Production method of low-salt high-quality fish sauce

Abstract

The invention discloses a production method of low-salt high-quality fish sauce, and belongs to the technical field of food processing. The production method of the low-salt high-quality fish sauce specifically comprises the following steps: filtering the raw material fish sauce through a filter bag and a ceramic membrane in sequence to obtain clear feed liquid; pumping the obtained feed liquid into a raw material chamber of a nanofiltration charge membrane system for two-stage desalination; according to the invention, high-efficiency desalination (the salt content is reduced from 25.23 g / 100mL to 5.60 g / 100mL) is realized, and amino acid nitrogen (0.97 g / 100mL), free amino acid (91.26 mg / g), organic acid (61.96 mg / g) and volatile flavor substances (68 types) of the fish sauce are remarkably reserved; the method is mild in process, free of pollution, low in energy consumption and suitable for industrial production, solves the problems of high salt content, flavor loss, membrane pollution and the like of traditional fish sauce, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to a method for producing low-salt, high-quality fish sauce, belonging to the field of food processing technology. Background Technology

[0002] Fish sauce is a traditional condiment, rich in various amino acids and other nutrients, and has a unique flavor. However, its production process typically involves a high salt content, posing potential health risks to consumers and limiting its application in many food products. High salt content can mask other flavor components, affecting the balance and healthiness of the recipe. Even in traditional applications of fish sauce, such as preparing dipping sauces, compound seasoning sauces, marinating meats, and enhancing the umami flavor of soups, excessive salt can have significant drawbacks: for example, it can suppress the flavor layers of spices in dipping sauces; it can cause excessive dehydration and a tough texture when marinating meats; and in soups, the difficulty in precisely controlling the saltiness can easily lead to an overly salty broth, which in turn inhibits the expression of umami and affects the overall effect.

[0003] Current mainstream salt reduction technologies all have significant drawbacks: for example, in the formulation substitution method, potassium chloride (KCl) replacement causes bitterness threshold exceeding the limit (>500 ppm), while saltiness enhancers (such as IMP / GMP) face "clean label" compliance risks. Furthermore, while post-dilution processes can directly reduce salt, the simultaneous dilution of flavor compounds and increase in water activity shortens shelf life. In biodegradation methods, fermentation by salt-tolerant bacteria easily alters the flavor profile and has limited salt reduction (<15%); enzymatic hydrolysis technology struggles to eliminate free sodium. + It may also produce bitter peptides. In physical separation methods, reverse osmosis (RO) results in a loss rate of >40% of umami peptides (500-2000 Da) due to the indiscriminate retention of dense membranes; electrodialysis (ED) causes significant loss of key flavor amino acids and membrane fouling during desalination due to charge screening mechanisms; and nanofiltration (NF) has more complex limitations: it is difficult to avoid the synergistic loss of small molecule flavor substances during desalination, and directly processing high-salt products faces the dilemma of high operating pressure or high dilution ratio. These inherent defects, combined with membrane fouling problems, seriously restrict its technical and economic feasibility. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a precise separation technology with high ion selectivity, namely, a nanofiltration charged membrane system desalination technology that uses electric field drive and membrane sieving in synergy. This technology can efficiently and accurately remove salt from fish sauce, while solving problems such as large loss of flavor substances and serious membrane fouling during the desalination process of fish sauce.

[0005] To achieve the above objectives, the following technical solution is provided: This invention provides a method for producing low-salt, high-quality fish sauce, the method comprising the following steps: (1) Pretreatment The raw fish sauce is filtered through a filter bag and a ceramic membrane in sequence to obtain a clear liquid. (2) Staged electro-driven membrane desalination The feed solution obtained in step (1) is pumped into the feed chamber of the nanofiltration charged membrane system for two-stage desalination; the first-stage desalination is carried out for 60-90 minutes under the conditions of DC voltage 15-20V, current density 15-20mA / cm², feed flow rate 0.8-1.2L / min, and system pressure 0.1-0.2MPa, so that the NaCl concentration is reduced to 12%-15%; Secondary desalination: Adjust the DC voltage to 20-25V, the current density to 20-25mA / cm², the feed flow rate to 0.5-0.8L / min, and the system pressure to 0.2-0.3MPa. Continue running until the conductivity of the raw material chamber drops to 5-6mS / cm, and finally obtain desalted fish sauce with a salt content of 5%-8%.

[0006] In one embodiment, the fish sauce in step (1) is fish sauce produced by microbial fermentation of fish products.

[0007] In one embodiment, the size of the filter bag in step (1) is 1~3μm.

[0008] In one embodiment, the ceramic film in step (1) has a size of 0.22 μm.

[0009] In one embodiment, the temperature of the clarified liquid in step (1) is adjusted to 25-30°C.

[0010] In one embodiment, the nanofiltration charge membrane system in step (2) uses a dedicated membrane module consisting of 15 pairs of KSII type food-grade nanofiltration charge membranes to form a membrane stack. The cation membrane is made of titanium coated with ruthenium-iridium coating, and the anion membrane is made of titanium coated with iridium-tantalum double coating with a membrane area of ​​0.6 m². The membrane pairs are stacked alternately in the order of "anion membrane - raw material chamber partition - cation membrane - salt chamber partition". The thickness of the raw material chamber partition is set to 0.8 mm. The salt chamber partition has a diamond-shaped water distribution groove (pore diameter 3 mm) to enhance the turbulence of the feed liquid. Auxiliary chamber partitions are arranged on both sides of the membrane stack, and 0.1% citric acid solution is introduced as an auxiliary liquid to prevent electrode scaling and maintain the system pH stability (6.5-7.0).

[0011] In one embodiment, the method further includes an anti-pollution control system.

[0012] In one embodiment, the anti-fouling control system is specifically configured as follows: a circulation loop is formed by three corrosion-resistant magnetically driven pumps: the feed pump (flow rate 0-1.8 L / min) is responsible for feed liquid circulation, the salt chamber pump delivers the receiving liquid (5% NaCl solution), and the auxiliary pump supplies citric acid cleaning solution; online cleaning is initiated every 4 hours of operation: first, circulate with 1% NaOH solution (35°C) for 30 minutes, then rinse with 0.5% HNO3 solution for 20 minutes, with a membrane flux recovery rate ≥95%.

[0013] In one embodiment, the method further includes an intelligent monitoring module.

[0014] In one embodiment, the intelligent monitoring module is specifically configured to integrate a conductivity sensor (accuracy ±0.1mS / cm), a pressure transmitter (0-0.4MPa), and a temperature sensor, and adjust the DC power output in real time through a PLC control system. When the current fluctuation exceeds ±10%, it automatically switches to protection mode.

[0015] Another object of the present invention is to provide a fish sauce product obtained by the method described above.

[0016] In one embodiment, the salt content of the fish sauce product is reduced to 5.60 g / 100 mL, the amino acid nitrogen content is not less than 0.97 g / 100 mL, the free amino acid content is not less than 91.26 mg / g, the organic acid content is not less than 61.96 mg / g, and the number of volatile and semi-volatile flavor substances is not less than 68.

[0017] Beneficial effects: The method for producing low-salt, high-quality fish sauce of the present invention has the following advantages compared with the prior art: (1) High-efficiency desalination: The salt content was reduced from 25.23g / 100mL to 5.60g / 100mL, a reduction of 78%, which accurately met the low salt requirements; (2) Excellent preservation of umami and nutrition: amino acid nitrogen content reaches 0.97g / 100mL, free amino acid content is 91.26mg / g (56% higher than the comparison), and there is little loss of core components; (3) Richer flavor: 61.96 mg / g of organic acids (41% higher), 68 kinds of flavor substances (10 more), retaining the original flavor diversity and harmony; (4) The process is mild and pollution-free: no high temperature or chemical reagents are required, avoiding problems such as protein denaturation and odor, and minimizing damage to quality; the membrane is anti-fouling and can operate for a long time, with lower energy consumption than traditional technologies, making it suitable for industrial scale-up. Attached Figure Description

[0018] Figure 1The chromatograms are of fish sauce from Example 1 and Comparative Example 1; Figure 2 Radar graphs showing the sensory evaluation of fish sauce in Example 1 and Comparative Example 1. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the 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. The specific embodiments described below further illustrate the present invention.

[0020] The testing method involved in this invention 1. Determine the salt content in fish sauce samples according to the provisions of GB5009.44-2016; 2. Determine the amino acid nitrogen content in fish sauce samples according to the provisions of GB5009.235; 3. Determine the free amino acid content in fish sauce samples according to the provisions of GB5009.124-2016; 4. The organic acid content in fish sauce samples was tested according to the provisions of GB 5009.157-2016.

[0021] 5. Conduct sensory evaluation of the fish sauce samples. Ten participants (five women and five men, aged 25-35 years) were trained before the sensory evaluation. Sensory evaluations (fishy, ​​amine, meaty, soy sauce, sour, umami, salty, and color) were scored on a 10-point scale, with higher scores indicating a stronger flavor or color (reddish-brown) in the fish sauce.

[0022] 6. Gas chromatography-mass spectrometry was used to determine the volatile and / or semi-volatile flavor compounds in fish sauce. The specific extraction conditions are as follows: Weigh 5 g of fish sauce sample and dilute to 12 mL with ultrapure water, then transfer to a 20 mL headspace vial. Insert the DMU-SPME extraction head fiber into the headspace vial, with the upper coating remaining above the liquid surface and the lower coating immersed in the sample. The extraction temperature is 60℃, the stirring speed is 500 rpm, and the extraction time is 30 min, enabling integrated extraction of volatile and semi-volatile compounds.

[0023] Gas chromatography parameters: An Agilent 7890B nonpolar HP-5ms ultra-inert 30 m × 0.25 mm × 0.25 μm Agilent column was used for analysis; the initial temperature of the gas chromatography column oven was 35℃, held for 3 min, and then increased to 250℃ at a rate of 5℃ / min and held for 10 min; the injection method was splitless injection, the injection port temperature was 250℃; helium was used as the carrier gas, and the flow rate was 1 mL / min.

[0024] Mass spectrometry parameters: The instrument used was an Agilent 5977A, and the detection was performed in scanning mode with a scanning range of 35-500 m / z. The ion source was an electron impact ion source (70 eV) at 230 °C.

[0025] The preparation of fish sauce involved in the embodiments and comparative examples of the present invention includes the following steps: (1) Raw material pretreatment: Wash the fresh anchovies, mince them with a meat grinder, add 8% (w / w) of edible salt, mix well and set aside to obtain pretreated meat paste; (2) Preparation of activated Aspergillus oryzae: Soak soybeans overnight, steam for 2 h, cool to 30℃, mix with 2‰ (w / w) Aspergillus oryzae inoculum and 10% (w / w) flour, spread in a tray with a thickness of 1 cm, cover with double layer of damp gauze, and incubate in a constant temperature and humidity incubator at 30℃ and 80~90RH for 72 h, turning once a day to prevent clumping; (3) Primary fermentation: Inoculate the pretreated meat paste with 5% (w / w) activated Aspergillus oryzae and ferment at 43℃ for 8 days; (4) Secondary fermentation: The fermented material that has completed the first fermentation is supplemented with salt to 23% (w / w), mixed well, and irradiated with simulated fluorescent lamps for 8 hours a day. The fermentation temperature is maintained at 35°C using a heating mantle. The mixture is stirred at fixed points every day and fermented for 30 days. (5) Filtration and sterilization: The supernatant of the fish sauce after secondary fermentation is filtered through multiple layers of gauze and centrifuged. Then it is sterilized at 100℃ for 30 min and filled under aseptic conditions.

[0026] Example 1 A method for producing low-salt, high-quality fish sauce includes the following steps: (1) Pretreatment After sterilization, the fresh fish sauce was filtered through a 1μm filter bag and then microfiltered through a 0.22μm ceramic membrane at 0.15MPa. The permeate was collected. (2) Staged electro-driven membrane desalination Equipment commissioning: Assemble 15 pairs of KSII type membrane modules, introduce 0.1wt% citric acid solution into the auxiliary chamber, and add 5wt% NaCl solution into the receiving chamber; Desalination operation: First-stage desalination: voltage 18V, current density 18mA / cm², flow rate 1.0L / min, pressure 0.15MPa, run for 75min, sampled and measured NaCl content 13.5%; Secondary desalination: voltage 22V, current density 22mA / cm², flow rate 0.6L / min, pressure 0.25MPa, run for 60min, final NaCl content 9.2%.

[0027] (3) Online cleaning and system maintenance: Every 4 hours of operation, start the online cleaning program, use 1% NaOH solution to circulate and clean for 30 minutes at 35°C, and then rinse with 0.5% HNO3 solution for 20 minutes to restore membrane flux for the next round of desalination.

[0028] Comparative Example 1 The difference from Example 1 is that the fish sauce does not undergo the desalination process in step (2).

[0029] Results Analysis The performance of the fish sauce obtained in Example 1 and Comparative Example 1 was analyzed, and the results are shown in Tables 1 and 2. Table 1. Physicochemical properties of fish sauce in Example 1 and Comparative Example 1

[0030] Table 2. Volatile compounds and relative contents of fish sauce under different desalination conditions.

[0031] As shown in Tables 1 and 2, Example 1 exhibits a significant advantage over Comparative Example 1 in terms of fish sauce desalination and quality retention. The specific analysis is as follows: The salt content was significantly reduced: the salt content of Example 1 was 5.60 g / 100 mL, which was much lower than the 25.23 g / 100 mL of Comparative Example 1. This shows that the nanofiltration charge membrane technology used in the example can efficiently remove salt, effectively achieve the salt reduction target, and solve the core problem of high salt content in fish sauce.

[0032] Nutrients were well preserved: the amino acid nitrogen content in Example 1 was 0.97 g / 100 mL, higher than that in Comparative Example 1 (0.83 g / 100 mL). Amino acid nitrogen is a key indicator for measuring the umami and nutritional value of fish sauce. Its higher content indicates that the desalination process not only did not destroy the core umami components, but may have even reduced the loss, resulting in a more solid umami base.

[0033] Free amino acids are an important component of the flavor and nutrition of fish sauce. The free amino acid content of Example 1 is 91.26 mg / g, which is significantly higher than that of Comparative Example 1 (58.67 mg / g). This indicates that the example not only did not excessively lose free amino acids, but may have reduced their loss by optimizing the process.

[0034] The flavor profile is richer: the organic acid content in Example 1 was 61.96 mg / g, higher than the 43.95 mg / g in Comparative Example 1. Organic acids have a significant impact on the flavor profile of fish sauce (such as the balance of sourness and umami), and their retention better reflects the process's protection of flavor details. Furthermore, 68 flavor compounds were detected in the desalted fish sauce prepared in Example 1, significantly more than the 58 in Comparative Example 1. This may be due to the selective retention and concentration effect of the nanofiltration charge membrane system: nanofiltration membranes, based on size exclusion and charge repulsion, efficiently remove sodium... + and Cl - Simultaneously, it effectively retained and concentrated flavor precursors and neutral volatile components with molecular weights greater than 200 Da, allowing trace substances originally below the detection limit to be detected. Notably, some alcohols imparting green, floral, and sweet flavors, such as isononol, trans-2-octen-1-ol, linalool, and undecylol, were detected only in Example 1. Furthermore, esters and ketones with fruity, balsam, and jasmine aromas, such as phenethyl acetate and 2-pentadecanone, are also unique to Example 1. This indicates that during the desalting process, Example 1 better preserves the original characteristic flavor compounds of fish sauce, reduces the loss of volatile or easily lost flavor components, and maintains the unique flavor profile of fish sauce.

[0035] Low in salt and delicious: Figure 2 The nanofiltration charged membrane system demonstrates that while significantly reducing the saltiness and fishy smell of fish sauce, it also retains the characteristic flavor (umami, soy sauce flavor) and color (reddish-brown) of fish sauce, showing good sensory acceptance and application potential.

[0036] In summary, the technical solution of this invention can efficiently desalinate while retaining the nutritional components and flavor substances of fish sauce to the maximum extent, achieving the goal of "reducing salt without reducing quality".

[0037] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for producing a low-salt high-quality fish sauce, characterized by, The method comprises the following steps: (1) Pretreatment The raw fish sauce is filtered through a filter bag and a ceramic membrane in sequence to obtain a clarified feed liquid; (2) Two-stage electrically-driven membrane desalination The feed liquid obtained in step (1) is pumped into a raw material chamber of a nanofiltration electric charge membrane system for two-stage desalination; in the first-stage desalination, the system is operated under the conditions of a direct current voltage of 15-20 V, a current density of 15-20 mA / cm2, a feed liquid flow rate of 0.8-1.2 L / min, and a system pressure of 0.1-0.2 MPa for 60-90 min, so that the NaCl concentration is reduced to 12%-15%; in the second-stage desalination, the direct current voltage is adjusted to 20-25 V, the current density is adjusted to 20-25 mA / cm2, the feed liquid flow rate is adjusted to 0.5-0.8 L / min, and the system pressure is adjusted to 0.2-0.3 MPa, and the operation is continued until the electrical conductivity of the raw material chamber is reduced to 5-6 mS / cm, so that the desalinated fish sauce with a salt content of 5%-8% is finally obtained. The filter bag in step (1) has a size of 1-3 μm.

2. The method of claim 1, wherein, The ceramic membrane in step (1) has a size of 0.22 μm.

3. The method of claim 1, wherein, The temperature of the clarified feed liquid in step (1) is adjusted to 25-30 °C.

4. The method of claim 1, wherein, The special membrane assembly used in the nanofiltration electric charge membrane system in step (2) is a membrane stack composed of 15 pairs of KSII type food-grade nanofiltration electric charge membranes.

5. The method of claim 1, wherein, The method further comprises an anti-pollution control system and an intelligent monitoring module.

6. The method of claim 1, wherein, The anti-pollution control system is specifically configured as follows: three corrosion-resistant magnetic drive pumps are used to form a circulation loop; a raw material pump is responsible for the circulation of the feed liquid, a salt chamber pump is used to transport the receiving liquid, and an auxiliary pump is used to supply a citric acid cleaning solution; online cleaning is started every 4 h: first, 1% NaOH solution is circulated for 30 min, and then 0.5% HNO3 solution is used for flushing for 20 min, and the membrane flux recovery rate is ≥95%.

7. The method of claim 6, wherein, The intelligent monitoring module is specifically configured as follows: an electrical conductivity sensor, a pressure transmitter and a temperature sensor are integrated, and a PLC control system is used to adjust the output of the direct current power supply in real time; when the current fluctuation exceeds ±10%, the system is automatically switched to a protection mode.

8. The method of claim 7, wherein, 9. A fish sauce product obtained by the method of any one of claims 1-8. The salt content of the fish sauce product is reduced to 5.60 g / 100 mL, the amino acid nitrogen content is not less than 0.97 g / 100 mL, the free amino acid content is not less than 91.26 mg / g, the organic acid content is not less than 61.96 mg / g, and the number of volatile and semi-volatile flavor substances is not less than 68.

10. The fish sauce product of claim 9, characterized in that, ​

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