Preparation method of enzymolysis oyster juice

Abstract

The invention relates to the technical field of biological fermentation, and particularly discloses a preparation method of enzymolysis oyster juice, which comprises the following steps: mixing oyster meat and water, pulping, and grinding to obtain oyster slurry; then protease is added into the oyster pulp for enzymolysis for 10-14 h; after the enzymolysis is finished, activated carbon is added into the oyster slurry after the enzymolysis for adsorption, stirring and heat preservation are carried out, the heat preservation temperature is 75-85 DEG C, then concentration is carried out, and concentrated oyster slurry is obtained; adding edible salt into the concentrated oyster slurry, cooling to room temperature, and then carrying out filter pressing treatment to obtain the enzymolysis oyster juice. The enzymolysis time of the oyster meat is prolonged, the protein utilization rate of the oyster meat and amino nitrogen of the oyster juice can be increased, the mode of combining medium-temperature concentration with physical deodorization is adopted, the oyster fragrance of the oyster juice can be well reserved, the protein utilization rate of the oyster meat and the yield of the oyster juice are increased, the bitter and scorched taste of the oyster juice is reduced, and the flavor of the oyster juice is improved; and the quality of the oyster sauce is improved by applying the additive to the oyster sauce.

Description

Technical Field

[0001] The present application relates to the field of biological fermentation technology, and in particular to a method for preparing enzymatically hydrolyzed oyster juice. Background Art

[0002] The traditional method of making oyster sauce is to concentrate the juice obtained after cooking the raw oyster meat. As the market demand for oyster sauce increases, the traditional method of making oyster sauce is difficult to meet the strong demand of downstream, and this method does not make good use of the remaining oyster meat protein. At present, seasoning companies widely use bio-enzyme catalysis technology to prepare oyster sauce. This method mainly grinds the oyster meat, adds bio-enzyme hydrolysis after adding water or beating, and then uses high temperature for concentration reaction. After cooling, centrifugation is used to remove the sediment to obtain oyster sauce.

[0003] However, since oysters are rich in nutrients such as lipids and proteins, and their internal organs contain other substances such as seaweed, fatty acids are easily oxidized during the enzymatic hydrolysis process, and proteins produce ammonium salts under the action of microorganisms, resulting in unpleasant flavors such as fishy and seafood flavors. In order to remove these unpleasant flavors, high-temperature concentration is usually used to make the enzymatic hydrolyzed oyster juice undergo a Maillard reaction to generate a burnt flavor to reduce the unpleasant flavor, but this method will weaken the oyster flavor and sweet flavor of the oyster juice. In addition, the concentrated oyster juice contains a large amount of fat and insoluble precipitates, which need to be further removed by centrifugation before oyster juice can be obtained. The oyster juice prepared by this enzymatic hydrolysis process has a weak oyster flavor, a strong fishy smell, a low protein content, and a bitter and sticky taste. When used in oyster sauce, it seriously affects the sensory quality of oyster sauce.

[0004] Patent publication number CN117502629A discloses a fermented oyster juice and a preparation method thereof. The method produces oyster juice by combining solid-state fermentation and liquid fermentation, and reduces the production of fishy substances during the enzymatic hydrolysis process. However, the enzymatic hydrolysis cycle of the method is as long as 6-12 months, which is difficult to apply in large-scale production; Patent publication number CN117084393A discloses a flavored oyster juice and a preparation method and application thereof. The method compounds a wheat suspension with enzymatically hydrolyzed oyster juice, adds specific fermentation bacteria for fermentation, thereby reducing the bitterness and fishy smell of the enzymatically hydrolyzed oyster juice. The method uses a fermentation process to improve the sensory flavor of the enzymatically hydrolyzed oyster juice, but the actual operation is relatively complicated and the fermentation cycle is as long as 48 hours.

[0005] At present, the enzymatic hydrolysis of oyster juice usually uses microbial fermentation to remove the fishy smell in oyster juice. The disadvantage of this method is that the processing cycle is long and not conducive to production. There are few literature reports on the use of physical methods to remove the fishy smell in oyster juice. The enzymatic hydrolysis time of traditional oyster juice should not be too long. Too long will cause microorganisms to easily produce too much ammonium salt, resulting in low utilization rate of oyster meat and bitterness of the prepared oyster juice. At the same time, because oysters contain foreign matter such as fat and seaweed in the digestive gland, some unpleasant flavors will be produced during enzymatic hydrolysis and subsequent thermal processing. In order to reduce these flavor substances, the Maillard reaction of oyster juice has to be intensified to produce more aroma components, but this excessive reaction is also accompanied by the production of burnt and bitter tastes, which greatly weakens the original oyster flavor and sweet aroma of oyster juice. Summary of the invention

[0006] The purpose of the present application is to overcome the shortcomings of the above-mentioned prior art and provide a method for preparing enzymatic oyster juice. The present application adopts medium-temperature concentration combined with physical fishy removal, which can better retain the oyster flavor of the oyster juice, improve the utilization rate of oyster meat protein and the yield of oyster juice, reduce the bitterness and burnt taste of oyster juice, improve the flavor of oyster juice, and apply it to oyster sauce to improve the quality of oyster sauce.

[0007] To achieve the above purpose, the technical solution adopted by this application is:

[0008] The present application provides a method for preparing enzymatically hydrolyzed oyster juice, comprising the following steps:

[0009] S1, mixing oyster meat with water, beating and grinding to obtain oyster slurry; then adding protease to the oyster slurry for enzymatic hydrolysis for 10 to 14 hours;

[0010] S2, after the enzymatic hydrolysis is completed, activated carbon is added to the enzymatically hydrolyzed oyster slurry for adsorption, stirred and kept warm at a temperature of 75-85° C., and then concentrated to obtain concentrated oyster slurry;

[0011] S3. Add edible salt to the concentrated oyster slurry, cool to room temperature, and then perform filter press treatment to obtain enzymatically hydrolyzed oyster juice.

[0012] First, the enzymatic hydrolysis process of oysters is accompanied by lipid oxidation and the release of odors in their own internal organs, such as 2-methylbutanal, valeraldehyde, 1-penten-3-one and other fishy substances; secondly, the high-temperature thermal reaction process will intensify the oxidation of lipids and the production of some undesirable flavor substances such as sulfides, furfuryl alcohol, etc.; if low-temperature concentration is used, no burnt aroma substances will be produced, and some undesirable flavor substances cannot be reduced and covered up. At the same time, low temperature cannot inhibit the growth of microorganisms, and the concentration process will intensify the generation of odor in oyster juice; the purpose of using medium-temperature concentration in this application is that the aroma substances produced by the Maillard reaction in the medium-temperature process are greater than the undesirable flavor substances, which can retain the oyster flavor of the oyster juice, increase the sweet aroma of the oyster juice, and thus enhance the sensory flavor of the enzymatically hydrolyzed oyster juice.

[0013] After extensive research and experiments, the inventors of the present application discovered that by prolonging the enzymatic hydrolysis time (10 to 14 hours) the utilization rate of oyster meat and the amino nitrogen in oyster juice can be increased, and by using medium-temperature concentration combined with activated carbon adsorption technology, the fat components, foreign matter and undesirable flavor substances in oyster juice can be removed, thereby solving technical problems such as the bitterness of oyster juice and poor flavor of oyster juice due to high-temperature concentration, and better maintaining the oyster flavor and sweet aroma of the oyster juice.

[0014] Among them, the enzymatic hydrolysis time is extended (10 to 14 hours) because the enzymatic hydrolysis process produces ammonium bitter substances and undesirable flavor substances (such as fishy substances). The present application adds activated carbon with a good adsorption effect, which can remove large molecular lipid substances and foreign matter and other undesirable flavor components (fishy smell and burnt bitterness of oyster juice), effectively reduce the content of these undesirable flavor substances, thereby achieving the purpose of improving the flavor of oyster juice.

[0015] As a preferred embodiment of the method for preparing enzymatically hydrolyzed oyster juice described in the present application, the amount of activated carbon added is 2-3% of the mass of the oyster juice after enzymatic hydrolysis.

[0016] The present application uses the above-mentioned added amount of activated carbon to remove the problem of bitterness of oyster juice caused by ammonium salts produced due to long enzymatic hydrolysis time, thereby increasing the protein content in oyster juice, reducing fishy substances and unpleasant flavor components, and significantly improving the sensory quality and yield of oyster juice.

[0017] As a preferred embodiment of the method for preparing enzymatically hydrolyzed oyster juice described in the present application, the amount of activated carbon added is 2.5% of the mass of the oyster slurry after enzymatic hydrolysis.

[0018] The activated carbon of the present application is preferably added in the above amount, which can better adsorb ammonium salts, significantly improve the sensory quality of oyster juice, and further improve the overall quality of enzymatically hydrolyzed oyster juice.

[0019] As a preferred embodiment of the method for preparing enzymatically hydrolyzed oyster juice described in the present application, the mesh size of the activated carbon is 40 to 80 meshes.

[0020] In the technical solution of the present application, the above mesh number of activated carbon can better improve the protein content in oyster juice and the yield of oyster juice; the larger the mesh number of activated carbon, the more it will affect the protein content in oyster juice and the yield of oyster juice. The reason may be that the larger the mesh number of activated carbon, the finer the particles, the stronger its adsorption capacity and the smaller the gaps between the particles, which makes it easy for large molecular proteins to be retained, reducing the protein content in oyster juice. When applied to oyster sauce, the thickness of oyster sauce will be inconsistent; of course, the smaller the mesh number, the smaller the specific surface area of ​​activated carbon, which will lead to poor adsorption effect of activated carbon, which is not conducive to removing bad flavor components in oyster juice and large particles of foreign matter in oyster digestive glands.

[0021] As a preferred embodiment of the method for preparing enzymatically hydrolyzed oyster juice described in the present application, the mesh size of the activated carbon is 60 meshes.

[0022] As a preferred embodiment of the method for preparing enzymatically hydrolyzed oyster juice described in the present application, in step S2, the insulation temperature is 80°C.

[0023] As a preferred embodiment of the method for preparing enzymatically hydrolyzed oyster juice described in the present application, in the step S2, the concentration multiple is 1 to 1.2 times.

[0024] The medium-temperature concentration adopted in the present application can better preserve the oyster aroma and sweet aroma, reduce the burnt bitterness, and thus enhance the sensory flavor of the oyster juice.

[0025] The present application also provides enzymatically hydrolyzed oyster juice prepared by the above-mentioned method for preparing enzymatically hydrolyzed oyster juice.

[0026] The present application increases the utilization rate of protein by prolonging the enzymatic hydrolysis time of oyster meat, and then uses activated carbon adsorption treatment to remove the problem of bitterness of oyster juice caused by ammonium salts produced due to excessively long enzymatic hydrolysis time. When the mesh size and addition amount of activated carbon are further optimized, the problem of high fat content in enzymatically hydrolyzed oyster juice and other foreign matter causing strong fishy smell and difficulty in storage of oyster juice can be solved. The problem of low protein content, insufficient taste and low oyster juice yield after centrifugation of enzymatically hydrolyzed oyster juice can also be solved. At the same time, medium-temperature concentration can better retain the oyster aroma and sweet aroma, reduce the burnt bitterness, and thus enhance the sensory flavor of oyster juice.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] The present application provides a method for preparing enzymatically hydrolyzed oyster juice. The present application significantly improves the utilization rate of oyster meat and the amino nitrogen content by more than 0.1g / 100g by extending the enzymatic hydrolysis time by 2-4h; in the preparation process, activated carbon is added to reduce the ammonium salt in the oyster juice by more than 60%, increase the protein content in the oyster juice by more than 50%, reduce the fat and fatty acid content by about 80%, reduce the proportion of fishy substances and bad flavor components by about 30%, and significantly improve the sensory quality of the oyster juice, and also significantly improve the yield of the oyster juice; and the present application adopts a medium-temperature concentration method to prepare oyster juice with a strong oyster flavor, a thick taste and a weak fishy smell, and no anti-fishy smell during storage, and the sensory flavor of the oyster juice is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The flavor profile of the enzymatically hydrolyzed oyster sauce prepared in Example 1;

[0030] Figure 2 This is the spectrum of the centrifuged oyster juice serum prepared in Comparative Example 1. DETAILED DESCRIPTION

[0031] In order to better illustrate the purpose, technical solutions and advantages of the present application, the present application will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] In the following examples and comparative examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified, and the components and raw materials used in each parallel experiment are of the same type.

[0033] In the following examples and comparative examples, a composite flavor protease containing aminopeptidase and carboxypeptidase was used, which can be purchased from Dongheng Huadao.

[0034] Example 1: A method for preparing enzymatically hydrolyzed oyster juice

[0035] This embodiment provides a method for preparing enzymatically hydrolyzed oyster juice, comprising the following steps:

[0036] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature (50°C to 55°C, preferably 55°C), and stirring is started to add a composite flavor protease containing aminopeptidase and carboxypeptidase (the addition amount of the composite flavor protease is 0.8% of the oyster slurry) for enzymatic hydrolysis for 10 hours; after the enzymatic hydrolysis is completed, 2.5% activated carbon with a mesh size of 60 is added to the enzymatically hydrolyzed oyster slurry, stirred evenly, and then heated to 80°C for insulation, concentrated to 1 times, and then added with edible salt (mass concentration is 20%), and then cooled to room temperature, and finally subjected to filter pressing to obtain enzymatic hydrolyzed oyster juice.

[0037] Example 2: A method for preparing enzymatically hydrolyzed oyster juice

[0038] This embodiment provides a method for preparing enzymatically hydrolyzed oyster juice, comprising the following steps:

[0039] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 12 hours; after the enzymatic hydrolysis is completed, 2.5% activated carbon with a mesh size of 60 is added to the enzymatically hydrolyzed oyster slurry, stirred evenly, and then heated to 80°C for insulation, concentrated to 1 times, edible salt is added, and then cooled to room temperature, and finally filtered by pressure to obtain enzymatic hydrolyzed oyster juice.

[0040] Example 3: A method for preparing enzymatically hydrolyzed oyster juice

[0041] This embodiment provides a method for preparing enzymatically hydrolyzed oyster juice, comprising the following steps:

[0042] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 10 hours; after the enzymatic hydrolysis is completed, 2.0% activated carbon with a mesh size of 60 is added to the enzymatically hydrolyzed oyster slurry, stirred evenly, and then heated to 80°C for insulation, concentrated to 1 times, edible salt is added, and then cooled to room temperature, and finally filtered to obtain enzymatic hydrolyzed oyster juice.

[0043] Example 4: A method for preparing enzymatically hydrolyzed oyster juice

[0044] This embodiment provides a method for preparing enzymatically hydrolyzed oyster juice, comprising the following steps:

[0045] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 12 hours; after the enzymatic hydrolysis is completed, 2.5% activated carbon with a mesh size of 80 is added to the enzymatically hydrolyzed oyster slurry, stirred evenly, and then heated to 80°C for insulation, concentrated to 1 times, edible salt is added, and then cooled to room temperature, and finally filtered by pressure to obtain enzymatic hydrolyzed oyster juice.

[0046] Example 5: A method for preparing enzymatically hydrolyzed oyster juice

[0047] This embodiment provides a method for preparing enzymatically hydrolyzed oyster juice, comprising the following steps:

[0048] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 12 hours; after the enzymatic hydrolysis is completed, 2.5% activated carbon with a mesh size of 80 is added to the enzymatically hydrolyzed oyster slurry, stirred evenly, and then heated to 85°C for insulation, concentrated to 1 times, edible salt is added, and then cooled to room temperature, and finally filtered by pressure to obtain enzymatic hydrolyzed oyster juice.

[0049] Example 6: A method for preparing enzymatically hydrolyzed oyster juice

[0050] This embodiment provides a method for preparing enzymatically hydrolyzed oyster juice, comprising the following steps:

[0051] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 12 hours; after the enzymatic hydrolysis is completed, 2.5% activated carbon with a mesh size of 40 is added to the enzymatically hydrolyzed oyster slurry, stirred evenly, and then heated to 85°C for insulation, concentrated to 1 times, edible salt is added, and then cooled to room temperature, and finally filtered by pressure to obtain enzymatic hydrolyzed oyster juice.

[0052] Example 7: A method for preparing enzymatically hydrolyzed oyster juice

[0053] This embodiment provides a method for preparing enzymatically hydrolyzed oyster juice, comprising the following steps:

[0054] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 10 hours; after the enzymatic hydrolysis is completed, 2.0% activated carbon with a mesh size of 40 is added to the enzymatically hydrolyzed oyster slurry, stirred evenly, and then heated to 75°C for insulation, concentrated to 1 times, edible salt is added, and then cooled to room temperature, and finally filtered by pressure to obtain enzymatic hydrolyzed oyster juice.

[0055] Example 8: A method for preparing enzymatically hydrolyzed oyster juice

[0056] This embodiment provides a method for preparing enzymatically hydrolyzed oyster juice, comprising the following steps:

[0057] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 14 hours; after the enzymatic hydrolysis is completed, 3.0% activated carbon with a mesh size of 40 is added to the enzymatically hydrolyzed oyster slurry, stirred evenly, and then heated to 75°C for insulation, concentrated to 1 times, edible salt is added, and then cooled to room temperature, and finally filtered by pressure to obtain enzymatic hydrolyzed oyster juice.

[0058] Comparative Example 1

[0059] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) is enzymatically hydrolyzed for 10 hours; after the enzymatic hydrolysis is completed, the temperature is increased to 105-110° C. for concentration treatment, edible salt is added after the concentration is 1 times, and then the oyster juice is cooled to room temperature; the concentrated oyster juice is centrifuged at a speed of 4000 r / min, and the precipitate is removed to obtain a centrifuged oyster juice clear liquid.

[0060] Comparative Example 2

[0061] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) is enzymatically hydrolyzed for 8 hours; after the enzymatic hydrolysis is completed, the temperature is increased to 105-110° C. for concentration treatment, edible salt is added after the concentration is 1 times, and then the oyster juice is cooled to room temperature; the concentrated oyster juice is centrifuged at a speed of 4000 r / min, and the precipitate is removed to obtain a centrifuged oyster juice clear liquid.

[0062] Comparative Example 3

[0063] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is raised to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 10 hours; after the enzymatic hydrolysis is completed, 2.5% activated carbon with a mesh size of 60 is added, the temperature is raised to 105-110°C for concentration treatment, edible salt is added after concentration by 1 times, and then the mixture is cooled to room temperature, and finally a filter press treatment is performed to obtain enzymatic hydrolyzed oyster juice.

[0064] Comparative Example 4

[0065] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to the optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 10 hours; after the enzymatic hydrolysis is completed, 2.5% chitosan is added to the enzymatically hydrolyzed oyster slurry, stirred evenly, and then heated to 80°C for insulation, concentrated to 1 times, edible salt is added, and then cooled to room temperature, and finally filtered to obtain enzymatic hydrolyzed oyster juice.

[0066] Comparative Example 5

[0067] The whole oyster meat is used as a raw material, mixed with an appropriate amount of water and then pulped (the mass ratio of oyster meat to water is 1:3; for example, 1 kg of oyster meat and 3 kg of water), and then ground to obtain oyster slurry; the temperature of the oyster slurry is increased to an optimal enzymatic hydrolysis temperature, stirring is started, and a composite flavor protease containing aminopeptidase and carboxypeptidase is added (the amount of the composite flavor protease added is 0.8% of the oyster slurry) for enzymatic hydrolysis for 10 hours; after the enzymatic hydrolysis is completed, 2.5% activated carbon with a mesh size of 100 is added, the temperature is increased to 105-110°C for concentration treatment, edible salt is added after concentration by 1 times, and then the mixture is cooled to room temperature, and finally a filter press treatment is performed to obtain enzymatic hydrolyzed oyster juice.

[0068] Test examples, sensory evaluation

[0069] The enzymatically hydrolyzed oyster juice prepared in Examples 1 to 8 and the centrifuged oyster juice supernatant or enzymatically hydrolyzed oyster juice prepared in Comparative Examples 1 to 5 were used to calculate the yield and boiled into oyster sauce for sensory evaluation.

[0070] 1. Physical and chemical index testing:

[0071] The amino nitrogen in oyster juice is detected by the method of "GB / T 5009.39-2003"; the volatile basic nitrogen in oyster juice is detected by the method of "GB 5009.228-2016 National Food Safety Standard Determination of Volatile Basic Nitrogen in Food"; the protein in oyster juice is detected by the method of "GB 5009.5-2016 National Food Safety Standard Determination of Protein in Food"; the fat in oyster juice is detected by the method of "GB 5009.6-2016 National Food Safety Standard Determination of Fat in Food"; the fatty acids in oyster juice are detected by "GB5009.168-2016 National Food Safety Standard Determination of Fatty Acids in Food"; the reducing sugar in food is detected by "GB 5009.7-2016 National Food Safety Standard Determination of Reducing Sugar in Food".

[0072] 2. Weigh a certain amount of oyster meat and record it as X1. After pulping, grind it and then perform enzymatic hydrolysis. After the enzymatic hydrolysis, centrifuge it at 10,000 rpm for 15 minutes to remove the clear liquid and then weigh it as X2. The oyster meat utilization rate is calculated as follows: (X1-X2)÷X1×100%; the oyster juice yield rate refers to the ratio of the actual yield to the theoretical yield after the enzymatic hydrolyzed oyster juice is concentrated by one time.

[0073] 3. The oyster juice samples (enzymatically hydrolyzed oyster juice or centrifuged oyster juice clear liquid) of Examples 1 to 8 and Comparative Examples 1 to 5 were selected for quality detection and their flavor components were analyzed.

[0074] 4. Sensory evaluation method: 10 professional assessors were organized to conduct sensory evaluation on oyster juice and oyster sauce samples with different processing methods. The following scoring table 1 is the evaluation standard. A sensory score of 80 points or more indicates that the sensory flavor of the oyster sauce is good.

[0075] Table 1

[0076] Serial number Aroma (0-5 points) Taste (0-5 points) Level (0-100 points) 1 Rich oyster flavor, no fishy smell (4-5) Sweet and rich taste, no fishy smell (4-5) Excellent (90-100) 2 Better oyster flavor, slightly burnt taste (3-4) Sweet and rich taste with a slight burnt taste (3-4) Good (80-90) 3 Oyster aroma is average, with a slight seafood flavor (2-3) The taste is thin and the richness is not good (2-3) Average (70-80) 4 Oyster aroma is slightly weak, with a fishy smell (1-2) Thin taste, bitter and burnt taste (2-3) Passed (60-70)

[0077] The results are shown in Table 2.

[0078] Table 2

[0079]

[0080]

[0081] According to the analysis of the test results in Table 2, comparing Example 1 and Example 2, as the enzymatic hydrolysis process of oyster meat prolongs, a large amount of ammonium salts, i.e., volatile basic nitrogen, will be produced in the enzymatic hydrolyzate due to the action of microorganisms, and the use of high-temperature concentration will further aggravate the production of ammonium salts. The ammonium salts in the oyster juice in Comparative Example 1 increased from 116 mg / 100 ml after enzymatic hydrolysis to 183 mg. The increase in ammonium salts will make the oyster juice bitter and affect the taste of the oyster sauce. After adding activated carbon treatment, the ammonium salts are significantly reduced, and the reduction range is in the range of 60-90%. According to this conclusion, the application of activated carbon can appropriately prolong the enzymatic hydrolysis time of oyster meat, improve the utilization rate of oyster meat and increase the content of amino nitrogen in oyster juice. Compared with Comparative Examples 1 and 2, the utilization of oyster sauce in Examples 1 to 8 is increased by about 5-10%, and the amino acid nitrogen is increased by more than 0.1 g / 100 g.

[0082] In addition, from the test results of fat and fatty acids in Example 1 and Comparative Example 1, activated carbon can reduce the content of fatty acids and fat, and can reduce the production of more fishy components due to oxidation in the subsequent production process, further improving the sensory flavor of oyster sauce. From the results of applying oyster sauce after 30 days of storage of oyster sauce, it can be concluded that 0.48g / 100g of fatty acids and 0.61g / 100g of fat remain in the traditional enzymatic hydrolysis oyster sauce. These substances undergo oxidation reactions during storage and are converted into other undesirable flavor substances, resulting in a significant decrease in the quality of the oyster sauce after cooking, which indirectly causes the quality of the oyster sauce to decline during storage. In contrast, the quality of the oyster sauce in Example 1 is stable during storage, and the sensory flavor does not change significantly.

[0083] In addition, from the results of Example 5 and Example 6, it can be concluded that the larger the mesh number of the activated carbon, as in Comparative Example 5, the more it affects the protein content in the oyster juice and the yield of the oyster juice. The reason may be that the larger the mesh number of the activated carbon, the finer the particles, the stronger its adsorption capacity and the smaller the gaps between the particles, which makes it easy for large molecular proteins to be retained, reducing the protein content in the oyster juice. When applied to oyster sauce, the thickness of the oyster sauce will be inconsistent; of course, the smaller the mesh number, the smaller the specific surface area of ​​the activated carbon, which will lead to a worse adsorption effect of the activated carbon, which is not conducive to removing the bad flavor components in the oyster juice and large particles of foreign matter in the oyster digestive gland.

[0084] The medium-temperature concentration treatment adopted in the present application can better retain the reducing sugar in the oyster juice, prevent the high temperature from causing the reducing sugar to react with the protein to produce burnt and mushy tastes, and affect the sensory flavor of the oyster juice. It can be concluded from the sensory scores in the examples that the sensory flavor is better than that of Comparative Examples 1 and 3.

[0085] Compared with the traditional enzymatic hydrolysis oyster juice processing technology, the present application adopts a filter press process to produce oyster juice in one process, and the oyster juice yield is basically above 90%. The traditional enzymatic hydrolysis process uses centrifugation to remove oil, seaweed and other sediments in the oyster juice in one process, and centrifugation is required more than two times to produce clarified oyster juice, which increases the loss of oyster juice.

[0086] Comparative Example 4 is compared with Example 1. After replacing chitosan with activated carbon, the ammonium salt, fatty acid, and lipid content increased significantly, and the protein content decreased significantly. In the preparation of oyster juice and oyster sauce, the sensory flavor was significantly deteriorated. This may be because chitosan cannot inhibit the proliferation of microorganisms during the low-temperature concentration process. In addition, compared with the indifferent adsorption effect of activated carbon, chitosan has limited adsorption capacity and cannot remove most of the bad flavor substances, resulting in a heavier oyster smell in the oyster sauce.

[0087] The oyster sauce samples of Comparative Example 1 and Example 1 were selected for flavor component analysis (as shown in Table 3).

[0088] Table 3

[0089]

[0090]

[0091] As shown in Table 3, after enzymatic hydrolysis of oyster meat, medium-temperature concentration combined with activated carbon adsorption treatment was used. Compared with the traditional enzymatic hydrolysis oyster juice processing technology, the proportion of fishy components and bad flavors decreased from 32.1% to 3.43%, among which the representative fishy odor substance 1-penten-3-one decreased from 1.99% to 0.07%, and the large molecular sulfide odor components dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, and furfuryl methyl sulfide were basically removed, indicating that activated carbon has a good adsorption effect on these bad flavor substances, thereby improving the flavor of oyster juice.

[0092] The oyster sauce flavor of Example 1 is as follows Figure 1 As shown, the oyster sauce flavor profile of Comparative Example 1 is as follows Figure 2 shown.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present application.

Claims

1. A method for preparing enzymatically hydrolyzed oyster juice, characterized in that: The following steps are involved: S1, mixing oyster meat with water, beating and grinding to obtain oyster slurry; then adding protease to the oyster slurry for enzymatic hydrolysis for 10 to 14 hours; S2, after the enzymatic hydrolysis is completed, activated carbon is added to the enzymatically hydrolyzed oyster slurry for adsorption, stirred and kept warm at a temperature of 75-85° C., and then concentrated to obtain concentrated oyster slurry; S3. Add edible salt to the concentrated oyster slurry, cool to room temperature, and then perform filter press treatment to obtain enzymatically hydrolyzed oyster juice.

2. The method for preparing enzymatically hydrolyzed oyster juice according to claim 1, characterized in that: The added amount of the activated carbon is 2-3% of the mass of the oyster slurry after enzymolysis.

3. The method for preparing enzymatically hydrolyzed oyster juice according to claim 2, characterized in that: The added amount of the activated carbon is 2.5% of the mass of the oyster slurry after enzymatic hydrolysis.

4. The method for preparing enzymatically hydrolyzed oyster juice according to claim 1, characterized in that: The mesh number of the activated carbon is 40 to 80 meshes.

5. The method for preparing enzymatically hydrolyzed oyster juice according to claim 4, characterized in that: The mesh number of the activated carbon is 60 meshes.

6. The method for preparing enzymatically hydrolyzed oyster juice according to claim 1, characterized in that: In step S2, the insulation temperature is 80°C.

7. The method for preparing enzymatically hydrolyzed oyster juice according to claim 1, characterized in that: In the step S2, the concentration factor is 1 to 1.2 times.

8. Enzymatically hydrolyzed oyster juice prepared by the method for preparing enzymatically hydrolyzed oyster juice according to any one of claims 1 to 7.

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