Minced fish quality improver, minced fish powder preservable at room temperature, and preparation method thereof

Abstract

A minced fish (surimi) quality improver comprising gelatin, egg white protein, maltodextrin, glutamine transaminase, vitamin C, tea polyphenol, trehalose and degraded konjac gum at a mass ratio of 1:(

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of minced fish food processing, and in particular relates to a minced fish quality improver, minced fish powder preservable at room temperature, and a preparation method thereof. BACKGROUND

[0002] Minced fish is a minced meat produced by collecting raw fish meat, rinsing, dehydrating and then refined filtering. After added with salt and pounded, it can form a gel-like minced fish article by heating. Since the myofibrillar proteins in the minced fish will denature and thus fail to form a gel when the minced fish is stored at room temperature, the minced fish is currently usually stored and transported in frozen form, and meanwhile added with antifreeze agents such as sugars and phosphates to allow it to be preserved for a long time. Traditional frozen minced fish has the following disadvantages: first, if the minced fish exists in a frozen form, it needs to be thawed and cut before processing, which will increase the costs of storage, transportation and processing; and second, freeze damage during frozen storage and temperature fluctuations during transportation will also denature the proteins in the minced fish, thereby reducing the quality of a final minced fish product. In view of this, if minced fish powder preservable at room temperature is developed, which can obtain the same quality as frozen minced fish after rehydration, it will not only greatly save transportation and storage costs, but also make the processing manners of minced fish articles more diversified, and greatly promote the rapid development of the minced fish industry. Moreover, since the rehydration of minced fish powder is simple in operation and can be done at home, its practicality will be significantly improved. SUMMARY (0003] A first objective of the present disclosure is to provide a novel minced fish quality improver, which can be employed to modify minced fish to obtain minced fish powder preservable at room temperature.

[0004] Specifically, the minced fish quality improver provided by the present disclosure contains gelatin, egg white protein, maltodextrin, glutamine transaminase, vitamin C, tea polyphenol, trehalose and degraded konjac gum at a mass ratio of 1 :(0.3-3):(0.5-5):(0.3-3):(0.5-5):(0.5-5 ):(0.5-5):(0.5-5).

[0005] A second objective of the present disclosure is to provide a method for preparing the aforementioned minced fish quality improver, which includes uniformly mixing gelatin, egg white protein, maltodextrin, glutamine aminotransferase, vitamin C, tea polyphenol, trehalose and degraded konjac gum.

[0006] A third objective of the present disclosure is to provide a method for preparing minced fish powder preservable at room temperature, which includes sequentially subjecting a fish meat block to pounding with nothing, pounding with salt and pounding with materials to obtain minced fish, wherein the aforementioned minced fish quality improver is added during the process of pounding with materials, and subsequently drying and then sieving the minced fish to obtain the minced fish powder that is preservable at room temperature.

[0007] A fourth objective of the present disclosure is to provide minced fish powder preservable at room temperature prepared by the aforementioned method.

[0008] The key to the minced fish quality improver provided by the present disclosure is that the gelatin, the egg white protein, the maltodextrin, the glutamine aminotransferase, the vitamin C, the tea polyphenol, the trehalose and the degraded konjac gum are coordinated to slow down the reduction of the strength of the minced fish gel. It is supposed that the reason may be due to the follows. During a process of storage at room temperature, due to the fluffy body of dry protein powder, oxygen is easy to enter, and make the protein oxidized. The vitamin C and the tea polyphenol themselves have good antioxidant properties, which eliminates the adverse effects brought about by oxygen from the “external” side. The addition of the gelatin and the egg white protein can make them co-aggregate with the protein powder to form a hydration film, thereby protecting readily oxidizable groups and eliminating the adverse effects brought about by oxygen from the “internal” side. The maltodextrin, the trehalose and the degraded konjac gum are rich in hydroxyl groups, which easily form bound water with water, so that it will not cause excessive aggregation of proteins. The glutamine transaminase can promote the cross-linking of proteins to form a gel, thereby compensating for the reduction of gel strength caused by external factors. That is, the minced fish quality improver of the present disclosure complements and promotes each other and synergistically endows the minced fish powder with excellent gel strength from multiple dimensions.

[0009] The present disclosure has the following beneficial effects.

[0010] In the present disclosure, minced fish powder preservable at room temperature is prepared from traditional minced fish by vacuum freeze drying, and the quality of the minced fish is improved by adding with the minced fish quality improver containing the gelatin, the egg white protein, the maltodextrin, the glutamine aminotransferase, the vitamin C, the tea polyphenol, the trehalose and the degraded konjac gum. So that it can not only avoid the high energy consumption and high cost caused by the frozen storage and transportation of traditional minced fish, but also greatly enrich the diversity of minced fish articles. On one hand, the minced fish quality improver provided by the present disclosure can stabilize the minced fish protein and stabilize the properties of minced fish during processes of pre-freezing, vacuum freeze drying and room temperature preservation, and on the other hand it can be compounded with proteins in the subsequent heating and gelation process to improve its quality. BRIEF DESCRIPTION OF THE DRAWINGS 10011] FIG. 1 is a graph showing the results of salt-soluble protein content change of the obtained minced fish powder stored at room temperature for 30 d in each example and comparative example.

[0012] FIG. 2 is a graph showing the results of whiteness change of the obtained minced fish powder stored at room temperature for 30 d in each example and comparative example.

[0013] FIG. 3 is a graph showing the results of water holding capacity change of the obtained minced fish powder after being rehydrated and heated to prepare a gel in each example and comparative example.

[0014] FIG. 4 is a graph showing the results of gel strength change of the obtained minced fish powder after being rehydrated and heated to prepare a gel in each example and comparative example. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] The minced fish quality improver provided by the present disclosure contains gelatin, egg white protein, maltodextrin, glutamine transaminase (TGase), vitamin C, tea polyphenol, trehalose and degraded konjac gum. Based on the content of the gelatin as 1 part by mass, the contents of the egg white protein and the glutamine transaminase are each independently 0.3-3 parts by mass, e.g., 0.3, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3 parts by mass, or any value therebetween; the contents of the maltodextrin, the vitamin C, the tea polyphenol, the trehalose and the degraded konjac gum are each independently 0.5-5 parts by mass, e.g., 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5 parts by mass, or any value therebetween.

[0016] In a preferred embodiment, the contents of the gelatin, the egg white protein and the glutamine transaminase are each independently 1-3 parts by mass, and the contents of the maltodextrin, the vitamin C, the tea polyphenol, the trehalose and the degraded konjac gum are each independently 2-5 parts by mass. At this time, each component can cooperate better to achieve the effect of improving the gel strength of the minced fish powder. Specifically, the contents of the gelatin, the egg white protein and the glutamine transaminase are preferably 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3 parts by mass independently, or any value therebetween. The contents of the maltodextrin, the vitamin C, the tea polyphenol, the trehalose and the degraded konjac gum are preferably 2-5 parts by mass independently, e.g., 2, 2.5, 3, 3.5, 4, 4.5, 5 parts by mass, or any value therebetween.

[0017] Konjac glucomannan, the main active ingredient of the konjac gum, is a water-soluble non-ionic high-molecular polysaccharide. It is a linear random copolymer formed by binding D-glucose with D-mannose in a molar ratio of 1:1.6 through P-l,4-pyranosidic bonds and a small amount of P~ 1,3-pyranosidic bonds, with 5%-10% acetyl substituted residues. The term “degraded konjac gum” refers to a product formed by the cleavage of at least part of the P-l,4-pyranosidic bonds in the konjac gum. The inventors of the present disclosure have found that when the selected degraded konjac gum satisfies the viscosity of 2,000-4,000 mPa.s detected as a solution with a concentration of 1 wt% under a condition of25°C, it is more conducive to the formation of bound water in the system and can better retain the gel properties of the minced fish. Specifically, the viscosity of the degraded konjac gum detected as a solution with a concentration of 1 wt% under a condition of25°C may be illustratively 2,000, 2,200, 2,400, 2,600, 2,800, 3,000, 3,200, 3,400, 3,600, 3,800, 4,000 mPa.s, or any value therebetween.

[0018] In a specific embodiment, the degraded konjac gum is obtained by degrading konjac gum with an abalone visceral crude enzyme. Preferably, the abalone visceral crude enzyme is obtained by mixing abalone viscera with a phosphate buffer, then conducting tissue homogenizing, then centrifugally separating under a condition of 0°C-4°C to obtain supernatant, removing impurities and fishy odour from the obtained supernatant by using activated carbon, and then freeze-drying. The addition amount of the abalone visceral crude enzyme is preferably 1-3 U / g, e.g., 1, 1.5, 2, 2.5, 3 U / g, or any value therebetween. Moreover, the conditions of the degradation preferably include a temperature of 45°C-50°C, e.g., 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, or any value therebetween; and a time of 30-120 min, e.g., 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, or any value therebetween.

[0019] A method for preparing the minced fish quality improver provided by the present disclosure includes uniformly mixing gelatin, egg white protein, maltodextrin, glutamine aminotransferase, vitamin C, tea polyphenol, trehalose and degraded konjac gum. There is no particular limitation in the manner of mixing each component uniformly. All components can be added at the same time and then mixed uniformly, or some of the components can be mixed uniformly first and then the remained components are added and mixed uniformly.

[0020] A method for preparing the minced fish powder preservable at room temperature provided by the present disclosure includes sequentially subjecting a fish meat block to pounding with nothing, pounding with salt and pounding with materials to obtain minced fish, wherein the aforementioned minced fish quality improver is added during the process of pounding with materials, and subsequently drying and then sieving the minced fish to obtain the minced fish powder that is preservable at room temperature.

[0021] In the present disclosure, specific examples of the fish meat block include but are not limited to: at least one of a Nemipterus virgatus block, a Trichiuridae block, and a Muraenesox cinereus block. The fish meat block may be a fresh fish meat block, a frozen fish meat block, or a chilled fish meat block, and the fish meat block is preferably the fresh fish meat block. The fresh fish meat block is obtained according to the following method: removing muscle from the back of a fish, washing the muscle with ice water until the muscle is clean, then cutting the muscle into small blocks, rinsing the small blocks in a rinsing liquid, and then drying by draining. The addition amount of the rinsing liquid is preferably 1-10 times the mass of the fish meat block, e.g., 1 time, 2 times, 4 times, 6 times, 8 times, 10 times, or any value therebetween. The rinsing temperature is preferably 0-4°C, e.g., 0°C, 1 °C, 2°C, 3°C, 4°C, or any value therebetween. The steps of the rinsing may specifically be to first employ a sodium citrate aqueous solution with a concentration of 0.05-0.2% for stirring and rinsing for 5-15 min, then employ a calcium chloride aqueous solution with a concentration ofO. 1-0.2% for stirring and rinsing for 5-15 min, and finally employ distilled water for repeatedly rinsing for 1-5 times with a time of each rinsing being 1-10 min.

[0022] In the present disclosure, the pounding with nothing, the pounding with salt and the pounding with materials are usually carried out in a mixing and kneading machine (chopping machine). The mixing and kneading machine can be double wall structure, and a cooling medium (ice-water mixture) is continuously circulated to keep the temperature at 0-4°C during the mixing and kneading process. The pounding with salt is preferably carried out in the following manner: dissolving an edible salt in water, and then adding the solution to the minced fish along with ice water, wherein a moisture content of the minced fish is controlled at 80-85%, and the addition amount of the edible salt is 2-3% of the mass of the fish meat after drying by draining. The time for the pounding with nothing is preferably 5-10 min, e.g., 5, 6, 7, 8, 9, 10 min, or any value therebetween. The time for the pounding with salt is preferably 2-10 min, e.g., 2, 4, 6, 8, 10 min, or any value therebetween. The time for the pounding with materials is preferably 2-10 min, e.g., 2, 4, 6, 8, 10 min, or any value therebetween.

[0023] In the present disclosure, based on the mass percentage of the minced fish, the addition amount of the minced fish quality improver in terms of the degraded konjac gum is preferably 0.5-2 wt%, e.g., 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, or any value therebetween.

[0024] In the present disclosure, the drying manner is freeze drying. The drying manner and condition preferably enable the water content of the minced fish to be controlled at 1-3%, e.g., 1%, 1.5%, 2%, 2.5%, 3%, or any value therebetween. Freeze drying is preferably carried out in the following manner: the minced fish is first subjected to ultra-low temperature pre-freezing at a temperature of -60°C ~ -80°C for 10-12 h, and then the pre-frozen minced fish is first freeze-dried at a vacuum degree below 30 Pa and a temperature of -30°C~0°C for 16-18 h, and then the previously vacuum-freeze-dried minced fish is freeze-dried at a vacuum degree below 30 Pa and a temperature of 0°C-30°C for 28-30 h. Moreover, a mesh size employed for the sieving is preferably 20-100 meshes.

[0025] In a preferred embodiment, a method for preparing the minced fish powder preservable at room temperature includes the following steps:

[0026] SI . raw material pretreatment: muscle is removed from the back of a fish, washed with ice water until the muscle is clean, and then cut the muscle into small blocks, and rinse the small blocks in a rinsing liquid, and then dry by draining;

[0027] S2. mixing and kneading: firstly, the fish meat of SI is pounded with nothing in a mixing and kneading machine for 5-10 min, then add edible salt and pound with salt for 2-10 min, and finally add the minced fish quality improver and pound for 2-10 min to obtain fresh minced fish;

[0028] S3, powdering: the fresh minced fish of S2 is vacuum freeze-dried, crushed and sieved to obtain the minced fish powder preservable at room temperature.

[0029] Moreover, the present disclosure further provides minced fish powder preservable at room temperature prepared by the aforementioned method.

[0030] The minced fish powder provided by the present disclosure can be preserved at room temperature, and a minced fish gel with jelly-like texture can be obtained by simply rehydrating, heating and cooling of the minced fish powder. Compared with traditional frozen minced fish, the present disclosure can not only retain the gel properties of minced fish, but also realize the roomtemperature storage of minced fish and save storage and transportation costs. It can also greatly enrich the processing manners of minced fish articles, meet consumers' curiosity, and realize consumers' operation at home.

[0031] The present disclosure will be described in detail by examples below.

[0032] In order to make the objectives, technical solutions and advantages of the embodiments in the present disclosure clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present disclosure with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are a part rather than all of the embodiments of the present disclosure.

[0033] In the following examples and comparative examples, the parts of each raw material refer to parts by mass, unless otherwise specified.

[0034] The sources of the raw materials employed in the following preparation examples and comparative preparation examples are as follows:

[0035] gelatin, purchased from Guidechem Chemical Network, with a CAS number of 9000-70-8;

[0036] egg white protein, purchased from Macklin, with a CAS number of 9006-59-1;

[0037] maltodextrin, purchased from Guidechem Chemical Network, with a CAS number of 9050-36-6;

[0038] TG enzyme, purchased from Guidechem Chemical Network, with a CAS number of 80146-85-6;

[0039] vitamin C, purchased from Guidechem Chemical Network, with a CAS number of 50-81-7 ;

[0040] Tea polyphenol, purchased from Guidechem Chemical Network, with a CAS number of 283-519-7; and

[0041] Trehalose, purchased from Guidechem Chemical Network, with a CAS number of 99-20-7. Preparation Example 1

[0042] SI. Preparation of degraded konjac gum: The abalone viscera were washed with clean water until clean and cutted into narrow strips of 1 -3 cm. The strips were mixed with a 20 mM phosphate buffer, then placed in a tissue masher and homogenized, and then centrifuged at 10,000 xg under a condition of 4°C for 20 min, and the supernatant was taken. The supernatant was mixed with 3% activated carbon under conditions of 4°C and 180 rpm for 30 min to remove impurities and fishy odour, and then freeze-dried in vacuum to obtain an abalone visceral crude enzyme. 200 U / g of the abalone visceral crude enzyme was evenly added into 100 mL of the konjac gum solution (2%), fully mixed well, and then heated at 50°C for reaction for 30 min. After the reaction was completed, the mixture was placed in a boiling water bath for enzyme inactivation for 10 min, and subsequently freeze-dried in vacuum and then crushed to obtain degraded konjac gum powder. The viscosity of the degraded konjac gum powder detected as a solution with a concentration of 1 wt% under a condition of 25°C was 4,865 mPa.s.

[0043] S2. Preparation of minced fish quality improver: 1 part of gelatin, 3 parts of egg white protein, 2 parts of maltodextrin, 1 part of TG enzyme, 5 parts of vitamin C, 2 parts of tea polyphenol, 5 parts of trehalose and 5 parts of the degraded konjac gum powder obtained in the step SI are stirred and mixed uniformly to obtain a minced fish quality improver. Preparation Example 2

[0044] SI. Preparation of degraded konjac gum: The abalone viscera were washed with clean water until clean and cut into narrow strips of 1-3 cm. The strips were mixed with a 20 mM phosphate buffer, then placed in a tissue masher and homogenized, and then centrifuged at 10,000 xg under a condition of 4°C for 20 min, and the supernatant was taken. The supernatant was mixed with 3% activated carbon under conditions of 4°C and 180 rpm for 30 min to remove impurities and fishy odour, and then freeze-dried in vacuum to obtain an abalone visceral crude enzyme. 200 U / g of the abalone visceral crude enzyme was evenly added into 100 mL of the konjac gum solution (2%), fully mixed well, and then heated at 50°C for reaction for 60 min. After the reaction was completed, the mixture was placed in a boiling water bath for enzyme inactivation for 10 min, and subsequently freeze-dried in vacuum and then crushed to obtain degraded konjac gum powder. The viscosity of the degraded konjac gum powder detected as a solution with a concentration of 1 wt% under a condition of 25°C was 3,775 mPa.s. 10045] S2. Preparation of minced fish quality improver: 3 parts of gelatin, 1 part of egg white protein, 5 parts of maltodextrin, 3 parts of TG enzyme, 2 parts of vitamin C, 5 parts of tea polyphenol, 2 parts of trehalose and 3 parts of the degraded konjac gum powder obtained in the step SI were stirred and mixed uniformly to obtain a minced fish quality improver. Preparation Example 3

[0046] SI. Preparation of degraded konjac gum: the method was the same as that of preparation example 1.

[0047] S2. Preparation of minced fish quality improver: 2 parts of gelatin, 2 parts of egg white protein, 3 parts of maltodextrin, 2 parts of TG enzyme, 4 parts of vitamin C, 3 parts of tea polyphenol, 3 parts of trehalose and 4 parts of the degraded konjac gum powder obtained in the step S1 were stirred and mixed uniformly to obtain a minced fish quality improver. Comparative Preparation Example 1

[0048] The minced fish quality improver was prepared according to the method of preparation example 1, except that the gelatin and the egg white protein were both replaced by the vitamin C in the same parts by mass, and the remaining conditions were the same as those of preparation example 1. Thus a reference minced fish quality improver was obtained. Comparative Preparation Example 2

[0049] The minced fish quality improver was prepared according to the method of preparation example 1, except that the vitamin C and the tea polyphenol were both replaced by the gelatin in the same parts by mass, and the remaining conditions were the same as those of preparation example 1. Thus a reference minced fish quality improver was obtained. Comparative Preparation Example 3

[0050] The minced fish quality improver was prepared according to the method of preparation example 1, except that the degraded konjac gum was replaced by the maltodextrin in the same parts by mass, and the remaining conditions were the same as those of preparation example 1. Thus a reference minced fish quality improver was obtained. Comparative Preparation Example 4

[0051] The minced fish quality improver was prepared according to the method of preparation example 1, except that maltodextrin was replaced by the trehalose in the same parts by mass, and the remaining conditions were the same as those of preparation example 1. Thus a reference minced fish quality improver was obtained. Comparative Preparation Example 5

[0052] The minced fish quality improver was prepared according to the method of preparation example 1, except that the trehalose was replaced by the maltodextrin in the same parts by mass, and the remaining conditions were the same as those of preparation example 1. Thus a reference minced fish quality improver was obtained. Example 1 This embodiment disclosed a method for preparing minced fish powder preservable at room temperature, and the specific steps were as follows:

[0053] SI. raw material pretreatment: muscle was removed from the back of fresh Nemipterus virgatus, washed with ice water until the muscle was clean, and the muscle was cut into blocks of 1 -2 cm. The fish meat blocks were first stirred and rinsed with a sodium citrate aqueous solution in a concentration of 0.1% for 10 min, then stirred and rinsed with a calcium chloride aqueous solution in a concentration of 0.15% for 10 min, and finally rinsed with distilled water repeatedly for 3 times, each rinsing time was 5 min, and the water temperature for rinsing was controlled at 0°C, so as to obtain pre-treated fish meat blocks.

[0054] S2. mixing and kneading: firstly, the pre-treated fish meat blocks of SI were pounded with nothing for 5 min; then the pounded minced fish was added with an aqueous solution of edible salt and pounded with salt for 2 min, wherein the addition amount of the edible salt was 2.5% of the mass of the fish meat; and finally the minced fish was added with the minced fish quality improver obtained in preparation example 1 and pounded with materials for 10 min (based on the mass percentage of the minced fish, the addition amount of the minced fish quality improver in terms of the degraded konjac gum was 0.5 wt%), so as to obtain fresh minced fish.

[0055] S3, drying and powdering: firstly the fresh minced fish of S2 was subjected to ultra-low temperature pre-freezing at a temperature of -60°C for 10 h, then the pre-frozen minced fish was freeze-dried at a vacuum degree of 25 Pa and a temperature of -30°C for 18 h, and then freeze-dried at a vacuum degree of 25 Pa and a temperature of 0°C for 28 h, and then crushed and passed through a 20-meshes sieve to obtain minced fish powder preservable at room temperature. Example 2

[0056] This example disclosed a method for preparing minced fish powder preservable at room temperature, and the specific steps were as follows:

[0057] SI. raw material pretreatment: muscle was removed from the back of fresh Trichiuridae, washed with ice water until the muscle was clean, and the muscle was cutted into blocks of 1-2 cm. The fish meat blocks were first stirred and rinsed with a sodium citrate aqueous solution in a concentration of 0.1% for 5 min, then stirred and rinsed with a calcium chloride aqueous solution in a concentration of 0.1 % for 10 min, and finally rinsed with distilled water repeatedly for 3 times, each rinsing time was 5 min, and the water temperature for rinsing was controlled at 4°C, so as to obtain pre-treated fish meat blocks.

[0058] S2. mixing and kneading: firstly, the pre-treated fish meat blocks of SI were pounded with nothing for 10 min; then the pounded minced fish was added with an aqueous solution of edible salt and pounded with salt for 10 min, wherein the addition amount of the edible salt was 2% of the mass of the fish meat; and finally the minced fish was added with the minced fish quality improver obtained in preparation example 2 and pounded with materials for 2 min (based on the mass percentage of the minced fish, the addition amount of the minced fish quality improver in terms of the degraded konjac gum was 2 wt%), so as to obtain fresh minced fish.

[0059] S3, drying and powdering: firstly the fresh minced fish of S2 was subjected to ultra-low temperature pre-freezing at a temperature of -80°C for 12 h, then the pre-frozen minced fish was freeze-dried at a vacuum degree of 28 Pa and a temperature of 0°C for 16 h, and then freeze-dried at a vacuum degree of 28 Pa and a temperature of 30°C for 30 h, and then crushed and passed through a 100-meshes sieve to obtain minced fish powder preservable at room temperature. Example 3

[0060] This example disclosed a method for preparing minced fish powder preservable at room temperature, and the specific steps were as follows:

[0061] SI. raw material pretreatment: muscle was removed from the back of fresh Muraenesox cinereus, washed with ice water until the muscle was clean, and the muscle was cut into blocks of 1-2 cm. The fish meat blocks were first stirred and rinsed with a sodium citrate aqueous solution in a concentration of 0.1% for 15 min, then rinsed with a calcium chloride aqueous solution in a concentration of 0.2% for 10 min, and finally stirred and rinsed with distilled water repeatedly for 3 times, each rinsing time was 5 min, and the water temperature for rinsing was controlled at 2°C, so as to obtain pre-treated fish meat blocks.

[0062] S2. mixing and kneading: firstly, the pre-treated fish meat blocks of SI were pounded with nothing for 5 min; then the pounded minced fish was added with an aqueous solution of edible salt and pounded with salt for 5 min, wherein the addition amount of the edible salt was 3% of the mass of the fish meat; and finally the minced fish was added with the minced fish quality improver obtained in preparation example 3 and pounded with materials for 8 min (based on the mass percentage of the minced fish, the addition amount of the minced fish quality improver in terms of the degraded konjac gum was 1 wt%), so as to obtain fresh minced fish. 10063] S3, drying and powdering: firstly the fresh minced fish of S2 was subjected to ultra-low temperature pre-freezing at a temperature of -70°C for 12 h, then the pre-frozen minced fish was freeze-dried at a vacuum degree of 20 Pa and a temperature of -10°C for 17 h, and then freeze-dried at a vacuum degree of 20 Pa and a temperature of10°C for 29 h, and then crushed and passed through a 50-meshes sieve to obtain minced fish powder preservable at room temperature. Comparative Example 1

[0064] The minced fish powder preservable at room temperature was prepared according to the method of Example 1, except that no minced fish quality improver was added, and the remaining conditions were the same as those of example 1. Thus the minced fish powder preservable at room temperature was obtained. Comparative Example 2

[0065] The minced fish powder preservable at room temperature was prepared according to the method of example 1, except that the minced fish quality improver obtained in preparation example 1 was replaced by the minced fish quality improver obtained in comparative preparation example 1 in the same parts by mass, and the remaining conditions were the same as those of Example 1. Thus the minced fish powder preservable at room temperature was obtained. Comparative Example 3

[0066] The minced fish powder preservable at room temperature was prepared according to the method of Example 1, except that the minced fish quality improver obtained in preparation example 1 was replaced by the minced fish quality improver obtained in comparative preparation example 2 in the same parts by mass, and the remaining conditions were the same as those of Example 1. Thus the minced fish powder preservable at room temperature was obtained. Comparative Example 4

[0067] The minced fish powder preservable at room temperature was prepared according to the method of Example 1, except that the minced fish quality improver obtained in preparation example 1 was replaced by the minced fish quality improver obtained in comparative preparation example 3 in the same parts by mass, and the remaining conditions were the same as those of Example 1. Thus the minced fish powder preservable at room temperature was obtained. Comparative Example 5

[0068] The minced fish powder preservable at room temperature was prepared according to the method of Example 1, except that the minced fish quality improver obtained in preparation example 1 was replaced by the minced fish quality improver obtained in comparative preparation example 4 in the same parts by mass, and the remaining conditions were the same as those of Example 1. Thus the minced fish powder preservable at room temperature was obtained. Comparative Example 6

[0069] The minced fish powder preservable at room temperature was prepared according to the method of Example 1, except that the minced fish quality improver obtained in preparation example 1 was replaced by the minced fish quality improver obtained in comparative preparation example 5 in the same parts by mass, and the remaining conditions were the same as those of Example 1. Thus the minced fish powder preservable at room temperature was obtained. Test Example

[0070] (1) The minced fish powder preservable at room temperature obtained in the aforementioned examples and comparative examples was stored at room temperature for 30 d, and was tested for physical and chemical properties (including the determination of salt-soluble protein content and whiteness) every 5 d. The specific testing method was as follows.

[0071] 1) Determination of salt-soluble protein content: 1 g of minced fish powder was weighed, added with 10 times the volume of a buffer ( 20mM Tris-HCl, pH 8.0, containing 0.6 M NaCl), homogenized at 10,000 r / min for 90 s, extracted at 4°C for 12 h, and centrifuged under conditions of 4°C and 12,000 r / min for 10 min. The obtained supernatant was determined for its protein content by a Coomassie Brilliant Blue method. The obtained results were as shown in FIG. 1.

[0072] 2) Determination of whiteness: I.*, a*, and b* values of the minced fish powder were measured by using a colorimeter. The formula for calculating the whiteness value was as follows: whiteness= 100 - (100 - L*)2 + a*2 + b*2. The obtained result was shown in FIG. 2.

[0073] (2) The minced fish powder preservable at room temperature obtained in the aforementioned examples and comparative examples were stored at room temperature for 30 d, and were determined for gel properties (including water holding capacity of the gel and gel strength) every 15 d. The specific method was as follows:

[0074] The minced fish powder preservable at room temperature was added with 4 times the volume of water and mixed evenly, then filled into a mold, heated and cooled to obtain a minced fish gel with a jelly-like texture.

[0075] 1) Determination of water holding capacity: The minced fish gel was cut into small long strips and recorded with a mass of Ml. The sample was wrapped with three layers of filter paper and placed into a 50 mL centrifuge tube, and centrifuged under conditions of 4°C and 5,000 xg for 15 min. The sample after centrifugation was weighed and recorded with the mass of M2. The formula for calculating water holding capacity was as follows:

[0076] Water holding capacity / % = M2 / M1 x 100%. The obtained results were as shown in FIG. 3.

[0077] 2) Determination of gel strength: the gel strength was measured by using a texture analyzer. The prepared minced fish gel was equilibrated at room temperature for 30 min. A P / 5s spherical probe was used with a pre-test rate of 1 mm / s, a test rate of 0.5 mm / s, a post-test rate of 2 mm / s, a deformation degree of 60%, and a trigger force of 5 gf. The formula for calculating the gel strength was as follows:

[0078] gel strength / (g x mm) = breaking force x breaking distance. The obtained results were as shown in FIG. 4.

[0079] FIG. I shows the change in the salt-soluble protein content of minced fish powder persevered at room temperature for 30 d. As can be seen from FIG. 1, compared with minced fish powder without addition of the quality improver, adding the minced fish quality improver of the present disclosure can delay the decrease in the salt-soluble protein content of minced fish powder during storage.

[0080] FIG. 2 shows the change in whiteness of minced fish powder persevered at room temperature for 30 d. As can be seen from FIG. 2, compared with minced fish powder without addition of the quality improver, adding the minced fish quality improver of the present disclosure can delay the decrease in the whiteness value of the minced fish powder during storage.

[0081] FIG. 3 shows the change in water holding capacity of a minced fish gel prepared from minced fish powder persevered at room temperature for 30 d. As can be seen from FIG. 3, compared with the minced fish gel without addition of the quality improver, adding the minced fish quality improver of the present disclosure can delay the decrease in water holding capacity of the minced fish gel.

[0082] FIG. 4 shows the change in gel strength of a minced fish gel prepared from minced fish powder persevered at room temperature for 30 d. As can be seen from FIG. 4, compared with the minced fish gel without addition of the quality improver, adding the minced fish quality improver of the present disclosure can delay the decrease in gel strength of the minced fish gel.

[0083] The aforementioned results show that the minced fish powder provided by the present disclosure still has the ability to form a minced fish gel after being preserved at room temperature for 30 d. Moreover, for storage at room temperature for 30 d, although the salt-soluble protein content, whiteness value, water holding capacity of the gel and gel strength of the minced fish powder provided by the present disclosure are decreased, they are still superior than those of the existing minced fish powder.

[0084] Although the embodiments of the present disclosure have been shown and described above, it is to be understood that the aforementioned embodiments are illustrative and are not to be construed as limitations on the present disclosure. Without departing from the principle and spirit of the present disclosure, changes, modifications, substitutions and variations can be made to the aforementioned embodiments within the scope of the present disclosure by those of room skills in the art.

Claims

WHAT IS CLAIMED IS:

1. A minced fish quality improver, containing gelatin, egg white protein, maltodextrin, glutamine transaminase, vitamin C, tea polyphenol, trehalose and degraded konjac gum at a mass ratio of 1 :(0.3-3):(0.5-5):(0.3-3):(0.5-5):(0.5-5):(0.5-5):(0.5-5).2.The minced fish quality improver according to claim 1, wherein the contents of the gelatin, the egg white protein and the glutamine transaminase are each independently 1 -3 parts by mass, and the contents of the maltodextrin, the vitamin C, the tea polyphenol, the trehalose and the degraded konjac gum are each independently 2-5 parts by mass.3.The minced fish quality improver according to claim 1, wherein the viscosity of the degraded konjac gum as a solution with a concentration of lwt% detected under a condition of 25°C is 2,000-4,000 mPa.s.

4. A method for preparing the minced fish quality improver according to any one of claims 1 -3, wherein the method comprises uniformly mixing gelatin, egg white protein, maltodextrin, glutamine aminotransferase, vitamin C, tea polyphenol, trehalose and degraded konjac gum.

5. The method for preparing the minced fish quality improver according to claim 4, wherein the method further comprises a step of preparing the degraded konjac gum by degrading konjac gum with an abalone visceral crude enzyme.

6. The method for preparing the minced fish quality improver according to claim 5, wherein an addition amount of the abalone visceral crude enzyme is 1-3 U / g.

7. The method for preparing the minced fish quality improver according to claim 5, wherein the abalone visceral crude enzyme is obtained by mixing abalone viscera with a phosphate buffer, then conducting tissue homogenizing, then centrifugally separating under a condition of 0°C-4°C to obtain supernatant, removing impurities and fishy odour from the obtained supernatant by using activated carbon, and then freeze-drying.

8. The method for preparing the minced fish quality improver according to claim 5, wherein conditions for the degradation comprise a temperature of 45°C-50°C and a time of 30-120 min.

9. A method for preparing minced fish powder preservable at room temperature, the method comprises sequentially subjecting a fish meat block to pounding with nothing, pounding with salt and pounding with materials to obtain minced fish, wherein the minced fish quality improver according to any one of claims 1 -3 is added during the process of pounding with materials, and subsequently drying and then sieving the minced fish to obtain the minced fish powder that is preservable at room temperature.

10. The method for preparing minced fish powder preservable at room temperature according to claim 9, wherein the fish meat block is a fresh fish meat block; the fish meat block is selected from at least one of a Nemipterus virgatus block, a Trichiuridae block, and a Muraenesox cinereus block.

11. The method for preparing minced fish powder preservable at room temperature according to claim 10, wherein the fresh fish meat block is obtained according to the following method: removing muscle from the back of a fish, washing the muscle with ice water until the muscle is clean, then cutting the muscle into small blocks, rinsing the small blocks in a rinsing liquid, and then drying by draining.

12. The method for preparing minced fish powder preservable at room temperature according to claim 11, wherein an addition amount of the rinsing liquid is 1-10 times the mass of the fish meat block.

13. The method for preparing minced fish powder preservable at room temperature according to claim 11, wherein a temperature of the rinsing is 0-4°C.

14. The method for preparing minced fish powder preservable at room temperature according to claim 11, wherein steps of the rinsing are to first employ a sodium citrate aqueous solution with a concentration of 0.05-0.2% for stirring and rinsing for 5-15 min, then employ a calcium chloride aqueous solution with a concentration of 0.1 -0.2% for stirring and rinsing for 5-15 min, and finally employ distilled water for repeatedly rinsing for 1-5 times with a time of each rinsing being 1-10 min.

15. The method for preparing minced fish powder preservable at room temperature according to claim 9, wherein the pounding with nothing, the pounding with salt and the pounding with materials are carried out in a mixing and kneading machine.

16. The method for preparing minced fish powder preservable at room temperature according to claim 9, wherein the pounding with salt is carried out in the following manner: dissolving edible salt in water, and then adding the solution to the minced fish along with ice water, wherein a moisture content of the minced fish is controlled at 80-85%, and an addition amount of the edible salt is 2-3% of the mass of the fish meat after drying by draining.

17. The method for preparing minced fish powder preservable at room temperature according to claim 9, wherein a time of the pounding with nothing is 5-10 min.

18. The method for preparing minced fish powder preservable at room temperature according to claim 9, wherein a time of the pounding with salt is 2-10 min.

19. The method for preparing minced fish powder preservable at room temperature according to claim 9, wherein a time of the pounding with materials is 2-10 min.

20. The method for preparing minced fish powder preservable at room temperature according to claim 9, wherein based on the mass percentage of the minced fish, an addition amount of the minced fish quality improver in terms of the degraded konjac gum is 0.5-2 wt%.

21. The method for preparing minced fish powder preservable at room temperature according to claim 9, wherein the drying manner is freeze drying.

22. The method for preparing minced fish powder preservable at room temperature according to claim 21, wherein the drying manner and condition enable the water content of the minced fish to be controlled at 1-3%.

23. The method for preparing minced fish powder preservable at room temperature according to claim 21, wherein the freeze drying is carried out in the following manner: the minced fish is first subjected to ultra-low temperature pre-freezing at a temperature of -60°C ~ -80°C for 10-12 h to obtain pre-frozen minced fish, and then the pre-frozen minced fish is first freeze-dried at a vacuum degree below 30 Pa and a temperature of -30°C~0°C for 16-18 h to obtain previously freeze-dried minced fish, and then the previously freeze-dried minced fish is freeze-dried at a vacuum degree below 30 Pa and a temperature of 0°C-30°C for 28-30 h.

24. The method for preparing minced fish powder preservable at room temperature according to claim 21, wherein a mesh size employed for the sieving is 20-100 meshes.

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