Low-salt shrimp paste fermentation apparatus and method

Abstract

This invention discloses a low-salt shrimp paste fermentation device and method, relating to the field of shrimp paste preparation technology; it includes a fermentation tank with two layers: an inner insulation layer and an outer protective shell; a connecting structure between the inner and outer layers; a temperature control system; an exhaust pipe; a stirring buoyancy cage, including a horizontally arranged cage body with horizontal shafts at both ends, the horizontal shafts extending out of the insulation layer and connecting to the connecting structure; a stirring body located outside the stirring buoyancy cage, connected to the stirring buoyancy cage; a main bag installed in the stirring buoyancy cage; the main bag is filled with nitrogen gas and has a branch pipe connected to the stirring body; an installation cavity is opened in the stirring body, and an exhaust valve is installed in the installation cavity; an exhaust port is opened on the stirring body, and the end of the branch pipe is connected to the exhaust valve and connected to the exhaust port; a rotating pressing component is installed outside the protective shell to solve the technical problem that ammonia emissions can easily introduce air and bring in contaminants, damaging the fermentation process.

Description

Technical Field

[0001] This invention relates to the field of shrimp paste preparation technology, specifically to a low-salt shrimp paste fermentation equipment and method. Background Technology

[0002] Shrimp paste, also known as shrimp roe, is a traditional condiment in coastal areas of my country. The main ingredient is typically small shrimp, including white shrimp, mantis shrimp, and spotted shrimp. The production method involves natural fermentation. After washing the raw materials, they are placed in a vat with a generous amount of salt, mixed thoroughly, smoothed, and exposed to sun and dew. The mixture is stirred twice daily for 15-30 days to complete fermentation. Once fermented, shrimp paste has a slightly reddish color, a fine texture, and a superior flavor.

[0003] Shrimp paste is prepared in two ways: high-salt shrimp paste and low-salt shrimp paste. High-salt shrimp paste has a high salt content, which is not conducive to the growth of microorganisms, so the fermentation time is long, and the high salt content will inhibit the formation of flavor substances.

[0004] Low-salt shrimp paste has a lower salt content and is more like a green food. However, due to its lower salt content, the bacterial colony is harder to control, making it easier for harmful bacteria to grow.

[0005] Existing industrial shrimp paste production methods, such as CN201410602935.7 (a method for making shrimp paste and its dedicated equipment) and CN202211442600.4 (a method for making low-salt shrimp paste), reveal that the former uses soybeans and compound enzymes for targeted enzymatic hydrolysis to make shrimp paste, while the latter uses spices. However, these methods have the following problems: 1) Low-to-medium temperature fermentation produces a large amount of ammonia in the early stages, mainly volatile components such as ammonia gas and trimethylamine, which also brings obvious off-odors. The comparative documents suggest directly opening the tank lid for ventilation, which is not advisable as it allows air to enter and introduces the possibility of contaminating bacteria.

[0006] 2) Existing fermentation equipment, such as CN202020717189.7 Fermentation and blending equipment, mostly have a stirring function and use a motor for rotation control. However, most existing stirring is fixed-point stirring, which is not conducive to the movement of the sauce at the bottom.

[0007] 3) Currently, the common practice is to stir and separate the ammonia from the shrimp paste, and then open the exhaust valve to release the gas. However, while releasing the ammonia, it is difficult to ensure that air will not enter the tank. Summary of the Invention

[0008] To overcome the above shortcomings, this invention provides a low-salt shrimp paste fermentation equipment and method to solve the technical problem that ammonia emissions can easily introduce airborne bacteria, thereby damaging the fermentation process.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A low-salt shrimp paste fermentation device, comprising:

[0011] The fermentation tank has two layers: an inner insulation layer and an outer protective shell; a connecting structure is installed between the inner and outer layers.

[0012] The temperature control system is used for heating and temperature control of the inner layer.

[0013] The exhaust pipe is located at the top of the fermentation tank and extends into the insulation layer; a one-way valve and a main exhaust valve are installed at the top.

[0014] A stirring buoyancy cage includes a cage body, which is arranged horizontally and has horizontal shafts at both ends. The horizontal shafts extend out to form an insulation layer that connects to a connecting structure. An agitator is provided on the outside of the stirring buoyancy cage and is connected to the stirring buoyancy cage.

[0015] The main bag is installed in the mixing buoyancy cage; the main bag is filled with nitrogen and has a branch pipe connected to the mixing body; an installation cavity is opened in the mixing body and an exhaust valve is installed in the installation cavity; an exhaust port is opened on the mixing body; the end of the branch pipe is connected to the exhaust valve and connected to the exhaust port.

[0016] The rotating pressure component, installed outside the protective housing, is used to press down on and drive the rotation of the connecting structure.

[0017] In a further technical solution, the connection structure includes a mounting plate, a ring portion is provided on the mounting plate, a conical cylinder is provided in the middle of the ring portion, and constraint holes are distributed radially in the ring portion;

[0018] The rotating pressing component includes a rotary motor, the output end of which is connected to a drive shaft. A connecting assembly plate is installed on the end of the drive shaft away from the rotary motor. The connecting assembly plate has a snap-fit ​​groove that is compatible with the conical cylinder.

[0019] A movable shaft is provided inside the connecting assembly plate. When the connecting assembly plate is engaged with the tapered cylinder, it compresses the movable shaft into the constraint hole.

[0020] In a further technical solution, a guide groove is provided on the insulation layer. The diameter of the guide groove is not less than the outer diameter of the horizontal axis, and an elastic sealing component is installed outside the guide groove.

[0021] The connecting assembly includes a connecting body, with a snap-fit ​​groove in the middle of the connecting body; the snap-fit ​​groove has a lateral groove axially arranged, which extends and penetrates to the lateral outer wall of the connecting body; a movable shaft is installed in the lateral groove, with one end of the movable shaft extending into the snap-fit ​​groove and having an inclined surface, so that when the conical cylinder is inserted into the snap-fit ​​groove, the inclined surface abuts against the conical cylinder.

[0022] In a further technical solution, a fixing ring is provided at the end of the lateral groove away from the snap-fit ​​groove. The fixing ring is sleeved on the movable shaft and fixedly installed on the connecting body.

[0023] A position ring plate is installed on the movable shaft, and the position ring plate is located in the lateral groove; a connecting spring is installed between the position ring plate and the fixed ring, one end of the connecting spring is fixed to the side of the fixed ring facing the snap groove, and the other end is fixed to the position ring plate.

[0024] In a further technical solution, the protective shell is provided with a guide groove two, and a sliding plate is installed on the guide groove two. The sliding plate is adapted to be installed on the guide groove two; the sliding plate is connected to the body of the rotary motor.

[0025] A transmission cylinder is also installed on the skateboard; a descent pole is installed on the top of the transmission cylinder, and the pole body is installed on the protective housing; the output end of the descent pole is used to push the transmission cylinder to drive the transmission shaft to descend in height.

[0026] In a further technical solution, the connection structure also includes a split column, which is integrally formed with the mounting plate. A protective cylinder is installed on the end of the horizontal axis facing the split column, and a synchronous spring is installed inside the protective cylinder. One end of the synchronous spring is fixedly connected to the horizontal axis, and the other end is sleeved on the split column and fixedly connected to the mounting plate.

[0027] In a further technical solution, the drive shaft is a threaded shaft, and a threaded center hole is provided on the connecting body, which is threadedly connected to the threaded shaft; a guide rod is also installed on the slide plate, and the guide rod is arranged laterally; the connecting body is sleeved on the guide rod.

[0028] S1. Raw material selection and pretreatment:

[0029] Select the target shrimp as raw material, remove impurities and wash them clean with water;

[0030] Mixing: Mix the target shrimp with soybeans and supplementary shrimp shells in a certain proportion (e.g., the mass ratio of soybeans:shrimp shells:shrimp heads is (2.45~3.74):1:(0.65~0.82) to enhance the flavor and freshness, while improving the utilization rate of raw materials;

[0031] Drain and centrifuge or use a centrifuge to remove surface moisture;

[0032] S2. Grinding and Gelatinization: Grind the processed shrimp feed into a fine paste using a meat grinder, stone mill, or chopper; if using a low-speed stone mill, control the speed at 10-30 r / min to avoid generating too much heat at high speeds that could damage the protein structure;

[0033] S3. Sterilization: The surface of the pulverized and gelatinized shrimp feed is sterilized by high-temperature sterilization at 121°C for 15-30 minutes to reduce the number of miscellaneous bacteria in the raw materials and provide a competitive advantage for the subsequent inoculation of fermentation agents.

[0034] S4. Enzymatic hydrolysis: After sterilization, alkaline protease is added to the gelatinized shrimp feed for enzymatic hydrolysis. The mixture is then hydrolyzed in a water bath at 50-55℃ for a certain time, followed by high-temperature enzyme inactivation. The supernatant is collected by centrifugation.

[0035] S5. Ingredient Mixing: Mix the treated supernatant, soybean meal, and wheat bran again according to the proportion of main ingredients and auxiliary ingredients; the mass ratio of main ingredients to auxiliary ingredients is 3:2; and add no more than 5% spices to the auxiliary ingredients;

[0036] S6. Koji making: Mix the koji material prepared in step S5 into the inoculated koji starter, which is a microbial fermentation agent; place the mixture in a constant temperature and humidity chamber for koji making.

[0037] The temperature for koji making is 28–32℃, the humidity is controlled at 85%–95%, and the time is 40–72 hours;

[0038] S6. Brine preparation and mixing:

[0039] Salt solution preparation: Mix KCl:NaCl:water in a mass ratio of 7:3:50 to form salt solution;

[0040] Mixing: Mix the prepared brine with the koji (fermented starter culture) at a mass ratio of (1:1.5) to (1:3), stir well, and then transfer the mixture to the fermentation equipment.

[0041] S7. Fermentation: A constant-temperature fermentation method is used.

[0042] The mixed koji material from step S6 was fermented under constant temperature conditions; the temperatures were:

[0043] Low-temperature fermentation (10-20℃) is conducive to the slow formation of flavor compounds, while inhibiting the growth of spoilage bacteria;

[0044] Medium-temperature fermentation (21–37°C) can accelerate the fermentation process;

[0045] Fermentation time ranges from 15 to 45 days;

[0046] Fermentation temperature has a significant impact on the flavor composition of low-salt shrimp paste: shrimp paste fermented at 10℃ and 15℃ has a higher relative content of aroma compounds such as alcohols and ketones, while shrimp paste fermented at 20℃ and 25℃ has a higher relative content of ammonia. Volatile compounds can be significantly distinguished at different temperatures.

[0047] S8. Sterilization: High-temperature instantaneous sterilization: Contact the fermented sauce at 121℃ for 5-15 minutes;

[0048] After fermentation, the shrimp paste undergoes sterilization to stop fermentation, kill spoilage microorganisms, and ensure product safety.

[0049] S9. Fill the finished shrimp paste into suitable containers, seal them, and sterilize again as needed. After filling, instantaneous sterilization at 120℃ can be used to ensure long-term storage safety.

[0050] The present invention has the following beneficial effects:

[0051] 1. This invention uses a main fermentation chamber filled with nitrogen, which is opened after the first fermentation stage, simultaneously opening the main exhaust valve. The nitrogen gas impacts the shrimp paste, causing internal ammonia to rise and be discharged through the main exhaust valve. Firstly, the nitrogen pushes the ammonia away more quickly, increasing the pressure within the fermentation tank and minimizing the chance of air entering. Secondly, filling with nitrogen increases the content of ester-containing microorganisms at the bottom, reducing isobutanol production and contributing to flavor stability in the finished low-salt shrimp paste.

[0052] 2. This invention uses a rotating motor to drive a transmission shaft to rotate, thereby pushing the connecting assembly plate to achieve lateral pushing. It also ensures the detachability of the connecting assembly plate to the ring body, so that when the rotating motor is separated from the stirring buoyancy cage, the stirring buoyancy cage can float to the surface of the sauce by its own buoyancy. And because the two horizontal shafts are constrained in the guide groove, the floating effect and floating position are ensured.

[0053] 3. The present invention adopts the process of "first starting beneficial bacteria with low salt - removing ammonia - then adding salt to inhibit spoilage bacteria", which not only obtains the flavor advantage in a low salt environment, but also ensures product safety by using an appropriate salt concentration in the later stage. Attached Figure Description

[0054] Figure 1 This is a front view of the low-salt shrimp paste fermentation equipment proposed in this invention;

[0055] Figure 2 This is a schematic diagram of the internal structure of the low-salt shrimp paste fermentation equipment proposed in this invention. Figure 1 ;

[0056] Figure 3 for Figure 2 Enlarged view of part A;

[0057] Figure 4 This is a cross-sectional view of the stirring buoyancy cage proposed in this invention;

[0058] Figure 5 for Figure 4 Enlarged view of part B;

[0059] Figure 6for Figure 4 Enlarged view of part C;

[0060] Figure 7 This is a schematic diagram of the structure of the connecting body of the present invention;

[0061] Figure 8 This is a schematic diagram of the internal structure of the low-salt shrimp paste fermentation equipment proposed in this invention. Figure 2 ;

[0062] Figure 9 for Figure 8 Enlarged view of part D;

[0063] Figure 10 for Figure 8 Enlarged view of part E;

[0064] Figure 11 This is a schematic diagram of the external structure of the connection structure proposed in this invention.

[0065] legend:

[0066] 1. Fermentation tank body; 11. Insulation layer; 12. Protective shell; 13. Guide groove one; 14. Elastic sealing component; 15. Slide plate; 16. Transmission cylinder; 17. Guide groove two;

[0067] 2. Connecting structure; 21. Mounting plate; 22. Ring body; 23. Conical cylinder; 25. Split column; 26. Protective cylinder; 27. Synchronous spring;

[0068] 3. Temperature control system;

[0069] 4. Exhaust pipe; 41. Check valve; 42. Main exhaust valve;

[0070] 5. Agitator buoyancy cage; 51. Cage body; 52. Horizontal shaft; 53. Agitator body; 54. Exhaust port;

[0071] 6. Main bladder bag; 61. Branch pipe; 62. Exhaust valve;

[0072] 7. Rotating pressing component; 71. Rotary motor; 72. Drive shaft; 73. Snap-fit ​​groove; 74. Movable shaft; 75. Connecting body; 76. Fixing ring; 77. Positioning ring plate; 78. Connecting spring; 79. Lowering pole; 710. Guide rod. Detailed Implementation

[0073] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0074] Example 1

[0075] like Figure 1-6 The image shows one embodiment of the present invention, which covers a low-salt shrimp paste fermentation device, comprising:

[0076] The fermentation tank 1 has two layers; the inner layer is equipped with an insulation layer 11, and the outer layer is equipped with a protective shell 12; a connecting structure 2 is installed between the inner and outer layers.

[0077] Temperature control system 3 is used for heating and controlling the temperature inside the inner layer. This invention only shows a simplified diagram of the bottom heating pipes. The temperature control system also includes temperature detectors, a temperature controller, and an external power supply. The external power supply heats the bottom heating pipes. Multiple temperature detectors are distributed within the insulation layer to detect the temperature. The temperature controller compares the detected temperature with the set temperature. When the temperature exceeds the set temperature, the external power supply is disconnected to maintain the insulation layer temperature. Different temperatures will produce different colonies in different fermentation processes.

[0078] The exhaust pipe 4 is located at the top of the fermentation tank 1 and extends into the insulation layer 11. A one-way valve 41 and a main exhaust valve 42 are installed at the top. The one-way valve ensures that gas can only exit and not enter, preventing backflow of air and the introduction of oxygen and bacteria. A pressure relief valve and an ammonia sensor can also be installed on the exhaust pipe. The ammonia sensor can accurately remove the discharged ammonia, effectively solving the ammonia odor problem in low-salt fermentation. The pressure relief valve reduces the internal pressure and avoids excessive pressure during fermentation.

[0079] It can also be equipped with related sub-components and subsystems such as pH meter, dissolved oxygen sensor, and cleaning system. The pH meter detects the internal acidity and alkalinity, the dissolved oxygen sensor is used to prevent odor-causing oxidation reactions, and the cleaning system can clean the fermentation tank after fermentation for the next fermentation.

[0080] like Figure 2 and 4 As shown, the stirring buoyancy cage 5 includes a cage body 51, which is arranged horizontally and has horizontal shafts 52 at both ends. The horizontal shafts 52 extend out to form an insulation layer 11 and are connected to the connecting structure 2. A stirring body 53 is provided on the outside of the stirring buoyancy cage 5, and the stirring body 53 is connected to the stirring buoyancy cage 5.

[0081] A main bag 6 is installed in the stirring buoyancy cage 5. The main bag 6 is filled with nitrogen and has a branch pipe 61 connecting to the stirring body 53. An installation cavity is formed within the stirring body 53, and an exhaust valve 62 is installed within the installation cavity. An exhaust port 54 is formed on the stirring body 53, and the end of the branch pipe 61 is connected to the exhaust valve 62 and leads to the exhaust port 54. This invention uses a main bag filled with nitrogen, which is opened after the first fermentation is complete, simultaneously opening the main exhaust valve. The nitrogen impact on the shrimp paste causes the internal ammonia to rise and be discharged through the main exhaust valve. Firstly, the nitrogen pushes the ammonia to separate more quickly, increasing the pressure inside the fermentation tank and ensuring a lower chance of air entering the fermentation tank. Secondly, filling with nitrogen can increase the content of ester-containing microorganisms at the bottom, reducing isobutanol production and contributing to the flavor stability of the finished low-salt shrimp paste.

[0082] The role of nitrogen in the fermenter:

[0083] 1. Antioxidant and Preservative Effects: Isolating oxygen is the core function of nitrogen. First, it effectively prevents natural pigments (such as astaxanthin) from oxidizing and causing shrimp paste to discolor; second, it protects nutrients such as unsaturated fatty acids from being destroyed; finally, it creates an oxygen-deficient environment, directly inhibiting the growth of some spoilage bacteria.

[0084] 2. Buffering and protection: The strong adsorption of oxygen by nitrogen creates a stable microenvironment for the formation and retention of key aroma components such as aldehydes, ketones, and alcohols.

[0085] 3. Pressure Support and System Stability: Nitrogen filling creates a positive pressure environment, preventing outside air from being drawn back into the tank. Simultaneously, nitrogen protects the tank from being crushed by atmospheric pressure, maintaining the stability of the equipment structure.

[0086] Actual effects of increasing nitrogen content:

[0087] A. Stronger antibacterial and antioxidant properties: Higher concentration and purer nitrogen can more thoroughly replace oxygen in the tank, thus achieving stronger anti-corrosion and antioxidant effects.

[0088] B. Flavor Adjustment: Increasing nitrogen concentration actually provides microorganisms with a richer source of assimilated nitrogen, especially increasing the content of esters that impart floral and fruity aromas. This can increase the content of aroma compounds such as ethyl acetate, phenylethyl acetate, ethyl laurate (esters, often with floral and fruity aromas), and 2,3-butanediol (with a creamy aroma).

[0089] C. Reduce the formation of isobutanol. Excessive isobutanol content will produce a fusel oil odor, and the isobutanol content will decrease accordingly.

[0090] Furthermore, such as Figure 2As shown, a rotating pressing component 7 is installed outside the protective housing 12 to press down on and drive the connecting structure 2 to rotate. The rotating pressing component 7 includes a rotary motor 71, the output end of which is connected to a drive shaft 72. A connecting assembly plate is installed at the end of the drive shaft 72 away from the rotary motor 71. The drive shaft 72 is a threaded shaft with a threaded center hole on the connecting body 75, which is threaded onto the threaded shaft. A guide rod 710 is also installed on the sliding plate 15, and the guide rod 710 is arranged laterally. The connecting body 75 is sleeved on the guide rod 710.

[0091] This invention uses a rotating motor to drive a transmission shaft to rotate, thereby pushing the connecting assembly plate and achieving lateral pushing. It also ensures the detachability of the connecting assembly plate to the ring body, so that when the rotating motor is separated from the stirring buoyancy cage, the stirring buoyancy cage can float to the surface of the sauce by its own buoyancy. And because the two horizontal shafts are constrained in the guide groove, the floating effect and floating position are ensured.

[0092] like Figure 5 As shown, the connection structure 2 includes a mounting plate 21, a ring portion 22 is provided on the mounting plate 21, a tapered cylinder 23 is provided in the middle of the ring portion 22, and constraint holes 24 are distributed radially in the ring portion 22.

[0093] The connecting structure 2 also includes a split column 25, which is integrally formed with the mounting plate 21. A protective cylinder 26 is installed on the outer end of the horizontal shaft 52 facing the split column 25, and a synchronous spring 27 is installed inside the protective cylinder 26. One end of the synchronous spring 27 is fixedly connected to the horizontal shaft 52, and the other end is sleeved on the split column 25 and fixedly connected to the mounting plate 21. The present invention's design of the split column and horizontal shaft ensures that the connecting structure can be compressed in the lateral direction, facilitating actual installation. Furthermore, the synchronous spring ensures synchronized rotation of the horizontal shaft and the connecting structure, allowing the rotation of the connecting structure to drive the rotation of the stirring buoyancy cage.

[0094] Example 2

[0095] like Figure 7-11 As shown, this is another embodiment of the present invention, based on embodiment 1, as follows: Figure 7 As shown, a movable shaft 74 is provided inside the connecting assembly plate, such as... Figure 9 As shown, when the connecting combination plate is snapped onto the tapered cylinder 23, the extruded movable shaft 74 is inserted into the constraint hole 24.

[0096] like Figure 7As shown, the connecting assembly includes a connecting body 75, with a snap-fit ​​groove 73 in the middle of the connecting body 75; the snap-fit ​​groove 73 is adapted to the conical cylinder 23; the snap-fit ​​groove 73 is axially provided with a lateral groove, which extends and penetrates to the lateral outer wall of the connecting body 75; a movable shaft 74 is installed in the lateral groove, one end of which extends into the snap-fit ​​groove 73 and is provided with an inclined surface; when the conical cylinder 23 is inserted into the snap-fit ​​groove 73, the inclined surface abuts against the conical cylinder 23. Figure 8 As shown, a guide groove 13 is provided on the insulation layer 11. The diameter of the guide groove 13 is not less than the outer diameter of the horizontal axis 52, and an elastic sealing member 14 is installed outside the guide groove 13.

[0097] like Figure 9 and 10 As shown, a fixing ring 76 is provided at the end of the lateral groove away from the snap-fit ​​groove 73. The fixing ring 76 is sleeved on the movable shaft 74 and fixedly installed on the connecting body 75.

[0098] A position ring plate 77 is installed on the movable shaft 74, and the position ring plate 77 is located in the lateral groove; a connecting spring 78 is installed between the position ring plate 77 and the fixed ring 76, one end of the connecting spring 78 is fixed to the side of the fixed ring 76 facing the snap groove 73, and the other end is fixed to the position ring plate 77.

[0099] The protective housing 12 has a guide groove 17, on which a sliding plate 15 is installed. The sliding plate 15 is fitted onto the guide groove 17. The sliding plate 15 is connected to the body of the rotary motor 71. A transmission cylinder 16 is also installed on the sliding plate 15. A descending electric rod 79 is installed on the top of the transmission cylinder 16, and the rod body of the descending electric rod 79 is installed on the protective housing 12. The output end of the descending electric rod 79 is used to push the transmission cylinder 16 to drive the transmission shaft 72 to descend. This invention achieves the up-and-down sliding of the horizontal shaft by setting it in the guide groove. The end is connected to the tapered cylinder through a snap-fit ​​groove. The tapered cylinder squeezes the movable shaft into the constraint hole to complete the constraint in the non-axial direction, ensuring that synchronous rotation can be achieved.

[0100] A low-salt shrimp paste fermentation process includes the following steps:

[0101] S1. Raw material selection and pretreatment:

[0102] Select the target shrimp as raw material, remove impurities and wash them clean with water;

[0103] Mixing: Mix the target shrimp with soybeans and supplementary shrimp shells in a certain proportion, with a mass ratio of 2.45-3.74:1:0.65-0.82; this mass ratio is a common content ratio set by the applicant in the shrimp paste process.

[0104] Drain and centrifuge or use a centrifuge to remove surface moisture;

[0105] S2. Grinding and gelatinization: Grind the processed shrimp feed into a fine paste using a meat grinder, stone mill, or chopper; if using a low-speed stone mill, control the rotation speed at 10-30 r / min.

[0106] S3. Sterilization: The surface of the pulverized and gelatinized shrimp feed is sterilized by high-temperature sterilization at 121℃ for 15-30 minutes to reduce the number of miscellaneous bacteria in the raw materials.

[0107] S4. Enzymatic hydrolysis: After sterilization, alkaline protease is added to the gelatinized shrimp feed for enzymatic hydrolysis. After a certain period of enzymatic hydrolysis in a water bath at 50-55℃, the enzyme is inactivated by high temperature. Centrifuge and take samples of the supernatant: After enzymatic hydrolysis, the protein in the raw material is decomposed into amino acids and small peptides, which is beneficial to the subsequent utilization of microorganisms and the accumulation of umami substances.

[0108] S5. Ingredient Mixing: Mix the treated supernatant, soybean meal, and wheat bran again according to the proportion of main ingredients and auxiliary ingredients; the mass ratio of main ingredients to auxiliary ingredients is 3:2; and add no more than 5% spices to the auxiliary ingredients;

[0109] S6. Koji making: Mix the koji material prepared in step S5 into the inoculated koji starter, which is a microbial fermentation agent; place the mixture in a constant temperature and humidity chamber for koji making.

[0110] The temperature for koji making is 28–32℃, the humidity is controlled at 85%–95%, and the time is 40–72 hours;

[0111] S6. Brine preparation and mixing:

[0112] Salt solution preparation: Mix KCl:NaCl:water in a mass ratio of 7:3:50 to form salt solution;

[0113] Mixing: Mix the prepared brine with the koji (fermented starter) at a mass ratio of 1:1.5 to 1:3, stir well, and then transfer the mixture to a low-salt shrimp paste fermentation device.

[0114] S7. Fermentation: A constant-temperature fermentation method is used.

[0115] The mixed koji from step S6 is fermented under constant temperature conditions; the temperatures are: low-temperature fermentation at 10-20℃ and medium-temperature fermentation at 21-37℃, with fermentation times ranging from 15 to 45 days. Low-temperature fermentation is beneficial for the slow formation of flavor compounds and inhibits the growth of spoilage bacteria. The two fermentations can be performed using a single fermentation tank or two sets of parallel fermentation tanks. A single fermentation tank requires a second fermentation to achieve the desired temperature increase, and ammonia needs to be initially vented multiple times. Two sets of parallel fermentation tanks require connecting transfer pipes and material pumps at the bottom of the fermentation tanks for sauce delivery, and temperature control is also necessary. The first fermentation (low-temperature fermentation) uses a low salt content, while the second fermentation (medium-temperature fermentation) uses a higher salt content.

[0116] The mixed koji material is placed into the insulation layer 11 of the fermentation tank 1, and nitrogen gas is pre-introduced into the main bag 6. After the fermentation is completed at low temperature, the rotary motor 71 is turned on, and the drive shaft 72 rotates to push the connecting body 75 to engage with the mounting plate 21. Then the lowering rod 79 is started, and the output end drives the slide plate 15 to descend, causing the stirring buoyancy cage 5 to rotate, and the lateral stirring body 53 to stir the fermentation product. At this time, the main exhaust valve 42 is opened by the external controller. The main exhaust valve 42 is a solenoid valve, and nitrogen gas in the main bag 6 is introduced into the fermentation product to complete the stirring and ammonia blowing effect, and the ammonia gas is discharged.

[0117] S8. Sterilization: High-temperature instantaneous sterilization: Contact the fermented sauce at 121℃ for 5-15 minutes;

[0118] S9. Filling: Fill the finished shrimp paste into suitable containers, seal them, and sterilize again as needed; after filling, instantaneous sterilization at 120℃ can be used to ensure long-term storage safety.

[0119] The shrimp paste production method of this invention obtains flavor by adding spices. The spices can be one of cinnamon powder, aloe vera extract, konjac protein powder, or perilla; used to remove fishy odors, enhance aroma, and help inhibit spoilage microorganisms. In the first fermentation of this invention, the amount of salt added is relatively small, controlled at 6%–9%, ​​to allow some beneficial microorganisms to proliferate early and produce flavor substances. After the first fermentation, the ammonia produced during fermentation is removed by rapid stirring, and a low-ammonia environment is created by nitrogen blowing. Then, an equal amount of salt is added, controlling the total salt content to 12%–18% for a second fermentation. Through the process of "first initiating beneficial bacteria with low salt—removing ammonia—then adding salt to inhibit spoilage bacteria," both the flavor advantages of a low-salt environment are obtained, and the product safety is ensured by using an appropriate salt concentration in the later stages.

[0120] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-salt shrimp paste fermentation device, characterized in that, include: The fermentation tank (1) is provided with two layers; the inner layer is provided with an insulation layer (11), and the outer layer is provided with a protective shell (12); a connecting structure (2) is installed between the inner and outer layers. Temperature control system (3) for heating and temperature control of the inner layer; The exhaust pipe (4) is located at the top of the fermentation tank (1) and extends into the insulation layer (11); a one-way valve (41) and a main exhaust valve (42) are installed at the top. The stirring buoyancy cage (5) includes a cage body (51), which is arranged horizontally and has horizontal shafts (52) at both ends. The horizontal shafts (52) extend out of the insulation layer (11) and are connected to the connecting structure (2). A stirring body (53) is provided on the outside of the stirring buoyancy cage (5), and the stirring body (53) is connected to the stirring buoyancy cage (5). The main bag (6) is installed in the stirring buoyancy cage (5); the main bag (6) is filled with nitrogen and is provided with a branch pipe (61) connected to the stirring body (53); an installation cavity is provided in the stirring body (53) and an exhaust valve (62) is provided in the installation cavity; an exhaust port (54) is provided on the stirring body (53); the end of the branch pipe (61) is connected to the exhaust valve (62) and connected to the exhaust port (54); The rotating pressing component (7) is installed outside the protective housing (12) and is used to press down on and drive the rotation of the connecting structure (2).

2. The low-salt shrimp paste fermentation equipment according to claim 1, characterized in that, The connection structure (2) includes a mounting plate (21), a ring body (22) is provided on the mounting plate (21), a conical cylinder (23) is provided in the middle of the ring body (22), and constraint holes (24) are distributed radially in the ring body (22). The rotating pressing component (7) includes a rotating motor (71), the output end of the rotating motor (71) is connected to a drive shaft (72), and a connecting assembly plate is installed at the end of the drive shaft (72) away from the rotating motor (71). A snap-fit ​​groove (73) is provided on the connecting assembly plate, and the snap-fit ​​groove (73) is adapted to the conical cylinder (23). A movable shaft (74) is provided inside the connecting assembly plate. When the connecting assembly plate is snapped onto the tapered cylinder (23), the movable shaft (74) is squeezed and inserted into the constraint hole (24).

3. The low-salt shrimp paste fermentation equipment according to claim 2, characterized in that, A guide groove (13) is provided on the insulation layer (11). The groove diameter of the guide groove (13) is not less than the outer diameter of the horizontal axis (52), and an elastic sealing member (14) is installed outside the guide groove (13). The connecting assembly includes a connecting body (75), and a snap-fit ​​groove (73) is provided in the middle of the connecting body (75); the snap-fit ​​groove (73) is provided with a lateral groove in the axial direction, the lateral groove extends and penetrates to the lateral outer wall of the connecting body (75); the movable shaft (74) is installed in the lateral groove, one end of the movable shaft (74) extends into the snap-fit ​​groove (73) and is provided with an inclined surface, when the conical cylinder (23) is inserted into the snap-fit ​​groove (73), the inclined surface abuts against the conical cylinder (23).

4. The low-salt shrimp paste fermentation equipment according to claim 3, characterized in that, A fixing ring (76) is provided at the end of the side groove away from the snap-fit ​​groove (73). The fixing ring (76) is sleeved on the movable shaft (74) and fixedly installed on the connecting body (75). A position ring plate (77) is installed on the movable shaft (74), and the position ring plate (77) is located in the lateral groove; a connecting spring (78) is installed between the position ring plate (77) and the fixed ring (76), one end of the connecting spring (78) is fixed to the side of the fixed ring (76) facing the snap groove (73), and the other end is fixed to the position ring plate (77).

5. The low-salt shrimp paste fermentation equipment according to claim 2, characterized in that, The protective housing (12) is provided with a guide groove (17), and a sliding plate (15) is installed on the guide groove (17). The sliding plate (15) is adapted to be installed on the guide groove (17); the sliding plate (15) is connected to the body of the rotary motor (71). A transmission cylinder (16) is also installed on the slide (15); a descending electric rod (79) is installed on the top of the transmission cylinder (16), and the rod body of the descending electric rod (79) is installed on the protective housing (12); the output end of the descending electric rod (79) is used to push the transmission cylinder (16) to drive the transmission shaft (72) to descend in height.

6. The low-salt shrimp paste fermentation equipment according to claim 5, characterized in that, The connection structure (2) also includes a split column (25), which is integrally set with the mounting plate (21). A protective cylinder (26) is installed on the end of the horizontal shaft (52) facing the split column (25), and a synchronous spring (27) is installed inside the protective cylinder (26). One end of the synchronous spring (27) is fixedly connected to the horizontal shaft (52), and the other end is sleeved on the split column (25) and fixedly connected to the mounting plate (21).

7. The low-salt shrimp paste fermentation equipment according to claim 5, characterized in that, The drive shaft (72) is a threaded shaft, and a threaded center hole is provided on the connecting body (75), which is threadedly connected to the threaded shaft; a guide rod (710) is also installed on the slide plate (15), and the guide rod (710) is arranged horizontally; the connecting body (75) is sleeved on the guide rod (710).

8. A low-salt shrimp paste fermentation process, characterized in that, Includes the following steps: S1. Raw material selection and pretreatment: Select the target shrimp as raw material, remove impurities and wash them clean with water; Mixing: Mix the target shrimp with soybeans and supplementary shrimp shells in a certain proportion, with a mass ratio of (2.45~3.74):1:(0.65~0.82); Drain and centrifuge or use a centrifuge to remove surface moisture; S2. Grinding and gelatinization: Grind the processed shrimp feed into a fine paste using a meat grinder, stone mill, or chopper; if using a low-speed stone mill, control the rotation speed at 10-30 r / min. S3. Sterilization: The surface of the pulverized and gelatinized shrimp feed is sterilized by high-temperature sterilization at 121℃ for 15-30 minutes to reduce the number of miscellaneous bacteria in the raw materials. S4. Enzymatic hydrolysis: After sterilization, alkaline protease is added to the gelatinized shrimp feed for enzymatic hydrolysis. The mixture is then hydrolyzed in a water bath at 50-55℃ for a certain time, followed by high-temperature enzyme inactivation. The supernatant is collected by centrifugation. S5. Ingredient Mixing: Mix the treated supernatant, soybean meal, and wheat bran again according to the proportion of main ingredients and auxiliary ingredients; the mass ratio of main ingredients to auxiliary ingredients is 3:2; and add no more than 5% spices to the auxiliary ingredients; S6. Koji making: Mix the koji material prepared in step S5 into the inoculated koji starter, which is a microbial fermentation agent; place the mixture in a constant temperature and humidity chamber for koji making. The temperature for koji making is 28–32℃, the humidity is controlled at 85%–95%, and the time is 40–72 hours; S6. Brine preparation and mixing: Salt solution preparation: Mix KCl:NaCl:water in a mass ratio of 7:3:50 to form salt solution; Mixing: Mix the prepared brine with the koji (fermented starter) at a mass ratio of (1:1.5) to (1:3), stir well, and then transfer the mixture to the low-salt shrimp paste fermentation equipment described in claim 6. S7. Fermentation: A constant-temperature fermentation method is used. The mixed koji material from step S6 is fermented under constant temperature conditions; the temperatures are: low-temperature fermentation at 10-20℃ and medium-temperature fermentation at 21-37℃, with fermentation times ranging from 15 to 45 days. The mixed koji material is placed in the insulation layer (11) of the fermentation tank (1), and nitrogen gas is introduced into the main bag (6) beforehand. When the fermentation is completed at low temperature, the rotary motor (71) is turned on, and the drive shaft (72) rotates to push the connecting body (75) to engage with the mounting plate (21). Then the lowering rod (79) is started, and the output end drives the slide plate (15) to descend, so that the stirring buoyancy cage (5) rotates, and the lateral stirring body (53) stirs in the fermentation product. At this time, the main drain valve (42) is opened by the external controller. The main drain valve (42) is an electromagnetic valve. Nitrogen gas in the main bag (6) is introduced into the fermentation product to complete the stirring and ammonia blowing effect, and ammonia gas is discharged. S8. Sterilization: High-temperature instantaneous sterilization: Contact the fermented sauce at 121℃ for 5-15 minutes; S9. Filling: Fill the finished shrimp paste into suitable containers, seal them, and sterilize them again as needed; after filling, instant sterilization at 120℃ can be used to ensure the safety of long-term storage.

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