of fruits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANXI UNIV
- Filing Date
- 2026-04-28
- Publication Date
- 2026-06-05
Smart Images
Figure CN122139808A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of food preservation and edible biopolymer materials technology, and in particular to a hydrogel loaded with gluten bran oligopeptide GK-8, its preparation method and application. Background Technology
[0002] Fruits are an important part of the Chinese diet, rich in vitamins, minerals, and various phytochemicals. However, after harvesting, fruits continue to undergo intense respiration and transpiration, and are susceptible to mechanical damage and microbial contamination, leading to rapid dehydration, wilting, browning, nutrient loss, and spoilage. Statistics show that post-harvest losses of fruits and vegetables in my country reach 20%–30%, becoming a key bottleneck restricting the industry's development. While traditional low-temperature cold chain and modified atmosphere storage technologies are effective, their high equipment and operating costs make them difficult to implement comprehensively across vast, dispersed production areas and distribution channels. The use of chemical preservatives (such as sulfites and benzimidazoles) poses drug residues and potential food safety risks, contradicting current trends towards green and safe consumption. Therefore, developing safe, efficient, and biodegradable novel edible preservation materials has become an urgent technical challenge in this field.
[0003] Edible hydrogels, based on natural polymers, can form a dense protective coating on the surface of fruits, extending shelf life by blocking oxygen, inhibiting microbial growth, and reducing moisture loss, while also exhibiting good biodegradability and food safety. Oxidized hyaluronic acid (OHA) and carboxymethyl chitosan (CMCS) are two biopolymers that combine these advantages. Oxidation of hyaluronic acid introduces active aldehyde groups, while the carboxymethyl chitosan molecular chain contains abundant amino groups. The two can form a dynamically cross-linked composite hydrogel (O / C hydrogel) through a Schiff base reaction. This gel system possesses in-situ gelation, self-healing, and good moisturizing and film-forming properties, showing application potential in fruit preservation. However, the preservation function of existing O / C hydrogels is relatively limited. Their antibacterial performance mainly relies on the limited antibacterial effect of cationic amino groups on the carboxymethyl chitosan molecular chain, resulting in a narrow antibacterial spectrum and low efficiency. This makes it difficult to effectively inhibit the growth and reproduction of common pathogenic microorganisms on fruit surfaces, such as gray mold and penicillium, leading to very limited medium- and long-term storage and preservation effects. Meanwhile, the system itself lacks effective antioxidant activity and cannot effectively remove excess free radicals generated by post-harvest metabolism of fruit. Therefore, it cannot fundamentally block membrane lipid peroxidation, tissue browning, and nutrient loss caused by oxidative stress, making it difficult to meet the core requirements for shelf-life preservation of fresh fruit. Although some studies have attempted to add antioxidants such as ascorbic acid and tea polyphenols to hydrogels, small molecule antioxidants diffuse rapidly, have short durations of action, and exhibit burst release, failing to achieve long-term protection.
[0004] Therefore, how to functionalize and modify the existing OHA / CMCS hydrogel system to simultaneously possess broad-spectrum and efficient antibacterial properties and long-lasting antioxidant properties, in order to solve the problem of single function and poor preservation effect of existing preservation materials, is a technical challenge that urgently needs to be overcome by those skilled in the art. Summary of the Invention
[0005] The purpose of this invention is to provide a hydrogel loaded with gluten bran oligopeptide GK-8, its preparation method, and its application, so as to solve the problems existing in the prior art.
[0006] To achieve the above objectives, the present invention provides the following solution:
[0007] This invention provides a hydrogel loaded with gluten oligopeptide GK-8, using oxidized hyaluronic acid and carboxymethyl chitosan dynamically cross-linked by Schiff base bonds as the gel matrix, and loading gluten oligopeptide GK-8 inside to form a ternary composite hydrogel system; the amino acid sequence of the gluten oligopeptide GK-8 is GLSFDFYK.
[0008] Preferably, the amino group on the gluten oligopeptide GK-8 is cross-linked with the aldehyde group on the oxidized hyaluronic acid through dynamic Schiff base bonds, participating in the formation of the gel network structure.
[0009] This invention also provides a method for preparing a hydrogel loaded with gluten bran oligopeptide GK-8, comprising the following steps:
[0010] Disperse bran oligopeptide GK-8 in phosphate buffer, add oxidized hyaluronic acid, stir to dissolve, and obtain an oxidized hyaluronic acid solution containing bran oligopeptide GK-8;
[0011] Carboxymethyl chitosan was dispersed in phosphate buffer and stirred to dissolve, thus obtaining a carboxymethyl chitosan solution;
[0012] The oxidized hyaluronic acid solution containing gluten oligopeptide GK-8 was mixed with the carboxymethyl chitosan solution and cross-linked to obtain the hydrogel loaded with gluten oligopeptide GK-8.
[0013] Preferably, the oxidized hyaluronic acid is prepared by the following steps: hyaluronic acid is oxidized with sodium periodate, and ethylene glycol is added to terminate the reaction after the reaction is completed. The oxidized hyaluronic acid is obtained by dialysis and freeze-drying. The mass ratio of sodium periodate to hyaluronic acid is (1-2):1.
[0014] Preferably, the dialysis bag used in the dialysis has a molecular rejection capacity of 3000 Da, the dialysis medium is deionized water, the dialysis time is 72 h to 96 h, and the water is changed 4 to 5 times a day.
[0015] Preferably, in the oxidized hyaluronic acid solution containing bran oligopeptide GK-8, the concentration of bran oligopeptide GK-8 is 0.25 mg / mL to 2 mg / mL; the mass ratio of the oxidized hyaluronic acid to the volume ratio of the phosphate buffer is (1% to 3%):1 (w / v).
[0016] Preferably, in the carboxymethyl chitosan solution, the mass ratio of carboxymethyl chitosan to the volume ratio of phosphate buffer is (1%–3%):1 (w / v).
[0017] Preferably, the volume ratio of the oxidized hyaluronic acid solution containing gluten oligopeptide GK-8 to the carboxymethyl chitosan solution is (0.5-2):1.
[0018] The present invention also provides a method for preserving fruit by using a hydrogel loaded with gluten oligopeptide GK-8 for preservation.
[0019] Preferably, the method includes the following steps: simultaneously spraying the precursor solution of the hydrogel loaded with gluten oligopeptide GK-8 onto the surface of the fruit by atomization, so that it crosslinks in situ to form a hydrogel film; the precursor solution is an independently packaged oxidized hyaluronic acid solution and a carboxymethyl chitosan solution containing gluten oligopeptide GK-8.
[0020] The present invention achieves the following beneficial technical effects compared to the prior art:
[0021] This invention provides a hydrogel loaded with gluten bran oligopeptide GK-8, its preparation method, and its applications. A novel ternary composite hydrogel system is constructed by loading the gluten bran-derived amphiphilic oligopeptide GK-8, which has a specific amino acid sequence, into a dynamic cross-linked network of oxidized hyaluronic acid and carboxymethyl chitosan. The amino groups on GK-8 form dynamic Schiff base bonds with the aldehyde groups on oxidized hyaluronic acid, participating not only in the formation of the gel network but also enabling the sustained and slow release of GK-8, thus exerting a long-lasting antioxidant effect and overcoming the short-duration effect of traditional small-molecule antioxidants. Simultaneously, thanks to the unique amphiphilic molecular structure of GK-8, it can significantly enhance the inhibitory effect of the original gel matrix on common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus, compensating for the insufficient antibacterial properties of carboxymethyl chitosan, and achieving a synergistic effect of both antibacterial and antioxidant functions. Furthermore, the hydrogel precursor solution of this invention can be rapidly cross-linked in situ on the surface of irregular fruits such as strawberries to form a thin film via atomization, which is simple to operate and highly adaptable. Experiments have shown that strawberries coated with the hydrogel of this invention have a rot rate of only 51.39% after 8 days of storage, which is much lower than the 88.89% of the control group. It can also effectively maintain the firmness of the fruit and the content of soluble solids, and significantly extend the shelf life. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 To observe the structure of the O-GK-8 / C hydrogel using scanning electron microscopy;
[0024] Figure 2 This demonstrates the self-healing ability of the O-GK-8 / C hydrogel.
[0025] Figure 3 Rheological analysis of O-GK-8 / C hydrogel using alternating step strain scanning;
[0026] Figure 4 The antibacterial effect of O-GK-8 / C hydrogel on Escherichia coli and Staphylococcus aureus;
[0027] Figure 5 The scavenging rate of the hydrogel against ABTS free radicals;
[0028] Figure 6 Images showing the changes in appearance and freshness of strawberries over a 6-day storage period;
[0029] Figure 7 Statistics on the rot rate of strawberries during an 8-day storage period;
[0030] Figure 8 The changes in weight loss of strawberries during an 8-day storage period;
[0031] Figure 9 Changes in the firmness of strawberries during an 8-day storage period;
[0032] Figure 10 The change in total soluble solids (TSS) content of strawberries during an 8-day storage period. Detailed Implementation
[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0034] The purpose of this invention is to provide a hydrogel loaded with gluten bran oligopeptide GK-8, its preparation method, and its application, in order to solve the problems existing in the prior art.
[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0036] In this embodiment of the invention, unless otherwise specified, all raw materials and reagents used are commercially available products in the art. The phosphate-buffered saline (PBS) is a standard PBS buffer with pH 7.4 and a strength of 0.01 M. The amino acid sequence of the gluten bran oligopeptide GK-8 is derived from a published Chinese invention patent (CN202411247054.8). GK-8 was synthesized using a solid-phase polypeptide synthesis method (Fmoc method), purified by high-performance liquid chromatography (HPLC), and its molecular weight was detected by mass spectrometry (MS). The measured molecular weight results were consistent with the theoretical molecular weight. The purity of the HPLC chromatogram was greater than 98%, and the MS chromatogram showed that the m / z peak of [M+2H]2+ was 489.0, and its molecular weight was calculated to be 976.0, which is consistent with the theoretical molecular weight. This confirms that the chemical structure of the oligopeptide GK-8 is correct, and the amino acid sequence is: GLSFDFYK.
[0037] Example 1
[0038] A method for preparing a hydrogel loaded with gluten bran oligopeptide GK-8 specifically includes the following steps:
[0039] (1) Preparation of oxidized hyaluronic acid (OHA): Weigh 1 g of hyaluronic acid (HA) and dissolve it in 100 mL of deionized water. Stir thoroughly until it is completely dissolved. Then slowly add 15 mL of 0.1 g / mL sodium periodate aqueous solution. After the addition is complete, react at room temperature in the dark for 10 h. Then add 1 mL of ethylene glycol and continue stirring for 30 min to terminate the reaction. After the reaction is complete, transfer the solution to a 3000 Da dialysis bag and dialyze in the dark for 72 h, changing the water 5 times a day. After the dialysis is complete, freeze-dry the solution to obtain white foamy sponge-like OHA solid.
[0040] (2) Preparation of OHA solution containing GK-8: Weigh 25 mg of GK-8 powder and dissolve it in 50 mL of PBS. Stir thoroughly until completely dissolved, then add 1 g of the prepared OHA and stir thoroughly until completely dissolved to obtain OHA solution containing GK-8. The concentration of GK-8 in the system is 0.5 mg / mL, and the mass ratio of OHA to the volume of the PBS solution containing oligopeptide GK-8 is 2% (w / v).
[0041] (3) Preparation of CMCS solution: Weigh 1 g of carboxymethyl chitosan (CMCS) powder and dissolve it in 50 mL of PBS. Stir thoroughly to dissolve completely to obtain CMCS solution. The mass ratio of CMCS to PBS is 2% (w / v).
[0042] (4) The prepared OHA solution containing GK-8 was mixed with the CMCS solution at a volume ratio of 1:1 to obtain a hydrogel loaded with gluten oligopeptide GK-8, denoted as O-GK-8 / C.
[0043] The O-GK-8 / C prepared in this embodiment was freeze-dried, and the hydrogel sample was vertically cut open, its surface was sputtered with gold, and its cross-sectional morphology was observed by high-magnification scanning electron microscopy (SEM). The results are as follows. Figure 1 As shown in the figure, the hydrogel has a continuous and uniform three-dimensional porous network structure with a pore size of approximately 100 μm.
[0044] Self-healing performance testing of hydrogels: Two methods were used to evaluate the self-healing performance of hydrogels: direct macroscopic observation and rotational rheology. For direct macroscopic observation, hydrogels stained with Rhodamine B and methylene blue were prepared separately. The two colored hydrogels were cut in half with a scalpel, and then placed together to observe the healing process, which was recorded using a camera. Figure 2 As shown, it can be observed that O-GK-8 / C hydrogels of different colors can reform into a complete hydrogel within 10 minutes after contact, and do not break upon removal, indicating that the hydrogel has good self-healing ability. Rotational rheometer testing was conducted using an alternating step strain scanning experiment with a constant frequency of 10 Hz, where the strain switched from 1% to 500% at approximately 100-second intervals, to evaluate the self-healing properties of the hydrogel. The results are as follows... Figure 3 As shown, the storage modulus of the hydrogel under 1% low strain is higher than its loss modulus, indicating a complete gel state. Under 500% high strain, the loss modulus is higher than the storage modulus, indicating that the hydrogel network structure is disrupted. When the strain is switched to 1%, the hydrogel recovers to a state where the storage modulus is higher than the loss modulus. After three cycles of alternating high and low strains, the hydrogel can still recover to a gel state where the storage modulus is higher than the loss modulus, demonstrating its excellent self-healing and repair capabilities. It can form a complete hydrogel film on irregular planes, meeting the requirements of fruit preservation scenarios.
[0045] Example 2
[0046] A method for preparing a hydrogel loaded with gluten bran oligopeptide GK-8 specifically includes the following steps:
[0047] (1) Preparation of OHA: Same as step (1) in Example 1.
[0048] (2) Preparation of OHA solutions containing different concentrations of GK-8: Weigh 100 mg of GK-8 powder and dissolve it in 50 mL of PBS. Stir thoroughly to ensure complete dissolution. Then, take the dissolved solution and dilute it with PBS in a gradient manner. Including the mother solution, GK-8 solutions with concentrations of 0.25 mg / mL, 0.5 mg / mL, 1 mg / mL, 1.5 mg / mL and 2 mg / mL were finally prepared. The prepared OHA was added to each solution and stirred thoroughly to ensure complete dissolution. The mass ratio of OHA to the volume of the PBS solution containing GK-8 was 2% (w / v).
[0049] (3) Preparation of CMCS solution: Same as step (3) in Example 1.
[0050] (4) The prepared OHA solutions containing different concentrations of GK-8 were mixed with CMCS solutions at a volume ratio of 1:1 to obtain hydrogels O-GK-8 / C loaded with gluten oligopeptide GK-8. The GK-8 content in the gel system was 0.125 mg / mL, 0.25 mg / mL, 0.5 mg / mL, 0.75 mg / mL and 1 mg / mL, respectively.
[0051] Choose Escherichia coli ( E. coli Gram-negative bacteria) and Staphylococcus aureus ( S.aureus The antibacterial properties of hydrogels were evaluated using a plate count method for two typical bacteria (GK-8 and Gram-positive bacteria). The specific steps were as follows: *Escherichia coli* strains were passaged in LB medium and enriched by shaking at 220 rpm and 37°C for 14 h. Hydrogels with different GK-8 contents prepared under aseptic conditions were added to LB liquid medium at a volume ratio of 1:10. The enriched *E. coli* suspension was then added to LB liquid medium containing the hydrogel at a volume ratio of 1:100. The medium was incubated at 220 rpm and 37°C for 12 h. The incubated suspensions were then diluted by the same factor, and 100 μL of each diluted suspension was spread onto solid plates. The plates were incubated at 37°C for 12 h. Afterward, the colonies on the plates were observed, photographed, and counted. The evaluation procedure for *Staphylococcus aureus* was the same. Figure 4 The corresponding plate colony diagrams and calculated colony counts are shown. The results indicate that the hydrogel exhibits the most significant antibacterial performance when the content of the wheat bran oligopeptide GK-8 is 0.25 mg / mL. The antibacterial effect gradually decreases with increasing concentration. This may be due to the amphiphilic nature of the oligopeptide GK-8; as the concentration increases, the amphiphilic oligopeptide GK-8 more easily forms aggregates, thus masking the enhanced antibacterial activity against CMCS. Therefore, 0.25 mg / mL was selected as the optimal GK-8 concentration for subsequent applications.
[0052] Example 3
[0053] In this embodiment, the preparation method of the hydrogel loaded with gluten oligopeptide GK-8 is the same as in Example 1 (final concentration of GK-8: 0.25 mg / mL).
[0054] In this embodiment, the antioxidant capacity of the hydrogel loaded with gluten oligopeptide GK-8 was evaluated using the ABTS free radical scavenging experiment. An O / C hydrogel without GK-8 was used as a comparison. The preparation method of the O / C hydrogel without GK-8 specifically includes the following steps: (1) Preparation of OHA: Same as step (1) in Example 1; (2) Preparation of OHA solution: Weigh 1 g of the prepared OHA and dissolve it in 50 mL of PBS and stir thoroughly until it is completely dissolved. The mass ratio of OHA to PBS is 2% (w / v); (3) Preparation of CMCS solution: Same as step (3) in Example 1; (4) Mix the prepared OHA solution and CMCS solution at a volume ratio of 1:1 to obtain the O / C hydrogel.
[0055] The specific steps of the ABTS free radical scavenging experiment are as follows: Prepare a 7 mM ABTS solution and a 2.5 mM potassium persulfate solution. Mix these two solutions in equal volumes and react in the dark for 12–14 h. Dilute with anhydrous ethanol to obtain an absorbance of 0.70 ± 0.02 at 734 nm, thus preparing the ABTS working solution. Incubate 600 μL of different hydrogels with 6 mL of the ABTS working solution at room temperature in the dark. Simultaneously, incubate 600 μL of GK-8 (0.25 mg / mL) with 6 mL of the ABTS working solution under the same conditions. Measure the absorbance of the ABTS supernatant at 734 nm after different incubation times using a multi-factor microplate detection system. The ABTS working solution alone serves as a blank control group. Figure 5 The results of the ABTS radical scavenging rate of the hydrogel over time showed that the GK-8 solution group had a significant ABTS radical scavenging ability, rapidly scavenging free radicals in the early stage of the reaction, and then the reaction slowed down until it stopped. The ABTS radical scavenging rate of hydrogels O-GK-8 / C with the same amount of GK-8 and O / C hydrogel without added GK-8 increased with the increase of incubation time. Moreover, the free radical scavenging rate of hydrogel O-GK-8 / C increased faster and the scavenging effect was stronger than that of O / C. The scavenging rate of O-GK-8 / C hydrogel was not as high as that of GK-8 solution of the same concentration in the early stage of the reaction, but the free radical scavenging rate was higher than that of GK-8 solution at 3 h as the time extended. This indicates that GK-8 can achieve continuous and slow release after being loaded into hydrogel, and has long-term antioxidant capacity.
[0056] Example 4
[0057] In this embodiment, strawberries were coated with a hydrogel loaded with gluten oligopeptide GK-8 to evaluate the preservation effect of the hydrogel on strawberries. The preliminary steps for preparing the hydrogel loaded with gluten oligopeptide GK-8 were the same as steps (1), (2), (3), and (4) in Example 1. The OHA solution containing GK-8 and the CMCS solution were placed in two hand-operated spray bottles, respectively. The spray pump was pressed to spray the solutions in both spray bottles onto the surface of the strawberries simultaneously, so that the two solutions crosslinked in situ on the surface of the strawberries to form a hydrogel film. The number of times the spray pumps were pressed was consistent to control the crosslinking of the OHA solution containing gluten oligopeptide GK-8 and the CMCS solution at a volume ratio of 1:1. After the hydrogel film was formed and stabilized, the strawberries coated with the hydrogel loaded with gluten oligopeptide GK-8 were placed in a fume hood and air-dried for 1 hour to control the water content of the gel, so as to avoid the strawberry surface absorbing water for a long time due to excessive water content, which would cause hydration damage to the strawberry skin and accelerate decay and spoilage. During the wrapping process, the storage status of the strawberries was photographed at different time points. Based on the area of rot on the fruit surface, the strawberries were divided into five rot levels: 0, no rot; 1, 0 < rot rate < 25%; 2, 25% ≤ rot rate < 50%; 3, 50% ≤ rot rate < 75%; 4, 75% ≤ rot rate ≤ 100%. The change in rot rate of the strawberries during storage was calculated based on the rot level. Simultaneously, changes in the weight, firmness, and total soluble solids (TSS) of the wrapped strawberries were measured during storage, with untreated strawberries serving as a control group.
[0058] like Figure 6 The changes in appearance and freshness of strawberries observed during storage showed that on the second day of storage, a few strawberries in the control group exhibited small areas of softening skin. On the fourth day of storage, the strawberries in the control group showed obvious mold growth, which gradually worsened thereafter, with most strawberries softening and shrivelding. The hydrogel group loaded with gluten oligopeptide GK-8 showed mold growth on the fourth day of storage, while the remaining strawberries maintained good texture. The rot rate statistics showed (…). Figure 7 On the second day of storage, strawberries in the control group began to rot, and the rot rate increased rapidly thereafter, reaching a maximum of 88.89% on the eighth day. In contrast, the rot rate in the hydrogel group loaded with gluten oligopeptide GK-8 increased slowly from the third day of storage, reaching only 51.39% on the eighth day. This indicates that the hydrogel effectively slowed down the rot process of strawberries and extended their shelf life.
[0059] like Figure 8 The results of weight loss changes in strawberries during 8 days of storage showed that the control group experienced a weight loss rate of 53.97% after 8 days of storage. In contrast, the hydrogel group loaded with gluten oligopeptide GK-8 experienced a weight loss rate of only 30.80% after 8 days of storage. This is likely because the hydrogel provided a stable humidity environment, slowing down the evaporation and loss of moisture from the strawberries. Furthermore, it effectively protected the integrity of the strawberries through its antioxidant and antibacterial effects, thus significantly reducing the weight loss rate.
[0060] In this embodiment, a texture analyzer was used to assess the firmness of strawberries. A P / 2 type probe with a diameter of 2 mm was used, with a trigger force of 0.05 N. The probe was slowly inserted into each strawberry at a speed of 1 mm / s, and the puncture distance was set to 15 mm. Figure 9 To investigate the changes in strawberry firmness during 8 days of storage, the firmness of strawberries in different groups gradually decreased during storage. These changes were mainly related to the degradation of nutrients (polysaccharides and proteins) and cell wall pectin. The hydrogel loaded with gluten oligopeptide GK-8 effectively maintained the firmness of the strawberries during storage. After 8 days, the firmness of strawberries in the control group decreased from 2.21 N to 0.79 N, while the firmness of strawberries in the gluten oligopeptide GK-8-loaded hydrogel group decreased to 1.02 N. This hydrogel effectively delayed the change in strawberry firmness during storage.
[0061] This embodiment uses a refractometer to measure and evaluate the total soluble solids (TSS) of strawberries. Strawberry juice is dropped onto the sample cell of the refractometer to detect TSS. During fruit storage, respiration causes TSS to accumulate continuously until full ripeness. In the early stages of storage, the TSS content increases significantly due to the hydrolysis of polysaccharides into monosaccharides and other soluble compounds. However, with prolonged storage, respiration and hydrolysis in strawberries consume large amounts of sugars and organic acids, leading to gradual fruit aging and a subsequent decrease in TSS content. Figure 10 To illustrate the changes in TSS content in strawberries during 8 days of storage, the TSS content in strawberries from different treatment groups showed a trend of first increasing and then decreasing. In the control group, polysaccharides may have been largely hydrolyzed into monosaccharides in the early stages of storage, resulting in a rapid increase in TSS content followed by a rapid decrease due to respiration. In contrast, the TSS content in the hydrogel group showed a trend of slow increase and slow decrease, indicating that the hydrogel loaded with gluten oligopeptide GK-8 can slow down fruit ripening and maintain fruit quality.
[0062] This invention has illustrated its principles and implementation methods using specific examples. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the principles of this invention. Therefore, the content of this specification should not be construed as limiting the invention.
Claims
1. A hydrogel loaded with gluten bran oligopeptide GK-8, characterized in that, A ternary composite hydrogel system was formed by using oxidized hyaluronic acid and carboxymethyl chitosan, which are dynamically cross-linked by Schiff base bonds, as the gel matrix and loaded with gluten oligopeptide GK-8. The amino acid sequence of the gluten oligopeptide GK-8 is GLSFDFYK.
2. The hydrogel loaded with gluten bran oligopeptide GK-8 according to claim 1, characterized in that, The amino groups on the gluten oligopeptide GK-8 and the aldehyde groups on the oxidized hyaluronic acid are cross-linked through dynamic Schiff base bonds, participating in the formation of the gel network structure.
3. A method for preparing a hydrogel loaded with gluten bran oligopeptide GK-8 as described in claim 1 or 2, characterized in that, Includes the following steps: Disperse bran oligopeptide GK-8 in phosphate buffer, add oxidized hyaluronic acid, stir to dissolve, and obtain an oxidized hyaluronic acid solution containing bran oligopeptide GK-8; Carboxymethyl chitosan was dispersed in phosphate buffer and stirred to dissolve, thus obtaining a carboxymethyl chitosan solution; The oxidized hyaluronic acid solution containing gluten oligopeptide GK-8 was mixed with the carboxymethyl chitosan solution and cross-linked to obtain the hydrogel loaded with gluten oligopeptide GK-8.
4. The method for preparing the hydrogel loaded with gluten bran oligopeptide GK-8 according to claim 3, characterized in that, The oxidized hyaluronic acid is prepared by the following steps: hyaluronic acid is oxidized with sodium periodate, and ethylene glycol is added to terminate the reaction after the reaction is completed. After dialysis and freeze-drying, oxidized hyaluronic acid is obtained; the mass ratio of sodium periodate to hyaluronic acid is (1-2):
1.
5. The method for preparing the hydrogel loaded with gluten bran oligopeptide GK-8 according to claim 4, characterized in that, The dialysis bag used has a molecular weight cutoff of 3000 Da, the dialysis medium is deionized water, the dialysis time is 72 h to 96 h, and the water is changed 4 to 5 times a day.
6. The method for preparing the hydrogel loaded with gluten bran oligopeptide GK-8 according to claim 3, characterized in that, In the oxidized hyaluronic acid solution containing bran oligopeptide GK-8, the concentration of bran oligopeptide GK-8 is 0.25 mg / mL to 2 mg / mL; the mass ratio of the oxidized hyaluronic acid to the volume ratio of the phosphate buffer is (1% to 3%):1 (w / v).
7. The method for preparing the hydrogel loaded with gluten bran oligopeptide GK-8 according to claim 3, characterized in that, In the oxidized hyaluronic acid solution containing bran oligopeptide GK-8, the concentration of bran oligopeptide GK-8 is 0.25 mg / mL to 2 mg / mL; the mass ratio of the oxidized hyaluronic acid to the volume ratio of the phosphate buffer is (1% to 3%):1 (w / v).
8. The method for preparing the hydrogel loaded with gluten bran oligopeptide GK-8 according to claim 3, characterized in that, The volume ratio of the oxidized hyaluronic acid solution containing gluten oligopeptide GK-8 to the carboxymethyl chitosan solution is (0.5-2):
1.
9. A method for preserving fruit, characterized in that, Preservation is performed using the hydrogel loaded with gluten oligopeptide GK-8 as described in claim 1 or 2.
10. The fruit preservation method according to claim 9, characterized in that, Includes the following steps: The precursor solution of the hydrogel loaded with gluten oligopeptide GK-8 was simultaneously sprayed onto the surface of the fruit by atomization, so that it crosslinked in situ to form a hydrogel film; the precursor solution was an oxidized hyaluronic acid solution and a carboxymethyl chitosan solution containing gluten oligopeptide GK-8, which were separately packaged.