Preparation method of selenium-rich edible salt

Abstract

The invention relates to a preparation method of selenium-rich edible salt, and belongs to the technical field of edible salt. The preparation method comprises the following steps: (1) coating an iodine-containing substance with a coating material to prepare iodine-containing coated particles; (2) coating a selenium-containing substance with a coating material to prepare selenium-rich coated particles; and (3) uniformly mixing and stirring the iodine-containing coated particles, the selenium-rich coated particles, edible salt and / or other acceptable food seasoning components to obtain the selenium-rich edible salt. According to the invention, water-soluble dietary fiber (oat bran extract) and food-grade collagen peptide are mixed as a coating material; insoluble dietary fibers (oat bran leaching powder) and porous deproteinized dictyophora indusiata powder are mixed to serve as an adsorption carrier, a selenium-rich nutrient solution and a potassium iodate solution are adsorbed and dried through the adsorption carrier and then coated with a coating material, and the two coated particles are mixed with salt in proportion, so that oxidation of selenium-containing components and direct contact of selenium and iodine are avoided, and the selenium-rich nutrient solution is prepared. And the stability of the product is maintained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of edible salt, in particular to a preparation method of iodine-containing selenium-rich salt. BACKGROUND

[0002] Selenium is an essential trace element for the human body. If the daily dietary selenium intake is insufficient, various selenium proteins in the body cannot be fully expressed, which will affect the normal play of many physiological functions of the body. According to the Dietary Nutrient Reference Intakes for Chinese Residents (2023 Edition), the recommended daily intake (RNI) of dietary selenium for Chinese residents is 60 micrograms for people over 12 years old and adults, and 78 micrograms for lactating mothers.

[0003] Most of the selenium in animals, plants and human bodies is derived from soil. From a worldwide perspective, soil selenium deficiency is very common. There is a north-south selenium deficiency belt in China from the three provinces of Northeast China to the Yungui Plateau. The average soil selenium content in the low-selenium belt is only 0.1 mg / kg. 72% of the cities (counties) in China are in a state of severe selenium deficiency or low selenium, of which the content of ≤0.02 mg / kg accounts for 29%, which is a severe selenium deficiency area, which leads to insufficient dietary selenium intake among Chinese residents.

[0004] In order to improve the selenium nutritional status of the public, it is an effective nutritional intervention means to enrich selenium in table salt. China has implemented the application of selenium-rich salt in selenium-deficient areas for more than 40 years. Early products mostly used inorganic selenium such as sodium selenite as an additive, but due to its low bioavailability and potential toxic side effects, the current food safety standards have limited its use in edible salt.

[0005] Currently, selenium-rich edible salt is generally produced using food raw materials rich in organic selenium, but there is a common problem of poor stability. This is because iodized salt is the main edible salt in China due to the prevention and treatment of iodine deficiency disorders. The organic selenium component is mostly reducing, while the iodine agent used in the edible salt is potassium iodate, which has oxidizing properties. The coexistence of the two in the edible salt leads to the easy oxidation-reduction reaction between the iodine in the edible salt and the selenium-containing raw material, resulting in changes in the color of the product appearance (such as yellowing), loss of iodine and decrease in selenium activity, which seriously affects the quality stability of the product.

[0006] Therefore, it is a technical problem to be solved in the field to develop a preparation method of selenium-rich edible salt that can effectively isolate iodine and selenium and improve the storage stability of the product. SUMMARY

[0007] The purpose of the present application is to provide a preparation method of selenium-rich edible salt, which uses an adsorption carrier to adsorb and dry the selenium-rich nutrient solution and the potassium iodate solution, then uses a coating material to coat, and then mixes the two coated microparticles with edible salt in proportion, which avoids the oxidation of selenium and the direct contact between selenium and iodine, and maintains the stability of the product.

[0008] To achieve the above object, the present application provides the following technical solutions.

[0009] The preparation method of the selenium-rich edible salt comprises the following steps: (1) coating an iodine-containing substance with a coating material to prepare iodine-containing coated particles; (2) coating a selenium-containing substance with the coating material to prepare selenium-rich coated particles; and (3) mixing and stirring the iodine-containing coated particles, the selenium-rich coated particles, edible salt and / or other acceptable food seasoning ingredients to obtain the selenium-rich edible salt.

[0010] The iodine-containing coated particles and the selenium-rich coated particles are mixed and stirred with edible salt to obtain a basic selenium-rich edible salt; and the iodine-containing coated particles, the selenium-rich coated particles, edible salt and other acceptable food seasoning ingredients are mixed and stirred to obtain a selenium-rich flavored edible salt.

[0011] The food seasoning ingredients include shiitake mushroom powder, tricholoma matsutake powder and spices.

[0012] The coating material in step (1) and step (2) is a mixed coating liquid composed of oat bran extract and food-grade collagen peptide.

[0013] The preparation method of the oat bran extract comprises the following steps: ① spraying purified water into oat bran uniformly, and using a double-screw extrusion puffing machine to obtain oat bran puffing particles; and ② crushing the oat bran puffing particles to 20 mesh or less, adding purified water, stirring, heating, leaching and centrifuging to obtain oat bran extract and oat bran precipitate.

[0014] The iodine-containing substance and the selenium-containing substance in step (1) and step (2) are first adsorbed by an adsorption carrier, and then coated with the coating material.

[0015] The preparation method of the adsorption carrier comprises the following steps: (a) rinsing the oat bran precipitate with purified water and drying it to a water content of ≤5%, and crushing it to 60 mesh to obtain oat bran leaching powder; (b) bamboo shoot powder preparation: ① drying fresh bamboo shoots after removing impurities and washing, cutting them into segments, and then drying them to a bamboo shoot water content of ≤5%, and airflow crushing them through a 30-mesh sieve to obtain porous bamboo shoot powder; ② mixing cellulase, hemicellulase and purified water uniformly, and adjusting the pH to 4.8 to obtain a composite enzyme solution; ③ adding the composite enzyme solution to the porous bamboo shoot powder, stirring and enzymatic hydrolysis at 45-50°C for 2-3 hours, inactivating the enzyme after the enzymatic hydrolysis is completed, and filtering; ④ performing first deproteinization on the enzymatically hydrolyzed bamboo shoot powder with alkaline protease, and then performing second deproteinization with papain, filtering and rinsing to neutral, and drying and crushing through a 60-mesh sieve to obtain porous deproteinized bamboo shoot powder; and ⑤ mixing the oat bran leaching powder and the porous deproteinized bamboo shoot powder uniformly to obtain the adsorption carrier; the mass ratio of the porous deproteinized bamboo shoot powder to the oat bran leaching powder is 1:0.5-5.

[0016] The mass ratio of the porous deproteinized bamboo shoot powder to the oat bran leaching powder is preferably 1:1.

[0017] Preparation of selenium-enriched coated microparticles: ① Add food-grade soluble selenium-enriched raw materials to pure water and remove impurities through a microporous filter membrane to obtain a selenium-enriched nutrient solution; (tangerine peel extract can be added) ② Spray the selenium-enriched nutrient solution onto a heated adsorption carrier, then coat it with a coating material, dry it to remove dust, and obtain selenium-enriched coated microparticles with a particle size of 160-830μm, a selenium content of 5.0-8.0 mg / kg, and a water content of ≤4.0%.

[0018] Preparation of iodine-coated microparticles: ① Prepare potassium iodate solution and remove impurities using a microporous filter membrane; ② Spray the potassium iodate solution onto the heated adsorption carrier, then coat it with a coating material, and dry it through an 80-mesh sieve to obtain iodine-coated microparticles with a particle size of 160-830 μm, an iodine content of 4.0-6.3 g / kg, and a water content of ≤4.0%.

[0019] The present invention also provides selenium-enriched edible salt prepared by the above method.

[0020] The beneficial effects of adopting the above technical solution are:

[0021] This invention first puffs oat bran to form a porous structure, then extracts water-soluble dietary fiber. The water-soluble dietary fiber (oat bran extract) is mixed with food-grade collagen peptides as a coating material. Insoluble dietary fiber (oat bran extract powder) and porous deproteinized bamboo fungus powder are mixed as an adsorbent carrier. Selenium-enriched nutrient solution and potassium iodate solution are adsorbed and dried using the adsorbent carrier, then coated with the coating material. The two coated particles are then mixed with salt in a specific ratio. This avoids oxidation of the selenium raw material and direct contact between selenium and iodine, maintaining product stability. This method can also be used to prepare easily oxidized or odor-prone fortified edible salt products such as iron-enriched edible salt, zinc-enriched edible salt, and DHA-enriched edible salt.

[0022] Advantages of the process of this invention:

[0023] High raw material utilization: Oat bran is utilized throughout the entire process of "expansion-extraction-coating", with the extract used for coating and no waste generated;

[0024] High stability: Multiple coatings (using oat extract and collagen as raw materials) can keep the selenium and iodine content in the product stable. The loss rate in accelerated testing is lower than that of uncoated products. During the shelf life, the product will not turn yellow or discolor, and will remain stable.

[0025] High safety: All raw materials are food-grade, and the adsorbent carrier and coating material (made from oat bran and bamboo fungus) are edible, with no risk of additional additives.

[0026] Good sensory qualities: The particle size of the coated microparticles is similar to that of table salt. When mixed with table salt, the resulting selenium-enriched edible salt is similar in appearance to traditional table salt. Selenium-enriched edible salt has no unpleasant taste and does not affect consumers' usage habits. Detailed Implementation

[0027] The following embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] All raw materials used in this invention were purchased from the market.

[0029] Refined edible salt (non-iodized) (sodium chloride ≥ 99.1g / 100g) and low-sodium salt (non-iodized) (potassium chloride ≥ 25g / 100g) were purchased from Jiangsu Ruifeng Salt Industry Co., Ltd.

[0030] Oat bran was purchased from Henan Longhu Food Technology Co., Ltd.;

[0031] Potassium iodate (≥99.0%), a food additive, was purchased from Yingcheng Huaxin Potassium Iodate Co., Ltd.

[0032] The concentrated tangerine peel extract powder (food-grade tangerine peel extract 10:1) was purchased from Xi'an Benshuo Biotechnology Co., Ltd.

[0033] The selenium-enriched mushroom powder (selenium content 800mg / kg, organic selenium 790mg / kg, organic selenium / total selenium ratio greater than 95%) was purchased from Shaanxi Shengmi Biotechnology Co., Ltd.

[0034] Example 1

[0035] The specific method for preparing selenium-enriched edible salt is as follows.

[0036] Step 1: Preparation of oat bran extract

[0037] (1) Spray 5 kg of purified water evenly into 100 kg of oat bran, and feed it into a twin-screw extruder. The feeding section temperature is 115℃, the compression section temperature is 125℃, and the extrusion section setting temperature is 135-150℃ to obtain oat bran puffed granules. Immediately air-cool to room temperature to avoid pore collapse. Through the process of starch gelatinization, gas expansion, and instantaneous pressure relief under high temperature and high pressure, a connected porous structure is formed inside the oat bran fiber, providing sites for subsequent adsorption of selenium and iodine.

[0038] (2) Crush the oat bran puffed granules to below 20 mesh, put them into a stirring extraction tank, add pure water at a solid-liquid ratio of 1:10 (i.e., 10kg granules + 100kg pure water), stir, heat to 70-80℃, and extract for 60-90 minutes.

[0039] After extraction, the mixture was pumped into a centrifuge and centrifuged at 4000 rpm for 10 minutes to separate the supernatant (oat bran extract) and the precipitate (oat bran precipitate).

[0040] The supernatant contains starch, as well as water-soluble dietary fiber such as β-glucan and pectin. The supernatant is collected and used for subsequent preparation of the coating solution.

[0041] Step 2: Preparation of coating materials

[0042] Take 50L of the supernatant (oat bran extract) collected after centrifugation in the previous step, add 1100g of food-grade collagen peptides (90% of which have a relative molecular weight of less than 10000), heat to 60℃ and stir until dissolved, then transfer to a vacuum concentration tank and concentrate under vacuum at 60℃ to 15L (solids content ≥ 10%) to obtain an oat extract-collagen mixed coating solution (coating material), for later use. The oat extract provides viscosity, and the collagen peptides enhance the flexibility of the coating layer; together, they form a dense insulating membrane.

[0043] Step 3: Preparation of the adsorption support

[0044] I. Preparation of Porous Deproteinized Bamboo Fungus Powder

[0045] Drying: Select fresh bamboo fungus, remove impurities, rinse with water, drain, and cut into 1-2cm pieces. Blanch in 90–95°C hot water for 1.5–2 minutes, then rapidly cool to inhibit oxidase activity and prevent browning. Drain the bamboo fungus pieces and place them in a freeze dryer. First, freeze at -35 to -30°C for 3 hours to allow internal moisture to form ice crystals. Then, activate the vacuum system, maintaining a vacuum degree ≤30Pa, and raise the temperature to 35°C for vacuum sublimation drying for 4–10 hours, until the moisture content of the bamboo fungus is ≤5%, resulting in loose and porous dried bamboo fungus.

[0046] Airflow pulverization and pore expansion: Dry bamboo fungus is put into an airflow pulverizer, the airflow pressure is set to 0.8MPa and the feed rate is 50kg / h. Particles are pulverized and pores are formed through high-speed collision. After passing through a 20-mesh vibrating screen, preliminary porous bamboo fungus powder is obtained.

[0047] Composite enzymatic hydrolysis optimizes pore size:

[0048] Prepare the compound enzyme solution: Mix food-grade cellulase and hemicellulase in a mass ratio of cellulase (5000U / g): hemicellulase (5000U / g) = 2:1, add purified water to prepare a solution with an enzyme concentration of 0.8%, and adjust the pH to 4.8.

[0049] The preliminary porous bamboo fungus powder and the compound enzyme solution were mixed at a mass ratio of 1:10 and placed in a 304 stainless steel reaction vessel. The mixture was enzymatically hydrolyzed for 2.5 hours at 48℃ and 150r / min with stirring. After the enzymatic hydrolysis was completed, the temperature was raised to 85℃ and kept at that temperature for 20 minutes to inactivate the enzyme. The bamboo fungus powder was then collected by filtration.

[0050] Protein removal process:

[0051] First protein removal: Mix the enzymatically hydrolyzed bamboo fungus powder with 0.5% food-grade alkaline protease solution at a mass ratio of 1:12, adjust the pH to 9.0, react at 55℃ and 180r / min for 1.5 hours, filter, and rinse with pure water until neutral.

[0052] Second deproteinization: Add 0.3% (w / w) of food-grade papain solution (w / w ratio 1:10), adjust the pH to 6.2, react at 52℃ and 180r / min for 1 hour, filter, rinse again until neutral, dry in a 70℃ hot air dryer until the moisture content is ≤3%, crush and pass through a 60-mesh sieve to obtain porous deproteinized bamboo fungus powder for later use.

[0053] II. Preparation of Oat Bran Extract Powder

[0054] The oat bran precipitate was washed with purified water at a mass ratio of 1:5, and then centrifuged again. This process was repeated twice to obtain a wet-based oat fiber adsorbent carrier. The washing solution can be recycled for subsequent extractions.

[0055] The wet-based oat fiber adsorbent carrier was put into a hot air dryer, the temperature was set at 70℃ and the air volume at 4000m³ / h, and it was dried for 4 hours until the moisture content was ≤5%; then it was put into an air jet mill, pulverized, and passed through a 60-mesh vibrating screen to obtain oat bran extract powder.

[0056] Porous deproteinized bamboo fungus powder and oat bran extract powder are mixed evenly at a mass ratio of 1:0.5-5 to form an adsorption carrier.

[0057] Adsorbent carrier A: Porous deproteinized bamboo fungus powder and oat bran extract powder in a mass ratio of 1:0.5;

[0058] Adsorbent carrier B: Porous deproteinized bamboo fungus powder and oat bran extract powder in a 1:1 mass ratio;

[0059] Adsorbent carrier C: Porous deproteinized bamboo fungus powder to oat bran extract powder in a mass ratio of 1:2;

[0060] Adsorbent carrier D: Porous deproteinized bamboo fungus powder to oat bran extract powder in a mass ratio of 1:3;

[0061] Adsorbent carrier E: Porous deproteinized bamboo fungus powder and oat bran extract powder in a mass ratio of 1:5.

[0062] Step 4: Preparation of potassium iodate solution

[0063] Add 700g of food-grade potassium iodate to 10kg of purified water and stir until dissolved to obtain a potassium iodate solution with an iodine concentration of approximately 40g / kg. Filter the solution through a 100-mesh screen to remove impurities and set aside.

[0064] Step 5: Preparation of selenium-enriched nutrient solution

[0065] Mix 3 kg of the supernatant (oat bran extract) obtained in the first step with 12 kg of purified water, add 1 kg of selenium-enriched mushroom powder (crushed to 1200 mesh) and 10 g of dried tangerine peel extract, stir, heat to 50°C to dissolve, adjust the pH of the solution to 5.5 to 6.5 with citric acid-sodium citrate buffer, homogenize with a homogenizer, filter through a 100-mesh screen to remove impurities, and obtain a selenium-enriched nutrient solution with suitable viscosity (selenium concentration of about 50 mg / kg) for later use.

[0066] Step 6: Preparation of selenium-enriched coated microparticles

[0067] Add 20 kg of adsorbent carrier to a stirred spray tank, and control the temperature inside the tank at 50℃ (using a jacket for temperature control). Heating can make the pore structure of the adsorbent carrier more open, which can increase the penetration rate of selenium nutrient solution.

[0068] Turn on the spray head and spray at a speed of 100–200 g / min. Spray 3.2 kg of selenium-enriched nutrient solution in 3 applications.

[0069] Spray while stirring. For the first spray, spray 30% (0.96kg) and continue stirring for 10 minutes after spraying to allow the selenium solution to penetrate deep into the pores. For the second spray, spray 40% (1.28kg) and stir for 15 minutes after spraying. For the third spray, spray 30% (0.96kg) and stir for 15 minutes after spraying.

[0070] Excessive selenium-enriched nutrient solution can lead to carrier adsorption saturation. 1 kg of carrier can adsorb ≤0.20 kg of selenium-enriched solution. Excessive amount will cause free selenium solution to drip, resulting in selenium loss and subsequent coating and aggregation.

[0071] The carrier, after adsorbing the selenium-rich solution, was transferred to a hot air circulating dryer and dried using a gradient temperature increase method.

[0072] First stage (0-60 minutes): Temperature 60℃, to remove surface free water;

[0073] Second stage (61-120 minutes): Temperature 75℃, remove bound water from pores;

[0074] The third stage (121-150 minutes): The temperature is gradually reduced from 75℃ to below 50℃, and the air volume is 2000m³ / h to achieve slow cooling and shaping, preventing particle breakage or selenium oxidation due to excessive temperature difference.

[0075] Dry to a moisture content of ≤5% to obtain selenium-enriched adsorption microparticles, and cool to room temperature for later use.

[0076] First coating: Add 20kg of selenium-enriched adsorbent microparticles to a stirring spray tank, control the temperature inside the tank at 50℃, stir, and spray 2.0kg of oat extract-collagen mixed coating solution (coating material); after spraying, continue stirring for 3 minutes to ensure that the coating solution is evenly attached to the surface of the selenium-enriched adsorbent microparticles; transfer to a hot air dryer and dry at 75℃ for 30-60 minutes until the moisture content is ≤5.0%.

[0077] Second coating: Coating the intermediate layer, thickening and densifying the layer, and isolating selenium from the outside environment.

[0078] After the first coating, the selenium-enriched adsorbent particles are transferred back to the spray tank, stirred, and 2.0 kg of coating liquid is sprayed. After spraying, the mixture is stirred for 3 minutes. Then, it is transferred to a hot air dryer and dried at 75°C for 30-60 minutes until the moisture content is ≤5.0%.

[0079] The third coating, covering the surface: improves stability and adapts to subsequent mixing.

[0080] After the second coating, transfer the microparticles back to the spray tank and stir 1.8 kg of coating liquid; stir for 3 minutes after spraying; transfer to a hot air dryer and dry at 75℃ for 30-60 minutes until the moisture content is ≤4.0%.

[0081] Three coatings ensure the thickness of the coating layer while avoiding particle agglomeration caused by excessive spraying in a single spray.

[0082] After the selenium-enriched microparticles were coated three times and cooled to room temperature, they were fed into a vibrating sieve. A 20-mesh sieve was used to intercept oversized impurities, and a 100-mesh sieve was used to separate fine powder and agglomerates. The material remaining between the two sieves was the selenium-enriched coated microparticles. The selenium content was determined using the GB5009.93-2017 method.

[0083] The final product consists of selenium-enriched coated microparticles with a particle size of 160-830 μm, a selenium content of 7.7 mg / kg, and a water content of ≤4.0%. These microparticles are then sealed and stored in a light-proof container for later use.

[0084] Step 7: Preparation of Iodine-Coated Microparticles

[0085] 10 kg of adsorbent carrier was added to a stirred spray tank, and the temperature inside the tank was controlled at 50℃ (using a jacket for temperature control) to stabilize the carrier temperature at 45-50℃. The heated adsorbent carrier has a more open pore structure, which can increase the permeation rate of potassium iodate solution.

[0086] Turn on the spray nozzle and spray 1.60 kg of potassium iodate solution in 3 applications:

[0087] Spray while stirring. For the first spray, spray 30% (0.48 kg) and continue stirring for 10 minutes after spraying to allow the potassium iodate solution to penetrate deep into the pores. For the second spray, spray 40% (0.64 kg) and stir for 15 minutes after spraying. For the third spray, spray 30% (0.48 kg) and stir for 15 minutes after spraying.

[0088] The maximum adsorption capacity of a 10kg carrier for potassium iodate solution is ≤2.2kg.

[0089] The carrier, after adsorbing potassium iodate solution, was transferred to a hot air circulating dryer and dried using a gradient temperature increase method.

[0090] First stage (0-60 minutes): Temperature 65℃, to remove surface free water;

[0091] Second stage (61-120 minutes): Temperature 80℃, to remove bound water from pores;

[0092] The third stage (121-150 minutes): The temperature is gradually reduced from 80℃ to below 50℃, and the air volume is 2000m³ / h to achieve slow cooling and shaping, preventing particle breakage or selenium oxidation due to excessive temperature difference.

[0093] Dry to a moisture content of ≤5% to obtain potassium iodate adsorbent particles, and cool to room temperature for later use.

[0094] First coating: Add 10.0 kg of potassium iodate adsorbent microparticles to a stirring spray tank, control the temperature inside the tank at 50℃, stir, and spray 1.0 kg of oat extract-collagen mixed coating solution (coating material); after spraying, continue stirring for 3 minutes to ensure that the coating solution is evenly attached to the surface of the potassium iodate adsorbent microparticles; transfer to a hot air dryer and dry at 75℃ for 30-60 minutes until the moisture content is ≤5.0%.

[0095] Second coating: Coating the intermediate layer, thickening and densifying the layer, and isolating selenium from the outside environment.

[0096] After the first coating, the potassium iodate adsorbent particles were transferred back to the spray tank, stirred, and 1.0 kg of coating solution was sprayed. After spraying, the mixture was stirred for 3 minutes. The mixture was then transferred to a hot air dryer and dried at 75°C for 30-60 minutes until the moisture content was ≤5.0%.

[0097] The third coating, covering the surface: improves stability and adapts to subsequent mixing.

[0098] After the second coating, transfer the microparticles back to the spray tank and stir 0.9 kg of coating liquid; stir for 3 minutes after spraying; transfer to a hot air dryer and dry at 75℃ for 30-60 minutes until the moisture content is ≤4.0%.

[0099] Three coatings ensure the thickness of the coating layer while avoiding particle agglomeration caused by excessive spraying in a single spray.

[0100] After the potassium iodate microparticles were coated three times, they were cooled to room temperature and fed into a vibrating sieve. A 20-mesh sieve was used to intercept oversized impurities, and a 100-mesh sieve was used to separate fine powder and agglomerates. The material remaining between the two sieves was the potassium iodate coated microparticles. The iodine content was determined using the GB5009.267-2020 method.

[0101] The final product consists of potassium iodate coated microparticles with a particle size of 160-830 μm, an iodine content of 6.1 g / kg, and a water content of ≤4.0%. These microparticles are then sealed and stored in a light-proof container for later use.

[0102] The formation and surface integrity of the coated microparticles prepared using different adsorbent carriers were observed, and their encapsulation efficiency was measured. The results are shown in Table 1.

[0103] Table 1. Performance comparison of adsorbents with different ratios

[0104]

[0105] Encapsulation efficiency determination method: Take 25g of the prepared iodine-containing or selenium-enriched microparticles, add 150g of purified water, shake for 2 minutes, centrifuge at 4000 rpm for 1 minute, and discard the supernatant. Wash the precipitate twice, combine all supernatants, and make up to 500ml. Measure the residual iodine or selenium content in the supernatant, and record it as the unencapsulated amount. Subtract the unencapsulated amount from the initial total amount added to obtain the actual encapsulated amount in the microparticles, and divide it by the total amount to obtain the encapsulation efficiency.

[0106] The results showed that when the mass ratio of porous deproteinized bamboo fungus powder to oat bran extract powder was 1:1, the resulting coated microparticles had a moderate particle size, high encapsulation rate, and intact surface structure, exhibiting the best overall performance. Therefore, this ratio was adopted as the preferred solution in subsequent embodiments.

[0107] Step 8: Preparation of selenium-enriched edible salt

[0108] The preparation method is as follows: 24.4 kg of salt, 22.0 kg of selenium-enriched coated microparticles and 3.6 kg of iodine-containing coated microparticles (both types of coated microparticles are prepared using adsorption carrier B) are mixed to make a premix, and then 950 kg of salt is mixed with the premix and stirred for 10 minutes.

[0109] Performance testing:

[0110] Standard indicators: sodium chloride content, selenium content, iodine content, and moisture content.

[0111] Table 2 Quality of Selenium-Enriched Salt Finished Product (according to GB 2721-2015 "Edible Salt")

[0112]

[0113] Stability testing: An accelerated test was conducted at 45°C, 75% humidity, and 800 lux light. After 150 days of storage, the loss rate of selenium and iodine and changes in appearance were tested.

[0114] Comparative Example 1:

[0115] The traditional method for preparing selenium-enriched edible salt without using isolation and coating technology. Potassium iodate was prepared into a 20 g / kg solution. 165 g of the potassium iodate solution was sprayed into 100 kg of commercially available refined salt and stirred evenly. Then, 20.0 g of selenium-enriched mushroom powder (organic selenium content 800 mg / kg, organic selenium content 790 mg / kg) was added to the salt and mixed evenly to obtain the control sample (i.e., Comparative Example 1). Its selenium content was measured to be 158 μg / kg, organic selenium content 154 μg / kg, and iodine content 25.0 mg / kg.

[0116] The selenium-enriched edible salt prepared in Example 1 of this invention and the sample of Comparative Example 1 (control group) were placed in sealed transparent PE bags and subjected to accelerated aging tests in a constant temperature and humidity chamber to detect changes in indicators and appearance.

[0117] Table 3 Stability Comparison Table

[0118]

[0119]

[0120] The data above shows that:

[0121] Regarding appearance stability: Comparative Example 1 showed visible yellowing on day 60 and became significantly yellow after 90 days, indicating a significant oxidation reaction; while the product of this invention maintained its original color throughout the entire test period, demonstrating that the coating layer effectively blocked the interaction between the external environment and internal components. Moreover, Comparative Example 1 showed visible brown powder containing selenium.

[0122] Regarding iodine retention: Comparative Example 1 showed an iodine loss rate of 15.0%, which is much higher than the 1.1% of the present invention. This indicates that a significant redox reaction occurred between potassium iodate and reducing organic selenium in the uncoated state, leading to iodine volatilization and causing the product to turn yellow.

[0123] Regarding the retention rate of organic selenium: the decrease in organic selenium content in Comparative Example 1 was due to oxidation by potassium iodate; while the present invention significantly slows down this process through the physical isolation mechanism of "adsorption and coating".

[0124] Example 2

[0125] The preparation method of selenium-enriched, low-sodium mushroom-flavored edible salt is as follows.

[0126] The preparation methods for selenium-enriched coated microparticles and iodine-containing coated microparticles are the same as in Example 1.

[0127] The composition by weight percentage is as follows: 92.55% low-sodium salt (components are 75% sodium chloride and 25% potassium chloride), 2.50% selenium-enriched coated microparticles, 2.0% shiitake mushroom powder, 2.5% button mushroom powder, and 0.45% iodine-containing coated microparticles.

[0128] The preparation method is as follows: 25.0 kg of selenium-enriched coated microparticles are mixed with 20.0 kg of shiitake mushroom powder, 25 kg of button mushroom powder and 4.5 kg of iodine-containing coated microparticles to make a premix. Then, 925.5 kg of low-sodium salt is mixed with the premix and stirred for 10 minutes.

[0129] Performance testing:

[0130] Standard indicators: iodine content, sodium chloride content, potassium chloride content, selenium content.

[0131] Stability testing: An accelerated test was conducted at 45°C, 75% humidity, and 800 lux light. After 150 days of storage, the loss rate of selenium and iodine and changes in appearance were tested.

[0132] Table 4. Product Specifications of Selenium-Enriched Low-Sodium Mushroom Flavored Edible Salt (QB / T 2020-2024 Flavored Edible Salt, specifically Low-Sodium Flavored Edible Salt)

[0133]

[0134] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for the preparation of a selenium-enriched edible salt, characterized in that: The method comprises the following steps: (1) preparing iodine-containing coated particles by coating iodine-containing substances with coating materials; (2) preparing selenium-rich coated particles by coating selenium-containing substances with coating materials; (3) mixing and stirring iodine-containing coated particles, selenium-rich coated particles, edible salt and / or other acceptable food seasoning ingredients to obtain selenium-rich edible salt.

2. The process for the preparation of selenium enriched edible salt as claimed in claim 1 wherein: The coating material in step (1) and step (2) is a mixed coating liquid composed of oat bran extract and food-grade collagen peptide.

3. The process for the preparation of selenium enriched edible salt as claimed in claim 2, wherein: The preparation method of the oat bran extract is as follows: (1) spraying purified water into oat bran uniformly, and using a double-screw extrusion puffing machine to obtain oat bran puffing particles; (2) crushing the oat bran puffing particles to 20 mesh or less, adding purified water, stirring, heating, leaching and centrifuging to obtain oat bran extract and oat bran precipitate.

4. The process for the preparation of selenium enriched edible salt as claimed in claim 3, wherein: The iodine-containing substances and selenium-containing substances in step (1) and step (2) are first adsorbed by an adsorption carrier, and then coated with coating materials.

5. The process for the preparation of selenium enriched edible salt as claimed in claim 4, wherein: The preparation method of the adsorption carrier is as follows: (1) rinsing the oat bran precipitate with purified water and drying it to a water content of ≤5%, and crushing it to 60 mesh to obtain oat bran leaching powder; (2) bamboo shoot powder preparation: ① drying fresh bamboo shoots after removing impurities and cutting them into segments to a bamboo shoot water content of ≤5%, and airflow crushing them through a 30-mesh sieve to obtain porous bamboo shoot powder; ② adjusting the pH of a composite enzyme solution prepared by stirring cellulase and hemicellulase in purified water to 4.8; ③ adding the composite enzyme solution to the porous bamboo shoot powder and stirring for 2-3 hours at 45-50°C for enzymatic hydrolysis, inactivating the enzyme after the enzymatic hydrolysis is completed, and filtering; ④ removing protein from the enzymatically hydrolyzed bamboo shoot powder by first using alkaline protease and then papain, filtering and rinsing to neutral, and drying and crushing to 60 mesh to obtain porous deproteinized bamboo shoot powder; and ⑤ mixing the oat bran leaching powder and the porous deproteinized bamboo shoot powder uniformly to obtain the adsorption carrier; the mass ratio of the porous deproteinized bamboo shoot powder to the oat bran leaching powder is 1:0.5-5.

6. The process for the preparation of selenium enriched edible salt as claimed in claim 5 wherein: Preparation of selenium-rich coated particles: ① adding food-grade selenium-rich raw materials to purified water and stirring to obtain a selenium-rich nutrient solution; ② spraying the selenium-rich nutrient solution onto the heated adsorption carrier, then coating with coating materials, and drying to remove dust to obtain selenium-rich coated particles with a particle size of 160-830 μm, a selenium content of 5.0-8.0 mg / kg, and a water content of ≤4.0%.

7. The process for the preparation of selenium enriched edible salt as claimed in claim 5 wherein: Preparation of iodine-containing coated particles: ① preparing a potassium iodate solution and removing impurities with a microporous filter membrane; ② spraying the potassium iodate solution onto the heated adsorption carrier, then coating with coating materials, and drying to remove dust to obtain iodine-containing coated particles with a particle size of 160-830 μm, an iodine content of 4.0-6.3 g / kg, and a water content of ≤4.0%.

8. The process for the preparation of selenium enriched edible salt as claimed in claim 5 wherein: The mass ratio of the porous deproteinized bamboo shoot powder to the oat bran leaching powder is 1:

1.

9. The selenium-rich edible salt prepared by the method of any one of claims 6, 7 or 8.

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