Konjac glucomannan-based preservative as well as preparation method and application thereof

Abstract

The invention provides a konjac glucomannan-based preservative. The konjac glucomannan-based preservative is prepared from the following raw materials: konjac glucomannan, pullulan, tea polyphenol, nisin, 0.6 to 1 part of epsilon-polylysine and glycerol. The konjac glucomannan-based preservative prepared according to the limited preparation method can form a coating protection layer on the surface of the euphausia superba, so that the protease activity of the euphausia superba body can be effectively inhibited, the antioxidant and antibacterial effects are improved, and the preservation time is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of food preservation technology, and particularly relates to a konjac glucomannan-based preservative as well as a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the background of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art that is publicly known.

[0003] Antarctic krill is a kind of crustacean zooplankton living in the Southern Ocean, and is rich in resources, playing an important role in the food chain in the Southern Ocean, being food for seals, whales and penguins, and being an important marine biological resource. Antarctic krill is the highest protein-containing organism ever discovered, with a protein content of more than 50%, and is also rich in amino acids and vitamin A necessary for human tissues. The protein contained in ten Antarctic krill is equivalent to the nutritional value of 200 grams of roasted meat, and is the largest animal protein library on earth.

[0004] However, the development and utilization of Antarctic krill resources faces several technical bottlenecks, mainly in the following two aspects: first, Antarctic krill has a high-activity protease system in its body, which can easily cause autolysis after being caught, thereby accelerating the corruption process. The unsaturated fatty acid content in Antarctic krill is relatively high, which is also prone to oxidation, thereby causing Antarctic krill to deteriorate. A large number of bacteria breed in Antarctic krill during the deterioration process, further accelerating the deterioration process. Second, during centralized fishing operations, due to the limitation of processing capacity, the krill raw materials are often difficult to be processed in time, resulting in a significant decrease in quality, which seriously restricts the efficient utilization of resources. At present, frozen storage is the main preservation method for Antarctic krill, but the quality deterioration problem is prominent, mainly manifested in the quality changes caused by key factors such as lipid oxidation, protein denaturation, and sublimation and recrystallization of ice crystals. It is worth noting that repeated freezing and thawing processes can further exacerbate lipid oxidation and protein oxidation, especially inducing myofibrillar protein denaturation, ultimately causing irreversible deterioration of shrimp meat quality, and the content and composition of myofibrillar protein play an important role in maintaining shrimp meat quality.

[0005] Therefore, there is an urgent need for a preservative that can inhibit the protease activity of Antarctic krill, has antioxidant and antibacterial properties, and has a long preservation time. SUMMARY

[0006] In order to overcome the above problems, the present application provides a konjac glucomannan-based preservative as well as a preparation method and application thereof.

[0007] To achieve the above technical purposes, the present application adopts the following technical solutions: The first aspect of the present application provides a konjac glucomannan-based fresh-keeping agent, raw materials of which include, by weight: Konjac glucomannan 10-20 parts, pullulan 9-11 parts, tea polyphenol 4-6 parts, streptococcal bacteriocin 1-2 parts, ε-polylysine 0.8-1.2 parts, and glycerol 5-7.5 parts; The molecular weight of the konjac glucomannan is (1.2-1.7) × 10 5 Da.

[0008] The second aspect of the present application provides a preparation method of the konjac glucomannan-based fresh-keeping agent of the first aspect, comprising the following steps: (1) Dissolve konjac glucomannan and pullulan in water to obtain a first mixed solution, and heat treat the first mixed solution to obtain a colloidal solution, denoted as A solution; (2) Dissolve tea polyphenol in water to obtain a tea polyphenol aqueous solution, and disperse streptococcal bacteriocin and ε-polylysine in a citric acid solution to obtain a second mixed solution, and add the tea polyphenol aqueous solution to the second mixed solution to obtain B solution after mixing; (3) Add glycerol to the A solution, and after uniform mixing, add B solution to obtain a third mixed solution; (4) Homogenize, remove bubbles, and cold storage and stand to obtain the konjac glucomannan-based fresh-keeping agent.

[0009] In one or more embodiments, in step (1), the konjac glucomannan and the pullulan are added to the water in batches and multiple times, and the stirring rate during the dispersion process is 800-1000 r / min, and the stirring time is 12-18 min. Since the konjac glucomannan is prone to clumping, it needs to be added to the water in batches and multiple times, and high-speed stirring can ensure that the powder is fully dispersed.

[0010] In one or more embodiments, in step (1), the concentration of the konjac glucomannan in the first mixed solution is 3%-6% (w / v).

[0011] In one or more embodiments, in step (1), the temperature of the heat treatment is 50-60 ℃, and the time is 1-2 h.

[0012] In one or more embodiments, in step (1), the stirring rate during the heat treatment is 300-400 r / min, and the stirring time is 1.5-2.0 h. After the reaction is completed, the solution becomes uniform, viscous, and semi-transparent or clear colloidal solution, and then naturally cools.

[0013] In step (1), the preparation and pretreatment of the film-forming matrix realizes the efficient synergy and performance complementation between low molecular weight konjac glucomannan and pullulan. Compared with the conventional aqueous solution reaction system, the process first overcomes the technical difficulty of konjac glucomannan easy to form a ball through precise feeding sequence and dispersion control; then, the process promotes the two polysaccharide molecules to interweave to form a uniform and stable three-dimensional network structure through sufficient hydration and molecular chain stretching at a specific temperature, which not only significantly improves the compactness, oxygen resistance and mechanical strength of the composite film, but also lays a solid foundation for the effective loading and synergistic effect of the subsequent functional components, thereby breaking through the application bottleneck of insufficient film-forming performance of single polysaccharide.

[0014] In one or more embodiments, in step (2), the mass fraction of tea polyphenols in the tea polyphenol aqueous solution is 1%-1.4% (w / v). The prepared tea polyphenol aqueous solution is sealed with a plastic wrap, stored in the dark at a cool place, and used within 2 h to prevent premature oxidation of polyphenols.

[0015] In one or more embodiments, in step (2), the concentration of streptococcal bacteriocin in the second mixed solution is 0.32%-0.48% (w / v).

[0016] In one or more embodiments, in step (2), the concentration of citric acid in the citric acid solution is 0.05-0.1 mol / L. The acidic solvent is more conducive to the dissolution and stability of streptococcal bacteriocin.

[0017] In one or more embodiments, in step (2), the volume ratio of the tea polyphenol aqueous solution to the second mixed solution is (0.9-1.1):1, preferably 1:1.

[0018] In one or more embodiments, in step (3), glycerol is added to the A liquid in a dropwise manner, and stirring is continuously performed during the addition process at a rate of 300-400 r / min.

[0019] In one or more embodiments, in step (4), the homogenization method includes high-speed homogenization and high-pressure homogenization; wherein, the high-speed homogenization is homogenized at 8000-10000 r / min for 3-5 min; and the high-pressure homogenization is cyclically homogenized at 25-40 MPa for 2-3 times. This process can greatly improve the uniformity and stability of the system and ensure the preservation effect.

[0020] In one or more embodiments, in step (4), the method for removing bubbles is: degassing at (-0.08)-(-0.09) MPa for 9-12 min.

[0021] In one or more embodiments, in step (4), the temperature for refrigeration is 3-5 ℃, and the time for standing is 6-24 h. The refrigeration and standing can allow the molecules to interact with each other sufficiently, eliminate internal stress, and make the system reach a final stable state.

[0022] In a third aspect of the present application, the konjac glucomannan-based preservative prepared by the preparation method of the second aspect is applied to preservation of Euphausia superba.

[0023] In one or more embodiments, the method for application includes: washing and draining fresh Euphausia superba, forming a protective coating layer on the surface of the Euphausia superba by using the konjac glucomannan-based preservative through dipping or coating, and then packing the Euphausia superba into a packaging bag and storing in a refrigerator.

[0024] Preferably, the temperature for refrigeration is 3-5 ℃.

[0025] The present application has the following beneficial effects: The present application provides a konjac glucomannan-based preservative, which comprises: konjac glucomannan, pullulan, tea polyphenol, streptococcal peptide, 0.6-1 parts of epsilon-polylysine, and glycerol. The konjac glucomannan-based preservative prepared by the defined preparation method can form a protective coating layer on the surface of Euphausia superba, effectively inhibit protease activity of Euphausia superba, improve antioxidant and antibacterial effects, and prolong the preservation time. Specifically, the konjac glucomannan and the pullulan are fully hydrated and molecular chain stretched at a defined temperature, which promotes the two polysaccharide molecules to interweave and form a uniform and stable three-dimensional network structure. After cooling, a composite film with good stability, strong compactness, strong oxygen barrier property, and high mechanical strength is obtained. The glycerol as a plasticizer effectively improves the toughness of the film. Not only can it reduce the wear and tear during transportation, but also can effectively reduce juice loss and oxidation reaction due to its excellent barrier property (water vapor barrier property and oxygen barrier property), thereby prolonging the preservation time. The tea polyphenol effectively inhibits autolytic enzyme activity and lipid oxidation of Euphausia superba. The streptococcal peptide and epsilon-polylysine are used in combination, which significantly expands the antibacterial spectrum and has a strong inhibitory effect on gram-positive bacteria and gram-negative bacteria. This multi-target mechanism fundamentally solves the problem of rapid quality deterioration of Euphausia superba caused by enzymatic autolysis, microbial spoilage, and oxidation deterioration.

[0026] (2) The application can form a "freshness-protecting barrier" on the surface of shrimps. This dense edible film can not only inhibit microbial growth and delay protein and fat decomposition, but also significantly maintain the freshness, safety and flavor of the sample. Moreover, it is safe, non-toxic, environmentally friendly and easy to use, providing an ideal solution for efficient preservation and food safety. The TBA value of the Euphausia superba treated by the preservative at the end of the storage period (20 d) is only 0.85 mg MDA / kg, which is significantly lower than that of the untreated sample (2.51 mg MDA / kg). The total number of colonies is only 1.90 x 10 7 CFU / g, which is significantly lower than that of the untreated sample (9.65 x 10 7 CFU / g); the K value is only 16.32%, which is significantly lower than that of the untreated sample (33.09%); and the content of main flavor substances is as high as 28.02%, which is more than 130% higher than that of the untreated sample (11.98%). The preservative effectively slows down the occurrence of black head of Euphausia superba and maintains good sensory quality.

[0027] (3) All raw materials (KGM, tea polyphenol, pullulan, nisin, epsilon-polylysine and glycerol) of the application are natural edible components or food additives, which are safe, non-toxic and directly edible, avoiding the residual risk of traditional chemical preservatives. At the same time, the preservative has good water solubility and biodegradability, and is friendly to the environment. Its application can reduce the dependence of Euphausia superba on chemical preservatives such as sulfite during preservation, and provide a safer and healthier preservation solution for the market, which meets the pursuit of clean label food by consumers. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which form a part of the present description, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of the application illustrated in the drawings and their descriptions are used to explain the application and are not intended to limit the application.

[0029] Figure 1 The preservation effect of the preservative on Euphausia superba in Example 1, Comparative Example 1 and Comparative Example 7. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0031] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0032] In order to solve the problems of short preservation period, easy blackening and rapid quality deterioration of the existing Antarctic krill preservation technology, especially the technical bottlenecks of insufficient antibacterial and antioxidant effect of the traditional preservative, poor film performance and poor environmental tolerance, the present application provides a konjac glucomannan-based preservative, which comprises konjac glucomannan, pullulan, tea polyphenol, lactococcus lactis peptide, 0.6-1 parts of epsilon-polylysine and glycerol. The konjac glucomannan-based preservative prepared by the defined preparation method can form a coating protective layer on the surface of Antarctic krill, which can not only effectively inhibit the protease activity of Antarctic krill, improve the antioxidant and antibacterial effect, but also prolong the preservation time. Specifically, the konjac glucomannan and pullulan are fully hydrated and molecular chain stretched at the defined temperature, which promotes the interweaving of the two polysaccharide molecules to form a uniform and stable three-dimensional network structure. After cooling, a stable, dense, strong oxygen barrier and high mechanical strength composite film is obtained, and the glycerol as a plasticizer effectively improves the toughness of the film. Not only can it reduce the transportation wear, but also due to its excellent barrier property (water vapor barrier property and oxygen barrier property), it can effectively reduce juice loss and oxidation reaction, prolong the preservation time; tea polyphenol can effectively inhibit the autolytic enzyme activity and lipid oxidation of Antarctic krill; the combined use of lactococcus lactis peptide and epsilon-polylysine can significantly expand the antibacterial spectrum and has a strong inhibitory effect on gram-positive and negative bacteria; this multi-target mechanism fundamentally solves the problem of rapid quality deterioration of Antarctic krill caused by enzymatic autolysis, microbial spoilage and oxidation deterioration. The thiobarbituric acid value (TBA) of the Antarctic krill treated by the preservative at the end of storage (20 d) is only 0.85 mg MDA / kg, which is significantly lower than that of the untreated Antarctic krill (2.51 mg MDA / kg); the total number of colonies is only 1.90x10 7 CFU / g, which is significantly lower than that of the untreated Antarctic krill (9.65x10 7 CFU / g); the K value is only 16.32%, which is significantly lower than that of the untreated Antarctic krill (33.09%); the main flavor substance content is as high as 28.02%, which is more than 130% higher than that of the untreated Antarctic krill (11.98%). The preservative effectively slows down the occurrence of black head of Antarctic krill and maintains good sensory quality.

[0033] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0034] The molecular weight of konjac glucomannan in the following examples is 1.2769 x 10 6 Da.

[0035] Example 1 Preparation of konjac glucomannan-based preservative: (1) 3.0 g of konjac glucomannan and 3.0 g of pullulan were mixed uniformly and then added to 100 mL of sterile distilled water in multiple batches, and magnetic stirring (900 r / min) was performed for 15 min to form a uniform first mixed solution; the first mixed solution was transferred to a water bath at 55 °C, and then the stirring speed was reduced to 350 r / min, and constant temperature stirring was continued at this temperature for 2 h, after which the reaction was completed, and the solution became a uniform, viscous, semi-transparent or clear colloidal solution; the solution was removed from the water bath and moved to a room temperature environment for natural cooling, and the colloidal solution was labeled as solution A.

[0036] (2) 1.20 g of tea polyphenol was added to 100 mL of sterile distilled water, and after mixing uniformly, a tea polyphenol aqueous solution was obtained; 0.40 g of streptococcalin and 0.24 g of ε-polylysine were dissolved in 100 mL of 0.05 mol / L citric acid solution, and after mixing uniformly, a second mixed solution was obtained; the tea polyphenol aqueous solution was added to the second mixed solution, and after mixing uniformly, solution B was obtained.

[0037] (3) Under room temperature and moderate stirring (350 r / min) conditions, 1.5 mL of glycerol was added dropwise to solution A, and then solution B was added, and after mixing uniformly, a third mixed solution was obtained.

[0038] (4) The third mixed solution was homogenized at 8000 r / min for 3 min, and then homogenized at 25 MPa for 2 cycles, and the homogenized solution was degassed at -0.08 MPa for 10 min. The finally prepared composite preservative solution was placed in a 4 °C refrigerated environment for 12 h, and a konjac glucomannan-based preservative was obtained.

[0039] Example 2 Preparation of konjac glucomannan-based preservative: (1) 4.5 g konjac glucomannan and 3.0 g pullulan were mixed uniformly, and then were added into 100 mL sterile distilled water in batches, and a uniform first mixed solution was formed by magnetic stirring (800 r / min) for 18 min; the first mixed solution was transferred to a water bath at 55 °C, and then the stirring speed was reduced to 400 r / min, and the solution was stirred at this temperature for 1.5 h, and then the reaction was completed; the solution was taken out of the water bath and moved to a room temperature environment, and was naturally cooled; the colloidal solution was recorded as A solution.

[0040] (2) 1.50 g tea polyphenol was added into 100 mL sterile distilled water, and a tea polyphenol aqueous solution was obtained after mixing uniformly; 0.50 g streptococcal bacteriocin and 0.30 g ε-polylysine were dissolved in 100 mL 0.075 mol / L citric acid solution, and a second mixed solution was obtained after mixing uniformly; the tea polyphenol aqueous solution was added into the second mixed solution, and B solution was obtained after mixing uniformly.

[0041] (3) 1.5 mL glycerol was added into A solution under the conditions of room temperature and medium speed stirring (350 r / min), and then B solution was added, and a third mixed solution was obtained after mixing uniformly.

[0042] (4) The third mixed solution was homogenized at 9000 r / min for 4 min, and then was subjected to cyclic homogenization under a pressure of 30 MPa for 2 times; the homogenized solution was degassed under a pressure of -0.085 MPa for 10 min. The finally prepared composite preservative solution was placed in a cold storage environment at 4 °C for 12 h, and a konjac glucomannan-based preservative was obtained.

[0043] Example 3 Preparation of a konjac glucomannan-based preservative: (1) 6.0 g konjac glucomannan and 3.0 g pullulan were mixed uniformly, and then were added into 100 mL sterile distilled water in batches, and a uniform first mixed solution was formed by magnetic stirring (800 r / min) for 18 min; the first mixed solution was transferred to a water bath at 55 °C, and then the stirring speed was reduced to 400 r / min, and the solution was stirred at this temperature for 1.5 h, and then the reaction was completed; the solution was taken out of the water bath and moved to a room temperature environment, and was naturally cooled; the colloidal solution was recorded as A solution.

[0044] (2) 1.80 g tea polyphenol was added into 100 mL sterile distilled water, and a tea polyphenol aqueous solution was obtained after mixing uniformly; Dissolve 0.60 g of streptococcalin and 0.36 g of ε-polylysine in 100 mL of 0.10 mol / L citric acid solution, and obtain a second mixed solution after uniform mixing; add a tea polyphenol aqueous solution to the second mixed solution, and obtain B liquid after uniform mixing.

[0045] (3) Under the conditions of room temperature and moderate stirring (350 r / min), add 1.5 mL of glycerol to A liquid, then add B liquid, and obtain a third mixed solution after uniform mixing.

[0046] (4) Homogenize the third mixed solution at 9000 r / min for 4 min, then cycle homogenization twice under a pressure of 40 MPa, and degas the homogenized solution under-0.09 MPa for 10 min. The finally prepared composite preservative solution is placed in a 4 °C refrigeration environment for 12 h, and a konjac glucomannan-based preservative is obtained.

[0047] Comparative Example 1 Comparative Example 1 Compared with Example 1, the molecular weight of konjac glucomannan is adjusted, the molecular weight of konjac glucomannan is 1.9087×10 6 Da, and other methods are the same as those in Example 1.

[0048] Comparative Example 2 Compared with Example 1, the molecular weight of konjac glucomannan is adjusted, the molecular weight of konjac glucomannan is 1.6397×10 6 Da, and other methods are the same as those in Example 1.

[0049] Comparative Example 3 Compared with Example 1, no konjac glucomannan is added, and other methods are the same as those in Example 1.

[0050] Comparative Example 4 Compared with Example 1, no pullulan is added, and other methods are the same as those in Example 1.

[0051] Comparative Example 5 Compared with Example 1, no glycerol is added, and other methods are the same as those in Example 1.

[0052] Comparative Example 6 Compared with Example 1, the ratio of konjac glucomannan and pullulan is adjusted to 5:1, and other methods are the same as those in Example 1.

[0053] Comparative Example 7 Compared with Example 1, the ratio of konjac glucomannan and pullulan is adjusted to 0.5:1, and other methods are the same as those in Example 1.

[0054] Comparative Example 8 Compared with Example 1, catechol was not added, and other methods were the same as those in Example 1.

[0055] Comparative Example 9 Compared with Example 1, no streptococcin, ε-polylysine was added, and other methods were the same as those in Example 1.

[0056] Example 4 Euphausia superba was respectively soaked with the preservatives prepared in Examples 1-3 and Comparative Examples 1-9 according to a material-liquid ratio of 1:3 (g / mL) for 30 min, taken out and drained, and then packed in polyethylene sealed bags and refrigerated at 4 ℃. Sampling and determination of indexes were performed regularly (on the 0th, 5th, 10th, 15th and 20th days).

[0057] Determination of volatile base nitrogen (TVB-N) value, thiobarbituric acid (TBA) value, total bacterial count, K value and main flavor substances (aldehyde substances) was performed. The specific methods were as follows: (1) TVB-N value was determined by semi-micro nitrogen determination; (2) TBA value was determined by spectrophotometry; (3) total bacterial count was determined by plate counting method; (4) K value was determined by high performance liquid chromatography and calculated; (5) main flavor substances (aldehyde substances) were analyzed by gas chromatography-mass spectrometry (GC-MS).

[0058] The detection results are shown in Table 1 and Figure 1 .

[0059] Table 1 Preservation effect of Euphausia superba

[0060] As shown by the data in Table 1, the preservatives prepared in Examples 1-3 had the best and stable comprehensive preservation effect on Euphausia superba, and the various spoilage indexes (TVB-N value, TBA value, total bacterial count and K value) were maintained at the lowest level, and the main flavor substances (aldehydes) could be best preserved. The data of Comparative Examples 1-9 confirmed that the specific ratio combination of konjac glucomannan and pullulan, the appropriate molecular weight and the antibacterial agent (streptococcin, ε-polylysine) were the core of the preservation system, and the absence of any component or the change of the key parameters (such as Comparative Examples 3, 4 and 9) would cause a significant decrease in the preservation performance, among which the absence of the film-forming matrix (konjac glucomannan) and the antibacterial agent had the most serious influence.

[0061] The molecular weight of konjac glucomannan is adjusted in Comparative Example 1 and Comparative Example 2: the mismatch of molecular weight will affect the film-forming property and stability, resulting in that each preservation index is worse than Example 1, but better than Comparative Example in which the core component is completely missing. Comparative Example 3 (without adding konjac glucomannan): konjac glucomannan is the main film-forming matrix and preservation carrier, and its absence will cause the preservation system to collapse, so each index will deteriorate sharply, far worse than other groups, similar to Comparative Example 9 (without adding antibacterial agent). Comparative Example 4 (without adding pullulan): pullulan has a synergistic film-forming effect with konjac glucomannan, and its absence will reduce the mechanical strength of the film and the preservation effect, resulting in a significant difference in index from Example 1. Comparative Example 5 (without adding glycerol): glycerol as a plasticizer, its absence will make the film brittle and easy to break, thereby reducing the physical barrier effect and the preservation effect, but the impact is less than the absence of the main component. Comparative Example 6 and Comparative Example 7 adjust the ratio of konjac glucomannan and pullulan: the imbalance of the ratio (whether 5:1 or 0.5:1) will destroy the best synergistic effect of the two polysaccharides, resulting in a decrease in film-forming performance and a decrease in preservation effect, and the greater the ratio deviation, the worse the effect. Comparative Example 8 (without adding tea polyphenol): tea polyphenol is an important antioxidant, and its absence mainly affects the antioxidant index (TBA value) and part of the flavor retention, but has less effect on microbial inhibition (total number of colonies) than Comparative Example 9 in which the antibacterial agent is missing. Comparative Example 9 (without adding streptococcal nisin and epsilon-polylysine): these two are core antibacterial agents, and their absence will cause a large number of microorganisms to reproduce, resulting in a sharp rise in TVB-N value, K value and total number of colonies, rapid degradation of flavor substances, and the worst preservation effect, similar to Comparative Example 3.

[0062] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A konjac glucomannan-based preservative, characterized in that, Its raw materials, by weight, include: Konjac glucomannan 10-20 parts, pullulan polysaccharide 9-11 parts, tea polyphenols 4-6 parts, nisin 1-2 parts, ε-polylysine 0.8-1.2 parts, and glycerol 5-7.5; The molecular weight of konjac glucomannan is (1.2-1.7) × 10⁻⁶. 5 Da.

2. The preparation method of the konjac glucomannan-based preservative according to claim 1, characterized in that, Includes the following steps: (1) Dissolve konjac glucomannan and pullulan in water to obtain a first mixed solution. Heat treat the first mixed solution to obtain a colloidal solution, denoted as solution A. (2) Dissolve tea polyphenols in water to obtain an aqueous solution of tea polyphenols; disperse nisin and ε-polylysine in citric acid solution to obtain a second mixture; add the aqueous solution of tea polyphenols to the second mixture and mix to obtain solution B; (3) Add glycerol to solution A, mix well, then add solution B to obtain the third mixture; (4) After homogenizing, degassing and refrigerating the third mixture, a konjac glucomannan-based preservative is obtained.

3. The preparation method according to claim 2, characterized in that, In step (1), konjac glucomannan and pullulan are added to water in batches and multiple times. During the dispersion process, the stirring speed is 800-1000 r / min and the stirring time is 12-18 min. Alternatively, in step (1), the concentration of konjac glucomannan in the first mixed solution is 3%~6% (w / v).

4. The preparation method according to claim 2, characterized in that, In step (1), the heat treatment temperature is 50~60 ℃ and the time is 1~2 h; Alternatively, in step (1), during the heat treatment process, the stirring rate is 300-400 r / min and the stirring time is 1.5-2.0h.

5. The preparation method according to claim 2, characterized in that, In step (2), the mass fraction of tea polyphenols in the tea polyphenol aqueous solution is 1%~1.4% (w / v); Alternatively, in step (2), the concentration of nisin in the second mixture is 0.32%~0.48% (w / v).

6. The preparation method according to claim 2, characterized in that, In step (2), the concentration of citric acid in the citric acid solution is 0.05-0.1 mol / L; Alternatively, in step (2), the volume ratio of the tea polyphenol aqueous solution to the second mixture is (0.9~1.1):1, preferably 1:

1.

7. The preparation method according to claim 2, characterized in that, In step (3), glycerol is added to solution A by dripping or slow addition, and stirring is carried out continuously during the addition process at a rate of 300-400 r / min. Alternatively, in step (4), the homogenization method includes high-speed homogenization and high-pressure homogenization; wherein, high-speed homogenization is homogenization at 8000-10000 r / min for 3-5 min; and high-pressure homogenization is homogenization in cycles at 25-40 MPa for 2-3 times.

8. The preparation method according to claim 2, characterized in that, In step (4), the method for removing air bubbles is as follows: degas at (-0.08) - (-0.09) MPa for 9~12 min; Alternatively, in step (4), the refrigeration temperature is 3~5 ℃ and the standing time is 6~24 h.

9. The application of the konjac glucomannan-based preservative according to claim 1 or the konjac glucomannan-based preservative prepared by any one of the preparation methods described in claims 2 to 7 in the preservation of Antarctic krill.

10. The application as described in claim 10, characterized in that, The application methods include: rinsing and draining fresh Antarctic krill, forming a protective coating layer of konjac glucomannan-based preservative on the surface of the Antarctic krill using immersion or coating methods, and then packing the Antarctic krill into packaging bags for refrigeration. Preferably, the refrigeration temperature is 3~5℃.

Images