A crayfish soaking liquid and its preparation method

Abstract

This invention discloses a method for preparing crayfish infusion, belonging to the field of food seasoning technology. The method includes the following steps: first, pulverizing spices and simultaneously preparing a basic infusion; mixing a portion of the pulverized spices with the basic infusion and boiling it; after cooling, adding a compound enzyme preparation consisting of neutral protease and flavor protease for incubation and enzymatic hydrolysis; after hydrolysis, heating to inactivate the enzyme; after cooling, adding food-grade chitosan, adjusting the pH with citric acid and incubating for cross-linking, then heating to solidify to obtain a modified basic infusion; sequentially adding spice oil, porous starch, and lime juice to the modified basic infusion, simultaneously performing ultrasonic treatment and stirring; finally, cooling, filtering, and instantaneous sterilization to obtain the finished product. This invention can effectively improve the flavor harmony and richness of the infusion, while significantly enhancing the storage stability of the system, reducing oil separation and flavor loss, and ensuring stable product quality throughout its shelf life.

Description

Technical Field

[0001] This invention relates to the field of food seasoning technology, specifically to a crayfish soaking liquid and its preparation method. Background Technology

[0002] In recent years, the market for pre-made crayfish seasoning has developed rapidly. Crayfish marinade has become a common product in homes and restaurants because it can quickly impart flavor to ingredients and simplify the cooking process.

[0003] Therefore, the core problems of existing crayfish marinade are concentrated in two aspects: flavor and stability. In terms of flavor, the combination of spices relies heavily on experience and lacks systematic ratio optimization, resulting in products with either an overly strong single flavor or poor integration of multiple flavors and insufficient aroma layers. At the same time, the processing method of spices is relatively simple, and flavor substances are not fully released, affecting the overall palatability. In terms of quality stability, the system homogeneity of marinade is poor, and phenomena such as layering and oil separation are prone to occur during storage. Moreover, flavor substances are easily lost due to volatilization and oxidation, resulting in a fading flavor and quality decline within the shelf life. In addition, some additives used to improve stability have failed to form a good match with the product flavor, and have instead affected the eating taste to some extent.

[0004] Therefore, it is necessary to provide a crayfish soaking solution and its preparation method to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a crayfish infusion liquid and its preparation method, so as to solve the problems of poor flavor coordination, thin taste, easy separation of oil and easy loss of flavor in existing crayfish infusion liquids during storage.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, this invention provides a crayfish marinade, comprising, by weight, the following ingredients: 15-20 parts light soy sauce, 8-12 parts Shaoxing wine, 5-8 parts fermented red bean curd sauce, 3-5 parts seafood sauce, 4-6 parts white sugar, 1-2 parts salt, 3-5 parts lime juice, 5-8 parts spices, 2-3 parts porous starch, 0.15-0.25 parts compound enzyme preparation, 0.3-0.5 parts food-grade chitosan, and 30-40 parts water; the spices are composed of 30-40% bell pepper, 25-35% Erjingtiao pepper, 15-20% Sichuan pepper, 5-10% star anise, 3-5% cinnamon, and 2-3% bay leaves; the porous starch is food-grade corn porous starch with a specific surface area ≥10m². 2 / g, with a pore size of 50-200nm; the compound enzyme preparation is composed of neutral protease and flavor protease in a weight ratio of 1.5-2.5:1, wherein the neutral protease has an enzyme activity of 5000-8000U / g and the flavor protease has an enzyme activity of 5000-8000U / g.

[0007] In this invention, spices are mixed in the following proportions: 30-40% bell pepper, 25-35% Erjingtiao pepper, 15-20% Sichuan pepper, 5-10% star anise, 3-5% cinnamon, and 2-3% bay leaves. The flavors of each component complement each other. The spicy and fragrant flavors of bell pepper and Erjingtiao pepper, the mild numbing flavor of Sichuan pepper, and the complex aroma of star anise, etc., form a layered flavor, avoiding a single, abrupt flavor. A compound enzyme preparation is prepared by combining neutral protease and flavor protease in a ratio of 1.5-2.5:1. The neutral protease first degrades large protein molecules into peptides, and the flavor protease further hydrolyzes the peptides into small flavor amino acids. This dual enzymatic hydrolysis significantly enhances the richness of the flavor. Porous starch, with its high specific surface area and specific pore size, adsorbs flavor substances. Food-grade chitosan forms a stable network with the system components. The two work synergistically to reduce flavor loss and improve the uniformity of the system, ultimately resulting in a balanced and harmonious flavor, rich aroma, and sweet aftertaste in the infusion liquid, while also laying a stable foundation for subsequent processes.

[0008] Preferably, the neutral protease is prepared by fermentation with Bacillus subtilis, and the flavor protease is prepared by fermentation with Aspergillus oryzae.

[0009] In this invention, the neutral protease is prepared by fermentation of Bacillus subtilis and the flavor protease is prepared by fermentation of Aspergillus oryzae. Bacillus subtilis has stable enzyme activity at an enzymatic hydrolysis temperature of 50-55℃, which can efficiently decompose large molecular proteins without harmful metabolites, ensuring food safety and enzymatic hydrolysis efficiency. The flavor protease secreted by Aspergillus oryzae has broad-spectrum hydrolysis characteristics, which can specifically recognize the hydrophobic amino acid sites of peptides, hydrolyze them to produce small molecular peptides and amino acids with rich flavor, and the strain has strong fermentation adaptability and is easy to scale up production. The two types of strains are respectively adapted to the structural synthesis requirements of the corresponding enzymes, ensuring stable enzyme activity and significant synergistic hydrolysis effect, thereby improving the flavor quality of the extract and product safety, and avoiding fluctuations in enzymatic hydrolysis effect caused by strain differences.

[0010] Preferably, the food-grade chitosan has a degree of deacetylation ≥85% and a molecular weight of 5000-10000 Da.

[0011] In this invention, the food-grade chitosan has a degree of deacetylation ≥85% and a molecular weight of 5000-10000 Da. The high degree of deacetylation gives the chitosan molecules sufficient amino groups, which are easily protonated under cross-linking conditions of pH 5.0-5.5, forming stable hydrogen bonds and ionic bonds with organic acids and proteins to construct a uniform colloidal network. The suitable molecular weight ensures the solubility of chitosan, allowing it to fully participate in the cross-linking reaction without agglomerating or clumping. The network structure it forms can both encapsulate flavor substances to reduce volatilization and improve the viscosity stability of the system, effectively solving the problems of layering and oil separation in the storage of the extract, extending the flavor stability during the shelf life, and not affecting palatability.

[0012] Preferably, the lime juice has a pH of 2.5-3.0 and a limonene content of ≥0.8 mg / mL.

[0013] In this invention, the lime juice has a pH of 2.5-3.0 and a limonene content of ≥0.8mg / mL. The mild acidic environment helps dissolve fat-soluble flavor substances in spices, balances the salty and sweet flavors, and enhances the refreshing taste. The high limonene content imparts a natural and fresh aroma, complementing the complex aroma of spices and enriching the flavor profile. Furthermore, the volatility is suppressed under the chitosan network coating, reducing aroma loss during storage. This results in a juice that not only has a distinctive and refreshing flavor but also helps to enhance the dissolution and retention of other flavor substances, achieving a balance between taste and flavor stability.

[0014] In a second aspect, the present invention provides a method for preparing crayfish soaking liquid, comprising the following steps: S1. The spices are pulverized, and a basic marinade is prepared by mixing water, light soy sauce, Shaoxing wine, fermented red bean curd juice, seafood sauce, white sugar and salt. S2. Mix 3-5 parts of the total amount of crushed spices with the basic infusion liquid and boil to obtain a basic infusion liquid containing spice residue; S3. Cool the basic extract containing spice residue to 50-55℃, add a compound enzyme preparation composed of neutral protease and flavor protease, and incubate at 50-55℃ and stirring rate of 50-80r / min for 15-20min to obtain the enzymatically hydrolyzed basic extract. S4. After enzymatic hydrolysis, heat to 70-75℃ and keep warm for 3-7 minutes to inactivate the enzyme and obtain the inactivated basic extract. S5. Cool the inactivated base extract to 45-50℃ and add food-grade chitosan; S6. Adjust the pH of the system to 5.0-5.5 with 0.5-1 mol / L citric acid, and crosslink at 45-50℃ for 20-25 min; S7. After crosslinking is completed, heat to 90-95℃ and hold for 8-12 minutes to perform curing treatment and obtain modified base impregnation solution; S8. Add spice oil, porous starch and lime juice to the modified base extract in sequence, and simultaneously perform ultrasonic treatment and stirring treatment; S9. After cooling and filtration, the mixture is instantaneously sterilized at 130-140℃ for 3-7 seconds to obtain crayfish infusion.

[0015] In this invention, the pulverized spices are used in two parts. One part is boiled with the base infusion to release water-soluble flavor, and the other part is used to prepare spice oil to provide fat-soluble aroma, ensuring a full release of flavor. The three steps of enzymatic hydrolysis, cross-linking, and solidification work together to first degrade macromolecular substances into flavor components and then build a stable system to ensure the unity of flavor and stability. The synergistic effect of ultrasonic treatment and stirring breaks the interfacial tension of oil droplets through ultrasonic cavitation, which makes the spice oil evenly dispersed. The adsorption efficiency of porous starch is improved after ultrasonic dispersion. The lime juice is quickly integrated after high-temperature stirring, avoiding uneven local flavor. It can stably produce crayfish infusion with balanced flavor, long shelf life, and consistent quality.

[0016] Preferably, in step S1, the spices are pulverized to 40-60 mesh; In step S2, mix 3-5 parts of the total amount of pulverized spices with the base infusion, bring to a boil over high heat, then simmer over low heat at 80-90℃ for 15-20 minutes.

[0017] In this invention, spices are pulverized to 40-60 mesh, brought to a boil over high heat, and then simmered over low heat at 80-90°C for 15-20 minutes. The specific particle size increases the contact area with the base infusion liquid, which is conducive to the dissolution of water-soluble flavor substances, while avoiding the difficulty of filtration and residue caused by excessively fine particles. During the simmering process, high-temperature boiling quickly kills microorganisms, while slow simmering over low heat allows flavor substances to be released slowly and is not easily volatilized. This improves the efficiency of flavor dissolution, ensures the purity of the taste and the richness of the aroma of the infusion liquid, reduces the risk of microbial contamination, and improves product safety.

[0018] Preferably, in step S3, the fermentation preparation step of the neutral protease is as follows: 1a: Using Bacillus subtilis as the starting strain, single colonies were picked and inoculated into seed culture medium. The seed culture medium consisted of 10 g / L tryptone, 5 g / L yeast extract, 5 g / L sodium chloride and water, and the pH was adjusted to 6.5-7.0. 2a: Place the inoculated seed culture medium at a temperature of 30-32℃ and a rotation speed of 180-220 r / min for 12-16 h with shaking, until the OD600 value of the bacterial solution reaches 1.8-2.2, to obtain activated seed solution; 3a: Inoculate the seed liquid into the fermentation medium at a volume ratio of 5-8%. The fermentation medium comprises, by weight, 10-15 parts corn flour, 8-12 parts soybean meal, 0.5-1 parts potassium dihydrogen phosphate, 0.1-0.3 parts magnesium sulfate, 0.3-0.5 parts sodium chloride, and 100 parts water. At the same time, adjust the pH of the fermentation system to 6.5-7.0. 4a: Place the fermentation system at a temperature of 30-32℃ and an aeration rate of 1:0.8-1.2 vvm for 48-60 hours. During the fermentation process, add 2% glucose solution every 12 hours. 5a: After fermentation is complete, the fermentation broth is filtered through a plate and frame filter to remove the cells and impurities, and the clear filtrate is collected; 6a: The clarified filtrate is concentrated to 1 / 5 of its original volume by ultrafiltration, with a molecular weight cutoff of 10 kDa. Then, it is spray-dried at an inlet air temperature of 180-190℃ and an outlet air temperature of 80-85℃ to obtain a neutral protease with an enzyme activity of 5000-8000 U / g.

[0019] In this invention, the seed culture medium provides sufficient nutrients, and the culture conditions of pH 6.5-7.0 and 30-32℃ are suitable for the growth of Bacillus subtilis. OD 600 Seed culture with a pH of 1.8-2.2 exhibits strong activity and rapidly adapts to the fermentation environment after inoculation. The complex carbon and nitrogen source and minerals in the fermentation medium promote protease synthesis, while appropriate aeration ensures dissolved oxygen requirements for aerobic fermentation. Regular glucose supplementation maintains sufficient carbon source, and ultrafiltration concentration and spray drying work together to retain enzyme activity and remove impurities, ensuring consistent flavor of the extract.

[0020] Preferably, in step S3, the fermentation preparation step of the flavor protease is as follows: 1b: Using Aspergillus oryzae as the starting strain, the strain was inoculated into PDA slant medium, which consisted of 200 g / L potato, 20 g / L glucose, 15-20 g / L agar and water. 2b: Incubate the inoculated PDA slant culture medium at 28-30℃ for 48-72 hours until the slant is covered with green spores, thus completing the activation of the strain; 3b: Wash the green spores off the slant with sterile physiological saline, filter through sterile gauze to remove mycelium, and prepare a spore suspension with a spore concentration of 1×10⁻⁶. 6 -1×10 7 cells / mL; 4b: Inoculate the spore suspension into the fermentation medium at a volume ratio of 3-5%. The fermentation medium comprises, by weight, 15-20 parts wheat bran, 5-8 parts soybean meal, 2-3 parts sucrose, 0.5-1 parts ammonium sulfate, 1-2 parts calcium carbonate, and 100 parts water. Adjust the pH of the fermentation system to 6.0-6.5. 5b: Place the fermentation system at a temperature of 28-30℃ and an aeration rate of 1:0.6-1.0 vvm for 72-96 hours, and control the pH of the system to be stable at 6.0-6.5 during the fermentation process; 6b: After fermentation is complete, centrifuge the fermentation broth at 8000-10000 r / min for 15-20 min to remove impurities and mycelium, and collect the supernatant; 7b: Slowly add ammonium sulfate to the supernatant until the saturation is 55%-65%, let it stand for 12-18 hours, and then centrifuge to collect the precipitate; 8b: Dissolve the precipitate in phosphate buffer solution with pH 5.8-6.2, place it in a dialysis bag and dialyze for 20-28 hours, changing the buffer solution every 6-10 hours to remove residual ammonium sulfate; 9b: The dialyzed solution was freeze-dried at a vacuum degree ≤10Pa and a temperature of -55℃~-45℃ to obtain a flavor protease with an enzyme activity of 5000-8000U / g.

[0021] In this invention, the PDA slant culture medium is suitable for the germination of Aspergillus oryzae spores, and the specific temperature and time of cultivation ensure sufficient spore production. The appropriate concentration of spore suspension inoculation avoids excessive competition for nutrients by the fungi. The natural carbon and nitrogen sources, nitrogen supplements, and pH adjusters in the fermentation medium work synergistically to meet the aerobic metabolic needs of Aspergillus oryzae and promote the synthesis of flavor proteases. Ammonium sulfate precipitation is used to specifically precipitate the target enzyme, and dialysis desalting and freeze drying avoid high-temperature denaturation and retain enzyme activity. Finally, a high-activity, high-purity flavor protease is obtained. The synergistic enzymatic hydrolysis effect with neutral protease is significant, and the process is controllable and impurities are thoroughly removed, ensuring food safety and enzymatic hydrolysis efficiency.

[0022] Preferably, in step S8, the preparation step of the spice oil is as follows: 1c: Take 2-3 parts of the total amount of spice after crushing and set aside; 2c: Prepare a mixture, which is made by mixing 1-2% saline and 30-40% ethanol in a volume ratio of 1:1.5-2, and the amount of the mixture is 3-5 times the weight of the spices; 3c: Place the spices and mixture in a sealed container and soak in a constant temperature water bath at 40-45℃ for 25-35 minutes, stirring intermittently 3-4 times during the process, each stirring for 30 seconds. 4c: After soaking, drain the mixture adhering to the surface of the spices and collect the drained spices; 5c: Place the drained spices in a dry pot and heat over low heat to 100-110℃. Maintain this temperature and sauté slowly for 8-10 minutes. 6c: After sautéing, cool the spices and oil together to room temperature; 7c: Filter through a 100-120 mesh filter cloth to remove spice residue, and collect the filtrate as spice oil.

[0023] In this invention, the spice oil preparation step involves a combination of soaking in a brine-ethanol mixture and slow high-temperature stir-frying. The brine-ethanol mixture can penetrate the interior of the spices, dissolving fat-soluble flavor substances. Soaking in a constant-temperature water bath at 40-45℃ and intermittent stirring further promote the release of flavor substances. Subsequently, slow stir-frying at 100-110℃ concentrates the flavor, and filtration through a 100-120 mesh filter cloth removes residues, resulting in a rich and pure spice oil flavor. This avoids the problem of insufficient flavor substance dissolution caused by traditional single stir-frying, providing the infusion liquid with a mellow fat-soluble aroma and enhancing the overall flavor profile.

[0024] Preferably, step S8 is performed as follows: after adding spice oil to the modified base extract, ultrasonic emulsify at 200-300W and 40kHz for 10-15 minutes; after adding porous starch, continue ultrasonic dispersion for 8-12 minutes; after adding lime juice, stir at 75-85℃ for 40-80 seconds. The cooling and filtration conditions in step S9 are as follows: after cooling to room temperature, filter with a 100-120 mesh filter cloth to remove impurities and residual fragrance residue.

[0025] In this invention, spice oil is emulsified by 200-300W, 40kHz ultrasound for 10-15 minutes to ensure that oil droplets are evenly dispersed in the aqueous system. Subsequently, porous starch is dispersed by ultrasound to improve its adsorption efficiency. Lime juice is stirred at 75-85℃ for 40-80 seconds to quickly integrate with the system. S9 uses a 100-120 mesh filter cloth to remove impurities and residual spice residue, making the infusion liquid pure. At the same time, ultrasound and stirring work together to avoid uneven flavor in certain areas. The filtration step ensures that the product has a smooth taste. Finally, the components of the infusion liquid are evenly mixed, have a consistent flavor, and are pure in texture.

[0026] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes a compound enzyme preparation to combine neutral protease and flavor protease at a ratio of 1.5-2.5:1. The two enzymes form a synergistic hydrolysis system. Neutral protease preferentially breaks the internal peptide bonds of large protein molecules, degrading them into short peptide fragments that are easily recognized by flavor protease. Simultaneously, the short peptides generated by the hydrolysis of neutral protease can activate the activity of flavor protease, enabling it to more efficiently target and hydrolyze the hydrophobic amino acid sites in the short peptides, accelerating the generation of small-molecule flavor amino acids. The synergistic effect of the two enzymes significantly improves the protein hydrolysis conversion rate, resulting in a significant increase in the total amount of free amino acids in the extract. Combined with the natural flavor components in seafood sauce, the taste is more mellow and sweet, solving the problems of insufficient hydrolysis and thin taste caused by traditional single-enzyme hydrolysis.

[0027] 2. This invention achieves synergistic effects by processing spices in two parts. One part is boiled with the base infusion liquid to fully release water-soluble flavor substances, laying the foundation for the spicy flavor of the infusion liquid. The other part is soaked in a brine-ethanol mixture and then slowly stir-fried to prepare spice oil, maximizing the dissolution of fat-soluble aroma components. The two types of flavor substances complement and superimpose each other. At the same time, porous starch, with its high specific surface area and specific pore structure, adsorbs and carries spice oil and volatile flavor components, avoiding excessive concentration or loss of flavor. This results in distinct and naturally integrated spicy and numbing aromas, improving the flavor imbalance problem caused by the single processing method of traditional spices.

[0028] 3. This invention leverages the adsorption properties of porous starch in synergy with compound enzymatic hydrolysis and staged processing of spices. The adsorbed flavor substances are slowly released during consumption, extending the duration of flavor perception. Simultaneously, porous starch, as a dispersion medium, helps stabilize the dispersion of spice oils in the aqueous system. Combined with subsequent ultrasonic treatment, it further breaks down the interfacial tension of oil droplets, preventing the aggregation of fat-soluble components. Furthermore, the network structure formed by porous starch and food-grade chitosan mutually supports each other, enhancing the viscosity stability of the system and reducing the risk of oil separation during storage, thus achieving a dual guarantee of flavor retention and system stability.

[0029] 4. This invention ensures a balanced spicy and numbing flavor through precise proportions of spices, avoiding a single, abrupt flavor; food-grade chitosan is limited to a specific degree of deacetylation and molecular weight, and cross-links under suitable pH conditions to form a stable colloidal network, which encapsulates flavor substances and enhances system stability; the specific pH and limonene content of lime juice balance the taste and enrich the aroma layers, taking into account flavor, stability and practicality. Attached Figure Description

[0030] Figure 1 This is a bar chart comparing the total free amino acid content of the crayfish extracts prepared in Examples 1-3 and Comparative Examples 1-6. Figure 2 Line graphs showing the comparison of limonene retention rates of crayfish extracts prepared in Examples 1-3 and Comparative Examples 1-6; Figure 3 The bar chart shows the viscosity comparison of the crayfish soaking liquids prepared in Examples 1-3 and Comparative Examples 1-6. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1 This embodiment provides a crayfish soaking liquid and its preparation method, as detailed below: Raw material composition: By weight, 18 parts light soy sauce, 10 parts Shaoxing wine, 6 parts fermented red bean curd sauce, 4 parts seafood sauce, 5 parts white sugar, 1.5 parts salt, 4 parts lime juice, 6 parts spices, 2.5 parts porous starch, 0.2 parts compound enzyme preparation, 0.4 parts food-grade chitosan, and 35 parts water; among which, the spices are composed of 35% bell pepper, 30% Erjingtiao pepper, 18% Sichuan pepper, 7% star anise, 5% cinnamon, and 5% bay leaves; the porous starch is food-grade corn porous starch with a specific surface area ≥10m². 2 / g, pore size 50-200nm; the compound enzyme preparation is composed of neutral protease and flavor protease in a weight ratio of 2:1, with neutral protease activity of 6500U / g and flavor protease activity of 6500U / g; the neutral protease is prepared by fermentation with Bacillus subtilis and the flavor protease is prepared by fermentation with Aspergillus oryzae; the degree of deacetylation of food-grade chitosan is ≥85% and the molecular weight is 5000-10000Da; the pH value of lime juice is 2.8 and the limonene content is ≥0.8mg / mL.

[0033] The following is a method for preparing crayfish soaking liquid provided in this embodiment: S1: Grind the spices to 50 mesh, and at the same time mix water, light soy sauce, Shaoxing wine, fermented bean curd juice, seafood sauce, white sugar and salt evenly to prepare the basic marinade; S2: Take 4 parts of the total amount of crushed spices and mix them with the basic infusion liquid. Bring to a boil over high heat, then reduce to low heat and simmer at 85°C for 18 minutes to obtain the basic infusion liquid containing spice residue. S3: Cool the basic extract containing spice residue to 52°C, add the compound enzyme preparation, and incubate at 52°C and a stirring rate of 65r / min for 18min to obtain the enzymatically hydrolyzed basic extract. The fermentation preparation steps for neutral protease are as follows: 1a: Using Bacillus subtilis as the starting strain, single colonies were picked and inoculated into seed culture medium. The seed culture medium consisted of 10 g / L tryptone, 5 g / L yeast extract, 5 g / L sodium chloride and water, and the pH was adjusted to 6.8. 2a: The inoculated seed culture medium was placed at 31℃ and 200 r / min and shaken for 14 h until the bacterial culture OD reached its limit. 600 When the value reaches 2.0, the activated seed solution is obtained; 3a: Inoculate the seed liquid into the fermentation medium at a volume ratio of 6%. The fermentation medium consists of 12 parts corn flour, 10 parts soybean meal, 0.8 parts potassium dihydrogen phosphate, 0.2 parts magnesium sulfate, 0.4 parts sodium chloride, and 100 parts water by weight. Adjust the pH of the fermentation system to 6.8. 4a: The fermentation system was placed at a temperature of 31℃ and an aeration rate of 1.0 vvm for 54 h. During the fermentation process, 2% glucose solution was added every 12 h. 5a: After fermentation is complete, the fermentation broth is filtered through a plate and frame filter to remove the cells and impurities, and the clear filtrate is collected; 6a: The clarified filtrate was concentrated to 1 / 5 of its original volume by ultrafiltration, with a molecular weight cutoff of 10 kDa. It was then spray-dried at an inlet temperature of 185°C and an outlet temperature of 82°C to obtain neutral protease. The fermentation preparation steps for flavor proteases are as follows: 1b: Using Aspergillus oryzae as the starting strain, the strain was inoculated into PDA slant medium, which consisted of 200 g / L potato, 20 g / L glucose, 18 g / L agar and water. 2b: Incubate the inoculated PDA slant culture medium at 29℃ for 60 hours until the slant is covered with green spores, thus completing the activation of the strain; 3b: Wash the green spores off the slant with sterile physiological saline, filter through sterile gauze to remove mycelium, and prepare a spore suspension with a spore concentration of 5 × 10⁻⁶. 6 cells / mL; 4b: Inoculate the spore suspension into the fermentation medium at a volume ratio of 4%. The fermentation medium consists of 18 parts wheat bran, 6 parts soybean meal, 2.5 parts sucrose, 0.8 parts ammonium sulfate, 1.5 parts calcium carbonate, and 100 parts water by weight. Adjust the pH of the fermentation system to 6.2. 5b: The fermentation system was placed at a temperature of 29℃ and an aeration rate of 0.8 vvm for 84 h, and the pH of the system was controlled to be stable at 6.2 during the fermentation process; 6b: After fermentation, centrifuge the fermentation broth at 9000 r / min for 18 min to remove impurities and mycelium, and collect the supernatant; 7b: Slowly add ammonium sulfate to the supernatant until the saturation is 60%, let stand at 4°C for 15 hours, and then centrifuge to collect the precipitate; 8b: Dissolve the precipitate in phosphate buffer solution at pH 6.0, place it in a dialysis bag and dialyze for 24 hours, changing the buffer solution every 8 hours to remove residual ammonium sulfate; 9b: The dialyzed solution was freeze-dried at a vacuum degree ≤10Pa and a temperature of -50℃ to obtain the flavor protease; S4: After enzymatic hydrolysis, heat to 72℃ and keep warm for 5 minutes to perform enzyme inactivation treatment and obtain the inactivated basic extract. S5: Cool the inactivated base extract to 48°C and add food-grade chitosan; S6: Adjust the pH of the system to 5.2 with 0.8 mol / L citric acid, and crosslink at 48℃ for 22 min; S7: After cross-linking is completed, heat to 92℃ and hold for 10 minutes to perform curing treatment and obtain modified base impregnation solution; S8: Add spice oil, porous starch and lime juice to the modified base extract in sequence. The specific operation is as follows: after adding spice oil, ultrasonic emulsify at 250W and 40kHz for 12min; after adding porous starch, continue ultrasonic dispersion for 10min; after adding lime juice, stir at 80℃ for 60s. The preparation steps for the spice oil are as follows: 1c: Take two portions of the total amount of spice after crushing and set aside; 2c: Prepare the mixture, which is made by mixing 1.5% saline and 35% ethanol in a volume ratio of 1:1.8. The amount of the mixture is 4 times the weight of the spices. 3c: Place the spices and mixture in a sealed container and soak in a 42°C constant temperature water bath for 30 minutes, stirring intermittently 3 times during the process, each stirring for 30 seconds; 4c: After soaking, drain the mixture adhering to the surface of the spices and collect the drained spices; 5c: Place the drained spices in a dry pot and heat over low heat to 105°C. Maintain this temperature and sauté slowly for 9 minutes. 6c: After sautéing, cool the spices and oil together to room temperature; 7c: Filter through a 110-mesh filter cloth to remove spice residue, and collect the filtrate as spice oil; S9: After cooling to room temperature, filter with a 110-mesh filter cloth to remove impurities and residual spice residue, and then sterilize at 135℃ for 5 seconds to obtain crayfish infusion liquid.

[0034] Example 2 This embodiment provides a crayfish soaking liquid and its preparation method, as detailed below: Raw material composition: By weight, 15 parts light soy sauce, 8 parts Shaoxing wine, 5 parts fermented red bean curd sauce, 3 parts seafood sauce, 4 parts white sugar, 1 part salt, 3 parts lime juice, 5 parts spices, 2 parts porous starch, 0.15 parts compound enzyme preparation, 0.3 parts food-grade chitosan, and 30 parts water; among which, the spices are composed of 30% bell pepper, 25% Erjingtiao pepper, 15% Sichuan pepper, 5% star anise, 3% cinnamon, and 2% bay leaves; the porous starch is food-grade corn porous starch with a specific surface area ≥10m². 2 / g, pore size 50-200nm; the compound enzyme preparation is composed of neutral protease and flavor protease in a weight ratio of 1.5:1, with neutral protease activity of 5000U / g and flavor protease activity of 5000U / g; the neutral protease is prepared by fermentation with Bacillus subtilis and the flavor protease is prepared by fermentation with Aspergillus oryzae; the degree of deacetylation of food-grade chitosan is ≥85% and the molecular weight is 5000-10000Da; the pH value of lime juice is 2.5 and the limonene content is ≥0.8mg / mL.

[0035] The following is a method for preparing crayfish soaking liquid provided in this embodiment: S1: Grind the spices to 40 mesh, and at the same time mix water, light soy sauce, Shaoxing wine, fermented bean curd juice, seafood sauce, white sugar and salt evenly to prepare the basic marinade; S2: Take 3 parts of the total amount of crushed spices and mix them with the basic infusion liquid. Bring to a boil over high heat, then reduce to low heat and simmer at 80°C for 15 minutes to obtain the basic infusion liquid containing spice residue. S3: Cool the basic extract containing spice residue to 50°C, add the compound enzyme preparation, and incubate at 50°C and a stirring rate of 50r / min for 15min to obtain the enzymatically hydrolyzed basic extract. The fermentation preparation steps of neutral protease are the same as those in Example 1, except that the fermentation time is adjusted to 48h, the spray drying inlet air temperature is 180℃, and the outlet air temperature is 80℃. The fermentation preparation steps of the flavor protease are the same as those in Example 1, except that the fermentation time is adjusted to 72h and the freeze-drying temperature is -55℃. S4: After enzymatic hydrolysis, heat to 70℃ and keep warm for 3 minutes to perform enzyme inactivation treatment and obtain the inactivated basic extract. S5: Cool the inactivated base extract to 45°C and add food-grade chitosan; S6: Adjust the pH of the system to 5.0 with 0.5 mol / L citric acid, and crosslink at 45℃ for 20 min; S7: After cross-linking is completed, heat to 90℃ and hold for 8 minutes to perform curing treatment and obtain modified base impregnation solution; S8: Add spice oil, porous starch and lime juice to the modified base extract in sequence. The specific operation is as follows: after adding spice oil, ultrasonic emulsify at 200W and 40kHz for 10min; after adding porous starch, continue ultrasonic dispersion for 8min; after adding lime juice, stir at 75℃ for 40s. The preparation steps for the spice oil are as follows: 1c: Take two portions of the total amount of spice after crushing and set aside; 2c: Prepare the mixture, which is made by mixing 1% saline and 30% ethanol at a volume ratio of 1:1.5. The amount of the mixture is 3 times the weight of the spices. 3c: Place the spices and mixture in a sealed container and soak in a 40°C constant temperature water bath for 25 minutes, stirring intermittently 3 times during the process, each stirring for 30 seconds; 4c: After soaking, drain the mixture adhering to the surface of the spices and collect the drained spices; 5c: Place the drained spices in a dry pot and heat over low heat to 100°C. Maintain this temperature and sauté slowly for 8 minutes. 6c: After sautéing, cool the spices and oil together to room temperature; 7c: Filter through a 100-mesh filter cloth to remove spice residue, and collect the filtrate as spice oil; S9: After cooling to room temperature, filter with a 100-mesh filter cloth to remove impurities and residual spice residue, and then sterilize at 130℃ for 3 seconds to obtain crayfish infusion liquid.

[0036] Example 3 This embodiment provides a crayfish soaking liquid and its preparation method, as detailed below: Raw material composition: By weight, 20 parts light soy sauce, 12 parts Shaoxing wine, 8 parts fermented red bean curd sauce, 5 parts seafood sauce, 6 parts white sugar, 2 parts salt, 5 parts lime juice, 8 parts spices, 3 parts porous starch, 0.25 parts compound enzyme preparation, 0.5 parts food-grade chitosan, and 40 parts water; among which, the spices are composed of 40% bell pepper, 35% Erjingtiao pepper, 20% Sichuan pepper, 10% star anise, 5% cinnamon, and 3% bay leaves; the porous starch is food-grade corn porous starch with a specific surface area ≥10m². 2 / g, pore size 50-200nm; the compound enzyme preparation is composed of neutral protease and flavor protease in a weight ratio of 2.5:1, with neutral protease activity of 8000U / g and flavor protease activity of 8000U / g; the neutral protease is prepared by fermentation of Bacillus subtilis and the flavor protease is prepared by fermentation of Aspergillus oryzae; the degree of deacetylation of food-grade chitosan is ≥85% and the molecular weight is 5000-10000Da; the pH value of lime juice is 3.0 and the limonene content is ≥0.8mg / mL.

[0037] The following is a method for preparing crayfish soaking liquid provided in this embodiment: S1: Grind the spices to 60 mesh, and at the same time mix water, light soy sauce, Shaoxing wine, fermented bean curd juice, seafood sauce, white sugar and salt evenly to prepare the basic marinade; S2: Take 5 parts of the total amount of crushed spices and mix them with the basic infusion liquid. Bring to a boil over high heat, then reduce to low heat and simmer at 90°C for 20 minutes to obtain the basic infusion liquid containing spice residue. S3: Cool the basic extract containing spice residue to 55°C, add the compound enzyme preparation, and incubate at 55°C and a stirring rate of 80r / min for 20min to obtain the enzymatically hydrolyzed basic extract. The fermentation preparation steps of neutral protease are the same as those in Example 1, except that the fermentation time is adjusted to 60h, the spray drying inlet air temperature is 190℃, and the outlet air temperature is 85℃. The fermentation preparation steps of the flavor protease are the same as those in Example 1, except that the fermentation time is adjusted to 96 h and the freeze-drying temperature is -45 °C. S4: After enzymatic hydrolysis, heat to 75℃ and keep warm for 7 minutes to perform enzyme inactivation treatment and obtain the inactivated basic extract. S5: Cool the inactivated base extract to 50°C and add food-grade chitosan; S6: Adjust the pH of the system to 5.5 with 1 mol / L citric acid, and crosslink at 50℃ for 25 min; S7: After cross-linking is completed, heat to 95℃ and hold for 12 minutes to perform curing treatment and obtain modified base impregnation solution; S8: Add spice oil, porous starch and lime juice to the modified base extract in sequence. The specific operation is as follows: after adding spice oil, ultrasonic emulsify at 300W and 40kHz for 15min; after adding porous starch, continue ultrasonic dispersion for 12min; after adding lime juice, stir at 85℃ for 80s. The preparation steps for the spice oil are as follows: 1c: Take 3 parts of the total amount of spice after crushing and set aside; 2c: Prepare the mixture, which is made by mixing 2% saline and 40% ethanol in a volume ratio of 1:2. The amount of the mixture is 5 times the weight of the spices. 3c: Place the spices and mixture in a sealed container and soak in a 45°C constant temperature water bath for 35 minutes, stirring intermittently 4 times during the process, each stirring for 30 seconds; 4c: After soaking, drain the mixture adhering to the surface of the spices and collect the drained spices; 5c: Place the drained spices in a dry pot and heat over low heat to 110°C. Maintain this temperature and sauté slowly for 10 minutes. 6c: After sautéing, cool the spices and oil together to room temperature; 7c: Filter through a 120-mesh filter cloth to remove spice residue, and collect the filtrate as spice oil; S9: After cooling to room temperature, filter with a 120-mesh filter cloth to remove impurities and residual spice residue, and then sterilize at 140℃ for 7 seconds to obtain crayfish infusion liquid.

[0038] Comparative Example 1 The only difference between this comparative example and Example 1 is that the spices were not mixed in the specified proportions. Specifically, the spices were 20% bell pepper, 20% Erjingtiao pepper, 30% Sichuan pepper, 15% star anise, 10% cinnamon, and 5% bay leaves. The other raw material components and preparation methods were the same as in Example 1.

[0039] Expected performance: The proportion of Sichuan pepper in the spices is too high, while the proportion of bell pepper and Erjingtiao pepper is insufficient, resulting in a prominent numbing taste in the infusion, an imbalance of spicy and fragrant flavors, and poor flavor harmony; the flavor complementarity of each spice component is weakened, the aroma is monotonous, and the overall flavor quality declines; the spice ratio does not affect the stability of the system related processes, there is no stratification or oil separation during storage, and the flavor substance retention effect is close to that of Example 1.

[0040] Comparative Example 2 The only difference between this comparative example and Example 1 is that the compound enzyme preparation is a single neutral protease, without the addition of flavor protease, while the other raw material components and preparation methods are the same as in Example 1.

[0041] Expected performance: The lack of flavor protease for targeted degradation of large protein molecules means that neutral protease alone cannot fully decompose proteins, polysaccharides and other substances in the raw materials, making it difficult to release sufficient amounts of small-molecule flavor peptides and flavor amino acids; the flavor of the infusion liquid is not mellow enough, the aroma intensity is reduced, and the overall flavor performance is poor; the flavor substances are not firmly bound to the system, and the flavor is easily lost during storage, with stability slightly worse than in Example 1, and no layering or oil separation occurs.

[0042] Comparative Example 3 The only difference between this comparative example and Example 1 is that the enzymatic hydrolysis treatment in step S3 was not performed; the other raw material components and preparation methods are the same as in Example 1.

[0043] Expected performance: Without enzymatic hydrolysis, macromolecular substances in spice residue and raw materials cannot be degraded and are difficult to convert into small-molecule flavor substances; the flavor of the infusion is bland, the taste is thin, the aroma is not fully released, and the overall flavor is lacking; macromolecular substances in the system are not decomposed, but this does not affect the system's stratification stability. There is no stratification or oil separation during storage, but the flavor retention effect is poor.

[0044] Comparative Example 4 The only difference between this comparative example and Example 1 is that the molecular weight of the food-grade chitosan is 20,000 Da, which exceeds the specified range. The other raw material components and preparation methods are the same as those in Example 1.

[0045] Expected performance: The chitosan has a large molecular weight, which reduces its solubility and results in poor cross-linking reaction with organic acids, proteins and other components in the soaking liquid, making it impossible to form a stable colloidal network structure; slight stratification and a small amount of oil separation are likely to occur during storage, and the stability of the system decreases; insufficient cross-linking effect leads to a weakened coating and protection effect on flavor substances, flavor is easily lost, and the overall quality is lower than that of Example 1.

[0046] Comparative Example 5 The only difference between this comparative example and Example 1 is that the spice oil was not prepared by soaking in a brine-ethanol mixture, but by directly frying the spices over low heat to extract the oil. The other raw material components and preparation methods are the same as in Example 1.

[0047] Expected performance: Without the pre-soaking treatment of brine-ethanol mixture, the fat-soluble flavor substances in spices cannot be fully dissolved, and high-temperature slow frying alone is not enough to release all the aroma components; the flavor oil prepared has insufficient flavor intensity, which leads to a single aroma layer in the soaking liquid and poor flavor coordination; the stability of the combination of flavor substances with the system is not affected, and there is no stratification or oil separation during storage, but the flavor retention effect is poor.

[0048] Comparative Example 6 The only difference between this comparative example and Example 1 is that step S8 was not ultrasonically treated, but only stirred and mixed. The other raw material components and preparation methods are the same as in Example 1.

[0049] Expected performance: Without ultrasonic emulsification and dispersion treatment, the mixing uniformity of spice oil, porous starch and modified base extract is insufficient, making it difficult for the system to form a stable and homogeneous state; obvious stratification and more oil separation are likely to occur during storage, and the stability of the system will decrease significantly; uneven mixing leads to uneven distribution of flavor substances, with some areas having an overly strong flavor and some areas having a weak flavor, resulting in poor flavor harmony, and flavor substances are easily lost with stratification and precipitation.

[0050] To compare the performance differences of the preparation methods provided in Examples 1-3 and Comparative Examples 1-6, the present invention provides the following experimental methods: I. Flavor Rating: Ten sensory evaluators were invited to rate the flavors from three dimensions: aroma intensity, taste richness, and flavor harmony. Each dimension was scored out of 10, for a total of 30 points. The average score was taken. II. Stability Test: The sample was sealed and stored at 25℃ for 30 days. The presence of layering or oil separation was observed. At the same time, the change rate of flavor score before and after storage was measured (change rate = (initial score - score after storage) / initial score × 100%). III. Enzymatic hydrolysis effect: The total amount of free amino acids in the extract was determined by the ninhydrin colorimetric method.

[0051] IV. Limonene Retention Rate Determination: 1. Sample pretreatment: Take 5 mL of crayfish soaking liquid, add 10 mL of n-hexane, vortex for 5 min, let stand for separation, take the upper organic phase, filter through a 0.22 μm organic phase filter membrane, and set aside for later use.

[0052] 2. Instruments and Chromatographic Conditions: Gas chromatograph (GC) equipped with flame ionization detector (FID); HP-5 capillary column (30m × 0.32mm × 0.25μm); column temperature program: initial temperature 60℃, hold for 2 min, increase to 150℃ at 5℃ / min, hold for 3 min; injection port temperature 200℃, detector temperature 250℃; carrier gas nitrogen, flow rate 1.0mL / min; split ratio 10:1; injection volume 1μL.

[0053] 3. Standard curve plotting: Prepare limonene standard solutions with concentrations of 10, 20, 50, 100, and 200 μg / mL, and determine them under the chromatographic conditions described above. Plot the standard curve with peak area as the ordinate and concentration as the abscissa, and calculate the regression equation.

[0054] 4. Determination and Calculation: The treated sample was determined according to the chromatographic conditions, and the limonene content was calculated by substituting the peak area into the regression equation. The initial limonene content (C0) and the limonene content (C1) after 30 days of storage were determined respectively. Limonene retention rate = (C1 / C0) × 100%.

[0055] V. System viscosity determination: 1. Instrument preparation: Use a rotational viscometer and select a suitable rotor (select rotor No. 2 or No. 3 of the NDJ-1 type viscometer according to the pre-test viscosity range). Place the instrument and sample in a 25℃ constant temperature water bath for equilibration for 30 minutes in advance.

[0056] 2. Sample preparation: After shaking the crayfish soaking liquid well, pour it into the viscometer sample cup. The sample volume should be enough to cover the rotor mark line to avoid generating air bubbles.

[0057] 3. Measurement process: Start the viscometer, adjust the rotation speed to 60 r / min, and read the value after the pointer stabilizes. Each sample is measured in parallel 3 times, and the average value is taken as the final viscosity value (unit: mPa·s).

[0058] VI. Sensory segmentation rating: 1. Selection and training of evaluators: Select 10 professionally trained sensory evaluators (aged 22-45, half male and half female) who are familiar with the evaluation criteria for the harmony of numbing and spicy flavors and can accurately distinguish differences in flavor intensity.

[0059] 2. Development of scoring criteria: Sensory numbing sensation rating (1-10 points): 1 point no numbing sensation, 3 points slight numbing sensation, 5 points moderate numbing sensation, 7 points obvious numbing sensation, 9 points strong numbing sensation, 10 points extremely strong numbing sensation (unacceptable). Sensory spiciness and harmony rating (1-10 points): 1 point is completely unharmonious (single flavor is prominent), 3 points is somewhat unharmonious, 5 points is basically harmonious, 7 points is harmonious, 9 points is highly harmonious, and 10 points is extremely harmonious (spicy and numbing flavors are naturally integrated).

[0060] 3. Evaluation process: After numbering the samples, they are randomly arranged. In an undisturbed sensory evaluation room, the evaluators taste each sample in sequence and score the numbing sensation and the balance of spiciness independently. After scoring, the evaluators rinse their mouths with water and wait 3 minutes before evaluating the next sample. The average score of 10 evaluators is taken as the final score.

[0061] The experimental data are as follows:

[0062] Based on the experimental data, the total flavor scores of Examples 1-3 were significantly higher than all comparative examples, with Example 1 scoring the highest, fully demonstrating the synergistic optimization effect of the raw material ratio and process parameters of this invention. Comparative Example 1, due to deviations in the spice ratio from the specified range and an excessively high proportion of Sichuan pepper, resulted in a prominent numbing flavor, leading to a flavor-spiciness balance score of only 5.7 points, far lower than the 8.6 points or higher of Examples 1-3. This confirms that the precise ratio of lantern pepper, Erjingtiao pepper, and Sichuan pepper in the spices is key to achieving a balanced flavor. The total amount of free amino acids directly reflects the flavor-enhancing effect of the enzymatic hydrolysis process. The total amount of free amino acids in Examples 1-3 was significantly higher than that in Comparative Examples 2 and 3. Comparative Example 3, having not undergone enzymatic hydrolysis, had the lowest amount of free amino acids, indicating that the combined enzymatic hydrolysis system of neutral protease and flavor protease can efficiently degrade large molecular proteins and polysaccharides in the raw materials, converting them into small molecular flavor amino acids, significantly improving the richness and mellowness of the infusion liquid. Comparative Example 2, using only a single neutral protease, lacked targeted enzymatic hydrolysis, resulting in a lower release efficiency of flavor substances compared to the combined enzyme system.

[0063] Limonene, a core flavor component in spices and lime juice, directly affects aroma intensity due to its retention rate. Examples 1-3 all achieved limonene retention rates exceeding 85%. However, in Comparative Example 5, because the spice oil preparation did not utilize a brine-ethanol mixture soaking, high-temperature slow frying alone was insufficient to fully dissolve fat-soluble flavor substances, resulting in a limonene retention rate of only 72.4% and poor aroma. This demonstrates that the brine-ethanol pre-soaking combined with high-temperature slow frying process effectively improves the dissolution and retention of flavor substances. In Comparative Example 4, the food-grade chitosan's molecular weight exceeded the specified range, leading to poor cross-linking and an inability to form a stable colloidal network structure. This not only resulted in a limonene retention rate of 78.6% but also slight stratification and a small amount of oil separation. In contrast, Examples 1-3 showed no stratification or oil separation, and the flavor score change rate was less than 5%, highlighting the significant role of chitosan with a molecular weight of 5000-10000 Da in cross-linking, curing, and encapsulating flavor substances.

[0064] The viscosity data further corroborated the effectiveness of the stabilization process. The viscosities of Examples 1-3 were between 35-42 mPa·s, within the suitable stable range, while the viscosity of Comparative Example 4 was only 29.7 mPa·s. Comparative Example 6, due to the lack of ultrasonic treatment, had a viscosity of 33.5 mPa·s and showed obvious stratification and significant oil separation. This indicates that the synergistic effect of chitosan crosslinking and ultrasonic emulsification and dispersion can effectively improve the uniformity and stability of the system. In the sensory evaluation, the spiciness of Examples 1-3 was controlled within the palatable range of 7.0-7.5, and the spiciness-fragrant balance score was above 8.6. In contrast, Comparative Example 1, due to the imbalance of spice proportions, had a spiciness-fragrant score as high as 9.3, and a spiciness-fragrant balance score of only 5.7.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A crayfish soaking liquid, characterized in that, By weight, the raw material components include: 15-20 parts light soy sauce, 8-12 parts Shaoxing wine, 5-8 parts fermented red bean curd sauce, 3-5 parts seafood sauce, 4-6 parts white sugar, 1-2 parts salt, 3-5 parts lime juice, 5-8 parts spices, 2-3 parts porous starch, 0.15-0.25 parts compound enzyme preparation, 0.3-0.5 parts food-grade chitosan, and 30-40 parts water; The spices are composed of 30-40% bell pepper, 25-35% Erjingtiao pepper, 15-20% Sichuan pepper, 5-10% star anise, 3-5% cinnamon, and 2-3% bay leaves; The porous starch is food-grade corn porous starch with a specific surface area ≥10m². 2 / g, with a pore size of 50-200nm; The compound enzyme preparation is composed of neutral protease and flavor protease in a weight ratio of 1.5-2.5:1, wherein the neutral protease has an enzyme activity of 5000-8000 U / g and the flavor protease has an enzyme activity of 5000-8000 U / g.

2. The crayfish soaking liquid according to claim 1, characterized in that, The neutral protease is prepared by fermentation with Bacillus subtilis, and the flavor protease is prepared by fermentation with Aspergillus oryzae.

3. The crayfish soaking liquid according to claim 1, characterized in that, The food-grade chitosan has a degree of deacetylation ≥85% and a molecular weight of 5000-10000 Da.

4. The crayfish soaking liquid according to claim 1, characterized in that, The lime juice has a pH of 2.5-3.0 and a limonene content of ≥0.8 mg / mL.

5. A method for preparing crayfish infusion liquid, used to prepare the crayfish infusion liquid according to any one of claims 1-4, characterized in that, Includes the following steps: S1. The spices are pulverized, and a basic marinade is prepared by mixing water, light soy sauce, Shaoxing wine, fermented red bean curd juice, seafood sauce, white sugar and salt. S2. Mix 3-5 parts of the total amount of crushed spices with the basic infusion liquid and boil to obtain a basic infusion liquid containing spice residue; S3. Cool the basic extract containing spice residue to 50-55℃, add a compound enzyme preparation composed of neutral protease and flavor protease, and incubate at 50-55℃ and stirring rate of 50-80r / min for 15-20min to obtain the enzymatically hydrolyzed basic extract. S4. After enzymatic hydrolysis, heat to 70-75℃ and keep warm for 3-7 minutes to inactivate the enzyme and obtain the inactivated basic extract. S5. Cool the inactivated base extract to 45-50℃ and add food-grade chitosan; S6. Adjust the pH of the system to 5.0-5.5 with 0.5-1 mol / L citric acid, and crosslink at 45-50℃ for 20-25 min; S7. After crosslinking is completed, heat to 90-95℃ and hold for 8-12 minutes to perform curing treatment and obtain modified base impregnation solution; S8. Add spice oil, porous starch and lime juice to the modified base extract in sequence, and simultaneously perform ultrasonic treatment and stirring treatment; S9. After cooling and filtration, the mixture is instantaneously sterilized at 130-140℃ for 3-7 seconds to obtain crayfish infusion.

6. The preparation method according to claim 5, characterized in that, In step S1, the spices are pulverized to 40-60 mesh; In step S2, mix 3-5 parts of the total amount of pulverized spices with the base infusion, bring to a boil over high heat, then simmer over low heat at 80-90℃ for 15-20 minutes.

7. The preparation method according to claim 5, characterized in that, In step S3, the fermentation preparation step of the neutral protease is as follows: 1a: Using Bacillus subtilis as the starting strain, single colonies were picked and inoculated into seed culture medium. The seed culture medium consisted of 10 g / L tryptone, 5 g / L yeast extract, 5 g / L sodium chloride and water, and the pH was adjusted to 6.5-7.

0. 2a: Place the inoculated seed culture medium in a shaking culture at a temperature of 30-32℃ and a rotation speed of 180-220 r / min for 12-16 h, until the bacterial OD of the culture solution is reached. 600 When the value reaches 1.8-2.2, the activated seed solution is obtained; 3a: Inoculate the seed liquid into the fermentation medium at a volume ratio of 5-8%. The fermentation medium comprises, by weight, 10-15 parts corn flour, 8-12 parts soybean meal, 0.5-1 parts potassium dihydrogen phosphate, 0.1-0.3 parts magnesium sulfate, 0.3-0.5 parts sodium chloride, and 100 parts water. At the same time, adjust the pH of the fermentation system to 6.5-7.

0. 4a: Place the fermentation system at a temperature of 30-32℃ and an aeration rate of 1:0.8-1.2 vvm for 48-60 hours. During the fermentation process, add 2% glucose solution every 12 hours. 5a: After fermentation is complete, the fermentation broth is filtered through a plate and frame filter to remove the cells and impurities, and the clear filtrate is collected; 6a: The clarified filtrate is concentrated to 1 / 5 of its original volume by ultrafiltration, with a molecular weight cutoff of 10 kDa. Then, it is spray-dried at an inlet air temperature of 180-190℃ and an outlet air temperature of 80-85℃ to obtain a neutral protease with an enzyme activity of 5000-8000 U / g.

8. The preparation method according to claim 5, characterized in that, In step S3, the fermentation preparation step of the flavor protease is as follows: 1b: Using Aspergillus oryzae as the starting strain, the strain was inoculated into PDA slant medium, which consisted of 200 g / L potato, 20 g / L glucose, 15-20 g / L agar and water. 2b: Incubate the inoculated PDA slant culture medium at 28-30℃ for 48-72 hours until the slant is covered with green spores, thus completing the activation of the strain; 3b: Wash the green spores off the slant with sterile physiological saline, filter through sterile gauze to remove mycelium, and prepare a spore suspension with a spore concentration of 1×10⁻⁶. 6 -1×10 7 cells / mL; 4b: Inoculate the spore suspension into the fermentation medium at a volume ratio of 3-5%. The fermentation medium comprises, by weight, 15-20 parts wheat bran, 5-8 parts soybean meal, 2-3 parts sucrose, 0.5-1 parts ammonium sulfate, 1-2 parts calcium carbonate, and 100 parts water. Adjust the pH of the fermentation system to 6.0-6.

5. 5b: Place the fermentation system at a temperature of 28-30℃ and an aeration rate of 1:0.6-1.0 vvm for 72-96 hours, and control the pH of the system to be stable at 6.0-6.5 during the fermentation process; 6b: After fermentation is complete, centrifuge the fermentation broth at 8000-10000 r / min for 15-20 min to remove impurities and mycelium, and collect the supernatant; 7b: Slowly add ammonium sulfate to the supernatant until the saturation is 55%-65%, let it stand for 12-18 hours, and then centrifuge to collect the precipitate; 8b: Dissolve the precipitate in phosphate buffer solution with pH 5.8-6.2, place it in a dialysis bag and dialyze for 20-28 hours, changing the buffer solution every 6-10 hours to remove residual ammonium sulfate; 9b: The dialyzed solution was freeze-dried at a vacuum degree ≤10Pa and a temperature of -55℃~-45℃ to obtain a flavor protease with an enzyme activity of 5000-8000U / g.

9. The preparation method according to claim 5, characterized in that, In step S8, the preparation steps of the spice oil are as follows: 1c: Take 2-3 parts of the total amount of spice after crushing and set aside; 2c: Prepare a mixture, which is made by mixing 1-2% saline and 30-40% ethanol in a volume ratio of 1:1.5-2, and the amount of the mixture is 3-5 times the weight of the spices; 3c: Place the spices and mixture in a sealed container and soak in a constant temperature water bath at 40-45℃ for 25-35 minutes, stirring intermittently 3-4 times during the process, each stirring for 30 seconds. 4c: After soaking, drain the mixture adhering to the surface of the spices and collect the drained spices; 5c: Place the drained spices in a dry pot and heat over low heat to 100-110℃. Maintain this temperature and sauté slowly for 8-10 minutes. 6c: After sautéing, cool the spices and oil together to room temperature; 7c: Filter through a 100-120 mesh filter cloth to remove spice residue, and collect the filtrate as spice oil.

10. The preparation method according to claim 5, characterized in that, The specific operation of step S8 is as follows: after adding spice oil to the modified base extract, ultrasonic emulsify at 200-300W and 40kHz for 10-15 minutes; after adding porous starch, continue ultrasonic dispersion for 8-12 minutes; after adding lime juice, stir at 75-85℃ for 40-80 seconds. The cooling and filtration conditions in step S9 are as follows: after cooling to room temperature, filter with a 100-120 mesh filter cloth to remove impurities and residual fragrance residue.

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