A preparation method of lutein ester microcapsules

Abstract

The present application relates to the field of lutein ester processing, and in particular to a method for preparing lutein ester microcapsules. In order to solve the problems of active ingredient loss and poor stability of lutein ester microcapsules obtained by the prior art preparation method, the present application provides a method for preparing lutein ester microcapsules, by washing, drying, crushing and ultrasonically treating marigold pollen, and using supercritical carbon dioxide extraction technology combined with tributyl citrate entrainer to efficiently extract lutein esters. Subsequently, the extract is mixed with the wall material to form an emulsion, and microcapsules are made using a supercritical fluid rapid expansion method. Finally, sucrose is added and high vacuum drying is performed after gradual cooling and freezing. Compared with traditional methods, the present application enhances the mechanical strength and thermal stability of the microcapsules, while reducing the loss of active ingredients and improving the quality and shelf life of the product.

Description

Technical Field

[0001] The present application relates to the field of lutein ester processing, and in particular to a method for preparing lutein ester microcapsules. Background Art

[0002] In today's rapidly developing food technology field, the demand for functional foods and health products is growing. Lutein esters, as an important carotenoid, have attracted much attention due to their significant antioxidant properties and benefits to eye health. It can effectively filter blue light, reduce retinal damage, and prevent eye diseases such as macular degeneration and cataracts. In addition, lutein esters also have multiple biological functions such as anti-inflammatory and immunomodulatory, so they have broad application prospects in the field of functional foods and health products. At present, the extraction of lutein esters mainly adopts solvent extraction and supercritical carbon dioxide extraction. In order to improve the stability and bioavailability of lutein esters in food, microencapsulation technology is an effective solution. By encapsulating lutein esters in wall materials to form tiny particles, it can effectively protect them from the influence of external environments such as light and oxidation, while improving their solubility and absorption efficiency. Microencapsulated lutein esters can not only maintain high stability during food processing and storage, but also achieve controlled release in the human digestive tract, so as to better exert their health effects.

[0003] Commonly used wall materials for microcapsules, such as maltodextrin, gum arabic, and casein, have good film-forming properties and biocompatibility, but they perform poorly in terms of mechanical strength, thermal stability, and light stability. For example, although maltodextrin has good film-forming properties, its mechanical strength is low; although gum arabic has good biocompatibility, its thermal stability and light stability are poor. Therefore, it is often difficult to meet all requirements by using a single wall material.

[0004] In the actual production process of microencapsulation, maintaining high purity and low water content of the product is also an issue that cannot be ignored. The existing microencapsulation process is mainly spray drying. The spray drying method sprays the emulsion containing lutein esters into hot air through a nozzle to evaporate the water quickly to form microcapsules. This method has high production efficiency, but it is easy to cause the loss or denaturation of active ingredients, affecting the quality of the final product. Therefore, finding a more gentle and effective drying method to reduce the impact on active ingredients is also the key to improving product quality. Summary of the invention

[0005] In order to solve the problem of active ingredient loss and poor stability of lutein ester microcapsules obtained by the prior art preparation method, the present application provides a method for preparing lutein ester microcapsules, which ensures the purity and uniformity of the raw materials by washing, drying, crushing and ultrasonic treatment of marigold pollen, and uses supercritical carbon dioxide extraction technology combined with tributyl citrate entrainer to efficiently extract lutein esters. Subsequently, the extract is mixed with casein, β-glucan, maltodextrin and glutamine transaminase to form an emulsion, and microcapsules are prepared by supercritical fluid rapid expansion method. In this process, lecithin is used as an emulsifier to improve the stability of the emulsion. Finally, sucrose is added and high vacuum drying is performed after gradually cooling and freezing to ensure that the product water content is less than 5%. Compared with the traditional method, the present application enhances the mechanical strength and thermal stability of the microcapsules, while reducing the loss of active ingredients and improving the quality and shelf life of the product.

[0006] The present application provides a method for preparing lutein ester microcapsules, comprising the following steps:

[0007] S1, washing marigold pollen with deionized water, removing surface impurities and drying, then crushing the washed marigold pollen to a particle size of 20-80 mesh, adding deionized water to the crushed marigold pollen and performing ultrasonic treatment, and then drying the treated marigold pollen to a moisture content of less than 5%;

[0008] S2, placing the marigold pollen obtained in S1 into a supercritical carbon dioxide extraction device, adding an entrainer for extraction, and obtaining an extract containing lutein esters;

[0009] S3, mixing the extract obtained in S2 with casein, β-glucan, maltodextrin and transglutaminase, adding lecithin to obtain a uniform emulsion, and performing microencapsulation by supercritical fluid rapid expansion method;

[0010] S4. Add sucrose to the microcapsules obtained in S3, and then quickly freeze to -20°C~-30°C, and then cool to -60°C~-70°C. Dry the frozen sample under high vacuum conditions, gradually heat it to 20-30°C, and then perform secondary drying to ensure that the moisture content of the final product is less than 5%.

[0011] Furthermore, the ultrasonic treatment time in step S1 is 10-30 minutes, and the drying temperature is 30°C-50°C.

[0012] Furthermore, the entrainer in step S2 is tributyl citrate, and the mass ratio of the entrainer to marigold pollen is 0.2-0.5:1.

[0013] Furthermore, in the supercritical carbon dioxide extraction in step S2, the pressure is 300-400 bar, the temperature is 40-60° C., and the time is 80-60 min.

[0014] Furthermore, in step S3, the addition ratio of the extract, casein, β-glucan and maltodextrin is 100-120 parts of extract, 2-6 parts of casein, 1-2 parts of β-glucan, and 1-3 parts of maltodextrin in terms of weight; the addition amount of the lecithin is 1%-3% of the total weight, and the addition amount of the glutamine transaminase is 0.1%-1% of the total weight.

[0015] Furthermore, in the supercritical fluid rapid expansion method in step S3, the fluid is carbon dioxide, the pressure is 13-20 MPa, the temperature is 20-30° C., and the inner diameter of the nozzle is 150-300 μm.

[0016] Furthermore, the amount of sucrose added in step S4 is 1%-5% of the weight of the microcapsules.

[0017] Furthermore, in step S4, the freezing time at -20°C to -30°C is 18-24 hours, and the freezing time at -60°C to -70°C is 40-48 hours.

[0018] The present application crushes the cleaned marigold pollen and then performs ultrasonic treatment. This step ensures the high purity and uniformity of the raw materials by physical methods, reducing the impact of impurities on the subsequent extraction process. The drying temperature is controlled at 30°C-50°C to avoid high temperature from destroying the structure of lutein esters, while ensuring that moisture is completely removed to prevent microbial growth. Appropriate particle size helps to improve the extraction efficiency, because smaller particles can increase the surface area and promote the release of active ingredients. Ultrasonic waves can produce cavitation effects, destroy the cell wall structure, and make the lutein esters in the cells easier to extract. These operations significantly improve the purity and uniformity of the raw materials, reduce impurity interference, and provide a high-quality raw material basis for subsequent steps. The marigold pollen treated above is placed in a supercritical carbon dioxide extraction device, and tributyl citrate is added as an entrainer, which not only improves the extraction efficiency, but also acts as a plasticizer and antioxidant in the subsequent microencapsulation process, enhancing the flexibility and stability of the microcapsules. The presence of tributyl citrate further enhances the extraction effect and ensures the recovery rate of the target component. In the supercritical carbon dioxide extraction process, the mechanism of tributyl citrate as an entrainer is that it contains multiple ester groups in its molecular structure, which can effectively dissolve lutein esters, making it easier to extract in a supercritical carbon dioxide environment. The high boiling point of tributyl citrate makes it less volatile during the extraction process, so that it can continue to play a role in the subsequent microencapsulation process. In the microencapsulation stage, tributyl citrate acts as a plasticizer to reduce the glass transition temperature of the wall material, increase the flexibility of the microcapsules, and prevent the microcapsules from breaking during storage and transportation. At the same time, tributyl citrate also has certain antioxidant properties, which can protect lutein esters from oxidative damage to a certain extent and extend the shelf life of the product. Supercritical carbon dioxide extraction is environmentally friendly and efficient, and can achieve efficient extraction under mild conditions, reduce the use of organic solvents, and improve product safety. Supercritical fluids have excellent solubility, can achieve efficient extraction at lower temperatures, and reduce the loss of heat-sensitive components.

[0019] The extract was mixed with casein, β-glucan, maltodextrin and transglutaminase, and then lecithin was added. Microencapsulation was performed by supercritical fluid rapid expansion method. Casein provided good film-forming property and biocompatibility, forming a solid protective layer; β-glucan and maltodextrin increased mechanical strength and stability; transglutaminase catalyzed the cross-linking reaction between proteins to form a more stable network structure. As a natural emulsifier, lecithin can improve the stability and fluidity of the emulsion and ensure the uniform dispersion of each component. The supercritical fluid rapid expansion method can solidify the emulsion in an instant to form tiny and uniform microcapsules. This method can not only effectively protect the active ingredients, but also ensure the yield and encapsulation rate of the microcapsules, reduce the loss of active ingredients under high temperature or long-term exposure, and ensure the purity and stability of the final product. The use of composite wall materials significantly enhances the mechanical strength, thermal stability and light stability of the microcapsules, prolongs the shelf life of the product, and the addition of lecithin improves the stability and fluidity of the emulsion, ensuring the uniformity and efficiency of microencapsulation. The selection of nozzle inner diameter ensures uniform distribution of microcapsule particle size and improves product quality consistency.

[0020] Sucrose, as a common protective agent, can form a glassy structure during the freeze-drying process, prevent the microcapsules from breaking, and protect the active ingredients. Gradually lowering the temperature helps to form a uniform ice crystal structure and reduce damage to the active ingredients. Sublimation drying under high vacuum conditions can effectively remove moisture while maintaining the integrity of the active ingredients. The addition of sucrose forms a glassy structure, which protects the integrity of the microcapsules during the freeze-drying process and reduces the loss of active ingredients. The main advantage of cooling the freezing process twice is to optimize the morphology and size of ice crystals, reduce the impact on the active ingredients, and ensure the integrity and stability of the microcapsule structure. The first cooling quickly cools the sample to a lower temperature. This step can quickly freeze the surface water and form small and evenly distributed ice crystals. The fine ice crystals reduce mechanical damage to the cell structure or the internal structure of the microcapsule and protect the active ingredients. If the temperature is lowered to an extremely low temperature at one time, it may cause the ice crystals to grow too fast and form larger ice crystals. These large ice crystals will damage the microcapsule structure and affect the quality of the final product. On the basis of the initial cooling, the temperature is further lowered to ensure that all water is completely frozen. Deep freezing helps stabilize the already formed fine ice crystals and prevents them from recrystallizing or merging into larger crystals during the subsequent drying process. Gradual cooling makes the internal and external temperatures of the sample tend to be consistent, avoiding thermal stress and structural damage caused by excessive temperature differences. This uniform cooling helps maintain the integrity of the microcapsules. Gradual cooling reduces the thermal shock to the sample and reduces the risk of damage to the active ingredients due to sudden temperature changes during the freezing process. Thermosensitive ingredients such as lutein esters are more likely to maintain their structure and function under such mild freezing conditions. Protective agents such as sucrose have begun to form a glassy structure during the initial cooling, which preliminarily fixes the microcapsule structure. As the temperature is further reduced, the glassy structure becomes more stable, effectively protecting the active ingredients from mechanical damage caused by ice crystal growth. After two coolings, most of the water in the sample has been frozen into fine ice crystals. When the temperature is further reduced to -60℃~-70℃, these ice crystals become more stable, which is conducive to the effective removal of water in the subsequent high vacuum sublimation drying process. Small and evenly distributed ice crystals are easier to remove during the sublimation drying process, reducing the time of the entire drying process and improving production efficiency.

[0021] The preparation method provided by the present application combines supercritical carbon dioxide extraction, supercritical fluid rapid expansion method and freeze drying, ensuring the efficient extraction of lutein esters and the successful implementation of microencapsulation. By selecting suitable entrainers and composite wall materials, not only the extraction efficiency is improved, but also the mechanical strength, thermal stability and light stability of the microcapsules are enhanced. The entire process is simple and can prepare lutein ester microcapsule products with high stability. DETAILED DESCRIPTION

[0022] Example 1

[0023] S1: Wash marigold pollen with deionized water, remove surface impurities and dry at 30°C until the moisture content is less than 5%, then crush the washed marigold pollen to a particle size of 20 mesh, add deionized water to the crushed marigold pollen and perform ultrasonic treatment for 10 minutes, and then dry the treated marigold pollen at 30°C until the moisture content is less than 5%.

[0024] S2: The treated marigold pollen is placed in a supercritical carbon dioxide extraction device, tributyl citrate is added as an entrainer, the mass ratio of the entrainer to the marigold pollen is 0.2:1, the extraction conditions are pressure 300 bar, temperature 40° C., and time 80 min, to obtain an extract containing lutein esters.

[0025] S3: The extract obtained in S2 is mixed with casein, β-glucan, maltodextrin and transglutaminase, and the specific addition ratio is 110 parts of extract, 2 parts of casein, 1 part of β-glucan, and 1 part of maltodextrin by weight; the addition amount of lecithin is 1% of the total weight, and the addition amount of transglutaminase is 0.1% of the total weight, and a uniform emulsion is obtained by stirring. Microencapsulation is performed by supercritical fluid rapid expansion method, and the specific parameters are as follows: the fluid is carbon dioxide, the pressure is 13MPa, the temperature is 20°C, and the inner diameter of the nozzle is 150 microns.

[0026] S4: Add sucrose to the microcapsules obtained in S3 in an amount of 1% of the weight of the microcapsules. Then quickly freeze to -20°C for 18 hours, then cool to -60°C for 40 hours, dry the frozen sample under high vacuum conditions, gradually heat to 20°C, and then perform secondary drying to ensure that the moisture content of the final product is less than 5%.

[0027] Example 2

[0028] S1: Wash marigold pollen with deionized water, remove surface impurities and dry at 40°C until the moisture content is less than 5%, then crush the washed marigold pollen to a particle size of 50 mesh, add deionized water to the crushed marigold pollen and perform ultrasonic treatment for 20 minutes, and then dry the treated marigold pollen at 40°C until the moisture content is less than 5%.

[0029] S2: The treated marigold pollen is placed in a supercritical carbon dioxide extraction device, tributyl citrate is added as an entrainer, the mass ratio of the entrainer to the marigold pollen is 0.35:1, the extraction conditions are pressure 350 bar, temperature 50° C., and time 70 min, to obtain an extract containing lutein esters.

[0030] S3: The extract obtained in S2 is mixed with casein, β-glucan, maltodextrin and transglutaminase, and the specific addition ratio is 100 parts of extract, 4 parts of casein, 1.5 parts of β-glucan, and 2 parts of maltodextrin by weight; the addition amount of lecithin is 2% of the total weight, and the addition amount of transglutaminase is 0.5% of the total weight, to obtain a uniform emulsion. Microencapsulation is carried out by supercritical fluid rapid expansion method, and the specific parameters are as follows: the fluid is carbon dioxide, the pressure is 16.5MPa, the temperature is 25°C, and the inner diameter of the nozzle is 225 microns.

[0031] S4: Add sucrose to the microcapsules obtained in S3 in an amount of 3% of the weight of the microcapsules. Then quickly freeze to -25°C for 21 hours, then cool to -65°C for 44 hours, dry the frozen sample under high vacuum conditions, gradually heat to 25°C, and then perform secondary drying to ensure that the moisture content of the final product is less than 5%.

[0032] Example 3

[0033] S1: Wash marigold pollen with deionized water, remove surface impurities and dry at 50°C until the moisture content is less than 5%, then crush the washed marigold pollen to a particle size of 80 mesh, add deionized water to the crushed marigold pollen and perform ultrasonic treatment for 30 minutes, and then dry the treated marigold pollen at 50°C until the moisture content is less than 5%.

[0034] S2: The treated marigold pollen is placed in a supercritical carbon dioxide extraction device, tributyl citrate is added as an entrainer, the mass ratio of the entrainer to the marigold pollen is 0.5:1, the extraction conditions are pressure 400 bar, temperature 60° C., and time 60 min, to obtain an extract containing lutein esters.

[0035] S3: The extract obtained in S2 is mixed with casein, β-glucan, maltodextrin and transglutaminase, and the specific addition ratio is 120 parts of extract, 6 parts of casein, 2 parts of β-glucan, and 3 parts of maltodextrin by weight; the addition amount of lecithin is 3% of the total weight, and the addition amount of transglutaminase is 1% of the total weight, to obtain a uniform emulsion. Microencapsulation is carried out by supercritical fluid rapid expansion method, and the specific parameters are as follows: the fluid is carbon dioxide, the pressure is 20MPa, the temperature is 30°C, and the inner diameter of the nozzle is 300 microns.

[0036] S4: Add sucrose to the microcapsules obtained in S3 in an amount of 5% of the weight of the microcapsules. Then quickly freeze to -30°C for 24 hours, then cool to -70°C for 48 hours, dry the frozen sample under high vacuum conditions, gradually heat to 30°C, and then perform secondary drying to ensure that the moisture content of the final product is less than 5%.

[0037] Comparative Example 1 Compared with Example 1, tributyl citrate was replaced with ethanol with a volume concentration of 95%.

[0038] Comparative Example 2 Compared with Example 1, step S4 is replaced by spray drying, and the spray drying steps are as follows:

[0039] The spray drying process was carried out using a spray dryer with an inlet temperature of 160 °C, a dispersion nozzle inner diameter of 0.7 mm, and a pressure of 0.06 MPa.

[0040] Compared with Example 1, Comparative Example 3 did not add glutamine aminotransferase.

[0041] Test method: Take the lutein ester microcapsules prepared in the example and the comparative example, place them in evaporating dishes respectively, and place them in an oven with a constant temperature of 150°C for 1 hour. During this period, a certain amount is taken out every 20 minutes, and the lutein ester content in the lutein ester microcapsules is determined. The preservation rate is calculated. The preservation rate of the lutein ester microcapsules is the ratio of the lutein ester content of the sample after a period of storage to the initial lutein ester content in the sample. The test results are shown in the following table.

[0042] Table 1 shows the high temperature stability test results of lutein ester microcapsules.

[0043]

[0044] The products obtained in the embodiment and the comparative example were tested using a TA.XTplus texture analyzer. The probe type was a P / 0.5 cylindrical probe. The test speed was 0.5 mm / s, the return speed was 1.0 mm / s, the trigger force was 5 gf, the maximum deformation was 70%, and the test results were shown in the following table.

[0045] Table 2 shows the strength test results of lutein ester microcapsules.

[0046]

[0047] Compared with the use of tributyl citrate as an entrainer, the use of 95% ethanol resulted in a significant decrease in the hardness, toughness, and thermal stability of the microcapsules. This suggests that tributyl citrate not only improves the extraction efficiency but also enhances the mechanical strength of the microcapsules during the microencapsulation process. Compared with freeze drying, the hardness and toughness of the microcapsules prepared by spray drying were lower. This may be due to the damage to the microcapsule structure caused by the higher temperature and pressure during the spray drying process, which affected its mechanical properties.

Claims

1. A method for preparing lutein ester microcapsules, characterized in that: The following steps are involved: S1, washing marigold pollen with deionized water, removing surface impurities and drying, then crushing the washed marigold pollen to a particle size of 20-80 mesh, adding an appropriate amount of deionized water to the crushed marigold pollen and performing ultrasonic treatment, and then drying the treated marigold pollen to a moisture content of less than 5%; S2, placing the marigold pollen obtained in S1 into a supercritical carbon dioxide extraction device, adding an entrainer for extraction, and obtaining an extract containing lutein esters, wherein the entrainer is tributyl citrate, and the mass ratio of the entrainer to the marigold pollen is 0.2-0.5:1; S3, mixing the extract obtained in S2 with casein, β-glucan, maltodextrin and transglutaminase, adding lecithin to obtain a uniform emulsion, and performing microencapsulation by supercritical fluid rapid expansion method; S4. Add sucrose to the microcapsules obtained in S3, and then quickly freeze to -20°C~-30°C, and then cool to -60°C~-70°C. Dry the frozen sample under high vacuum conditions, gradually heat it to 20-30°C, and then perform secondary drying to ensure that the moisture content of the final product is less than 5%.

2. The method for preparing lutein ester microcapsules according to claim 1, characterized in that: The ultrasonic treatment time in step S1 is 10-30 minutes, and the drying temperature is 30°C-50°C.

3. The method for preparing lutein ester microcapsules according to claim 1, characterized in that: In the supercritical carbon dioxide extraction in step S2, the pressure is 300-400 bar, the temperature is 40-60° C., and the time is 80-60 min.

4. The method for preparing lutein ester microcapsules according to claim 1, characterized in that: In step S3, the addition ratio of the extract, casein, β-glucan and maltodextrin is 100-120 parts of extract, 2-6 parts of casein, 1-2 parts of β-glucan, and 1-3 parts of maltodextrin in terms of weight; the addition amount of lecithin is 1%-3% of the total weight, and the addition amount of glutamine transaminase is 0.1%-1% of the total weight.

5. The method for preparing lutein ester microcapsules according to claim 1, characterized in that: In the supercritical fluid rapid expansion method described in step S3, the fluid is carbon dioxide, the pressure is 13-20 MPa, the temperature is 20-30° C., and the inner diameter of the nozzle is 150-300 μm.

6. The method for preparing lutein ester microcapsules according to claim 1, characterized in that: The amount of sucrose added in step S4 is 1%-5% of the weight of the microcapsules.

7. The method for preparing lutein ester microcapsules according to claim 1, characterized in that: The freezing time at -20°C to -30°C in step S4 is 18-24 hours, and the freezing time at -60°C to -70°C is 40-48 hours.

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