Green preparation process of high-purity fish oil powder

Abstract

The invention relates to the technical field of fish oil powder processing, and particularly discloses a green preparation process of high-purity fish oil powder, which comprises the following steps: taking a fish oil raw material, removing impurities at a low temperature of less than or equal to 15 DEG C, removing impurities and water, and carrying out molecular distillation at 120-150 DEG C and 1-5Pa to obtain high-purity fish oil with the purity of more than or equal to 90%. Then, preparing the raw materials according to specific parts by weight, premixing the high-purity fish oil with ascorbyl palmitate and lecithin, stirring for 30 minutes at the speed of 40-60 r / min under the protection of inert gas, and mixing with the modified starch and maltodextrin; the preparation method comprises the following steps: by taking deionized water as a solvent, emulsifying a mixture for 15-20 minutes by using a high-shear homogenizer under 20-30MPa to obtain an emulsion, preparing the emulsion into 20-50mu m fish oil powder particles by using a high-pressure spray dryer under specific air inlet and outlet temperature and atomization pressure, performing supercritical carbon dioxide extraction and secondary purification, and finally packaging by using an aluminum foil bag in a high-purity nitrogen environment. The whole process is green and environment-friendly, and the prepared fish oil powder is high in purity, uniform in particle size and high in stability.

Description

Technical Field

[0001] The present invention relates to the technical field of fish oil powder processing, and specifically to a green preparation process for high-purity fish oil powder. Background Art

[0002] With the improvement of people's living standards, pets are playing an increasingly important role in modern families. More and more people regard pets as family members and their attention to the health and nutrition of pets continues to rise. Fish oil is rich in polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These nutrients play an indispensable role in many aspects of the growth and development of pets, strengthening the immune system function, maintaining cardiovascular health, and improving the health of hair and skin.

[0003] In the field of pet food, traditional forms of fish oil addition often have many drawbacks. On the one hand, liquid fish oil faces stability problems during storage and use. It is easily oxidized to produce odors, which not only reduces the palatability of pet food but may also cause pets to refuse to eat. Moreover, the addition of liquid fish oil will change the original texture of pet food, affecting the shaping and mixing uniformity during food processing, bringing inconvenience to the production process.

[0004] To solve these problems, fish oil powder came into being. However, the quality of fish oil powder products on the current market varies. Some fish oil powder preparation processes are crude. In the raw material treatment stage, impurities, moisture, and harmful oxidation products in the fish oil raw materials cannot be effectively removed, resulting in a low purity of the final product. It not only fails to fully exert the nutritional effects of fish oil but may also introduce harmful substances that endanger the health of pets. For example, some crude fish oil powders contain excessive heavy metal impurities. Long-term feeding of pet food containing such fish oil powder will cause heavy metal accumulation in pets' bodies, damaging important organs such as the liver and kidneys.

[0005] In subsequent processing, if process parameters such as emulsification and drying are not properly controlled, the particle size distribution of the prepared fish oil powder is uneven, and agglomeration and caking are likely to occur. This not only affects the product appearance but also leads to poor dispersibility in pet food, resulting in uneven distribution of nutrients. Pets cannot obtain balanced nutrition after eating. In addition, fish oil is extremely easy to oxidize. If effective antioxidant protection measures, precise impurity removal, and deodorization processes are lacking during the preparation process, the prepared fish oil powder is prone to rancid odors, greatly shortening the product shelf life and at the same time reducing the pet's willingness to eat.

[0006] Traditional preparation processes also have deficiencies in environmental protection. Some processes involve the use of a large amount of organic solvents, which volatilize during production, polluting the environment and increasing production safety risks. Moreover, the residual organic solvents in fish oil powder products may also pose potential hazards to pets.

[0007] In view of the above-mentioned defects existing in the existing preparation process of fish oil powder, there is an urgent need for a process that can greenly and efficiently prepare high-purity fish oil powder to meet the growing market demand for high-quality pet food. The present invention aims to provide a brand-new green preparation process for high-purity fish oil powder, which comprehensively guarantees the high purity, high stability, good dispersibility and environmental friendliness of fish oil powder from the fine treatment of raw materials to the precise control of process parameters in each link and then to the environmental protection packaging, providing a high-quality nutritional source for the healthy growth of pets. Summary of the Invention

[0008] (I) Technical problems to be solved In view of the deficiencies of the prior art, the present invention provides a green preparation process for high-purity fish oil powder, which solves the problems raised in the above-mentioned background art.

[0009] (II) Technical solutions In order to achieve the above object, the present invention discloses a green preparation process for high-purity fish oil powder, which comprises the following steps: Step 1: Take fish oil raw materials for low-temperature impurity removal treatment, control the treatment temperature ≤ 15°C, remove impurities and moisture in the raw materials to obtain pure fish oil; then perform molecular distillation on the pure fish oil, control the distillation temperature at 120 - 150°C and the pressure at 1 - 5 Pa to obtain high-purity fish oil with a purity ≥ 90%.

[0010] Step 2: Prepare raw materials according to the following weight parts: 50 - 60 parts of high-purity fish oil, 20 - 30 parts of modified starch, 10 - 15 parts of maltodextrin, 1 - 3 parts of ascorbyl palmitate, 0.5 - 2 parts of lecithin; premix the high-purity fish oil with ascorbyl palmitate and lecithin and then add modified starch and maltodextrin, and stir for 30 minutes under the protection of inert gas, with the stirring speed of 40 - 60 r / min.

[0011] Step 3: Add the mixture to an emulsifying tank, use deionized water as the solvent, and the solvent dosage is 2 - 3 times the total weight of the mixture, and perform emulsification with a high-shear homogenizer, control the homogenization pressure at 20 - 30 MPa and the homogenization time at 15 - 20 minutes to obtain a uniform emulsion.

[0012] Step 4: Dry the emulsion through a high-pressure spray dryer, set the inlet air temperature at 160 - 180°C, the outlet air temperature at 80 - 90°C, and the atomization pressure at 1 - 2 MPa to obtain fish oil powder particles with a particle size range of 20 - 50 μm.

[0013] Step Five: Subject the fish oil powder particles to secondary purification using a supercritical carbon dioxide extraction device, controlling the extraction temperature at 35 - 45°C, the pressure at 20 - 30 MPa, and the extraction time at 2 - 3 hours to further remove impurities and odors.

[0014] Step Six: Package using aluminum foil bags. The packaging process is carried out in a nitrogen environment, controlling the nitrogen purity ≥ 99.9%, and sealing after packaging.

[0015] Preferably, in Step One, the low-temperature impurity removal treatment uses a low-temperature filtration device with a filtration pore size of 1 - 5 μm and a treatment time of 10 - 15 minutes.

[0016] Preferably, the inert gas in Step Two is nitrogen or helium with a gas purity ≥ 99.99%. Continuously introduce the gas during the mixing process and maintain the air pressure at 0.1 - 0.3 MPa.

[0017] Preferably, in Step Three, the rotor speed of the high-shear homogenizer is 3000 - 5000 r / min, and the stator gap is controlled at 0.1 - 0.5 mm.

[0018] Preferably, in Step Four, the nozzle aperture of the high-pressure spray dryer is 0.5 - 1.0 mm, and the number of nozzles is 3 - 5.

[0019] Preferably, in Step Five, the carbon dioxide flow rate of the supercritical carbon dioxide extraction device is 10 - 20 L / h, and the volume of the extraction kettle is 5 - 10 L.

[0020] Preferably, in Step Six, the thickness of the aluminum foil bag is 0.05 - 0.1 mm, the heat-sealing temperature is 120 - 150°C, and the heat-sealing time is 2 - 5 seconds.

[0021] Preferably, the present invention further includes a high-purity fish oil powder prepared by the above method, and its composition includes 50 - 60 parts of high-purity fish oil, 20 - 30 parts of modified starch, 10 - 15 parts of maltodextrin, 1 - 3 parts of ascorbyl palmitate, and 0.5 - 2 parts of lecithin; the particle size range of the fish oil powder is 20 - 50 μm, the moisture content ≤ 3%, and the purity ≥ 95%.

[0022] (III) Beneficial Technical Effects In the raw material processing stage, the method of low-temperature impurity removal combined with molecular distillation is adopted, demonstrating excellent purification ability. For the low-temperature impurity removal treatment, the treatment temperature is precisely controlled at ≤15°C, and with the help of a low-temperature filtration device with a pore size of 1 - 5μm, impurities and moisture in the raw materials can be efficiently removed within 10 - 15 minutes. It can not only effectively intercept mechanical impurities such as sediment and metal particles, but also significantly reduce the moisture content, creating ideal conditions for the subsequent molecular distillation. In the molecular distillation stage, within the distillation temperature range of 120 - 150°C and a low-pressure environment of 1 - 5Pa, the light and heavy molecular components in fish oil are precisely separated, resulting in a high-purity fish oil with a purity of ≥90%. Such delicate raw material pretreatment ensures product quality from the source, avoiding potential pet health hazards caused by residual impurities. Problems such as cumulative poisoning in pets caused by heavy metal impurities are effectively eliminated, and at the same time, it also lays a solid foundation for the smooth progress of subsequent processing steps.

[0023] Secondly, the unique raw material formula and mixing process ensure the stability and nutritional balance of the product. Prepare raw materials according to specific weight parts. Among them, 50 - 60 parts of high-purity fish oil are used as the core nutritional component, combined with 20 - 30 parts of modified starch and 10 - 15 parts of maltodextrin, which can not only optimize the product forming effect in subsequent processing but also play a good carrier role to ensure the uniform dispersion of fish oil. The addition of 1 - 3 parts of ascorbyl palmitate and 0.5 - 2 parts of lecithin is a more ingenious move. Ascorbyl palmitate, as an efficient antioxidant, can strongly inhibit the oxidation process of fish oil during the entire preparation process and subsequent product storage, prevent the generation of rancid odors, and greatly extend the product shelf life; lecithin has both emulsifying and antioxidant properties, further enhancing the dispersibility and stability of fish oil. Under the protection of an inert gas (nitrogen or helium, purity ≥99.99%), stir continuously at a speed of 40 - 60r / min for 30 minutes and maintain a pressure of 0.1 - 0.3MPa to create an oxygen-free and mild mixing environment, minimizing the oxidation risk to the greatest extent and ensuring the full and uniform fusion of each raw material, so that each fish oil powder product contains precisely proportioned nutritional components, providing stable and balanced nutritional supplements for pets.

[0024] The precise parameter setting of the emulsification and drying process brings about the ideal product form and quality. The mixture is added to the emulsification tank, deionized water is used as the solvent (the amount of solvent is 2-3 times the total weight of the mixture), and a high shear homogenizer (rotor speed 3000-5000r / min, stator gap 0.1-0.5mm) is used for emulsification at a homogenization pressure of 20-30MPa for 15-20 minutes, which can fully refine and disperse the raw materials to form a uniform and delicate emulsion. This emulsion state ensures the uniform formation of fish oil powder particles in the subsequent drying process. Through a high-pressure spray dryer (nozzle aperture 0.5-1.0mm, number of nozzles 3-5), the inlet temperature is set to 160-180℃, the outlet temperature is set to 80-90℃, and the atomization pressure is set to 1-2MPa, and finally the fish oil powder particles with a particle size range of 20-50μm are obtained. The advantages of this particle size range are significant. On the one hand, during the processing of pet food, the fish oil powder particles can be evenly dispersed to avoid agglomeration and caking, ensuring that the texture of the pet food is uniform and the nutrients in each bite of food are consistently distributed. On the other hand, the appropriate particle size is conducive to pet digestion and absorption, improving the bioavailability of fish oil nutrients, allowing pets to more efficiently absorb key nutrients such as EPA and DHA, promoting their growth and development, strengthening their immune system, and improving their hair and skin health.

[0025] Supercritical carbon dioxide extraction equipment is used for secondary purification. At an extraction temperature of 35-45°C and a pressure of 20-30MPa, the carbon dioxide flow rate is 10-20L / h, and the extraction is continued for 2-3 hours to further deeply remove impurities and odors. This process uses the special properties of supercritical carbon dioxide to accurately and selectively extract residual impurities, odorous substances, and possible trace harmful substances in fish oil powder, such as pesticide residues and polycyclic aromatic hydrocarbons, under mild conditions close to room temperature and low pressure, without damaging the nutritional components of fish oil. After secondary purification, the purity of fish oil powder is further improved, the odor is completely eliminated, and the product quality reaches a higher level, providing a purer and healthier source of nutrition for pets.

[0026] During the packaging process, it is packaged in an aluminum foil bag and carried out in a nitrogen environment (nitrogen purity ≥ 99.9%). The thickness of the aluminum foil bag is 0.05 - 0.1mm, the heat sealing temperature is 120 - 150°C, and the heat sealing time is 2 - 5 seconds, ensuring the stability of the product during storage and transportation. The aluminum foil bag has excellent barrier properties, can effectively block the intrusion of oxygen, water vapor and light, prevent the oxidation, moisture absorption and photo-degradation of fish oil powder. Combined with the oxygen-free space created by the nitrogen environment, it maximally extends the shelf life of the product and maintains the freshness and quality of the product. From production to the consumption terminal, the high-quality delivery of fish oil powder is guaranteed throughout the process, enabling pet owners to purchase with confidence and store for a long time pet food containing the fish oil powder of the present invention. Detailed implementation mode

[0027] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below. The preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0028] Example 1: Raw material preparation: Select high-quality fish oil raw materials. After testing, the initial purity of the raw materials is 70%, the moisture content is 8%, and the impurity content is 5%.

[0029] Prepare 20 parts of modified starch, 10 parts of maltodextrin, 1 part of ascorbyl palmitate, and 0.5 part of lecithin.

[0030] Low-temperature impurity removal and molecular distillation: Place the fish oil raw materials in a low-temperature filtration device, control the processing temperature at 10°C, the filtration pore size at 1μm, and the processing time at 10 minutes to effectively remove impurities and part of the moisture in the raw materials, and obtain pure fish oil. After testing, the moisture content drops to 3% and the impurity content is 1% at this time.

[0031] Carry out molecular distillation on the pure fish oil, set the distillation temperature at 120°C and the pressure at 1Pa. After distillation, high-purity fish oil is obtained, and its purity is detected to reach 90%.

[0032] Premixing and stirring: Premix 50 parts of high-purity fish oil with 1 part of ascorbyl palmitate and 0.5 part of lecithin, and then add 20 parts of modified starch and 10 parts of maltodextrin. Under nitrogen protection (nitrogen purity 99.99%), stir at a stirring speed of 40r / min for 30 minutes, continuously introduce nitrogen during the stirring process and maintain the air pressure at 0.1MPa.

[0033] Emulsification: Add the mixture into an emulsifying tank, using deionized water as the solvent, and the solvent dosage is 2 times the total weight of the mixture. Emulsify using a high-shear homogenizer with the rotor speed of the homogenizer at 3000 r / min, the stator gap controlled at 0.1 mm, the homogenization pressure controlled at 20 MPa, and the homogenization time of 15 minutes to obtain a uniform emulsion.

[0034] Drying: Dry the emulsion through a high-pressure spray dryer. The nozzle aperture of the high-pressure spray dryer is 0.5 mm, the number of nozzles is 3, the inlet air temperature is set at 160 °C, the outlet air temperature is 80 °C, and the atomization pressure is 1 MPa to obtain fish oil powder particles with a particle size range of 20 - 30 μm. After detection, the moisture content of the fish oil powder particles is 2.5% at this time.

[0035] Secondary purification: Purify the fish oil powder particles through a supercritical carbon dioxide extraction device for secondary purification, control the extraction temperature at 35 °C, the pressure at 20 MPa, the carbon dioxide flow rate at 10 L / h, the extraction kettle volume at 5 L, and the extraction time at 2 hours to further remove impurities and odors.

[0036] Packaging: Use an aluminum foil bag with a thickness of 0.05 mm for packaging. The packaging process is carried out in a nitrogen environment (nitrogen purity ≥ 99.9%), the heat-sealing temperature is 120 °C, the heat-sealing time is 2 seconds, and it is sealed after packaging.

[0037] The finally prepared fish oil powder is detected, and its composition includes 50 parts of high-purity fish oil, 20 parts of modified starch, 10 parts of maltodextrin, 1 part of ascorbyl palmitate, and 0.5 part of lecithin; the particle size range of the fish oil powder is 20 - 30 μm, the moisture content is 2%, and the purity is 95%.

[0038] Analysis: As can be seen from the data in Example 1, by strictly operating according to the process steps of the present invention and the effective cooperation of each link, the final fish oil powder product reaches an ideal state in key indicators such as purity, moisture content, and particle size, meeting the requirements of high-quality fish oil powder. For example, accurately controlling the temperature, aperture, and time in the low-temperature impurity removal link significantly reduces the raw material impurities and moisture, laying a foundation for improving the purity by molecular distillation in the subsequent step; the parameters in the emulsification and drying links are adapted to ensure the uniformity and appropriate particle size of the particles, the secondary purification further optimizes the product quality, and the packaging link ensures the storage stability of the product.

[0039] Example 2: Raw material preparation: Select fish oil raw materials with an initial purity of 75%, a moisture content of 7%, and an impurity content of 4%.

[0040] Prepare 25 parts of modified starch, 13 parts of maltodextrin, 2 parts of ascorbyl palmitate, and 1.5 parts of lecithin.

[0041] Low-temperature impurity removal and molecular distillation: Using a low-temperature filtration device, control the treatment temperature at 13°C, the filtration pore size at 3 μm, the treatment time at 13 minutes, the moisture content after impurity removal at 2.5%, and the impurity content at 0.8%.

[0042] Perform molecular distillation on pure fish oil at a distillation temperature of 135°C and a pressure of 3 Pa to obtain high-purity fish oil with a purity of 92%.

[0043] Premixing and stirring: Take 55 parts of high-purity fish oil and premix it with 2 parts of ascorbyl palmitate and 1.5 parts of lecithin. Add 25 parts of modified starch and 13 parts of maltodextrin, and stir at 50 r / min for 30 minutes under the protection of helium (purity 99.99%). Continuously introduce helium and maintain the air pressure at 0.2 MPa.

[0044] Emulsification: Add deionized water to the mixture (the solvent dosage is 2.5 times the total weight of the mixture), and emulsify it with a high-shear homogenizer at a rotor speed of 4000 r / min, a stator gap of 0.3 mm, a homogenization pressure of 25 MPa, and a homogenization time of 18 minutes to obtain an emulsion.

[0045] Drying: Dry the emulsion with a high-pressure spray dryer at a nozzle aperture of 0.8 mm, 4 nozzles, an inlet air temperature of 170°C, an outlet air temperature of 85°C, and an atomization pressure of 1.5 MPa to obtain fish oil powder particles with a particle size of 30 - 40 μm and a moisture content of 2.2%.

[0046] Secondary purification: Perform supercritical carbon dioxide extraction on the fish oil powder particles at an extraction temperature of 40°C, a pressure of 25 MPa, a carbon dioxide flow rate of 15 L / h, an extraction kettle volume of 8 L, and an extraction time of 2.5 hours.

[0047] Packaging: Pack it with a 0.08-mm aluminum foil bag in a nitrogen environment (purity ≥ 99.9%), with a heat-sealing temperature of 135°C and a heat-sealing time of 3.5 seconds for sealing.

[0048] Final fish oil powder: 55 parts of high-purity fish oil, 25 parts of modified starch, 13 parts of maltodextrin, 2 parts of ascorbyl palmitate, 1.5 parts of lecithin; particle size 30 - 40 μm, moisture content 1.8%, purity 96%.

[0049] Analysis: In Example 2, the proportions of some raw materials and process parameters were adjusted. The results showed that the product purity was further increased to 96%, the moisture content was even lower at 1.8%, and the particle size was evenly distributed between 30 - 40 μm. This indicates that reasonable optimization of process parameters, such as appropriately increasing the molecular distillation temperature and adjusting the emulsification and homogenization parameters, can improve the purity and reduce the moisture content while ensuring the product stability (appropriate particle size), making the comprehensive quality of the product better, and verifying the scientificity and flexibility of the process again.

[0050] Example 3: Raw material preparation: Select fish oil raw materials with an initial purity of 80%, a moisture content of 6%, and an impurity content of 3%.

[0051] Prepare 30 parts of modified starch, 15 parts of maltodextrin, 3 parts of ascorbyl palmitate, and 2 parts of lecithin.

[0052] Low-temperature impurity removal and molecular distillation: The low-temperature filtration equipment is controlled at 15°C with a pore size of 5 μm and processed for 15 minutes. After impurity removal, the moisture content is 2% and the impurity content is 0.6%.

[0053] The molecular distillation temperature is 150°C and the pressure is 5 Pa to obtain high-purity fish oil with a purity of 94%.

[0054] Premixing and stirring: 60 parts of high-purity fish oil are premixed with 3 parts of ascorbyl palmitate and 2 parts of lecithin, then 30 parts of modified starch and 15 parts of maltodextrin are added. Under nitrogen protection (purity 99.99%), stir at 60 r / min for 30 minutes with a gas pressure of 0.3 MPa.

[0055] Emulsification: The mixed material is added with deionized water (3 times the weight) and emulsified by a high-shear homogenizer with a rotor speed of 5000 r / min, a gap of 0.5 mm, a homogenization pressure of 30 MPa, and a time of 20 minutes to obtain an emulsion.

[0056] Drying: The emulsion is passed through a high-pressure spray dryer with a nozzle aperture of 1.0 mm, 5 nozzles, an inlet air temperature of 180°C, an outlet air temperature of 90°C, and an atomization pressure of 2 MPa to obtain fish oil powder particles with a particle size of 40 - 50 μm and a moisture content of 1.5%.

[0057] Secondary purification: Supercritical carbon dioxide extraction is carried out at 35 - 45°C, 20 - 30 MPa, a flow rate of 20 L / h, in a 10 L autoclave for 2 - 3 hours. In this example, the conditions are 45°C, 30 MPa, 20 L / h, a 10 L autoclave, and 3 hours.

[0058] Packaging: 0.1mm aluminum foil bag, nitrogen gas (≥99.9%), heat-sealed at 150°C for 5 seconds, sealed.

[0059] Final product: 60 parts of high-purity fish oil, 30 parts of modified starch, 15 parts of maltodextrin, 3 parts of ascorbyl palmitate, 2 parts of lecithin; particle size 40 - 50μm, moisture content 1%, purity 97%.

[0060] Analysis: In Example 3, raw materials with higher initial purity were used and each link was adjusted to the upper limit parameters. The purity of the produced fish oil powder was as high as 97%, the moisture content was only 1%, and the particle size was adapted to the upper limit range of industrial applications. It shows that high-quality raw materials combined with precise process control can maximize the potential of the process and prepare top-quality fish oil powder with ultra-high purity, low moisture content, and appropriate particle size, providing a high-quality product example for high-end application scenarios.

[0061] Comparative Example 1 (lacking the low-temperature impurity removal step) Raw material preparation: Select fish oil raw materials with the same initial purity (70%), moisture content (8%), and impurity content (5%) as in Example 1.

[0062] Prepare 20 parts of modified starch, 10 parts of maltodextrin, 1 part of ascorbyl palmitate, and 0.5 part of lecithin.

[0063] Molecular distillation: Directly perform molecular distillation on the fish oil raw material at a distillation temperature of 120°C and a pressure of 1Pa. Due to the raw material not being impurity-removed, local overheating and coking occurred during the distillation process, resulting in a decrease in distillation efficiency. The purity of the finally obtained "high-purity fish oil" was only 80%, and its color was relatively deep with an obvious strange smell.

[0064] Premixing and stirring: Premix 50 parts of this "high-purity fish oil" with 1 part of ascorbyl palmitate and 0.5 part of lecithin, then add 20 parts of modified starch and 10 parts of maltodextrin, and stir at a stirring speed of 40r / min for 30 minutes under nitrogen protection (nitrogen purity 99.99%). Continuously introduce nitrogen during the stirring process and maintain the air pressure at 0.1MPa.

[0065] Emulsification: Add the mixture into an emulsifying tank, using deionized water as the solvent, and the solvent dosage is 2 times the total weight of the mixture. Emulsification is carried out using a high-shear homogenizer. The rotor speed of the homogenizer is 3000 r / min, the stator gap is controlled at 0.1 mm, the homogenization pressure is controlled at 20 MPa, and the homogenization time is 15 minutes to obtain an emulsion. However, the stability of the emulsion is poor and there is a layering phenomenon.

[0066] Drying: Dry the emulsion through a high-pressure spray dryer. The nozzle aperture of the high-pressure spray dryer is 0.5 mm, the number of nozzles is 3, the inlet air temperature is set at 160 °C, the outlet air temperature is 80 °C, and the atomization pressure is 1 MPa. The obtained fish oil powder particles have uneven particle sizes, ranging from 10 - 60 μm, and some particles are sticky.

[0067] Secondary purification: Purify the fish oil powder particles through a supercritical carbon dioxide extraction device for the second time. Control the extraction temperature at 35 °C, the pressure at 20 MPa, the carbon dioxide flow rate at 10 L / h, the volume of the extraction kettle at 5 L, and the extraction time at 2 hours. Although the peculiar smell is improved to a certain extent, the impurities are not completely removed.

[0068] Packaging: Use an aluminum foil bag with a thickness of 0.05 mm for packaging. The packaging process is carried out in a nitrogen environment (nitrogen purity ≥ 99.9%), the heat sealing temperature is 120 °C, the heat sealing time is 2 seconds, and it is sealed after packaging.

[0069] The finally prepared fish oil powder is detected, and its composition includes 50 parts of high-purity fish oil, 20 parts of modified starch, 10 parts of maltodextrin, 1 part of ascorbyl palmitate, and 0.5 part of lecithin; the particle size of the fish oil powder is uneven, the moisture content is 4%, the purity is 82%, the product has a peculiar smell, and the stability is poor.

[0070] Analysis: Comparing Example 1 with Comparative Example 1, the lack of a low-temperature impurity removal step results in impurities and excessive moisture in the raw materials entering the subsequent processes, causing a series of problems. During molecular distillation, impurities cause local overheating and coking, reducing the purity and quality of fish oil; in the emulsification process, impurities affect the stability of the emulsion; after drying, the particles are uneven and sticky, and the final product has low purity, high moisture, residual peculiar smell, and poor stability, fully highlighting the key preposition of low-temperature impurity removal in this process and laying a foundation for ensuring product quality.

[0071] Comparative Example 2 (without secondary purification) Raw material preparation: Select fish oil raw materials with the same initial purity (75%), moisture content (7%), and impurity content (4%) as in Example 2.

[0072] Prepare 25 parts of modified starch, 13 parts of maltodextrin, 2 parts of ascorbyl palmitate, and 1.5 parts of lecithin.

[0073] Low-temperature impurity removal and molecular distillation: Using a low-temperature filtration device, control the treatment temperature at 13°C, the filtration pore size at 3 μm, the treatment time at 13 minutes. After impurity removal, the moisture content is 2.5% and the impurity content is 0.8%.

[0074] Perform molecular distillation on pure fish oil at a distillation temperature of 135°C and a pressure of 3 Pa to obtain high-purity fish oil with a purity of 92%.

[0075] Premixing and stirring: Take 55 parts of high-purity fish oil and premix it with 2 parts of ascorbyl palmitate and 1.5 parts of lecithin. Add 25 parts of modified starch and 13 parts of maltodextrin, and stir at 50 r / min for 30 minutes under the protection of helium (purity 99.99%). Continuously introduce helium and maintain the air pressure at 0.2 MPa.

[0076] Emulsification: Add deionized water to the mixture (the solvent dosage is 2.5 times the total weight of the mixture), and emulsify it with a high-shear homogenizer. The rotor speed is 4000 r / min, the stator gap is 0.3 mm, the homogenization pressure is 25 MPa, and the homogenization time is 18 minutes to obtain an emulsion.

[0077] Drying: Dry the emulsion with a high-pressure spray dryer. The nozzle aperture is 0.8 mm, the number of nozzles is 4, the inlet air temperature is 170°C, the outlet air temperature is 85°C, and the atomization pressure is 1.5 MPa to obtain fish oil powder particles with a particle size of 30 - 40 μm and a moisture content of 2.2%.

[0078] Packaging: Pack it with a 0.08 mm aluminum foil bag in a nitrogen environment (purity ≥ 99.9%). The heat-sealing temperature is 135°C and the heat-sealing time is 3.5 seconds for sealing.

[0079] Final fish oil powder: 55 parts of high-purity fish oil, 25 parts of modified starch, 13 parts of maltodextrin, 2 parts of ascorbyl palmitate, 1.5 parts of lecithin; particle size 30 - 40 μm, moisture content 2.2%, purity 92%, and the product has a slight fishy smell.

[0080] Analysis: Compared with Example 2, Comparative Example 2 omitted the secondary purification step. Although the previous process ensured a certain product quality (appropriate particle size, low moisture), the purity of the final product was maintained at 92% after molecular distillation, and there was a slight fishy smell because the volatile odor substances were not deeply removed. This shows that secondary purification is crucial to improving the purity of fish oil powder and eliminating odor, and is a key link in achieving high-quality products, meeting the market demand for purity and flavor.

[0081] Comparative Example 3 (Changing emulsification and drying parameters) Raw materials preparation: A fish oil raw material having the same initial purity (80%), moisture content (6%), and impurity content (3%) as in Example 3 was selected.

[0082] Prepare 30 parts of modified starch, 15 parts of maltodextrin, 3 parts of ascorbyl palmitate, and 2 parts of lecithin.

[0083] Low temperature impurity removal and molecular distillation: The low-temperature filtration equipment has a temperature control of 15°C, a pore size of 5μm, and a treatment time of 15 minutes. After impurities are removed, the moisture content is 2% and the impurities are 0.6%.

[0084] The molecular distillation temperature is 150℃ and the pressure is 5Pa to obtain high-purity fish oil with a purity of 94%.

[0085] Premixing and stirring: 60 parts of high-purity fish oil were premixed with 3 parts of ascorbyl palmitate and 2 parts of lecithin, and 30 parts of modified starch and 15 parts of maltodextrin were added. The mixture was protected by nitrogen (purity 99.99%) and stirred at 60r / min for 30 minutes at an air pressure of 0.3MPa.

[0086] emulsification: Deionized water was added to the mixture (the amount of solvent was 3 times the total weight of the mixture) and emulsified using a high shear homogenizer. However, the rotor speed was changed to 2000r / min, the stator gap was increased to 1mm, the homogenization pressure was controlled at 15MPa, and the homogenization time was 10 minutes to obtain an emulsion. At this time, the emulsion was obviously stratified and had extremely poor stability.

[0087] dry: The emulsion was dried by a high-pressure spray dryer. The nozzle aperture was adjusted to 1.5 mm, the number of nozzles remained at 5, the inlet air temperature was set to 140 °C, the outlet air temperature was set to 70 °C, and the atomization pressure was set to 0.5 MPa. The particle sizes of the obtained fish oil powder particles varied greatly, ranging from 5 to 100 μm. The particle surface was rough and the shape was irregular, and a large amount of powder adhered to the inner wall of the dryer.

[0088] Secondary purification: Supercritical carbon dioxide extraction was carried out with the extraction temperature controlled at 45°C, the pressure at 30 MPa, the carbon dioxide flow rate at 20 L / h, the extraction kettle volume at 10 L, and the extraction time at 3 hours.

[0089] Packaging: Use a 0.1 mm aluminum foil bag, heat-seal it at 150°C for 5 seconds in a nitrogen (≥99.9%) environment, and seal it.

[0090] The finally obtained fish oil powder was tested, and its composition included 60 parts of high-purity fish oil, 30 parts of modified starch, 15 parts of maltodextrin, 3 parts of ascorbyl palmitate, and 2 parts of lecithin; the particle size of the fish oil powder was extremely uneven, the moisture content was as high as 6%, the purity was 88%, the appearance of the product was rough, and the quality was poor.

[0091] Analysis: Comparing Example 3 with Comparative Example 3, the change of key parameters in the emulsification and drying links brought disastrous consequences. Too low rotor speed, too large stator gap, and mismatched homogenization pressure and time during emulsification made the emulsion unable to be evenly dispersed and stably formed. Furthermore, in the drying stage, inappropriate nozzle aperture, inlet and outlet air temperatures, and atomization pressure caused the formation of fish oil powder particles to get out of control, with uneven particle size, rough surface, serious adhesion, ineffective moisture removal, and the purity was reduced due to poor particle formation and impurity encapsulation, intuitively showing the rigorous scientific nature of the process parameters of the present invention. Precise cooperation in each link is required to ensure the production of high-quality fish oil powder.

[0092] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present invention. All equivalent changes and improvements made within the scope of the application of the present invention shall still fall within the scope covered by the patent of the present invention.

Claims

1. A green preparation process for high-purity fish oil powder, characterized in that: The steps include: Step 1: Take the fish oil raw material and perform low-temperature impurity removal treatment, control the treatment temperature ≤15°C, remove impurities and moisture in the raw material, and obtain pure fish oil; then perform molecular distillation on the purified fish oil, control the distillation temperature at 120-150°C and the pressure at 1-5Pa, and obtain high-purity fish oil with a purity of ≥90%; Step 2, prepare the following raw materials by weight: 50-60 parts of high-purity fish oil, 20-30 parts of modified starch, 10-15 parts of maltodextrin, 1-3 parts of ascorbyl palmitate, and 0.5-2 parts of lecithin; premix the high-purity fish oil with ascorbyl palmitate and lecithin, then add the modified starch and maltodextrin, and stir for 30 minutes under the protection of inert gas at a stirring speed of 40-60r / min; Step 3: Add the mixture into an emulsification tank, use deionized water as solvent, the amount of solvent is 2-3 times the total weight of the mixture, use a high shear homogenizer for emulsification, control the homogenization pressure at 20-30MPa, and the homogenization time is 15-20 minutes to obtain a uniform emulsion; Step 4: drying the emulsion through a high-pressure spray dryer, setting the air inlet temperature to 160-180°C, the air outlet temperature to 80-90°C, and the atomization pressure to 1-2MPa, to obtain fish oil powder particles with a particle size range of 20-50μm; Step 5: The fish oil powder particles are subjected to secondary purification by supercritical carbon dioxide extraction equipment, with the extraction temperature controlled at 35-45°C, the pressure at 20-30MPa, and the extraction time at 2-3 hours to further remove impurities and odors; Step 6: Use aluminum foil bags for packaging. The packaging process is carried out in a nitrogen environment, and the nitrogen purity is controlled to be ≥99.9%. The product is sealed after packaging.

2. The green preparation process of a high-purity fish oil powder according to claim 1, characterized in that: In the step 1, the low-temperature impurity removal treatment uses a low-temperature filtration device with a filtration pore size of 1-5 μm and a treatment time of 10-15 minutes.

3. The green preparation process of a high-purity fish oil powder according to claim 1, characterized in that: The inert gas in step 2 is nitrogen or helium, and the gas purity is ≥ 99.99%. During the mixing process, the gas is continuously introduced and the gas pressure is maintained at 0.1-0.3 MPa.

4. The green preparation process of a high-purity fish oil powder according to claim 1, characterized in that: In step 3, the rotor speed of the high shear homogenizer is 3000-5000r / min, and the stator gap is controlled at 0.1-0.5mm.

5. The green preparation process of a high-purity fish oil powder according to claim 1, characterized in that: In the step 4, the nozzle aperture of the high pressure spray dryer is 0.5-1.0 mm, and the number of nozzles is 3-5.

6. The green preparation process of high-purity fish oil powder according to claim 1, characterized in that: In the step 5, the carbon dioxide flow rate of the supercritical carbon dioxide extraction equipment is 10-20L / h, and the volume of the extraction kettle is 5-10L.

7. The green preparation process of high-purity fish oil powder according to claim 1, characterized in that: In step 6, the thickness of the aluminum foil bag is 0.05-0.1 mm, the heat sealing temperature is 120-150° C., and the heat sealing time is 2-5 seconds.

8. A high-purity fish oil powder, characterized in that: Prepared by the method of any one of claims 1 to 7, the composition includes 50-60 parts of high-purity fish oil, 20-30 parts of modified starch, 10-15 parts of maltodextrin, 1-3 parts of ascorbyl palmitate, and 0.5-2 parts of lecithin; the particle size range of the fish oil powder is 20-50μm, the moisture content is ≤3%, and the purity is ≥95%.