Preparation method and application of silver carp skin collagen-based antibacterial antioxidant active coating

Abstract

The invention discloses a preparation method and application of a silver carp skin collagen-based antibacterial active coating. The silver carp skin collagen-based antibacterial and antioxidant active coating is prepared from the following raw materials: collagen, epsilon-polylysine, carvacrol, sulfobutyl-beta-cyclodextrin and ultrapure water; wherein the stoichiometric ratio of the sulfobutyl-beta-cyclodextrin to the epsilon-polylysine is 40: 1, and the mass ratio of the sulfobutyl-beta-cyclodextrin to the carvacrol is 2: 1. The silver carp skin collagen is used as a coating substrate, and the natural antibacterial peptide epsilon-polylysine and the plant essential oil carvacrol play a synergistic antibacterial role. In addition, the epsilon-polylysine and the sulfobutyl-beta-cyclodextrin are crosslinked through electrostatic interaction. The silver carp skin collagen-based antibacterial antioxidant active coating prepared by the invention does not contain a reagent toxic to a human body, is high in safety, and has a good coating preservation effect on fresh fish balls. In addition, the method is simple in technological process and can be easily applied to the field of aquatic food preservation.

Description

Technical Field

[0001] The invention belongs to the field of aquatic product preservation, and particularly relates to a preparation method and application of a silver carp skin collagen-based antibacterial and antioxidant active coating. Background Art

[0002] In daily life, food is often contaminated by pathogenic microorganisms, leading to food waste, economic losses, and the risk of foodborne diseases. Although antibiotics are widely used to inhibit or kill pathogens, the problem of drug resistance is becoming increasingly serious. Approximately 700,000 people die each year worldwide from antibiotic-resistant infections.

[0003] Collagen is a non-toxic, biodegradable natural biomacromolecule with strong film-forming and UV-blocking properties. Due to its high safety, wide availability, and ability to serve as a carrier for active additives, collagen is an effective alternative to plastic packaging materials. ε-Polylysine is widely used in the food industry due to its unique structure and excellent properties, specifically removing endotoxins and reducing the activity of related enzymes. Carvacrol, a major component of oregano and thyme essential oils, possesses broad-spectrum antimicrobial properties as well as anti-inflammatory, anticancer, and antioxidant activities. However, its limited water solubility, low stability, and volatility limit its application in food preservation and storage.

[0004] Therefore, the development of packaging materials with antibacterial and antioxidant activities and that can be naturally degraded has important market prospects. Summary of the Invention

[0005] The present invention aims to provide a collagen-based active coating with simple preparation processes and antimicrobial and antioxidant properties, which can be used to preserve fresh fish balls. The coating's raw materials include fish collagen, the natural antimicrobial peptide ε-polylysine, the plant essential oil carvacrol, sulfobutyl-β-cyclodextrin, and ultrapure water. The coating has a stoichiometric ratio of sulfobutyl-β-cyclodextrin to ε-polylysine of 40:1, and a mass ratio of sulfobutyl-β-cyclodextrin to carvacrol of 2:1. The coating effectively inhibits microbial proliferation and oxidative spoilage reactions in aquatic products.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A silver carp skin collagen-based antibacterial and antioxidant active coating is prepared from the following raw materials: silver carp skin collagen, sulfobutyl-β-cyclodextrin, natural antibacterial peptide ε-polylysine, and plant essential oil carvacrol; wherein the stoichiometric ratio of sulfobutyl-β-cyclodextrin to ε-polylysine is 40:1, the mass ratio of sulfobutyl-β-cyclodextrin to carvacrol is 2:1, and the silver carp skin collagen content is 2%.

[0007] The method for producing the silver carp skin collagen-based antibacterial and antioxidant active coating comprises the following steps: (1) dissolving sulfobutyl-β-cyclodextrin and carvacrol in ultrapure water and adjusting the pH to 4 to obtain a sulfobutyl-β-cyclodextrin / carvacrol pre-solution; (2) dissolving ε-polylysine in ultrapure water and adjusting the pH to 5 to obtain an ε-polylysine solution; (3) The solutions obtained in step (1) and step (2) were mixed and placed in a constant temperature magnetic stirring water bath, and stirred to obtain an ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol active solution; (4) Adding silver carp skin collagen to the ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol active coating solution obtained in step (3) and stirring to fully dissolve the silver carp skin collagen to obtain the silver carp skin collagen-based antibacterial active coating solution.

[0008] Furthermore, the stirring conditions in step (3) are 50° C., 700 rpm, and the stirring time is 4 to 6 h.

[0009] Furthermore, the stirring conditions in step (4) are 50° C., 700 rpm, and the stirring time is 10 to 20 min.

[0010] The present invention also provides the use of the aforementioned silver carp skin collagen-based antibacterial active coating in the preservation of aquatic food, wherein the aquatic food is fresh fish balls. The specific operation steps are as follows: Soak the fresh fish balls in the silver carp skin collagen-based antibacterial and antioxidant active coating solution for 3 minutes, then take them out, dry them, and store them in a refrigerator at a temperature of 4°C.

[0011] The significant advantages of the present invention are: (1) The silver carp skin collagen-based antibacterial and antioxidant active coating of the present invention uses sulfobutyl-β-cyclodextrin as an intermediate to co-load carvacrol and ε-polylysine, which can effectively improve its bioavailability. It also has the advantages of high stability, biocompatibility, and easy preparation and modification. Silver carp skin collagen is used as the coating matrix, and a synergistic antibacterial effect is exerted through the natural antimicrobial peptide ε-polylysine and the plant essential oil carvacrol. ε-Polylysine and sulfobutyl-β-cyclodextrin are cross-linked through electrostatic interactions. The prepared coating does not contain toxic reagents and is highly safe. The coating raw materials are all biodegradable. (2) The silver carp skin collagen-based antibacterial and antioxidant active coating of the present invention can effectively reduce the proliferation rate of microorganisms and lipid oxidation in fresh fish balls, so that the fish balls remain fresh throughout the entire shelf life; (3) The preparation process of the silver carp skin collagen-based antibacterial and antioxidant active coating of the present invention is simple and can be easily applied to the field of aquatic food preservation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a graph showing the change trend of total colony count in fresh fish balls at 4°C over time.

[0013] Figure 2 This is a graph showing the change trend of TVB-N content in fresh fish balls at 4°C over time. DETAILED DESCRIPTION

[0014] To facilitate understanding of the present invention, the technical solutions of the present invention are further described below in conjunction with specific embodiments. Examples 1 and 2 describe in detail the specific amounts and preparation steps of sulfobutyl-β-cyclodextrin, carvacrol, ε-polylysine, and fish collagen, as well as the preparation methods of Comparative Examples 1 and 2.

[0015] Example 1 (1) Dissolve 0.675 g of sulfobutyl-β-cyclodextrin and 0.337 g of carvacrol in 250 ml of ultrapure water, and adjust the pH of the solution to pH 4 using 1 M HCl to obtain a sulfobutyl-β-cyclodextrin / carvacrol pre-solution; (2) Dissolve 0.062 g of ε-polylysine in 250 ml of ultrapure water and adjust the pH of the solution to pH 5 with 1 M HCl to obtain an ε-polylysine solution.

[0016] (3) The solutions obtained in step (1) and step (2) were mixed and placed in a constant temperature magnetic stirring water bath, and stirred at 50°C and 700 RPM for 5 h to obtain an ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol active coating solution.

[0017] (4) Add 20 g of silver carp skin collagen to the ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol active coating solution obtained in step (3), and continue stirring at 50°C and 700 RPM for 15 min to fully dissolve the silver carp skin collagen, thereby obtaining the silver carp skin collagen-based antibacterial and antioxidant active coating solution (GL-PL / SBE / CAR-L), wherein the silver carp skin collagen content is 2%.

[0018] Example 2 (1) Dissolve 1.35 g of sulfobutyl-β-cyclodextrin and 0.674 g of carvacrol in 250 ml of ultrapure water, and adjust the pH of the solution to pH 4 with 1 M HCl to obtain a sulfobutyl-β-cyclodextrin / carvacrol pre-solution; (2) Dissolve 0.124 g of ε-polylysine in 250 ml of UP aqueous solution and adjust the pH of the solution to pH 5 with 1 M HCl to obtain an ε-polylysine solution.

[0019] (3) The solutions obtained in step (1) and step (2) were mixed and placed in a constant temperature magnetic stirring water bath, and stirred at 50°C and 700 RPM for 5 h to obtain an ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol active coating solution.

[0020] (4) Add 20 g of silver carp skin collagen to the ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol active coating solution obtained in step (3), and continue stirring at 50°C and 700 RPM for 15 min to fully dissolve the silver carp skin collagen, thereby obtaining the silver carp skin collagen-based antibacterial and antioxidant active coating solution (GL-PL / SBE / CAR-H), wherein the silver carp skin collagen content is 2%.

[0021] Comparative Example 1 500 mL of ultrapure water.

[0022] Comparative Example 2 Weigh 20 g of silver carp skin collagen and add it to 500 ml of ultrapure water. Stir at 50°C and 700 RPM for 15 min to fully dissolve the silver carp skin collagen to obtain a collagen coating solution (GL).

[0023] Application Example 1 Fresh fish balls preservation effect test: The fish balls were divided into groups and soaked in different active coating solutions (Examples 1-2 and Comparative Examples 1-2) for 3 minutes. During the soaking process, the fish balls were stirred continuously to ensure that the surface of the fish balls was fully in contact with the active coating solution. Finally, the fish balls were removed and placed flat in a sterile packaging box and stored in a refrigerator at 4°C. During the storage period, samples were taken at specific time points for analysis to determine the number of microorganisms in the fish balls ( Figure 1 ), TVB-N ( Figure 2 ) changes over time. Fresh fish balls treated with a blank pure water solution served as control group 1 (Water); fresh fish balls treated with a collagen coating solution served as control group 2 (GL).

[0024] from Figure 1 It can be seen that after 16 hours, the total bacterial count (TVC) of the GL group increased the fastest (P≤0.05). This is mainly because the fish ball samples were not protected by antimicrobial active substances and the bacteria in the fish balls themselves were encapsulated, making them very suitable for microbial reproduction. By the 16th day, the TVC of the GL group reached 6.25 log 10 cfu·g −1 , exceeding the acceptable limit of 6.0log for fish ball products 10 cfu·g −1. In contrast, the surface of the fish balls was coated with a collagen-based antibacterial and antioxidant active protective layer, which could isolate some environmental microorganisms. At the same time, ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol had a strong antibacterial ability, and the TVC values ​​of the GL-PL / SBE / CAR-L group and the GL-PL / SBE / CAR-H group were smaller. In addition, it can be seen that as the content of ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol increased, the TVC also decreased significantly (P≤0.05). This shows that the addition of a collagen-based coating can effectively inhibit the proliferation of microorganisms and achieve the effect of long-term preservation of fish balls.

[0025] TVB-N is an important reference indicator for measuring whether fish balls have become corrupted. Its main components are ethylamine, trimethylamine, dimethylamine and ammonia. Figure 2 The initial TVB-N content of fresh fish balls was 3.41 mg / 100 g, indicating high quality and freshness. The TVB-N content in the Water and GL groups increased slowly during the early stages of storage, but increased dramatically after the fourth day, with the magnitude of increase significantly higher than that in the active coating preservation group (P ≤ 0.05). During the fish ball production process, surimi undergoes multiple washes with water, resulting in significant removal of water-soluble components, including TVB precursors. Therefore, the TVB-N content limit in surimi products should be lower than that in whole fish. The TVB-N content in the Water group reached 34.32 mg / 100 g by day 8, exceeding the acceptable threshold of 30 mg / 100 g for fish preservation. The TVB-N concentration in the GL group reached 36.89 mg / 100 g on day 12. While significantly lower than that in the Water group (P ≤ 0.05), it still exceeded the acceptable threshold of 30 mg / 100 g for fish meat preservation. At the end of storage, TVB-N values ​​reached 101.47 mg / 100 g in the Water group and 56.81 mg / 100 g in the GL group, indicating significant deterioration of the fish balls. In contrast, the TVB-N values ​​of the fish balls in the GL-PL / SBE / CAR-L and GL-PL / SBE / CAR-H groups changed little during storage, indicating that the fish balls had not deteriorated, remained fresh, and maintained good freshness.

[0026] The above are only some implementation examples of the present invention. Any changes and modifications made within the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A silver carp skin collagen-based antibacterial and antioxidant active coating, characterized by: The silver carp skin collagen-based antibacterial and antioxidant active coating is made from the following raw materials: silver carp skin collagen, sulfobutyl-β-cyclodextrin, natural antibacterial peptide ε-polylysine and plant essential oil carvacrol; wherein the stoichiometric ratio of sulfobutyl-β-cyclodextrin to ε-polylysine is 40:1, the mass ratio of sulfobutyl-β-cyclodextrin to carvacrol is 2:1, and the silver carp skin collagen content is 2%.

2. A method for preparing the silver carp skin collagen-based antibacterial and antioxidant active coating according to claim 1, characterized in that: The following steps are involved: (1) dissolving sulfobutyl-β-cyclodextrin and carvacrol in ultrapure water and adjusting the pH to 4 to obtain a sulfobutyl-β-cyclodextrin / carvacrol pre-solution; (2) dissolving ε-polylysine in ultrapure water and adjusting the pH to 5 to obtain an ε-polylysine solution; (3) The solutions obtained in step (1) and step (2) were mixed and placed in a constant temperature magnetic stirring water bath, and stirred to obtain an ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol active solution; (4) Adding silver carp skin collagen to the ε-polylysine / sulfobutyl-β-cyclodextrin / carvacrol active coating solution obtained in step (3) and stirring to fully dissolve the silver carp skin collagen to obtain the silver carp skin collagen-based antibacterial active coating solution.

3. The method according to claim 2, wherein: The stirring conditions in step (3) are 50°C, 700 rpm, and the stirring time is 4 to 6 hours.

4. The method according to claim 2, wherein: The stirring conditions in step (4) are 50°C, 700 rpm, and the stirring time is 10-20 min.

5. Use of the silver carp skin collagen-based antibacterial active coating according to claim 1 in the preservation of aquatic food.

6. The use according to claim 5, characterized in that: The aquatic food is fresh fish balls.

7. The use according to claim 5, characterized in that: Soak the fresh fish balls in the silver carp skin collagen-based antibacterial and antioxidant active coating solution for 3 minutes, then take them out, dry them, and store them in a refrigerator at a temperature of 4°C.

Images