Preparation method of normal-temperature frozen krill

Abstract

The present application belongs to the technical field of aquatic product processing, and relates to a preparation method of normal-temperature frozen krill, comprising the following steps: centrifuging precipitated protein after protein isoelectric point precipitation of krill slurry to obtain the precipitated protein, mixing the precipitated protein, milk and water, and then performing first high-pressure homogenization, then performing fermentation by using lactic acid bacteria, then adding a gelling agent and an acidity regulator, and then performing second high-pressure homogenization after uniform mixing; the gelling agent at least comprises deacetylated konjac glucomannan, k-carrageenan and hyaluronic acid. Compared with traditional krill products, the present application improves protein solubility and gel stability in the process of protein isoelectric point precipitation and fluorine removal of krill protein by twice high-pressure homogenization and synergistic effect of deacetylated konjac glucomannan, k-carrageenan and hyaluronic acid, simultaneously improves product flavor by adding milk and lactic acid bacteria fermentation, widens the application range of krill products, and enables normal-temperature storage, thereby effectively reducing storage and transportation energy consumption.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aquatic product processing, and particularly relates to a preparation method of normal-temperature Euphausia superba jelly. BACKGROUND

[0002] Euphausia superba is a kind of crustacean similar to shrimp, also known as "black-eyed shrimp", and is widely distributed in the Southern Ocean around the Antarctic. It is a unique aquatic product in the Antarctic sea area. The biomass of Euphausia superba is huge, estimated to be 10 to 20 billion tons, and the annual sustainable catch is about 1 to 2 billion tons. Euphausia superba has the characteristics of typical high protein and low fat, contains 8 essential amino acids required by the human body in a balanced manner, and is an ideal food protein source for humans. In addition, Euphausia superba also contains rich mineral elements, astaxanthin, polyunsaturated fatty acids and other active substances, and is hailed as the ideal food of the future for humans.

[0003] However, the fluorine content of Euphausia superba is extremely high, up to 350 mg / 100 g dry basis. The daily intake of fluorine for an adult is only 3-5 mg / kg, and the consumption of Euphausia superba without certain treatment can easily cause excessive intake of fluorine and cause fluorosis. The fluorine in Euphausia superba mainly exists on the shell, but due to the presence of highly active proteases in the body, the fluorine in the shell of Euphausia superba after death is easily dissolved into the shrimp meat, greatly limiting the development and application of Euphausia superba in food. In view of this problem, domestic and foreign scholars have developed a preparation method of Euphausia superba protein isolate based on protein isoelectric point precipitation. By adjusting the acid or alkali environment of the feed liquid to be far away from the isoelectric point of the protein, the protein is dissolved, the shell is removed, and then the isoelectric point is adjusted, and finally the precipitated protein with low fluorine content is obtained. However, although this method can effectively obtain low-fluorine-content protein isolate, the solubility and gel stability of the obtained protein are often poor, and further improvement is urgently needed.

[0004] As a kind of leisure snack, jelly is deeply loved by consumers because of its convenient consumption, smooth taste and delicious taste. Preparing gel food made of aquatic products into gel jelly food not only can improve the nutritional value of jelly, but also can further enrich the product form of jelly. At present, the gel food made of aquatic products mainly includes fish balls, fish intestines and shrimp paste. However, aquatic products have obvious fishy smell, and if they are directly processed by traditional processing and added into jelly, the taste and flavor of jelly will be seriously affected. Therefore, how to obtain normal-temperature Euphausia superba jelly with good protein solubility and gel stability and ensure its excellent taste is a key technical bottleneck in this field. SUMMARY

[0005] The present application aims to overcome the defects of poor protein solubility and gel stability caused by the isoelectric point precipitation of phosphorus shrimp protein, and provides a preparation method of room temperature phosphorus shrimp jelly, which can effectively obtain low-fluorine content of isolated protein, and has good protein solubility and gel stability and good taste of room temperature phosphorus shrimp jelly, which not only realizes the room temperature storage of phosphorus shrimp products, but also expands the market application range of phosphorus shrimp products.

[0006] The present application aims to overcome the defects of poor protein solubility and gel stability caused by the isoelectric point precipitation of phosphorus shrimp protein, and provides a preparation method of room temperature phosphorus shrimp jelly, which can effectively obtain low-fluorine content of isolated protein, and has good protein solubility and gel stability and good taste of room temperature phosphorus shrimp jelly, which not only realizes the room temperature storage of phosphorus shrimp products, but also expands the market application range of phosphorus shrimp products.

[0007] In order to achieve the above-mentioned application purpose, the present application provides a preparation method of room temperature phosphorus shrimp, comprising the following steps:

[0008] S1, isoelectric point precipitation: the pH value of the krill slurry is adjusted to alkaline by alkali, then the obtained filtrate is adjusted to isoelectric point precipitation by acid, and then the precipitated protein is obtained by centrifugation;

[0009] S2, first high-pressure homogenization: the precipitated protein, milk and water are mixed to form a slurry, and then the slurry is subjected to first high-pressure homogenization, and then the obtained homogenized liquid is heated and cooled to room temperature to obtain a krill protein solution;

[0010] S3, fermentation: the krill protein solution is fermented by lactic acid bacteria to obtain a krill protein fermentation liquor;

[0011] S4, sol: the sweetener and the gelling agent, which at least simultaneously contains deacetylated konjac glucomannan, k-carrageenan and hyaluronic acid, are dissolved in water under stirring, and then the obtained sol is heated and boiled to obtain a boiled sol;

[0012] S5, blending: the krill protein fermentation liquor, the boiled sol, the acidity regulator and the optional auxiliary materials are mixed uniformly to obtain a blending liquor;

[0013] S6, second high-pressure homogenization: the blending liquor is subjected to second high-pressure homogenization.

[0014] In a preferred embodiment, in step S1, the krill slurry is a pretreated slurry obtained by adding ice water to the thawed Antarctic krill and stirring to form a mud-like mass.

[0015] In a preferred embodiment, in step S1, the amount of ice water added is 1-5 times, more preferably 2 times, the mass of the frozen Antarctic krill.

[0016] In a preferred embodiment, in step S1, the operating conditions of the stirring include a water temperature of 0-4°C.

[0017] In a preferred embodiment, in step S1, the alkali is selected from at least one of sodium carbonate, potassium carbonate, ammonium sulfate, sodium hydroxide and potassium hydroxide.

[0018] In a preferred embodiment, in step S1, the concentration of the alkali is 0.5-2M.

[0019] In a preferred embodiment, in step S1, the pH value of the alkali is adjusted to 10.0-12.0.

[0020] In a preferred embodiment, in step S1, the acid is selected from one or a combination of several of hydrochloric acid, phosphoric acid and acetic acid.

[0021] In a preferred embodiment, in step S1, the concentration of the acid is 0.5-2M.

[0022] In a preferred embodiment, in step S1, the pH value of the acid solution is adjusted to 5.0-6.0.

[0023] In a preferred embodiment, in step S2, the operating conditions of the first high-pressure homogenization include a pressure of 50-70 MPa and a homogenization time of 3-5 min.

[0024] In a preferred embodiment, in step S2, the amount of the precipitated protein added is 18-50 parts by weight relative to 100 parts by weight of water.

[0025] In a preferred embodiment, in step S2, the milk is pasteurized fresh milk and / or ultra-high-temperature instant sterilized whole milk.

[0026] In a preferred embodiment, in step S2, the amount of the milk added is 2-4 times the weight of the precipitated protein.

[0027] In a preferred embodiment, in step S2, the heating conditions include a temperature of 95-100°C and a time of 5-15 min.

[0028] In a preferred embodiment, in step S3, the lactic acid bacteria are direct-vat-set lactic acid bacteria starter cultures.

[0029] In a preferred embodiment, in step S3, the fermentation conditions include a temperature of 30-40°C and a time of 10-15 hours.

[0030] In a preferred embodiment, in step S3, the viable cell count of the fermention solution of the krill protein is (1-3)×10 9 In a preferred embodiment, in step S3, the viable cell count of the fermention solution of the krill protein is (1-3)×10

[0031] In a preferred embodiment, in step S4, the sweetener is at least one selected from the group consisting of white granulated sugar, trehalose, maltose, glucose, xylitol, sorbitol, and sucralose.

[0032] In a preferred embodiment, in step S4, the amount of the sweetener added is 18-65 parts by weight relative to 100 parts by weight of water.

[0033] In a preferred embodiment, in step S4, the amount of the gelling agent added is 3-9 parts by weight relative to 100 parts by weight of water.

[0034] In a preferred embodiment, in step S4, the gelling agent is a combination of deacetylated konjac glucomannan, k-carrageenan, and hyaluronic acid at a weight ratio of 1:(0.3-0.8):(0.05-0.15).

[0035] In a preferred embodiment, in step S4, the conditions of the boiling include heating the boiling to 80-90℃ for 10-15 min.

[0036] In a preferred embodiment, in step S4, the boiling sol maintains a temperature of 70-80℃.

[0037] In a preferred embodiment, in step S5, the acidity regulator is a combination of citric acid and sodium citrate in a weight ratio of 1:(0.1-1).

[0038] In a preferred embodiment, in step S5, the acidity regulator is added in an amount of 5-15 parts by weight relative to 100 parts by weight of water.

[0039] In a preferred embodiment, in step S5, the auxiliary material is selected from one or more of preservatives, leavening agents, coloring agents, stabilizers, coagulants, and emulsifiers.

[0040] In a preferred embodiment, in step S5, the auxiliary material is added in an amount of 0.1-1 parts by weight relative to 100 parts by weight of water.

[0041] In a preferred embodiment, in step S6, the operating conditions of the second high-pressure homogenization include a pressure of 50-70 MPa and a homogenization time of 3-5 min.

[0042] In a preferred embodiment, the method for preparing the normal-temperature krill jelly further comprises, after the second high-pressure homogenization, sequentially performing the steps of filling, sterilization, and cooling.

[0043] Compared with the prior art, the present application improves the protein solubility and gel stability in the process of defluorination of krill protein by two high-pressure homogenizations and the synergistic effect of deacetylated konjac glucomannan, k-carrageenan, and hyaluronic acid, and significantly improves the flavor of the product and enables it to be stored at normal temperature by adding milk and using lactic acid bacteria fermentation. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The water holding capacity of the normal-temperature krill jelly. DETAILED DESCRIPTION

[0045] The method for preparing the normal-temperature krill provided by the present application comprises the following steps:

[0046] S1, isoelectric point precipitation: adjusting the pH value of the krill slurry to alkaline using alkali, filtering, adjusting the pH value of the obtained filtrate to the isoelectric point using acid, and then centrifuging to obtain the precipitated protein;

[0047] S2, first high-pressure homogenization: the precipitated protein and milk and water are mixed into a homogenate, and then the obtained homogenate is heated and cooled to room temperature to obtain a phosphorus shrimp protein solution;

[0048] S3, fermentation: the phosphorus shrimp protein solution is fermented by lactic acid bacteria to obtain a phosphorus shrimp protein fermentation liquor;

[0049] S4, sol: the sweetener and the gelling agent, which at least simultaneously contains deacetylated konjac glucomannan, k-carrageenan and hyaluronic acid, are dissolved in water under stirring, and then the obtained sol is heated and boiled to obtain a boiled sol;

[0050] S5, blending: the phosphorus shrimp protein fermentation liquor, the boiled sol, the acidity regulator and the optional auxiliary materials are mixed uniformly to obtain a blending liquor;

[0051] S6, second high-pressure homogenization: the blending liquor is subjected to second high-pressure homogenization.

[0052] In the preparation method of the above-mentioned normal-temperature phosphorus shrimp frozen product, in step S1, the phosphorus shrimp slurry can be a pretreated slurry obtained by adding ice water to the thawed Antarctic krill and stirring to form a mud group, can be a pretreated slurry obtained by stirring fresh Antarctic krill to form a mud group, or can be a purchased Antarctic krill mud. When the phosphorus shrimp slurry is obtained by adding ice water to the thawed Antarctic krill and stirring to form a mud group, the addition amount of the ice water is preferably 1-5 times the mass of the frozen Antarctic krill, such as 1, 2, 3, 4, 5 times or any value therebetween, and more preferably 2 times. The operating conditions of the stirring include a water temperature of preferably 0-4℃, such as 0℃, 1℃, 2℃, 3℃, 4℃ or any value therebetween.

[0053] In the preparation method of the above-mentioned normal-temperature phosphorus shrimp frozen product, in step S1, specific examples of the alkali solution include, but are not limited to, at least one of sodium carbonate, potassium carbonate, ammonium sulfate, sodium hydroxide and potassium hydroxide. The concentration of the alkali solution is preferably 0.5-2M, such as 0.5M, 1.0M, 1.5M, 2.0M or any value therebetween. The pH value adjusted by the alkali solution is preferably 10.0-12.0, such as 10.0, 10.5, 11.0, 11.5, 12.0 or any value therebetween. The inventors of the present application have found through in-depth research that the fluorine in Antarctic krill mainly exists on the shell, and most of the fluorine in Antarctic krill meat is transferred from the shell. It mainly exists in a free state and can be easily removed by the ionization of chemicals. At this time, the pH value is adjusted by the alkali solution to dissolve and separate the soluble protein, and the insoluble residue is removed by solid-liquid separation, which is the first step of the protein isoelectric point precipitation separation phosphorus shrimp protein defluorination process.

[0054] In the preparation method of the frozen krill at room temperature, in step S1, specific examples of the acid solution include, but are not limited to, one or a combination of hydrochloric acid, phosphoric acid and acetic acid. The concentration of the acid solution is preferably 0.5-2M, such as 0.5M, 1.0M, 1.5M, 2.0M or any value therebetween. The pH value of the acid solution is preferably adjusted to 5.0-6.0, such as 5.0, 5.2, 5.4, 5.6, 5.8, 6.0 or any value therebetween. In the second step of the defluorination process of the krill protein by isoelectric point precipitation separation, the filtrate obtained by filtration is adjusted to the isoelectric point by the acid solution to precipitate, and the obtained solid is a low-fluorine krill protein solution.

[0055] In the preparation method of the frozen krill at room temperature, in step S2, the operating conditions of the first high-pressure homogenization include a pressure of preferably 50-70MPa, such as 50MPa, 55MPa, 60MPa, 65MPa, 70MPa or any value therebetween; and a homogenization time of preferably 3-5min, such as 3min, 3.5min, 4min, 4.5min, 5min or any value therebetween. In the high-pressure homogenization process, due to the special structure of the homogenization valve in the high-pressure homogenizer, three effects are produced: cavitation effect, explosion effect and shear effect, thereby achieving the effects of emulsification, homogenization and dispersion of the protein solution.

[0056] In the preparation method of the frozen krill at room temperature, in step S2, the addition amount of the precipitated protein is preferably 18-50 parts by weight, such as 18, 20, 25, 30, 35, 40, 45, 50 parts by weight or any value therebetween, relative to 100 parts by weight of water.

[0057] In the preparation method of the frozen krill at room temperature, in step S2, the milk is preferably fresh milk subjected to pasteurization and / or full-fat milk subjected to ultra-high-temperature instant sterilization. The emulsification of milk protein in natural milk is better than that in formulated milk, so a specific milk is selected. The addition amount of the milk is preferably 2-4 times the weight of the precipitated protein, such as 2 times, 2.5 times, 3 times, 3.5 times, 4 times or any value therebetween. At this time, the milk is uniformly distributed in the system, which can effectively improve the flavor and taste of the krill at room temperature.

[0058] In the preparation method of the frozen krill at room temperature, in step S2, the heating conditions include a temperature of preferably 95-100℃, such as 95℃, 96℃, 97℃, 98℃, 99℃, 100℃ or any value therebetween; and a time of preferably 5-15min, such as 5min, 7min, 9min, 11min, 13min, 15min or any value therebetween.

[0059] In the preparation method of the normal-temperature krill frozen product, in step S3, the lactic acid bacteria preferably uses a direct-vat lactic acid bacteria starter. The fermentation conditions include a temperature of 30-40°C, such as 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, or any value therebetween; and a time of 10-15 hours, such as 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or any value therebetween. In addition, the viable cell count of the krill protein fermentation liquor preferably reaches (1-3)×10 9 9 9 9

[0060] In the preparation method of the normal-temperature krill frozen product, in step S4, specific examples of the sweetener include, but are not limited to, at least one of white granulated sugar, trehalose, maltose, glucose, xylitol, sorbitol, and sucralose. In step S4, the sweetener is preferably added in an amount of 18-65 parts by weight, such as 18, 20, 25, 30, 35, 40, 45, 50, 60, 65 parts by weight, or any value therebetween, relative to 100 parts by weight of water.

[0061] In the preparation method of the normal-temperature krill frozen product, in step S4, the gelling agent includes at least deacetylated konjac glucomannan, k-carrageenan, and hyaluronic acid, and preferably a combination of deacetylated konjac glucomannan, k-carrageenan, and hyaluronic acid. In step S4, the gelling agent is preferably added in an amount of 3-9 parts by weight, such as 3, 4, 5, 6, 7, 8, 9 parts by weight, or any value therebetween, relative to 100 parts by weight of water. The weight ratio of deacetylated konjac glucomannan to k-carrageenan in the gelling agent is preferably 1:(0.3-0.8), such as 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, or any value therebetween; and the weight ratio of deacetylated konjac glucomannan to hyaluronic acid in the gelling agent is preferably 1:(0.05-0.15), such as 1:0.05, 1:0.07, 1:0.09, 1:0.11, 1:0.13, 1:0.15, or any value therebetween. The use of deacetylated konjac glucomannan and k-carrageenan in combination in the gelling agent can significantly enhance the gel strength, and the combination with hyaluronic acid can produce a synergistic effect, making the gel more elastic and reducing the water separation phenomenon, which is conducive to enhancing the gel stability of the product.

[0062] ​​​​In the preparation method of the normal-temperature shrimp jelly, in step S4, the boiling conditions include a heating boiling temperature preferably at 80-90°C, such as 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, or any value between them; and a duration preferably at 10-15 min, such as 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, or any value between them. In addition, in step S4, the boiling sol maintains a temperature preferably at 70-80°C, such as 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, or any value between them. In step S4, the stirring conditions include a rotation speed preferably at 800-1000 rpm, such as 800, 850, 900, 950, 1000 rpm, or any value between them.

[0063] In the preparation method of the normal-temperature shrimp jelly, in step S5, the acidity regulator is preferably a combination of citric acid and sodium citrate, with a weight ratio preferably at 1:(0.1-1), such as 1:0.1, 1:0.3, 1:0.5, 1:0.7, 1:0.9, 1:1, or any value between them. In step S5, the acidity regulator is added in an amount preferably at 5-15 parts by weight, such as 5, 7, 9, 11, 13, 15 parts by weight, or any value between them, relative to 100 parts by weight of water.

[0064] In the preparation method of the normal-temperature shrimp jelly, in step S5, specific examples of the auxiliary material include, but are not limited to, one or several of preservatives, leavening agents, coloring agents, stabilizers, coagulants, and emulsifiers. In step S5, the auxiliary material is added in an amount preferably at 0.1-1 parts by weight, such as 0.1, 0.3, 0.5, 0.7, 0.9, 1 part by weight, or any value between them, relative to 100 parts by weight of water.

[0065] In the preparation method of the normal-temperature shrimp jelly, in step S5, the shrimp protein fermentation liquor, the boiling sol, the acidity regulator, and the optional auxiliary material are mixed uniformly to obtain a dispensing material liquid; wherein the mixing manner can be that all the raw materials are simultaneously fed and mixed together, or that part of the raw materials are fed and mixed first in any order, and then the remaining raw materials are added and mixed, without particular limitation. The mixing manner is preferably performed according to the following steps: the acidity regulator is dissolved in hot water, and then slowly added into the boiling sol while stirring; the shrimp protein fermentation liquor is added while stirring, and stirred and dissolved uniformly to obtain the dispensing material liquid.

[0066] In the preparation method of the normal-temperature krill jelly, in step S6, the operating conditions of the high-pressure homogenization include a pressure of 50-70 MPa, such as 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa or any value therebetween; and a homogenization time of 3-5 min, such as 3 min, 3.5 min, 4 min, 4.5 min, 5 min or any value therebetween.

[0067] In the preparation method of the normal-temperature krill jelly, the method further includes, after the second high-pressure homogenization, sequentially performed filling, sterilization and cooling steps. The filling is preferably filling and sealing of the material after the high-pressure homogenization on a jelly filling machine. The net content of the filling is preferably 10-40 g per piece, such as 10 g per piece, 20 g per piece, 30 g per piece, 40 g per piece or any value therebetween. The sterilization is preferably pasteurization of the filled product. The operating conditions of the sterilization include a temperature of 80-90℃, such as 80℃, 82℃, 84℃, 86℃, 88℃, 90℃ or any value therebetween; and a time of 10-20 min, such as 10 min, 12 min, 14 min, 16 min, 18 min, 20 min or any value therebetween. The cooling is preferably cooling of the product after the sterilization with water, to obtain the normal-temperature krill jelly.

[0068] The following will be described in detail through examples.

[0069] Example 1

[0070] A preparation method of a normal-temperature krill jelly, including the following steps:

[0071] S1, isoelectric point precipitation: after the frozen Antarctic krill is thawed, 2 times the mass of ice water is added to stir into a mud-like mass, and the water temperature is controlled to be 0℃, to obtain krill slurry; the krill slurry is adjusted to pH 11.0 with 1M NaOH, filtered with gauze, and then the filtrate is adjusted to pH 6.0 for isoelectric point precipitation, and then the precipitated protein is obtained by centrifugation;

[0072] S2, first high-pressure homogenization: 40g of the precipitated protein is added into a mixed solution of 80g of pasteurized fresh milk and 80g of distilled water, homogenized, and then poured into a high-pressure homogenizer for homogenization treatment at 60MPa for 5min, to prepare a uniform protein solution for standby use; then heated at 100℃ for 10min, and finally cooled to room temperature, to obtain a krill protein solution;

[0073] S3, fermentation: the krill protein solution is added with a direct-vat starter of lactic acid bacteria and stirred uniformly, and then fermented at 37℃ for 12h, to obtain a krill protein fermentation liquor with a viable bacterial count of 1×10 9

[0074] ​S4, Sol: 4g of deacetylated konjac glucomannan, 2.4g of k-carrageenan, 0.4g of hyaluronic acid and 40g of white granulated sugar were weighed according to the formula, and slowly and uniformly poured into 100g of water. To prevent caking, it needs to be stirred at high speed (1000rpm) while pouring. After the colloid was dissolved uniformly, it was slowly poured into a pot and heated to 85℃ for about 15min. The water was cooled quickly to 75℃, and a cooked sol was obtained;

[0075] S5, Dispensing: 2g of citric acid and 2g of sodium citrate were dissolved in 40g of hot water, and slowly added to the cooked sol. Stirring was performed during the addition to prevent local pH from being too low to cause colloid damage. The phosphor shrimp protein fermentation liquor was added while stirring to obtain a dispensing solution;

[0076] S6, Second high-pressure homogenization: The dispensing solution was homogenized by a high-pressure homogenizer at 60MPa for 5min to make the product more stable and obtain a smoother taste. A homogenized material was obtained;

[0077] S7, Filling: The homogenized material was filled and sealed on a jelly filling machine to obtain a filled product. The net content of the filled product was 40g per piece according to the design;

[0078] S8, Sterilization: After filling, the filled product was subjected to pasteurization at 85℃ for 15min to obtain a sterilized product;

[0079] S9, Cooling: The sterilized product was cooled with water to obtain a room temperature phosphor shrimp jelly.

[0080] Example 2

[0081] A preparation method of a room temperature phosphor shrimp jelly, comprising the following steps:

[0082] S1, Isoelectric point precipitation: After the frozen Antarctic krill was thawed, 2 times the mass of ice water was added and stirred into a mud-like mass. The water temperature was controlled at 2℃. A phosphor shrimp slurry was obtained. The pH of the phosphor shrimp slurry was adjusted to 11.0 with 1M NaOH. The filtrate was filtered with gauze, and then the pH was adjusted to 6.0 with 1M HCl for isoelectric point precipitation. The precipitated protein was obtained by centrifugation;

[0083] S2, First high-pressure homogenization: 66g of precipitated protein was added to a mixed solution of 190g of pasteurized fresh milk and 300g of distilled water. After homogenization, it was poured into a high-pressure homogenizer and homogenized at 60MPa for 5min to prepare a uniform protein solution for standby. It was heated at 100℃ for 10min, and then cooled to room temperature to obtain a phosphor shrimp protein solution;

[0084] S3, fermentation: adding direct-vat lactic acid bacteria starter into the krill protein solution and stirring uniformly, and then fermenting at 37℃ for 15h to obtain a krill protein fermentation liquor with a viable cell count of 2×10 9

[0085] S4, sol: weighing 6.3g deacetylated konjac glucomannan, 1.8g k-carrageenan, 0.6g hyaluronic acid and 65g white granulated sugar according to the formula, and slowly and uniformly pouring them into 100g water; to prevent caking, high-speed (1000rpm) stirring is required while pouring; then slowly pouring the mixture into a pot, heating and boiling to 100℃ for about 20min, and then rapidly cooling to 70℃ to obtain a boiled sol;

[0086] S5, blending: dissolving 1.8g citric acid and 1.8g sodium citrate in 36g hot water, and then slowly adding the boiled sol while stirring to prevent local pH from being too low to cause colloid damage; then adding the krill protein fermentation liquor while stirring to obtain a blended liquid;

[0087] S6, second high-pressure homogenization: homogenizing the blended liquid at 60MPa for 5min by using a high-pressure homogenizer to make the product more stable and obtain a smoother taste to obtain a homogenized material;

[0088] S7, filling: filling and sealing the homogenized material on a jelly filling machine to obtain a filled product, and the net content of the filled product is designed to be 20g per piece;

[0089] S8, sterilization: performing pasteurization on the filled product after filling at a temperature of 80℃ for 20min to obtain a sterilized product;

[0090] S9, cooling: cooling the sterilized product with water to obtain a room-temperature krill jelly.

[0091] Example 3

[0092] A method for preparing a room-temperature krill jelly, comprising the following steps:

[0093] S1, isoelectric point precipitation: after thawing the frozen Antarctic krill, adding 2 times the mass of ice water to stir into a mud-like mass, and controlling the water temperature to be 4℃ to obtain a krill slurry; adjusting the pH of the krill slurry to 11.0 with 1M NaOH, filtering with gauze, and then adjusting the pH of the filtrate to 6.0 with 1M HCl for isoelectric point precipitation, and then centrifuging to obtain precipitated protein;

[0094] ​S2, first high pressure homogenization: take 18 g of precipitated protein and add it to a mixed solution of 72 g of pasteurized fresh milk and 100 g of distilled water, homogenize and pour into a high pressure homogenizer, homogenize at 60 MPa for 5 min, prepare a uniform protein solution for standby; then heat at 100℃ for 10 min, and finally cool to room temperature to obtain a krill protein solution;

[0095] S3, fermentation: add a direct-vat fermentation starter to the krill protein solution and stir evenly, ferment at 37℃ for 12 h to obtain a krill protein fermentation liquor with a viable cell count of 1×10 9

[0096] S4, sol: weigh 1.9 g of deacetylated konjac glucomannan, 1.5 g of k-carrageenan, 0.2 g of hyaluronic acid and 18 g of white granulated sugar according to the formula, slowly and uniformly pour into 100 g of water, to prevent caking, high speed (1000 rpm) stirring is required, until the colloid is dissolved evenly; then slowly pour it into a pot, heat and cook to 100℃ for about 20 min, quickly cool to 70℃, and obtain a cooked sol;

[0097] S5, blending: dissolve 1.6 g of citric acid and 1.6 g of sodium citrate in 32 g of hot water, slowly add the cooked sol, stir while adding to prevent local pH from being too low and causing colloid damage, then add the krill protein fermentation liquor while stirring to dissolve evenly, and obtain a blending liquor;

[0098] S6, second high pressure homogenization: pass the blending liquor through a high pressure homogenizer at 60 MPa for 5 min to make the product more stable and obtain a smoother mouthfeel, and obtain a homogenized material;

[0099] S7, filling: fill and seal the homogenized material in a jelly filling machine to obtain a filled product, with a designed net content of 30 g per piece;

[0100] S8, sterilization: after filling, the filled product is pasteurized at 90℃ for 10 min to obtain a sterilized product;

[0101] S9, cooling: cool the sterilized product with water to obtain a room temperature krill jelly.

[0102] Comparative Example 1

[0103] Prepare a room temperature krill jelly according to the method of Example 1, except that in step S1, the isoelectric point precipitation treatment is not performed, and the krill slurry is directly subjected to the first high pressure homogenization of step S2, and the other conditions remain unchanged.

[0104] Comparative Example 2 ​

[0105] The normal temperature shrimp jelly was prepared according to the method of Example 1, except that in step S2, the amount of milk added was 0, and the other conditions were the same as in Example 1.

[0106] Comparative Example 3

[0107] The normal temperature shrimp jelly was prepared according to the method of Example 1, except that in step S3, no direct-vat lactic acid bacteria starter was added for fermentation, and the shrimp protein solution was directly added to step S5, and the other conditions were the same as in Example 1.

[0108] Comparative Example 4

[0109] The normal temperature shrimp jelly was prepared according to the method of Example 1, except that in steps S2 and S6, high-pressure homogenization was not used, but conventional stirring (500 rpm for 10 min) was used, and the other conditions were the same as in Example 1.

[0110] Comparative Example 5

[0111] The normal temperature shrimp jelly was prepared according to the method of Example 1, except that in step S4, deacetylated konjac glucomannan, k-carrageenan, and hyaluronic acid were all replaced with xanthan gum, and the other conditions were the same as in Example 1.

[0112] Comparative Example 6

[0113] The normal temperature shrimp jelly was prepared according to the method of Example 1, except that in step S4, deacetylated konjac glucomannan was replaced with k-carrageenan of the same weight, and the other conditions were the same as in Example 1.

[0114] Comparative Example 7

[0115] The normal temperature shrimp jelly was prepared according to the method of Example 1, except that in step S4, k-carrageenan was replaced with deacetylated konjac glucomannan of the same weight, and the other conditions were the same as in Example 1.

[0116] Comparative Example 8

[0117] The normal temperature shrimp jelly was prepared according to the method of Example 1, except that in step S4, k-carrageenan was replaced with lambda carrageenan of the same weight, and the other conditions were the same as in Example 1.

[0118] Comparative Example 9

[0119] The normal temperature shrimp jelly was prepared according to the method of Example 1, except that in step S4, no hyaluronic acid was added, and the other conditions were the same as in Example 1.

[0120] Test Example

[0121] (1) Sensory test: sensory evaluation was performed on the obtained normal temperature shrimp jelly samples of each example and the comparative example, and then comprehensive evaluation was performed according to indexes such as color, texture state and smell of the jelly. The specific evaluation criteria were as follows: texture state - uniform, no cracks, no bubbles; smell - special fermentation aroma held by lactic acid bacteria. The results are shown in Table 1.

[0122] (2) Fluorine content test: according to GB / T 5009.18-2003 "Method for determination of fluorine in food", the fluorine content of the obtained normal temperature shrimp jelly samples of each example and the comparative example was detected by using a fluorine ion selective electrode, so as to determine the fluorine content (mg / kg) of the normal temperature shrimp jelly samples. The results are shown in Table 2.

[0123] (3) Texture property test: the normal temperature shrimp jelly samples were cut into cylinders with a diameter of 3 cm and a height of 3 cm, and a texture analyzer was used to perform TPA test. The test parameters were as follows: P / 36R cylindrical probe, pre-test speed and test speed were both 1 mm / s, post-test speed was 2 mm / s, deformation degree was 50%, trigger force was 5 gf, and the hardness (N), elasticity (mm) and chewiness (N) of the normal temperature shrimp jelly samples were recorded. Each group of experiments was repeated for 3 times, and the average value was taken. The results are shown in Table 2.

[0124] (4) Gel strength test: the normal temperature shrimp jelly samples were cut into cylinders with a diameter of 3 cm and a height of 3 cm, and a texture analyzer was used to perform gel strength test. The test parameters were as follows: P / 5s spherical probe, pre-test speed was 1 mm / s, test speed was 0.5 mm / s, post-test speed was 2 mm / s, deformation degree was 50%, trigger force was 5 gf, and the first peak value (breaking force) and positive peak height (breaking distance) were recorded. The gel strength was calculated according to the following formula:

[0125] Gel strength (N*mm) = breaking force (N) x breaking distance (mm)

[0126] (5) Water holding capacity test: about 2 g of gel was weighed and cut into a strip, and the initial weight M was recorded. The gel was wrapped with three layers of filter paper and put into a 50 mL centrifuge tube, and then centrifuged at 4℃ and 5000 x g for 15 min. The weight of the sample after centrifugation was recorded as m. The water holding capacity (WHC, %) of the normal temperature shrimp jelly samples was calculated according to Formula (I). The results are shown in Table 2. Figure 1 .

[0127]

[0128] Table 1

[0129]

[0130] Table 2

[0131] Indicator Fluorine content (mg / kg) Hardness (N) Elasticity (mm) Chewiness (N) Gel strength (N*mm) Example 1 1.20±0.02 45.45±2.72 0.84±0.01 23.04±1.06 6.13±0.02 Example 2 1.31±0.01 41.52±1.81 0.83±0.02 19.31±0.73 6.47±0.38 Example 3 1.16±0.03 45.25±4.03 0.83±0.02 20.35±2.20 6.72±0.24 Comparative Example 1 11.38±0.25 30.18±1.92 0.59±0.02 3.68±0.35 2.27±0.19 Comparative Example 2 1.36±0.04 42.82±9.60 0.82±0.03 22.39±4.75 9.64±0.25 Comparative Example 3 1.22±0.06 47.31±1.46 0.87±0.03 25.70±1.47 6.55±0.21 Comparative Example 4 1.43±0.01 35.99±1.59 0.81±0.02 17.07±1.27 3.19±0.09 Comparative Example 5 1.25±0.03 18.17±0.16 0.84±0.05 7.61±0.78 2.30±0.03 Comparative Example 6 1.27±0.02 34.32±10.01 0.75±0.03 40.41±2.77 5.76±0.03 Comparative Example 7 1.55±0.08 104.99±1.37 0.77±0.02 41.51±4.26 8.24±0.11 Comparative Example 8 1.05±0.01 46.50±2.61 0.83±0.02 24.28±1.22 6.70±0.08 Comparative Example 9 1.11±0.06 21.47±1.97 0.84±0.02 9.62±0.67 1.93±0.03

[0132] From the results of Table 1, Table 2 and Figure 1 It can be seen from the results that, by twice high-pressure homogenization and the synergistic effect of deacetylated konjac glucomannan, k-carrageenan and hyaluronic acid, and by adding milk and lactic acid bacteria fermentation, a high-quality product with pink / pale pink color, uniform texture, no cracks, no bubbles, sweet and sour taste, and special fermentation aroma can be obtained, and the texture characteristics are moderate, and the taste is good. Among them, the protein solubility is reflected by the uniformity of the tissue, if the tissue is uniform, it means that the protein solubility is good, if the tissue is not uniform, it means that the protein solubility is not good; the gel stability is reflected by the gel strength and water holding capacity, and the higher the gel strength and water holding capacity, the better the gel stability. From the comparison of Example 1 and Comparative Example 1, it can be seen that the sample without protein isoelectric point precipitation treatment is yellow, has some flocculation, no cracks, no bubbles, and the fermentation aroma is not obvious, and the texture characteristics are poor. From the comparison of Example 1 and Comparative Examples 2-3, it can be concluded that when the milk and lactic acid bacteria fermentation are not used to prepare the room temperature shrimp jelly, the flavor of the obtained sample is insufficient, and the texture strength and hardness are large, which further leads to poor taste of the product. From the comparison of Example 1 and Comparative Example 4, it can be concluded that the sample without high-pressure homogenization treatment has dark color, some flocculation, and the overall sensory effect is poor, and the taste is poor. From the comparison of Example 1 and Comparative Examples 5-9, it can be seen that deacetylated konjac glucomannan, k-carrageenan and hyaluronic acid can play a synergistic role in improving protein solubility and gel stability, and the presence of hyaluronic acid also improves the water holding capacity of the room temperature shrimp jelly sample. In summary, by twice high-pressure homogenization and the synergistic effect of deacetylated konjac glucomannan, k-carrageenan and hyaluronic acid, the protein solubility and gel stability in the process of separating shrimp protein by protein isoelectric point precipitation are improved, and by adding milk and lactic acid bacteria fermentation, the product flavor is improved, and the above combination expands the application range of shrimp products.

[0133] As described above, the basic principles, main features and advantages of the present application are shown and described. Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples are only preferred embodiments of the present application, and cannot limit the scope of the present application, i.e. equivalent changes and modifications made according to the scope and content of the present application should still be within the scope of the present application. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing room-temperature krill jelly, characterized in that, The method includes the following steps: S1. Isoelectric point precipitation: The pH of the krill slurry was adjusted to 10.0-12.0 with alkaline solution and then filtered. The resulting filtrate was then adjusted to 5.0-6.0 with acid solution to precipitate the protein. The precipitated protein was then collected by centrifugation. S2. First high-pressure homogenization: After mixing and homogenizing the precipitated protein with milk and water, the first high-pressure homogenization is carried out. The operating conditions for the first high-pressure homogenization include a pressure of 50-70 MPa and a homogenization time of 3-5 min. After that, the homogenized liquid is heated and then cooled to room temperature to obtain a krill protein solution. S3. Fermentation: The krill protein solution is fermented with lactic acid bacteria to obtain krill protein fermentation liquid; S4, Sol: The sweetener and gelling agent are dissolved in water under stirring conditions, wherein the gelling agent contains at least simultaneously deacetylated konjac glucomannan in a mass ratio of 1:(0.3-0.8):(0.05-0.15). k - Carrageenan and hyaluronic acid are mixed, and then the resulting sol is heated and boiled to obtain a boiled sol; S5. Preparation: Mix the krill protein fermentation liquid, cooking sol, acidity regulator and optional auxiliary materials evenly to obtain the preparation liquid; S6. Second high-pressure homogenization: The prepared liquid is subjected to a second high-pressure homogenization. The operating conditions for the second high-pressure homogenization include a pressure of 50-70 MPa and a homogenization time of 3-5 min.

2. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S1, the krill slurry is a pretreated slurry obtained by thawing frozen Antarctic krill, adding ice water, and stirring it into a muddy mass.

3. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S1, the amount of ice water added is 1-5 times the mass of the frozen Antarctic krill.

4. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S1, the operating conditions for the crushing include a water temperature of 0-4°C.

5. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S1, the alkaline solution is selected from at least one of sodium carbonate, potassium carbonate, ammonium sulfate, sodium hydroxide, and potassium hydroxide.

6. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S1, the concentration of the alkaline solution is 0.5-2 M.

7. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S1, the concentration of the acid solution is 0.5-2 M.

8. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S2, the amount of the precipitated protein added is 18-50 parts by weight relative to 100 parts by weight of water.

9. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S2, the milk is pasteurized fresh milk and / or ultra-high temperature sterilized whole milk.

10. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S2, the amount of milk added is 2-4 times the weight of the precipitated protein.

11. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S2, the heating conditions include a temperature of 95-100°C and a time of 5-15 min.

12. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S3, the lactic acid bacteria are direct-inoculation lactic acid bacteria starter.

13. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S3, the fermentation conditions include a temperature of 30-40°C and a time of 10-15 hours.

14. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S3, the viable bacterial count of the krill protein fermentation broth reaches (1-3)×10⁻⁶. 9 per mL.

15. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S4, the sweetener is selected from at least one of granulated sugar, trehalose, maltose, glucose, xylitol, sorbitol and sucralose.

16. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S4, the amount of sweetener added is 18-65 parts by weight relative to 100 parts by weight of water.

17. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S4, the amount of gelling agent added is 3-9 parts by weight relative to 100 parts by weight of water.

18. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S4, the cooking conditions include heating and cooking to 80-90°C for 10-15 minutes.

19. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S4, the temperature of the sol-cooking process is maintained at 70-80°C.

20. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S5, the acidity regulator is a combination of citric acid and sodium citrate in a weight ratio of 1:(0.1-1).

21. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S5, the amount of acidity regulator added is 5-15 parts by weight relative to 100 parts by weight of water.

22. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S5, the excipients are selected from one or more of the following: preservatives, fermentation agents, colorants, stabilizers, coagulants, and emulsifiers.

23. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, In step S5, the amount of the excipient added is 0.1-1 parts by weight relative to 100 parts by weight of water.

24. The method for preparing room-temperature krill jelly according to claim 1, characterized in that, The method also includes filling, sterilization and cooling steps performed sequentially after a second high-pressure homogenization.

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