Method for preparing vinegar powder through reverse osmosis concentration and purification

Abstract

The invention relates to the technical field of vinegar powder, and discloses a method for preparing vinegar powder through reverse osmosis concentration and purification. The tubular reverse osmosis device with a long pipeline is adopted, liquid table vinegar is continuously introduced into a pipe core, pump pressure is controlled to enable water molecules in the liquid table vinegar to permeate outwards through a reverse osmosis membrane on the wall of the pipe core under the action of pressure, concentrated vinegar liquid is intercepted by the pipe core and is collected at a discharge port of the tubular reverse osmosis device, and the concentrated vinegar liquid can be recycled by controlling the flow of the concentrated vinegar liquid at the discharge port. Obtaining concentrated vinegar liquid with stable concentration; particularly, cellulose aerogel is added into liquid table vinegar, flavor substances of the table vinegar are adsorbed and fixed by utilizing surface charges and hydrophilicity of the cellulose aerogel, outward permeation of micromolecular nutrient components during reverse osmosis treatment is prevented, and nutrient component loss during reverse osmosis concentration is reduced; furthermore, an embedding agent and an anti-sticking agent are added into the concentrated table vinegar for spray drying, so that the vinegar powder is effectively prevented from adhering to the wall and depositing scale in the drying tower, the vinegar powder is prevented from being burnt, the cleaning frequency of the drying tower is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vinegar powder, and particularly relates to a method for preparing vinegar powder by reverse osmosis concentration and purification. Background Art

[0002] Vinegar powder is a new type of solid condiment with high added value obtained by spray drying liquid edible vinegar. Due to its easy storage, transportation and convenient use, it is gradually replacing traditional liquid edible vinegar. Especially, vinegar powder is rich in various nutritional components of liquid edible vinegar, such as organic acids, amino acids, polyphenols, flavonoids, etc., and has great application potential in health care and food seasonings. Vinegar powder has a moderate sour taste and pure flavor, and can be used in the processing of various foods. For example, during cooking, vinegar powder can be used as a condiment to add a sweet and sour taste to dishes, and is suitable for various cooking methods such as stir-frying, stewing, and pickling. In baked foods such as cakes and biscuits, adding an appropriate amount of vinegar powder can make the product taste more crispy and the color more golden and attractive. At the same time, vinegar powder is also widely used in the processing of foods such as jams, candied fruits, and candies to adjust the acidity and alkalinity of foods, prevent the reproduction of microorganisms, and extend the shelf life of products.

[0003] Edible vinegar is prepared by a brewing process. Especially for solid-state fermented vinegar, microbial metabolism is more sufficient, producing rich organic acids and amino acids, and having a rich aroma. At present, in order to improve the yield, it is necessary to add water multiple times to leach the fermented solid vinegar embryo, and the acidity of the finally collected edible vinegar is generally 3-6 g / 100 ml, and the largest proportion is water. If directly spray-dried to prepare vinegar powder, it will consume a huge amount of energy, have low efficiency, and the long high-temperature drying time is extremely likely to cause the loss of flavor nutrients such as amino acids in edible vinegar. Therefore, prior concentration of edible vinegar before spray drying is particularly important. Through concentration, most of the water in liquid edible vinegar can be excluded, the spray drying efficiency can be improved, the spray drying temperature and drying time can be reduced, and preferably, the nutrients such as amino acids in edible vinegar can be protected from being damaged.

[0004] The prior art has already disclosed the concentration technology for edible vinegar. Such as the vacuum evaporation concentration method, heating the edible vinegar to 40-60 °C, and evaporating and discharging the water in the edible vinegar through vacuum decompression. However, this method will cause some flavor substances in the edible vinegar to evaporate together. Moreover, a large amount of acidic wastewater is generated during the condensation treatment, causing great pressure on sewage treatment. In addition, vacuum evaporation concentration takes a long time and consumes a high amount of energy. In a high-temperature environment, the volatilization of flavor substances in the edible vinegar increases, resulting in a decrease in the flavor of the edible vinegar and affecting the flavor of the final vinegar powder.

[0005] In addition, the publicly disclosed vacuum freeze-drying method involves pre-freezing at low temperatures (generally -30 to -50°C), and using the principle of ice crystal sublimation to remove the water in edible vinegar under vacuum conditions. Although this method can better avoid the loss of the flavor of vinegar, the low-temperature refrigeration energy consumption is high. Especially when using a large-scale device for vacuum freeze-drying, the thickness of the material leads to an increased resistance to water evaporation, making large-scale production difficult.

[0006] The reverse osmosis membrane (RO) can separate the solvent and solute in a solution by applying pressure. Generally, the solution flows from a low concentration to a high concentration. The reverse osmosis membrane (RO) has extremely fine pores. Under the action of pressure, water molecules can pass through the reverse osmosis membrane, thus still separating salts and other solutes in the water. The reverse osmosis membrane technology has been maturely applied in seawater desalination. Therefore, the potential of using the reverse osmosis membrane for the concentration of edible vinegar is huge. However, due to the nutrients of many components in liquid vinegar and the organic substances with different molecular weight distributions, reverse osmosis concentration of edible vinegar is likely to cause the loss of nutrients, and small-molecule organic substances are likely to adhere to the membrane surface, causing membrane surface pollution. Summary of the Invention

[0007] When preparing vinegar powder, it is necessary to concentrate and spray-dry edible vinegar. Existing reverse osmosis concentration of edible vinegar is likely to cause the loss of nutrients, and small-molecule organic substances are likely to adhere to the membrane surface, causing membrane surface pollution. In view of these defects, the present invention proposes a method for preparing vinegar powder by reverse osmosis concentration and purification.

[0008] A method for preparing vinegar powder by reverse osmosis concentration and purification mainly includes the following steps:

[0009] S1. Stir the liquid edible vinegar and cellulose aerogel evenly at a mass ratio of 100:(0.2 - 0.3) at high speed, and continuously and quantitatively pump it into the tube core of the tubular reverse osmosis device through pump pressure. Control the pump pressure at 1.50 - 2.2 MPa and the feed port flow rate at 2.4 - 3.4 L / min. The water molecules in the liquid edible vinegar penetrate outward through the reverse osmosis membrane on the tube core wall under the action of pressure and enter the waste water collection pool; the tube core intercepts and concentrates the vinegar liquid, and continuously collects the concentrated vinegar liquid at the outlet of the tubular reverse osmosis device and stores it in the transfer tank; the tubular reverse osmosis device is a pipeline connected by spiral wound reverse osmosis membrane modules. The inner diameter of the tube core of the spiral wound reverse osmosis membrane module is 5 - 8 cm, and the pipeline length is 20 - 25 m; the reverse osmosis membrane can intercept substances with a particle size greater than 0.1 nm; the outlet controls the outlet flow rate to be 25 - 30% of the feed flow rate;

[0010] S2. The concentrated vinegar solution, embedding agent, and anti-sticking agent are homogenously dispersed in a homogenizer according to a mass ratio of 100:(10 - 12):(0.1 - 0.3) to form a vinegar slurry, which is fed into a centrifugal spray drying tower. High-temperature air at 140 - 155 °C is introduced, and the vinegar slurry is centrifugally spray-dried and settles at the bottom of the drying tower. After gas-solid separation by a secondary cyclone separator, the vinegar powder is collected at the bottom of the cyclone separator. The separated tail gas is introduced into a water film dust removal tower and collected by alkali liquor spraying.

[0011] S3. The vinegar powder collected by the cyclone separator is screened through a 50-mesh sieve and packaged to obtain the vinegar powder.

[0012] Preferably, the acidity of the liquid edible vinegar is 4 - 6 g / 100 mL.

[0013] Preferably, the particle size of the cellulose aerogel is ≤2 μm, the porosity is ≥90%, and the specific surface area is ≥200 m 2 / g. The cellulose aerogel has a good pore structure, stable surface charge, and hydrophilicity. When added to the liquid edible vinegar, it can preferably adsorb and fix flavor substances such as lactic acid, amino acids, polyphenols, flavonoids, sugars, and ligustrazine in the edible vinegar, preventing the loss of small-molecule nutrients during reverse osmosis treatment. On the other hand, by adding cellulose aerogel to the liquid edible vinegar, small-molecule amino acids, organic acids, sugars, etc. can be adsorbed and enriched into large-particle particles, preventing the direct attachment of amino acids, organic acids, etc. to the reverse osmosis membrane surface, reducing membrane element fouling, and improving the permeation effect and the lifespan of the membrane.

[0014] Particularly, the concentrated vinegar solution contains cellulose aerogel, which prevents flavor loss during later high-temperature drying and maximally retains the nutritional components and functional factors of the edible vinegar. At the same time, it can effectively prevent the vinegar powder from adhering to the inner wall of the drying tower.

[0015] Preferably, the reverse osmosis membrane is one of cellulose acetate reverse osmosis membrane and aromatic polyamide reverse osmosis membrane; it has good hydrophilicity, and under the action of pressure, water molecules in the liquid edible vinegar are quickly removed by reverse osmosis, and macromolecular nutritional components such as organic acids, amino acids, polyphenols, sugars, inorganic salts, and minerals are retained.

[0016] Particularly preferably, in order to prevent damage to the membrane caused by long-term high-pressure working conditions and water hammer during idling, the cellulose acetate reverse osmosis membrane or aromatic polyamide reverse osmosis membrane uses a polysulfone porous membrane as the support layer.

[0017] The tubular reverse osmosis device is designed with a long pipe and a small inner diameter. The liquid edible vinegar enters the pipe core at a stable pressure and a fixed feed flow rate, and is continuously concentrated by reverse osmosis during the flow in the long pipe, and the concentrated vinegar solution is collected at a stable flow rate at the outlet. The continuous concentration of the vinegar solution is realized, avoiding the influence of low efficiency of intermittent reverse osmosis and unstable concentration of the concentrated vinegar.

[0018] Preferably, the discharge port controls the discharge flow rate to make the acidity of the concentrated vinegar solution reach 16 - 20 g / 100 mL. Appropriate concentration can not only ensure that the centrifugal spraying does not clog the material, but also maximize the drying energy saving.

[0019] Preferably, the embedding agent is at least one of β - cyclodextrin and maltodextrin. Through the embedding agent, the nutritional components in the edible vinegar can be embedded and sealed to avoid oxidation and volatilization at high temperatures, thus facilitating the formation of stable vinegar powder solids. Particularly preferably, the embedding agent is β - cyclodextrin.

[0020] Preferably, the anti - sticking agent uses at least one of tricalcium phosphate, fumed silica, and ammonium ferric citrate. By using the anti - sticking agent, smooth vinegar powder particles are formed to prevent the vinegar powder from sticking to the wall and fouling in the drying tower, and to avoid caking of the vinegar powder during packaging, transportation, and use.

[0021] Preferably, the concentrated vinegar solution, the embedding agent, and the anti - sticking agent are homogenously dispersed in a homogenizer at a rotation speed of 400 - 800 r / min to form a vinegar slurry.

[0022] Preferably, the centrifugal rotation speed of the centrifugal spray drying is 8000 - 12000 r / min. Through high - speed centrifugation, the vinegar slurry forms fine droplets that come into contact with high - temperature air and are quickly dried, reducing the residence time of the material in the high - temperature drying environment.

[0023] Preferably, the inlet air temperature of the high - temperature air is controlled at 150 °C.

[0024] Preferably, the high - temperature air is converted into hot air by a heater and pressurized into the drying tower. The wind pressure is controlled at 600 - 800 kpa. Through the wind pressure, the atomized material rotates and disperses in a spiral shape to achieve the purpose of rapid drying. Adjust the feed flow rate of the centrifugal spray drying to keep the temperature in the drying tower at 120 - 130 °C.

[0025] By controlling the size of the damper of the induced draft fan of the secondary cyclone separator, the vinegar powder in the drying tower is introduced into the cyclone separator in a negative pressure manner in a timely manner. Preferably, the negative pressure at the bottom of the drying tower is controlled at 90 - 150 Pa, which can better control the water content of the vinegar powder ≤ 5%.

[0026] Preferably, the outlet air temperature of the separated tail gas is 90 - 95 °C.

[0027] Preferably, the water film dust removal tower is sprayed with sodium hydroxide lye with a concentration of 15 - 20 wt% to neutralize the volatile acid.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. When the present invention is used for reverse osmosis concentration of liquid edible vinegar, by adding cellulose aerogel, the flavor substances of the edible vinegar are adsorbed and fixed by using its surface charge and hydrophilicity, preventing the outward penetration of small molecule nutrients during reverse osmosis treatment and reducing the loss of nutrients during reverse osmosis concentration.

[0030] 2. The present invention utilizes a tubular reverse osmosis device with a long pipeline. Liquid edible vinegar is continuously introduced into the tube core. By controlling the pump pressure, water molecules in the liquid edible vinegar penetrate outward through the reverse osmosis membrane on the tube core wall under the action of pressure. The concentrated vinegar liquid is intercepted in the tube core and collected at the discharge port of the tubular reverse osmosis device. By controlling the flow rate of the concentrated vinegar liquid at the discharge port, a concentrated vinegar liquid with a stable concentration is obtained.

[0031] 3. The present invention adds an anti-sticking agent for spray drying in the concentrated vinegar, effectively preventing the vinegar powder from sticking to the wall and fouling in the drying tower, avoiding the coking and charring of the vinegar powder, reducing the cleaning frequency of the drying tower, and improving the production efficiency.

[0032] 4. The method for preparing vinegar powder of the present invention is continuous and stable, with high concentration efficiency, low energy consumption, less acidic wastewater, environmentally friendly, small floor area, and can be scaled up for implementation. Description of the Drawings

[0033] Figure 1 It is a simple process diagram of a process for preparing vinegar powder by reverse osmosis concentration and purification according to the present invention.

[0034] Among them: 1 - tubular reverse osmosis device; 2 - wastewater collection pool; 3 - transfer tank; 4 - homogenizing and dispersing machine; 5 - centrifugal spray drying tower; 6 - high-temperature air inlet; 7 - first-stage cyclone separator; 8 - first vinegar powder collection port; 9 - second-stage cyclone separator; 10 - second vinegar powder collection port; 11 - water film dust removal tower. Detailed Embodiments

[0035] The following elaborates in detail on the specific implementation technical means for realizing the present invention. Unless otherwise specified, the following supporting equipment, auxiliary devices, and technical terms are the conventional understandings of those skilled in the art. The raw materials and devices without limitations are obtained through commercial channels. The liquid edible vinegar is different concentrations of edible vinegar fermented and made by the applicant.

[0036] The process of a process for preparing vinegar powder by reverse osmosis concentration and purification according to the present invention is as Figure 1As shown, liquid edible vinegar is mixed with cellulose aerogel and then pumped into the core of the tubular reverse osmosis device 1. The feed inlet of the core is as shown by the arrow. Under the action of pressure, the water molecules in the liquid edible vinegar penetrate outward through the reverse osmosis membrane on the core wall and enter the waste water collection pool 2; the core intercepts and concentrates the vinegar liquid, and the concentrated vinegar liquid is continuously collected at the outlet of the tubular reverse osmosis device and stored in the transfer tank 3; the concentrated vinegar liquid, embedding agent and anti-sticking agent are dispersed in the homogenizer 4 to form a vinegar slurry; the vinegar slurry is introduced into the centrifugal spray drying tower 5 for centrifugal atomization; high-temperature air is introduced from the high-temperature air inlet 5. After the vinegar slurry is centrifugally spray-dried, it settles at the bottom of the drying tower; it is separated by the first-stage cyclone separator 7, and coarse-grained vinegar powder is collected at the first vinegar powder collection port 8; it is separated by the second cyclone separator 9 for gas-solid separation, and fine-grained vinegar powder is collected at the second vinegar powder collection port 10; the exhausted gas separated is introduced into the water film dust removal tower 11 for alkali solution spraying treatment.

[0037] Example 1

[0038] A method for preparing vinegar powder by reverse osmosis concentration and purification:

[0039] S1. Liquid edible vinegar with an acidity of 5 g / 100 mL is uniformly stirred at a high speed with cellulose aerogel having a particle size ≤ 2 μm, a porosity ≥ 90%, and a specific surface area ≥ 200 m 2 / g at a mass ratio of 100:0.2, and continuously and quantitatively pumped into the core of the tubular reverse osmosis device by pump pressure. The pump pressure is controlled at 1.8 MPa, and the feed inlet flow rate is 3.0 L / min. Under the action of pressure, the water molecules in the liquid edible vinegar penetrate outward through the reverse osmosis membrane on the core wall and enter the waste water collection pool; the core intercepts and concentrates the vinegar liquid, and the outlet flow rate is controlled at 0.75 L / min. The concentrated vinegar liquid is continuously collected at the outlet of the tubular reverse osmosis device and stored in the transfer tank; the acidity of the obtained concentrated vinegar liquid reaches 19.7 g / 100 mL; the tubular reverse osmosis device is a pipeline connected by spiral wound reverse osmosis membrane modules. The inner diameter of the core of the spiral wound reverse osmosis membrane module is 5 cm, and the pipeline length is 20 m; the reverse osmosis membrane is a cellulose acetate reverse osmosis membrane with a polysulfone porous membrane as the support layer that can intercept substances with a particle size greater than 0.1 nm;

[0040] S2. The concentrated vinegar solution, embedding agent β-cyclodextrin, and anti-caking agent ammonium ferric citrate are homogenously dispersed at a mass ratio of 100:11:0.1 in a homogenizer at a rotation speed of 800 r / min for 15 min to form a vinegar slurry. The vinegar slurry is introduced into a centrifugal spray drying tower with a centrifugal speed of 10,000 r / min. Through high-speed centrifugation, the vinegar slurry forms fine droplets that come into contact with air at 150 °C introduced from the high-temperature air inlet and are quickly dried. The air pressure at the high-temperature air inlet is controlled at 600 kPa. By adjusting the feed flow rate of the vinegar slurry to 0.83 L / min, the temperature in the drying tower is maintained at 125 °C. After centrifugal spray drying of the vinegar slurry, it settles at the bottom of the drying tower. After gas-solid separation by a secondary cyclone separator, by controlling the damper size of the induced draft fan of the secondary cyclone separator, the negative pressure in the drying tower is controlled at 100 Pa, the water content of the vinegar powder is controlled to be ≤5%, and the vinegar powder in the drying tower is timely introduced into the cyclone separator in a negative pressure manner. Among them, the first-stage cyclone separator separates and collects large-particle vinegar powder, the fine vinegar powder and gas enter the second-stage cyclone separator for gas-solid separation, the fine vinegar powder is collected at the bottom, and the temperature of the tail gas separated from the upper part is 90 °C, which is introduced into a water film dust removal tower and treated by spraying with 20 wt% sodium hydroxide alkaline solution;

[0041] S3. Mix the vinegar powder collected by the first-stage cyclone separator and the second-stage cyclone separator evenly, screen it through a 50-mesh sieve, and package it to obtain vinegar powder.

[0042] Example 2

[0043] A method for preparing vinegar powder by reverse osmosis concentration and purification:

[0044] S1. Liquid edible vinegar with an acidity of 4 g / 100 mL and cellulose aerogel with a particle size ≤2 μm, porosity ≥90%, and specific surface area ≥200 m 2 / g are stirred evenly at a high speed at a mass ratio of 100:0.25, and continuously and quantitatively pumped into the tube core of a tubular reverse osmosis device by pump pressure, controlling the pump pressure at 1.9 MPa and the feed port flow rate at 3.2 L / min. The water molecules in the liquid edible vinegar penetrate outward through the reverse osmosis membrane on the tube core wall under the action of pressure and enter the wastewater collection pool; the tube core intercepts and concentrates the vinegar solution, controlling the discharge port flow rate at 0.81 L / min, and continuously collecting the concentrated vinegar solution at the discharge port of the tubular reverse osmosis device and storing it in a transfer tank; the acidity of the obtained concentrated vinegar solution reaches 16.4 g / 100 mL; the tubular reverse osmosis device is a pipeline connected by spiral wound reverse osmosis membrane modules, the inner diameter of the tube core of the spiral wound reverse osmosis membrane module is 5 cm, and the pipeline length is 25 m; the reverse osmosis membrane is a cellulose acetate reverse osmosis membrane with a polysulfone porous membrane as the support layer that can intercept substances with a particle size greater than 0.1 nm;

[0045] S2. The concentrated vinegar solution, embedding agent β-cyclodextrin, and anti-sticking agent fumed silica are homogenized and dispersed in a homogenizer at a mass ratio of 100:10:0.2 for 15 min at a rotational speed of 600 r / min to form a vinegar slurry. The vinegar slurry is introduced into a centrifugal spray drying tower with a centrifugal speed of 12,000 r / min. Through high-speed centrifugation, the vinegar slurry forms fine droplets that come into contact with air at 145 °C introduced from the high-temperature air inlet and are quickly dried. The air pressure at the high-temperature air inlet is controlled at 800 kPa. By adjusting the feed flow rate of the vinegar slurry to 0.92 L / min, the temperature in the drying tower is maintained at 130 °C. After centrifugal spray drying of the vinegar slurry, it settles at the bottom of the drying tower. After gas-solid separation by a secondary cyclone separator, by controlling the damper size of the induced draft fan of the secondary cyclone separator, the negative pressure in the drying tower is controlled at 150 Pa, and the water content of the vinegar powder is controlled to be ≤5%. The vinegar powder in the drying tower is promptly introduced into the cyclone separator in a negative pressure manner. Among them, the first-stage cyclone separator separates and collects large-particle vinegar powder, and the fine vinegar powder and gas enter the second-stage cyclone separator for gas-solid separation. The fine vinegar powder is collected at the bottom, and the tail gas separated from the upper part has a temperature of 95 °C and is introduced into a water film dust removal tower for spray treatment with a 15 wt% concentration of sodium hydroxide alkaline solution;

[0046] S3. The vinegar powder collected by the first-stage cyclone separator and the second-stage cyclone separator is mixed evenly, screened through a 50-mesh sieve, and packaged to obtain vinegar powder.

[0047] Example 3

[0048] A method for preparing vinegar powder by reverse osmosis concentration and purification:

[0049] S1. Liquid edible vinegar with an acidity of 6 g / 100 mL and cellulose aerogel with a particle size ≤2 μm, porosity ≥90%, and specific surface area ≥200 m 2 / g are stirred evenly at a high speed at a mass ratio of 100:0.3, continuously and quantitatively pumped into the tube core of a tubular reverse osmosis device by pump pressure, with the pump pressure controlled at 2.0 MPa and the feed port flow rate at 2.8 L / min. The water molecules in the liquid edible vinegar penetrate outward through the reverse osmosis membrane on the tube core wall under the action of pressure and enter the wastewater collection pool. The tube core intercepts the concentrated vinegar solution, with the discharge port flow rate controlled at 0.84 L / min, and the concentrated vinegar solution is continuously collected at the discharge port of the tubular reverse osmosis device and stored in a transfer tank. The acidity of the obtained concentrated vinegar solution reaches 19.1 g / 100 mL. The tubular reverse osmosis device is a pipeline connected by spiral wound reverse osmosis membrane modules. The inner diameter of the tube core of the spiral wound reverse osmosis membrane module is 5 cm, and the pipeline length is 25 m. The reverse osmosis membrane is an aromatic polyamide reverse osmosis membrane with a polysulfone porous membrane as the support layer that can intercept substances with a particle size greater than 0.1 nm;

[0050] S2. The concentrated vinegar solution, maltodextrin as the embedding agent, and tricalcium phosphate as the anti-sticking agent are homogenized and dispersed at a rotation speed of 600 r / min for 15 min in a homogenizer according to a mass ratio of 100:12:0.2 to form a vinegar slurry. The vinegar slurry is introduced into a centrifugal spray drying tower with a centrifugal speed of 12,000 r / min. Through high-speed centrifugation, the vinegar slurry forms fine droplets and contacts with the air at 150 °C introduced from the high-temperature air inlet and dries rapidly. The air pressure at the high-temperature air inlet is controlled at 750 kPa. By adjusting the feed flow rate of the vinegar slurry to 1.00 L / min, the temperature in the drying tower is maintained at 120 °C. After the vinegar slurry is centrifugally spray-dried, it settles at the bottom of the drying tower. After gas-solid separation by a secondary cyclone separator, by controlling the damper size of the induced draft fan of the secondary cyclone separator, the negative pressure in the drying tower is controlled at 100 Pa, the water content of the vinegar powder is controlled ≤ 5%, and the vinegar powder in the drying tower is introduced into the cyclone separator in a negative pressure manner in a timely manner. Among them, the first-stage cyclone separator separates and collects large-particle vinegar powder, the fine vinegar powder and the gas enter the second-stage cyclone separator for gas-solid separation, the fine vinegar powder is collected at the bottom, and the tail gas temperature separated from the upper part is 95 °C, which is introduced into a water film dust removal tower and treated by spraying with a 15 wt% concentration of sodium hydroxide alkaline solution;

[0051] S3. The vinegar powder collected by the first-stage cyclone separator and the second-stage cyclone separator is mixed evenly, screened through a 50-mesh sieve, and packaged to obtain vinegar powder.

[0052] Comparative Example 1

[0053] When implementing the solution of Example 1, replacing the cellulose aerogel with cellulose with a particle size ≤ 2 μm has limited adsorption and fixation of small molecules in liquid edible vinegar. During high-pressure reverse osmosis, some small molecule amino acids and organic acids are likely to permeate and be lost with water. The amino acid content and organic acid content of the concentrated vinegar solution decrease.

[0054] Comparative Example 2

[0055] When implementing the solution of Example 1, the tube length of the tubular reverse osmosis device is adjusted to 8 m. The short pipeline is difficult to efficiently permeate. In order to ensure a feed port flow rate of 3.0 L / min and a discharge port flow rate of 0.75 L / min, it is necessary to increase the feed pump pressure to 2.6 MPa. This pressure exceeds the bearing pressure of the reverse osmosis membrane and is extremely likely to cause damage to the reverse osmosis module, resulting in the permeation and loss of small molecule substances.

[0056] Comparative Example 3

[0057] When implementing the solution of Example 1, canceling the anti-sticking agent ammonium ferric citrate during spray drying results in the phenomenon of vinegar powder adhering to the inner wall and fouling after the drying tower has worked for 5 h.

[0058] Test the nutritional components of the vinegar powder in Examples 1 - 3 and Comparative Examples 1 - 3. Among them: the content of organic acids was determined by reference to the high performance liquid chromatography (HPLC); the content of amino acids was determined by reference to "Determination of Amino Acids in Foods - GB / T 5009.124 - 2003"; the content of polyphenols was determined by reference to the Folin - Ciocalteu colorimetric method; the content of flavonoids was determined by reference to the method in "GB / T 19777"; the content of ligustrazine was determined by reference to the high performance liquid chromatography. The test results are shown in Table 1.

[0059] Table 1: Main Nutritional Components Table of Vinegar Powder

[0060]

[0061]

[0062] Through the above detection of the basic nutritional components of the vinegar powder, the preparation method of the present invention preferably retains the nutritional components of the vinegar. Especially when reverse osmosis dehydration and concentration of edible vinegar are carried out, the use of cellulose aerogel to adsorb and fix small - molecule substances effectively avoids the loss of small - molecule nutrients in the vinegar. And through reverse osmosis in the tubular reverse osmosis device with a long pipeline, reverse osmosis can be stably carried out under a relatively low pressure, avoiding damage to the reverse osmosis membrane.

[0063] Those skilled in the art should understand that the present invention is not limited by the above - mentioned embodiments. What is described in the above - mentioned embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for preparing vinegar powder by reverse osmosis concentration and purification, characterized in that: It includes the following steps: S1. Stir liquid edible vinegar and cellulose aerogel evenly at a mass ratio of 100:(0.2 - 0.3) at high speed, and continuously and quantitatively pump them into the tube core of a tubular reverse osmosis device through pump pressure. Control the pump pressure at 1.50 - 2.2 MPa and the feed port flow rate at 2.4 - 3.4 L / min. The water molecules in the liquid edible vinegar penetrate outward through the reverse osmosis membrane on the tube core wall under the action of pressure and enter the waste water collection pool; the tube core intercepts and concentrates the vinegar liquid, and continuously collects the concentrated vinegar liquid at the discharge port of the tubular reverse osmosis device and stores it in a transfer tank; the tubular reverse osmosis device is a pipeline connected by spiral wound reverse osmosis membrane modules, the inner diameter of the tube core of the spiral wound reverse osmosis membrane module is 5 - 8 cm, and the pipeline length is 20 - 25 m; the reverse osmosis membrane can intercept substances with a particle size greater than 0.1 nm; the discharge port controls the discharge flow rate to be 25 - 30% of the feed flow rate; S2. Homogenize and disperse the concentrated vinegar liquid, embedding agent, and anti - sticking agent at a mass ratio of 100:(10 - 12):(0.1 - 0.3) in a homogenizer to form vinegar slurry, send it into a centrifugal spray drying tower, introduce high - temperature air at 140 - 155 °C, and carry out centrifugal spray drying of the vinegar slurry, which settles at the bottom of the drying tower; Carry out gas - solid separation through a secondary cyclone separator, and collect vinegar powder at the bottom of the cyclone separator; the separated tail gas is introduced into a water film dust removal tower and collected by alkali liquid spraying; S3. Screen the vinegar powder collected by the cyclone separator through a 50 - mesh sieve, and package it to obtain vinegar powder.

2. The method for preparing vinegar powder by reverse osmosis concentration and purification according to claim 1, characterized in that: The acidity of the liquid edible vinegar is 4 - 6 g / 100 mL.

3. The method for preparing vinegar powder by reverse osmosis concentration and purification according to claim 1, wherein: The particle size of the cellulose aerogel is ≤ 2 μm, the porosity is ≥ 90%, and the specific surface area is ≥ 200 m 2 / g.

4. The method for preparing vinegar powder by reverse osmosis concentration and purification according to claim 1, characterized in that: The reverse osmosis membrane is one of cellulose acetate reverse osmosis membrane and aromatic polyamide reverse osmosis membrane.

5. The method for preparing vinegar powder by reverse osmosis concentration and purification according to claim 1, characterized in that: The discharge port controls the discharge flow rate so that the acidity of the concentrated vinegar liquid reaches 16 - 20 g / 100 mL.

6. The method for preparing vinegar powder by reverse osmosis concentration and purification according to claim 1, wherein: The embedding agent is at least one of β - cyclodextrin and maltodextrin.

7. The method for preparing vinegar powder by reverse osmosis concentration and purification according to claim 1, wherein: The anti - sticking agent uses at least one of tricalcium phosphate, fumed silica, and ammonium ferric citrate.

8. The method for preparing vinegar powder by reverse osmosis concentration and purification according to claim 1, characterized in that: The centrifugal speed of the centrifugal spray drying is 8000 - 12000 r / min; the wind pressure of the high - temperature air is controlled at 600 - 800 kPa.

9. The method for preparing vinegar powder by reverse osmosis concentration and purification according to claim 1, characterized in that: The negative pressure at the bottom of the drying tower is controlled at 90 - 150 Pa.

10. The method for preparing vinegar powder by reverse osmosis concentration and purification according to claim 1, characterized in that: The outlet air temperature of the separated tail gas is 90 - 95 °C; the water film dust removal tower uses a sodium hydroxide alkali solution with a concentration of 15 - 20 wt% for spraying.

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