Application of self-assembly bio-based composite preservative film and film-covering preservation method of leiocassis longirostris

Abstract

The invention discloses an application of a self-assembled bio-based composite preservative film and a film-covering preservation method of leiocassis longirostris, and relates to the field of aquatic product processing and preservation. According to the method, fresh and alive leiocassis longirostris is used as a raw material, is pre-treated, is wrapped by a composite coating, and is placed in a refrigerator at 4 DEG C for refrigeration. According to the method disclosed by the invention, a green composite coating is applied, and the coating has excellent antibacterial and antioxidant effects. In addition, compared with a non-degradable plastic preservative film, the bio-based composite coating is easier to accept by consumers due to the characteristics of safety and no pollution.

Description

Technical Field

[0001] This invention relates to the application of a self-assembled bio-based composite preservation film and a method for preserving catfish by coating. Background Technology

[0002] Prepared foods are highly susceptible to microbial contamination and spoilage during transportation and storage. This is particularly true for aquatic products, which are high in moisture and protein, where deterioration due to fat oxidation and protein degradation is especially prevalent. my country is a major producer and exporter of aquatic products, ranking first in the world for many years. However, the spoilage of aquatic products during storage and transportation not only causes significant economic losses but also severely restricts the further development of the aquatic product industry. Therefore, researching an effective method for preserving aquatic products is of paramount importance.

[0003] Existing preservation methods include refrigeration, freezing, modified atmosphere packaging, and ultra-high pressure (UAP). Compared to heat sterilization, room temperature and low temperature processing conditions can maximize the preservation of the original nutritional value and flavor of aquatic products. However, vacuum, modified atmosphere packaging, and UAP preservation methods have high equipment requirements, and hydroxyl radicals generated by irradiation can accelerate the oxidation of aquatic products. Therefore, researching an efficient, convenient, and environmentally friendly preservation method is particularly important. Film coating is an effective solution, typically involving covering the food surface with a protective film to delay oxidation, moisture evaporation, and microbial growth, thereby extending shelf life. Compared to non-degradable plastic films, biocompatible and sustainable bio-based coatings are increasingly attracting research attention. Bio-based coatings can be categorized into single coatings (polysaccharide-based coatings, protein-based coatings, lipid coatings) and composite coatings. Single coatings suffer from poor mechanical properties and weak barrier properties. However, researchers have found that multi-component blended composite coatings with added antibacterial and antioxidant agents can effectively improve the shortcomings of single coatings. Furthermore, it can delay the spoilage of aquatic products and extend their shelf life. Chen et al. prepared a gelatin composite coating using gelatin, sodium alginate, and polylactic acid, which enhanced the barrier and antibacterial properties of the coating. Meanwhile, during storage, the gelatin composite coating effectively inhibited the degradation of sea bass protein and lipid oxidation (CHEN JW, LI YX, WANG YF, et al. Food packaging and shelf life, 2022, 33: 100915). Liu et al. prepared a composite coating with a dense structure and smooth surface morphology using gelatin, chitosan, and thyme essential oil. In addition, the composite coating can inhibit microbial proliferation by interfering with carbohydrate, nitrogen, and nucleotide metabolism, thus maintaining the quality of golden pomfret meat (LIU Y, KAI Y, YANG H S. Food packaging and shelf life, 2023, 36: 101046). Xiao et al. developed a smart composite coating based on polyvinyl alcohol, chitosan, and curcumin. This coating improved the overall performance of the coating and extended the shelf life of fish, enabling real-time monitoring of the freshness of the fish. The degree of spoilage of the fish was determined by changes in the color of the coating (XIAO ZK, LIU CY, RONG XY, et al. International journal of biological macromolecules, 2023, 253: 127343). Summary of the Invention

[0004] The purpose of this invention is to provide an application of a self-assembled bio-based composite preservation film and a method for preserving catfish by coating.

[0005] The technical solution for achieving the objective of this invention is as follows:

[0006] Using water as a solvent, the ingredients are, by weight, 2000-4000 parts gelatin, 200-400 parts glycerol, and 200-400 parts active nanoparticles.

[0007] The method for preserving catfish according to the present invention includes the following steps:

[0008] (1) Select fresh, live catfish with intact parts and appropriate size for later use;

[0009] (2) Remove the head, tail, skin, and internal organs from the fresh catfish;

[0010] (3) Rinse the prepared catfish with sterile water and cut it into fish pieces of appropriate size;

[0011] (4) After coating the fish pieces with the UV sterilization coating, place them in the refrigerator.

[0012] Preferably, the fish pieces are approximately 3cm × 3cm × 2cm in size.

[0013] Preferably, the coating is subjected to ultraviolet irradiation for 30 minutes.

[0014] Preferably, the fish fillets are refrigerated at a temperature of 4°C.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) This invention can significantly reduce the proliferation of microorganisms in catfish meat during storage: compared with the control group, after 12 days of storage, the proliferation of microorganisms in the fish meat coated with the composite coating was inhibited. The total number of colonies and the number of psychrophilic bacteria decreased by 31.2% and 23.6%, respectively.

[0017] (2) This invention can significantly delay protein decomposition and lipid oxidation in catfish meat during storage: After 12 days of storage, the protein structure of the fish meat coated with the composite coating is stable, and the degree of lipid oxidation is low. Compared with the control group, the total volatile basic nitrogen (TVBN) and thiobarbituric acid value (TBA) decreased by 47.3% and 65.3%, respectively.

[0018] (3) After electronic nose principal component analysis, the smell of fish meat coated with composite coating was closer to that of fresh fish meat than that of the control group after storage.

[0019] (4) Compared with ultra-high pressure, vacuum and other room temperature and low temperature preservation methods, the present invention is simple to operate, safe and environmentally friendly, and does not have high requirements for equipment. Attached Figure Description

[0020] Figure 1 The effects of different preservation treatments on the total bacterial count (TVC) in catfish flesh during storage.

[0021] Figure 2 The effects of different preservation treatments on the total number of psychrophilic bacteria (TPC) in catfish flesh during storage.

[0022] Figure 3 The effects of different preservation treatments on the volatile basic nitrogen (TVBN) content of catfish flesh during storage.

[0023] Figure 4 The effects of different preservation treatments on thiobarbituric acid (TBA) in catfish meat during storage.

[0024] Figure 5 The effects of different preservation treatments on the volatile odor of catfish meat on day 0 and day 12. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings.

[0026] Example 1

[0027] Select fresh, live catfish that are intact and of suitable size. Remove the head, tail, skin, and internal organs from the live catfish. Rinse the processed catfish with sterile water and cut it into 3cm×3cm×2cm pieces. Wrap the fish pieces with a composite coating that has been sterilized by ultraviolet irradiation and then refrigerate them at 4℃.

[0028] Comparative Example 1

[0029] Select fresh, live catfish that are intact and of suitable size. Remove the head, tail, skin, and internal organs from the live catfish. Rinse the prepared catfish with sterile water and cut it into 3cm×3cm×2cm pieces. Then, refrigerate the fish pieces at 4℃.

[0030] Comparative Example 2

[0031] Select fresh, live catfish that are intact and of suitable size. Remove the head, tail, skin, and internal organs from the live catfish. Rinse the prepared catfish with sterile water and cut it into 3cm×3cm×2cm pieces. Wrap the fish pieces in plastic wrap that has been sterilized by UV irradiation and refrigerate at 4℃.

[0032] Comparative Example 3

[0033] Select fresh, live catfish that are intact and of suitable size. Remove the head, tail, skin, and internal organs from the live catfish. Rinse the processed catfish with sterile water and cut them into 3cm×3cm×2cm pieces. Coat the fish pieces with a pure gelatin coating that has been sterilized by ultraviolet irradiation and then refrigerate them at 4℃.

[0034] Characterization 1: Microbial Characterization

[0035] Microbiological experiments were conducted on the fish meat of the examples and comparative examples: 10g of fish meat was weighed and placed in a sterile homogenizing bag, 90mL of sterile physiological saline was added, the mixture was homogenized and patted for 2min, the supernatant was taken and serially diluted, and the appropriate concentration of the dilution was plated and placed in a constant temperature incubator at 37℃ and 4℃ for 2d and 10d respectively, in order to detect the total number of colonies and the number of psychrophilic bacteria in the fish meat.

[0036] like Figure 1 , Figure 2 As shown, the preservation method of this embodiment can effectively inhibit the proliferation of microorganisms in fish meat. Compared with the control group, the TVC and TPC of this embodiment were reduced by 31.2% and 23.6%, respectively. This is due to the excellent antibacterial effect of the coating. In addition, the chitosan in the coating can interact with cells and interfere with bacterial metabolism.

[0037] Characterization 2: Physicochemical properties

[0038] The degree of protein degradation in the fish meat of the examples and comparative examples was tested: 4g of fish meat was weighed, added to 20mL of distilled water, homogenized for 1 min, allowed to stand for 30 min, and then filtered. 1mL of filtrate, 1mL of saturated potassium carbonate solution, 1mL of hydrochloric acid absorption solution, and 1 drop of mixed indicator were added to a glass diffusion dish. The dish was sealed with a glass lid and placed in a constant temperature incubator at 37℃ for 2 h, then titrated with 0.01mol / L hydrochloric acid. TVBN was calculated using the following formula:

[0039]

[0040] In the formula, X is the TVBN of the fish meat (mg / 100g), v1 is the volume of hydrochloric acid consumed in the experimental group (mL), v2 is the volume of hydrochloric acid consumed in the blank group (mL), c1 is the concentration of hydrochloric acid (mol / L), and m1 is the sample mass (g).

[0041] from Figure 3 It can be seen that after storage, the fish meat in the example showed the lowest degree of protein degradation, with the TVBN value decreasing by 47.3% compared to the control group.

[0042] The degree of fat oxidation in the fish meat of the examples and comparative examples was detected as follows: 2g of sample was weighed and added to 20mL of trichloroacetic acid mixture, and stirred vigorously for 1 min. Then, it was shaken in a shaking incubator at 50℃ for 30 min. After filtration, 5mL of the supernatant was added to 5mL of thiobarbituric acid solution and incubated in a water bath at 90℃ for 30 min. After cooling, the absorbance was measured at λ = 532nm. TBA was calculated using the following formula:

[0043]

[0044] In the formula, x is the TBA / (mg MDA / kg) of the fish meat, c2 is the malondialdehyde concentration / (μg / mL), v3 is the filtrate volume / mL, and m2 is the fish meat mass / g.

[0045] The effects of different preservation treatments on fat oxidation in fish, such as Figure 4 As shown, the degree of fat oxidation in the fish meat of the embodiment remained at a minimum during storage, and the TBA of the fish meat of the embodiment decreased by 65.3% after storage.

[0046] Characteristic 3: Sensory identification

[0047] The odor of the fish meat in the examples and comparative examples was identified by an identification test: 3g of sample was weighed into a paper cup and enriched at room temperature for 30min. The flow rate was 200mL / min and the measurement time was 80s. Each sample was measured in triplicate.

[0048] like Figure 5 As shown, the variance contribution rate of principal component 1 is 82.3%, and the variance contribution rate of principal component 2 is 13%, totaling 95.3%. This indicates that these two components can represent the main volatile odor of fish meat, and the odor of fish meat is highly distinguishable before and after storage. Based on the projection of the examples and comparative examples onto coordinate axis 1, it can be seen that the odor of the examples is closer to that of the fresh samples compared to the comparative examples.

Claims

1. A green composite coating, characterized in that: with water as solvent, by weight, gelatin 2000-4000 parts, glycerol 200-400 parts, active nanoparticles 200-400 parts.

2. The method for preserving channel catfish according to claim 1, wherein It includes the following steps: (1) selecting fresh and live channel catfish with complete parts and appropriate size for standby; (2) removing the head, tail, skin and internal organs of the fresh and live channel catfish; (3) rinsing the treated channel catfish with sterile water and cutting it into fish pieces of appropriate size; (4) wrapping the fish pieces with the coating sterilized by ultraviolet irradiation and placing them in a refrigerator for cold storage.

3. The preparation method according to claim 2, characterized in that, The size of the fish pieces is about 3cm×3cm×2cm.

4. The production method according to claim 2, characterized by, The ultraviolet irradiation time of the coating is 30min.

5. The preparation method according to claim 2, characterized in that, The cold storage temperature of the fish pieces is 4℃.

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