A composite wall material for preparing fish oil microcapsules, its preparation method and application

Abstract

This invention provides a composite wall material for preparing fish oil microcapsules, its preparation method, and its application. Using pea protein, β-cyclodextrin, and carbon quantum dots as the composite wall material, it achieves excellent encapsulation effects, effectively delaying the oxidation of the core material by the external environment and preventing the oxidation of oils from affecting the product's shelf life. Compared to commercially available composite wall materials formed from pea protein and other compounds, the composite wall material of this invention increases the encapsulation rate by approximately 9%. Compared to using β-cyclodextrin as the wall material, the microcapsules encapsulated by this experimental composite wall material exhibit higher antioxidant properties and a longer shelf life. Furthermore, this invention provides technical support and new ideas for the material sourcing of fish oil microcapsule wall materials, showing promising application prospects.

Description

Technical Field

[0001] This invention belongs to the field of processing technology of excipients for health food and pharmaceutical preparations. Specifically, it relates to a composite wall material for preparing fish oil microcapsules, its preparation method and application. Background Technology

[0002] Fish oil contains abundant eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), among other n-3 polyunsaturated fatty acids (PUFAs). DHA is an essential amino acid that the human body cannot synthesize and must obtain from external sources. It has various benefits for the human body, such as aiding brain cell development, anti-aging, improving blood circulation, and lowering blood lipids. EPA, on the other hand, regulates blood lipids (lowers triglycerides and cholesterol), reduces blood viscosity (reduces platelet clotting ability), and softens blood vessels.

[0003] Currently, fish oils on the market have drawbacks such as easy oxidation and strong fishy smell during production, processing, and transportation. These problems greatly affect consumer demand for fish oil. Therefore, it is extremely important to stabilize it and maintain its original physiological activity during storage and application.

[0004] Microencapsulation can improve the production, processing, and transportation of fish oil, expanding its applications in the food industry. Microencapsulation technology utilizes natural or synthetic polymers to encapsulate a core material, forming tiny particles with semi-permeable or sealed membranes. Currently, most commercially available microencapsulation methods use natural macromolecules as wall materials for fish oil; however, these wall materials suffer from poor mechanical properties and heat and moisture resistance, and are prone to rupture during drying, resulting in reduced encapsulation efficiency.

[0005] Therefore, there is an urgent need to find a composite wall material for preparing fish oil microcapsules, so as to provide an ideal material for producing fish oil microcapsules with uniform particles, high solubility, high stability, strong antioxidant properties and high encapsulation rate, and eliminating fishy smell. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a composite wall material for preparing fish oil microcapsules, its preparation method, and its application. Pea protein (PPI), β-cyclodextrin (β-CD), and carbon quantum dots (CQDs) are used as the composite wall material. Fish oil is encapsulated using a freeze-drying method, resulting in fish oil microcapsules with uniform particles, smooth surfaces, and intact morphology. These microcapsules not only possess high solubility, high stability, strong antioxidant properties, and high encapsulation efficiency, effectively protecting the fish oil, delaying its oxidation, and extending its shelf life, but also eliminate fishy odor and exhibit targeted sustained-release capabilities.

[0007] To achieve the above objectives, the present invention employs the following solution:

[0008] On one hand, the present invention provides a fish oil microcapsule comprising a composite wall material and a core material, wherein the composite wall material comprises pea protein, β-cyclodextrin and carbon quantum dots, and the core material is fish oil.

[0009] In this invention, pea protein, β-cyclodextrin, and carbon quantum dots are selected as composite wall materials. Pea protein has lower allergenicity compared to soy protein; β-cyclodextrin can mask unpleasant odors and improve solubility and stability; CQDs can further enhance the physical properties of the wall material, improve the stability of microcapsules, and extend the shelf life of the product.

[0010] Furthermore, in the composite wall material, the mixing ratio of pea protein to β-cyclodextrin is 1 to 10:1 (w / v).

[0011] Preferably, in the composite wall material, the mixing ratio of pea protein to β-cyclodextrin is 1:1 (w / v).

[0012] In some implementations, the ratio of pea protein to β-cyclodextrin in the composite wall material was screened, and it was found that the best performance could be achieved when the optimal mixing mass ratio of PPI to β-CD was 1:1.

[0013] Furthermore, the mass ratio of the pea protein / β-cyclodextrin composite wall material solution to the core material is 1 to 10:1.

[0014] Preferably, the mass ratio of the pea protein / β-cyclodextrin composite wall material solution to the core material is 10:1.

[0015] In some embodiments, the mass ratio of pea protein / β-cyclodextrin composite wall material solution to core material was screened, and it was found that when the wall-to-core ratio was 10:1, the encapsulation efficiency (encapsulation rate) reached the highest level of 85.92%; at the same time, the loading rate also reached the highest level of 84%, showing good performance in improving the encapsulation efficiency and loading rate of fish oil.

[0016] Furthermore, in the composite wall material, the mass ratio of the pea protein / β-cyclodextrin mixed solution to carbon quantum dots is 5 to 100:1.

[0017] Preferably, in the composite wall material, the mass ratio of the pea protein / β-cyclodextrin mixed solution to carbon quantum dots is 20:1.

[0018] In some embodiments, the mass ratio of the pea protein / β-cyclodextrin mixed solution to carbon quantum dots in the composite wall material was screened, and it was found that when the mass ratio of PPI / β-CD to CQDs was 20:1, the fish oil microcapsules had the best encapsulation efficiency and good loading rate.

[0019] On the other hand, the present invention provides a method for preparing fish oil microcapsules as described in any of the above technical solutions, comprising the following steps:

[0020] 1) Preparation of wall material: Solid pure carbon quantum dots were prepared by Maillard reaction; pea protein and β-cyclodextrin solutions were prepared separately, with the mixing ratio of pea protein and β-cyclodextrin being 1 to 10:1 (w / v), and mixed to obtain wall material solution.

[0021] 2) Preparation of microcapsules: Microcapsules were prepared according to a mass ratio of pea protein / β-cyclodextrin composite wall material solution to core material of 1 to 10:1; a mixed solution was obtained according to a mass ratio of pea protein / β-cyclodextrin mixed solution to carbon quantum dots of 5 to 100:1, and then the mixed solution was mixed with fish oil according to a determined ratio and dried to obtain pea protein / β-cyclodextrin / carbon quantum dots / fish oil microcapsules.

[0022] Furthermore, in the preparation of the wall material, carbon quantum dots are prepared using glucose and L-lysine in a mass ratio of 1:1; the wall material solution contains 2% (w / v) pea protein and 2% (w / v) β-cyclodextrin.

[0023] In some embodiments, the present invention has screened an optimal preparation process for fish oil microcapsules, using a PPI:β-CD ratio of 1:1, a core-to-wall ratio of 1:10, and a PPI / β-CD:CQDs ratio of 20:1. Fish oil is encapsulated by freeze-drying to obtain fish oil microcapsules with uniform particles, smooth surfaces, and intact morphology, exhibiting optimal performance.

[0024] In another aspect, the present invention provides the use of a composite wall material for preparing fish oil microcapsules with high solubility, high stability, strong antioxidant properties, or high encapsulation efficiency, characterized in that the composite wall material comprises pea protein, β-cyclodextrin, and carbon quantum dots.

[0025] In another aspect, the present invention provides the use of a composite wall material for preparing formulations that can effectively resist digestion by saliva and gastric juice and promote sustained release in intestinal juice, characterized in that the composite wall material comprises pea protein, β-cyclodextrin and carbon quantum dots.

[0026] In another aspect, the present invention provides a composite wall material for preparing fish oil microcapsules with no fishy smell and a long shelf life, characterized in that the composite wall material comprises pea protein, β-cyclodextrin and carbon quantum dots.

[0027] In another aspect, the present invention provides the use of carbon quantum dots in the preparation of fish oil microcapsules with high stability, strong antioxidant properties and high encapsulation efficiency.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. The present invention screened and obtained an optimal preparation process for fish oil microcapsules, using a PPI:β-CD ratio of 1:1, a core-to-wall ratio of 1:10, and a PPI / β-CD:CQDs ratio of 20:1. Fish oil was encapsulated by freeze-drying to obtain fish oil microcapsules with uniform particles, smooth surfaces, and intact morphology. Pea protein is a nutritionally balanced plant protein that not only possesses the unique functionalities of plant proteins but also exhibits better solubility, stirring stability, gelling properties, and emulsifying properties compared to soy protein. Furthermore, microscopic observation reveals that it forms spherical shapes when used as a wall material, resulting in a smoother surface and improved microencapsulation efficiency. β-CD is a cyclic oligosaccharide that can form stable inclusion complexes with various chemicals, offering multiple functions including masking unpleasant odors, increasing solubility, and enhancing product stability. Due to the numerous functional groups on the surface of CQDs, they possess unique physical and chemical properties such as high water solubility, strong fluorescence, antioxidant activity, and good photostability. These properties can further enhance the physical properties of the wall material, improve the encapsulation rate, antioxidant capacity, and stability of microcapsules, and extend their shelf life.

[0030] 2. The PPI / β-CD / CQDs fish oil microcapsules prepared by this invention have uniform particle size and not only have high solubility, high stability, strong antioxidant properties and high encapsulation rate, effectively protecting fish oil, delaying its oxidation, and extending shelf life, but also eliminating fishy odor.

[0031] 3. The fish oil microcapsules prepared by this invention show a significantly reduced release rate of the core material in simulated oral saliva and gastric juice, but a release rate of 82.09% in simulated intestinal juice. This indicates that the microcapsules can effectively resist the digestion of fish oil by oral saliva and gastric juice, improve the targeted sustained-release ability of fish oil in intestinal juice, and facilitate human absorption.

[0032] 4. This invention uses PPI, β-CD and CQDs as composite wall materials, which are used in combination, providing technical support and new ideas for the material source of fish oil microcapsule wall materials, and has good application prospects. Attached Figure Description

[0033] Figure 1 The particle size of fish oil microcapsules under different wall materials.

[0034] Figure 2 A is a microstructure diagram of PPI microcapsules as wall materials obtained by SEM.

[0035] Figure 2 B is a microstructure diagram of β-CD microcapsules as wall material obtained by SEM.

[0036] Figure 2 C is a microstructure diagram of microcapsules using PPI / β-CD as the wall material, obtained by SEM.

[0037] Figure 2 D is a microstructure diagram of PPI / β-CD / CQDs as wall material obtained by SEM.

[0038] Figure 3 The FFA release rate of fish oil microcapsules in the in vitro simulation experiment.

[0039] Figure 4 This is a graph showing the changes in POV of fish oil microcapsules at different storage temperatures.

[0040] Figure 5 The graph shows the changes in TBA in fish oil microcapsules at different storage temperatures.

[0041] Figure 6 This is a graph showing the changes in the hygroscopicity of fish oil microcapsules under different relative humidity levels.

[0042] Figure 7 The graph shows the changes in the core material retention rate of fish oil microcapsules under different relative humidity conditions.

[0043] Figure 8 POV variation of fish oil microcapsules prepared with different wall materials.

[0044] Figure 9A The graph shows the turbidity curve and the relationship between ζ-potential and pH of the PPI solution.

[0045] Figure 9B To determine OD at different pH values 600 Changes with PPI concentration.

[0046] Figure 10 Encapsulation efficiency and loading rate of fish oil microcapsules with different wall-to-core ratios.

[0047] Figure 11 The effect of different concentrations of CQDs on the microencapsulation effect of fish oil.

[0048] Figure 12 Infrared spectra of PPI, β-CD, CQDs, fish oil and microcapsule samples. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the embodiments. It should be noted that the embodiments described below and the materials used are intended to facilitate the understanding of the present invention, and do not limit it in any way.

[0050] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0051] The materials and reagents used in the following examples were all obtained commercially, including pea protein (85%) purchased from Tianmen Hengchang Chemical Co., Ltd., β-cyclodextrin purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., fish oil purchased from Tmall Global Mulesi brand store.

[0052] Example 1: Preparation of fish oil microcapsules

[0053] This embodiment provides the optimal preparation method for fish oil microcapsules, and the steps are as follows:

[0054] (1) Preparation of wall materials

[0055] Step 1: Preparation of carbon quantum dots using the Maillard reaction. First, 0.6 g of glucose and 0.6 g of L-lysine were ultrasonically dissolved in 40 mL of deionized water and heated in a microwave oven for 10 min. During this process, the solution changed from colorless to pale yellow, eventually forming a solid, indicating the formation of carbon quantum dots. Then, the prepared carbon quantum dots were dissolved in a small amount of deionized water and centrifuged (10000 r / min, 10 min) to remove the solid precipitate, obtaining the supernatant. This supernatant was further filtered using a disposable syringe filter (0.22 μm) to remove solid impurities. Finally, the supernatant was placed in a dialysis bag and dialyzed in deionized water for 24 h, then transferred to a vacuum freeze dryer and dried for one day (-40℃) to obtain solid, pure carbon quantum dots.

[0056] Step 2: Preparation of PPI (pea protein) and β-CD (β-cyclodextrin) stock solutions. Dissolve 10g of PPI in 500ml of ultrapure water, stir at room temperature for 2h, adjust pH to 12 with 0.1M NaOH, and let stand for half an hour. Then heat in a constant temperature water bath at 88℃ for 30min to allow the pea protein to unfold and refold, then immediately cool to room temperature and adjust pH to 7. Centrifuge at 1600g / min for 15min to remove insoluble impurities, obtaining a 2% w / v PPI solution. Dissolve 10g of β-CD in 500mL of a mixture of ethanol and water (1:2), and keep at room temperature for 24h to obtain a 2% w / v β-CD solution. Mix the PPI and β-CD stock solutions to a PPI to β-CD mixing ratio of (1:1, w / v), keeping the total amount of the biopolymer mixture fixed at 2.00%, to obtain the wall material solution for later use.

[0057] (2) Preparation of microcapsules

[0058] Step 1: Weigh the core material and wall material solutions according to a core-to-wall ratio of 1:10 (m core material: m wall material). Homogenize the two solutions at room temperature for 3 minutes to form a uniform emulsion. Then, pre-freeze the emulsion in a -80°C freezer for 2 hours. Form microcapsules by freeze-drying (vacuum degree 0.1 mbar, cold trap temperature -54°C, partition temperature -10°C, time 25 hours (for complete freeze-drying)). Place the prepared microcapsule products in a desiccator for later use.

[0059] Step 2: Microcapsules with PPI / β-CD as the composite wall material were prepared. CQDs were then added to the PPI / β-CD solution to obtain a PPI / β-CD to CQDs mass ratio of 20:1. The mixture was then continuously stirred at 1200 rpm for 2 hours. The resulting PPI / β-CD / CQDs mixed solution was then mixed with fish oil at a predetermined ratio (10:1), homogenized at 10000 rpm for 3 minutes at room temperature, and then dried in a freeze dryer to obtain PPI / β-CD / CQDs / fish oil microcapsules.

[0060] (3) Determination of microcapsule encapsulation efficiency

[0061] Encapsulation efficiency % = [(Total oil content - Surface oil content) / Total oil content] × 100%

[0062] Surface oil determination: 2g of dried microcapsule powder (mass m) was transferred to a beaker containing 40mL of n-hexane and gently shaken for 1min. The entire filtrate was filtered through filter paper and transferred to a constant-weight round-bottom flask (mass m1). The n-hexane was then rotary evaporated, and the flask was dried in an oven at 105℃ to constant weight. After cooling to room temperature in a desiccator, the flask was weighed (mass m2).

[0063] Surface oil content % = (m2-m1) / m × 100%

[0064] Total oil determination: 2 g of dried microcapsule powder (mass m3) was mixed with 40 mL of ethanol and then sonicated for 20 min. An ice bath was used to control the dispersion temperature during sonication. After sonication, the supernatant was obtained by centrifugation. The sediment underwent two more extraction processes. The supernatants from the three extractions were mixed. All supernatants were transferred to a constant-volume round-bottom flask (mass m4), and most of the solvent was rotary evaporated. The flask was then dried in a 105°C oven to constant weight, cooled to room temperature in a desiccator, and weighed (mass m5).

[0065] Total oil content % = (m5 - m4) / m3 × 100%

[0066] Loading rate = (W2 - W1) / W2 × 100%

[0067] The optimal preparation method for fish oil microcapsules provided in this embodiment uses PPI, β-CD, and CQDs as wall materials and employs freeze-drying to encapsulate fish oil, resulting in microcapsules with uniform particle size, smooth surface, and intact morphology. Among these, pea protein has lower allergenicity compared to soy protein; β-cyclodextrin can mask unpleasant odors and improve solubility and stability; and CQDs can further enhance the physical properties of the wall materials, improve the antioxidant properties and stability of the microcapsules, and extend the shelf life of the product.

[0068] The fish oil microcapsules prepared using the optimal preparation method in this embodiment have high solubility, high stability, strong antioxidant properties, and high encapsulation efficiency. They are odorless, have a long shelf life, and possess targeted sustained-release capabilities. They can effectively resist the digestion of fish oil by oral saliva and gastric juice, and improve the sustained-release ability of fish oil in intestinal juice.

[0069] Example 2: Comparative Test of Fish Oil Microcapsule Performance with Different Wall Materials

[0070] To verify that the fish oil microcapsules prepared in Example 1 have optimal performance, fish oil microcapsules with different wall materials were prepared in this example, and their performance (particle size and zeta potential) was compared and tested. Specifically, the particle size and zeta potential of the microcapsules were measured using a zeta sizer laser particle size analyzer (Shanghai Sibaiji Instrument System Co., Ltd.): the dried microcapsules were appropriately dispersed in distilled water by vortex oscillation, and then an appropriate dispersion volume was placed in the instrument for analysis. All measurements were repeated at least three times and the average value was taken. Several methods were used (other preparation processes are as shown in Example 1):

[0071] 1. Prepare fish oil microcapsules (PPI / FO) with PPI as the wall material alone, and measure their particle size and ζ-potential;

[0072] 2. Prepare fish oil microcapsules (β-CD / FO) with β-CD as the wall material alone, and measure their particle size and ζ-potential;

[0073] 3. Prepare fish oil microcapsules (PPI / β-CD / FO) with PPI / β-CD as composite wall material, and measure their particle size and ζ-potential;

[0074] 4. Prepare fish oil microcapsules (PPI / β-CD / CQDs / FO) with PPI / β-CD / CQDs as composite wall material, and measure their particle size and ζ-potential;

[0075] 5. Prepare fish oil microcapsules (CQDs / FO) with CQDs as the wall material alone, and measure their particle size and ζ-potential;

[0076] 6. Prepare fish oil microcapsules (PPI / CQDs / FO) as composite wall material using PPI / CQDs, and measure their particle size and ζ-potential;

[0077] 7. Fish oil microcapsules (β-CD / CQDs / FO) were prepared as composite wall materials using β-CD / CQDs as a composite material, and their particle size and ζ-potential were measured.

[0078] The results are as follows Figure 1 As shown, Figure 1 This refers to the particle size of fish oil microcapsules under different wall materials. From Figure 1 From this, we can know that:

[0079] 1) Without the addition of CQDs, the particle size of PPI alone encapsulated fish oil is 809 μm, and its potential value is -40.57 mV. The particle size of β-CD alone encapsulated fish oil is 577 μm, and its potential value is -32.67 mV. The particle size of PPI / β-CD composite encapsulated fish oil is 602 μm, and its potential value is -30.84 mV.

[0080] 2) Compared with PPI alone encapsulated fish oil, the particle size of the PPI / β-CD composite encapsulated sample was significantly smaller, and the ζ-potential of the two samples was significantly different (p<0.5); compared with β-CD alone encapsulated fish oil, the particle size of the PPI / β-CD composite encapsulated sample was not significantly different, and the ζ-potential of the two samples was not significantly different.

[0081] 3) After the addition of CQDs, the particle size of the PPI / β-CD / CQDs fish oil microcapsules was 642 μm, and its potential value was -38.24 mV. Compared with PPI alone encapsulating fish oil, the particle size of the PPI / β-CD / CQDs composite encapsulation was significantly smaller. This may be because the addition of negatively charged CQDs neutralized some of the charge of PPI, making the overall structure of the microcapsules more compact, the particle size smaller, and the overall system more stable. Compared with the absolute values ​​of particle size and ζ-potential of β-CD alone encapsulating fish oil and PPI / β-CD composite encapsulating fish oil, the particle size of PPI / β-CD / CQDs composite encapsulation was slightly larger, but the difference among the three was not significant. However, the absolute value of the ζ-potential of PPI / β-CD / CQDs composite encapsulation was significantly increased, showing a significant difference among the three. The larger the absolute value of the potential, the better the stability of the microcapsules.

[0082] 4) In this embodiment, supplementary experiments were also conducted on CQDs as a wall material alone, PPI / CQDs as a composite wall material, and β-CD / CQDs as a composite wall material. The results showed that:

[0083] a) The particle size of CQDs encapsulating fish oil alone is 752 μm, with a potential value of -28.32 mV. Compared with PPI / β-CD / CQDs as a composite wall material, its particle size is significantly larger (p<0.5), and the absolute values ​​of their ζ-potentials also differ significantly (p<0.5); b) The particle size of PPI / CQDs encapsulating fish oil as a composite wall material is 728 μm, with a potential value of -36.37 mV. Compared with PPI / β-CD / CQDs as a composite wall material, its particle size is significantly larger (p<0.5). Compared to PPI / CQDs as a composite wall material, the particle size of Ds is significantly increased (p<0.5), while the absolute value of the ζ-potential of PPI / CQDs is also slightly decreased; c, the particle size of β-CD / CQDs as a composite wall material for encapsulating fish oil is 653μm, and its potential value is -34.35mV. Compared with PPI / β-CD / CQDs as a composite wall material, its particle size is slightly increased, but the difference between the two is not significant, while the absolute value of the ζ-potential of the two is significantly different (p<0.5).

[0084] Therefore, when CQDs are used alone as the wall material, or when PPI / CQDs or β-CD / CQDs are used as the composite wall material, the stability of fish oil microcapsules is lower than that of fish oil microcapsules using PPI / β-CD / CQDs as the composite wall material. This may be because when the three materials are used together to prepare the composite wall material, the negatively charged CQDs neutralize the charge in PPI, altering a certain property of the fish oil microcapsule composite wall material, thereby significantly reducing the particle size, significantly increasing the absolute value of the potential, and resulting in excellent stability.

[0085] A higher zeta potential (ζ-potential) indicates a greater surface charge on protein molecules, signifying stronger intermolecular repulsion and inhibited protein aggregation. This results in smaller effective particle sizes and greater system stability. Therefore, when using PPI, β-CD, and CQDs to prepare composite wall materials, the absolute value of the ζ-potential should be maximized to achieve a more compact microcapsule structure, greater system stability, and better microcapsule encapsulation, while simultaneously reducing the particle size of the fish oil microcapsules. Thus, PPI / β-CD / CQDs are the preferred composite wall material for preparing fish oil microcapsules.

[0086] Example 3: Comparative Test of Microstructure of Fish Oil Microcapsules with Different Wall Materials

[0087] To verify that the fish oil microcapsules prepared in Example 1 have the best performance, fish oil microcapsules with different wall materials were prepared in this example, and their microstructures were compared and tested. The following methods were used (other preparation processes are as shown in Example 1):

[0088] 1. Prepare fish oil microcapsules (PPI / FO) with PPI as the wall material alone and observe their microstructure;

[0089] 2. Prepare fish oil microcapsules (β-CD / FO) with β-CD as the wall material alone, and observe their microstructure;

[0090] 3. Prepare fish oil microcapsules (PPI / β-CD / FO) with PPI / β-CD as the composite wall material and observe their microstructure;

[0091] 4. Prepare fish oil microcapsules (PPI / β-CD / CQDs / FO) with PPI / β-CD / CQDs as composite wall material and observe their microstructure;

[0092] 5. Prepare fish oil microcapsules (CQDs / FO) with CQDs as the wall material alone, and observe their microstructure;

[0093] 6. Prepare fish oil microcapsules (PPI / CQDs / FO) with PPI / CQDs as composite wall material and observe their microstructure;

[0094] 7. Prepare fish oil microcapsules (β-CD / CQDs / FO) with β-CD / CQDs as composite wall material and observe their microstructure.

[0095] The results are as follows Figure 2 As shown, Figure 2 Image A shows the microstructure of PPI microcapsules as wall materials under SEM (scanning electron microscopy). Figure 2 B is a microstructure diagram of β-CD microcapsules as wall material obtained by SEM. Figure 2 C is a microstructure diagram of microcapsules using PPI / β-CD as the wall material, obtained by SEM. Figure 2 D is a microstructure diagram of microcapsules containing PPI / β-CD / CQDs as wall materials, obtained by SEM. Figure 2 From this, we can know that Figure 2 In A, the PPI / FO microcapsules are elliptical in shape, have a rough surface, and a particle size of 809 μm. Figure 2 In B, the β-CD / FO microcapsules are irregularly shaped with a relatively rough surface and a particle size of 577 μm. Figure 2 In C, the micromorphology of PPI / β-CD / FO microcapsules changed significantly. The particle size was 602 μm. Except for a few dents, the particles were relatively round and almost spherical, and had good integrity. Figure 2 In D, the PPI / β-CD / CQDs / FO microcapsules are nearly spherical in shape with a particle size of 642 μm, which is not significantly different from the particle size of the PPI / β-CD / FO microcapsules, and the two have similar structures.

[0096] In this embodiment, supplementary experiments were also conducted on CQDs as wall material alone, PPI / CQDs as composite wall material, and β-CD / CQDs as composite wall material. The results showed that when CQDs were used alone to encapsulate fish oil, or when PPI / CQDs or β-CD / CQDs were used as composite wall material, the fish oil microcapsules were irregular in shape, with extremely rough surfaces, and particle sizes of 752 μm, 728 μm, and 653 μm, respectively.

[0097] Therefore, it can be seen that in this embodiment, the microcapsules produced using PPI / β-CD and PPI / β-CD / CQDs condensation layers have similar structures and ideal morphology, which can effectively protect the encapsulated fish oil and increase the encapsulation effect.

[0098] Example 4: FFA release rate of fish oil microcapsules in in vitro simulation test

[0099] The FFA release rate of the fish oil microcapsules prepared in Example 1 was tested in an in vitro simulation experiment. The specific process was as follows: 20 mL of microcapsule reconstituted solution was added to 20 mL of simulated oral saliva, the pH value was adjusted to 6.80, and then they were placed in a shaker at 200 r / min at (37±1) ℃ and kept warm for 10 min. Then, 20 mL of the mixture of oral saliva and microcapsule reconstituted solution was taken out and mixed with simulated gastric juice at a volume ratio of 1:1. The pH value of the completely mixed reaction solution was adjusted to 2.5 with NaOH solution (1 mol / L), and then kept warm in a shaker at 200 r / min at (37±1) ℃ for 2 h. Finally, 30 mL of simulated gastric juice was taken, and the pH was adjusted to 7.0 with NaOH solution (1 mol / L). Simulated intestinal juice (containing 3.5 mL of bile salts (187.5 mg / mL), 1.5 mL of CaCl2 and NaCl solution) was then added to the mixture, and the pH was adjusted to 7.0. Simultaneously, 2.5 mL of lipase was rapidly added, and the temperature was maintained at a constant 37 ± 1 °C during intestinal juice digestion. The pH of the simulated intestinal juice was measured with a pH meter, and titrated with NaOH solution (0.05 mol / L) to maintain the pH at 7.0, with the volume of NaOH solution consumed recorded. The same digestion process described above was performed using a fish oil-free, unloaded emulsion. The amount of NaOH solution (0.05 mol / L) used was determined and then subtracted from the relevant sample. Using this method, the release rate of free fatty acids (FFA) in the sample was determined by measuring the amount of NaOH solution used during titration. The formula is as follows:

[0100] FFA(%)=100×(V×c×M) / m×2

[0101] In the formula:

[0102] V: Volume of NaOH solution used in titration, in L;

[0103] c: Concentration of NaOH, mol / L;

[0104] M: Average molar mass of fish oil, g / mol;

[0105] m: Mass of the oil phase, in grams.

[0106] The study compared fish oil microcapsules prepared with different wall materials using the following methods (the preparation process is shown in Example 1; where FFA is free fatty acid, and a higher FFA release rate indicates a higher degree of damage to the fish oil microcapsules):

[0107] 1. Prepare fish oil microcapsules (PPI / FO) with PPI as the wall material alone, and observe their FFA release rate;

[0108] 2. Prepare fish oil microcapsules (β-CD / FO) with β-CD as the wall material alone, and observe their FFA release rate;

[0109] 3. Prepare fish oil microcapsules (CQDs / FO) with CQDs as the wall material alone, and observe their FFA release rate;

[0110] 4. Prepare fish oil microcapsules (PPI / β-CD / FO) with PPI / β-CD as the composite wall material and observe their FFA release rate;

[0111] 5. Prepare fish oil microcapsules (PPI / CQDs / FO) with PPI / CQDs as composite wall material and observe their FFA release rate;

[0112] 6. Prepare fish oil microcapsules (β-CD / CQDs / FO) with β-CD / CQDs as composite wall material and observe their FFA release rate;

[0113] 7. Prepare fish oil microcapsules (PPI / β-CD / CQDs / FO) with PPI / β-CD / CQDs as composite wall material and observe their FFA release rate.

[0114] Figure 3 The FFA release rate of the PPI / β-CD / CQDs / FO microcapsules of this invention is from... Figure 3The results show that in the early stages of intestinal digestion, the release rate of FFA from the fish oil microcapsules increases significantly over time, possibly due to the digestion of residual surface oil on the microcapsule surface. However, as digestion progresses, the release rate of FFA slows down. In the later stages of intestinal digestion, the release rate reaches 82.09%, but not all FFA is released. This may be because the digestive capacity of simulated oral saliva and gastric juices on the microcapsule wall material is limited. The microcapsule wall material is composed of a complex aggregate of carbohydrates and proteins, and its structure is relatively dense. Gastric juice has limited digestive capacity for carbohydrates and proteins and cannot completely destroy the wall material of the microcapsules. It could also be because the core material is fish oil, and the released fatty acids are mainly long-chain polyunsaturated fatty acids. In digestive juices, long-chain free fatty acids easily combine with calcium to form calcium fatty acids, which have a certain inhibitory effect on digestion.

[0115] Meanwhile, this embodiment also tested the FFA release rate of fish oil microcapsules prepared with different wall materials. The test results were as follows: When the three materials were used alone or any two materials were used as composite wall materials: In the early stage of intestinal digestion (0-30 min), the FFA release rate increased continuously with time, and the magnitude was large. This may be due to the digestion of the surface oil remaining on the surface of the microcapsules; as the digestion time progressed (30-60 min), the FFA release rate slowed down, but continued to increase. This may be because it was used as a composite wall material with PPI / β-CD / CQDs. In comparison, the structure of a single material or any two materials used as wall materials is not as dense as that of the PPI / β-CD / CQDs composite wall material. Oral saliva and gastric juice cause greater damage to its structure, so it continues to be digested in saliva and gastric juice, and the release rate of FFA continues to increase. In the later stage of intestinal digestion (60-150 min), the release rate of FFA decreases significantly. This may be because the structure of the wall material has been largely destroyed in oral saliva and gastric juice, so a large amount of FFA is released. Therefore, the amount of FFA reaching the intestinal juice decreases significantly, and the release rate in the intestinal juice also decreases significantly.

[0116] Therefore, when PPI, β-CD, CQDs, PPI / β-CD, PPI / CQDs, or β-CD / CQDs are used as wall materials, the wall material structure is largely or completely destroyed by saliva or gastric juice during the mid-digestion period, and FFA is basically released, preventing fish oil from reaching the intestinal fluid for large-scale release, which is not conducive to human absorption. However, when the PPI / β-CD / CQDs of this invention are used as a composite wall material, the structure is dense, and saliva and gastric juice have very low ability to destroy its structure. Therefore, fish oil is not released in large quantities during the mid-digestion period. After reaching the intestinal fluid, the wall material structure is destroyed by the intestinal fluid, allowing fish oil to be released in large quantities in the intestinal fluid, which is beneficial to human absorption.

[0117] Therefore, the fish oil microcapsules prepared by this invention have targeted sustained-release capabilities and are not easily destroyed in oral saliva and gastric juice. The intestinal fluid environment promotes the diffusion of the core material, and the remaining core material is released in a stable and continuous manner, ultimately forming a sustained-release mode in which most of the core material is released into the intestine. Therefore, this invention preferably uses PPI / β-CD / CQDs as a composite wall material to prepare fish oil microcapsules.

[0118] Example 5: Effects of different storage temperatures on POV (peroxide value) and TBA (thiobarbituric acid) in fish oil microcapsules.

[0119] The POV and TBA of the fish oil microcapsules prepared in Example 1 were tested at different storage temperatures. The microcapsules were stored at temperatures of 4°C, 20°C, 40°C, and 60°C, and their POV values ​​were measured by iodometric titration and their TBA values ​​were determined by spectrophotometry. POV, or peroxide value, is an important indicator reflecting the oxidation state of fish oil; a smaller change in POV indicates more stable fish oil. TBA, or thiobarbituric acid, indicates a lower degree of oxidation of fish oil.

[0120] Specific results are as follows Figure 4 As shown, from Figure 4 The results show that the POV value of fish oil microcapsules increases at storage temperatures of 4℃, 20℃, 40℃, and 60℃: 1) At higher temperatures (40℃ and 60℃), the POV value of the microcapsule products increases more rapidly. This may be because the physical properties of the microcapsule wall material change under high temperature and long-term environment, thereby destroying the original dense structure, causing the fish oil to lose the protection of the wall material, resulting in the fish oil seeping out and being rapidly oxidized; 2) When fish oil microcapsules are stored at 4℃ and 20℃, the POV changes more slowly, which also indicates that low temperature is suitable for the storage of fish oil microcapsules.

[0121] The trend of TBA values ​​is consistent with that of POV values, as shown in the specific results. Figure 5 As shown, from Figure 5 The results show that the TBA value of the microcapsules increases relatively gently between low temperature (4℃) and normal temperature (20℃), indicating that the oxidation degree of fish oil microcapsules is low and the oxidation rate is slow. At 40℃, the oxidation degree of fish oil microcapsules increases significantly compared with low temperature and normal temperature. However, fish oil microcapsules begin to oxidize rapidly at a high temperature of 60℃.

[0122] Therefore, the fish oil microcapsules prepared by this invention are suitable for long-term storage in a low-temperature (low temperature or room temperature) environment, and should be kept away from high-temperature environments, otherwise the microcapsules are prone to rupture and lose their protective effect on the fish oil, resulting in the leakage and oxidation of the fish oil.

[0123] Example 6: Effect of different humidity environments on the hygroscopicity of fish oil microcapsules

[0124] The hygroscopicity of the fish oil microcapsules prepared in Example 1 was tested under different humidity environments. The microcapsules were stored under relative humidity conditions of 34%, 58%, 76%, and 93%, and their weight was measured in a sealed container with a saturated salt solution at 20°C to test their hygroscopicity.

[0125] Specific results are as follows Figure 6 As shown, from Figure 6 The results showed that the hygroscopicity of fish oil microcapsules changed over time when stored at relative humidity of 34%, 58%, 76%, and 93%, and the water absorption capacity of fish oil microcapsules differed significantly under different humidity conditions (p<0.05).

[0126] As humidity increases, the water absorption capacity of fish oil microcapsules also increases; however, when the relative humidity is low, the water absorption capacity of fish oil microcapsules slows down. Furthermore, experimental results show that under 93% humidity, the water absorption of fish oil microcapsules reaches its maximum on day 6, and then tends to stabilize; while under 76% humidity, the water absorption of fish oil microcapsules tends to level off after 10 days. This may be because the PPI / β-CD / CQDs composite wall material is water-soluble and easily absorbs moisture, but as storage time increases, the water absorption of the wall material decreases, and the hygroscopicity of the microcapsules tends to level off. At higher humidity, the wall material easily absorbs moisture, and compared to lower humidity environments, the moisture absorption rate of the microcapsules is faster.

[0127] There is a certain relationship between the moisture content of food and its shelf life. For fish oil microcapsules, when the wall material absorbs water, the shape, size, and integrity of the capsule wall change, causing the fish oil to lose its protective layer and significantly increasing its permeability. This makes the fish oil more susceptible to contact with the environment, leading to oxidation and rancidity, thus greatly shortening its shelf life. Furthermore, the rupture and decomposition of the microcapsule wall material also results in a large amount of fish oil being released into the environment, causing a continuous decrease in fish oil retention and affecting the quality of the microcapsules.

[0128] Therefore, the fish oil microcapsules prepared by this invention are suitable for long-term storage in an environment with a relative humidity of less than 34%.

[0129] Example 7: Effect of different humidity environments on the retention rate of fish oil microcapsule core material.

[0130] The core material retention rate of the fish oil microcapsules prepared in Example 1 was tested under different humidity environments. The microcapsules were stored under relative humidity conditions of 34%, 58%, 76%, and 93%, and the core material retention rate was tested by the change in weight.

[0131] Specific results are as follows Figure 7 As shown, from Figure 7 As can be seen, the retention rate of the core material decreases continuously with the increase of relative humidity. Under the condition of relative humidity of 34%, the change in the retention rate of the microcapsule core material is relatively slow with the increase of storage time. After 16 days of storage, the retention rate of the core material is still above 90%. However, when the relative humidity is 93%, the retention rate of the core material is only 36.80% after 16 days of storage.

[0132] Therefore, it can be seen that the higher the relative humidity, the faster the core material retention rate decreases. This may be because, in environments with high relative humidity, as the microcapsule product absorbs more and more moisture, the wall material dissolves, reducing the membrane's permeability and density, thus damaging the microcapsule structure. This leads to the permeation and release of the core material, which is then oxidized by the external environment, deteriorating the product's quality and also reducing the core material retention rate. Moreover, the higher the relative humidity in the environment, the more significant the decrease in the core material retention rate of the fish oil microcapsules (p<0.05). The changes in the hygroscopicity of fish oil microcapsules under different humidity conditions further illustrate that the fish oil microcapsule product of this invention should be stored in a dry environment as much as possible.

[0133] Example 8: Test of POV changes of microcapsules with different wall materials during fish oil storage

[0134] In this embodiment, the POV value of fish oil microcapsules prepared with different wall materials was tested using the iodometric colorimetric method. Several methods were employed (other preparation processes are as shown in Example 1; this experiment was conducted at 60°C because the comparison effect was most significant at this temperature, and other conditions such as relative humidity were also optimal):

[0135] 1. Unmicroencapsulated fish oil;

[0136] 2. Prepare fish oil microcapsules with PPI as the wall material alone (PPI / FO) and test their POV value;

[0137] 3. Prepare fish oil microcapsules (β-CD / FO) with β-CD as the wall material alone, and test their POV value;

[0138] 4. Prepare fish oil microcapsules (CQDs / FO) with CQDs as the wall material alone, and test their POV value;

[0139] 5. Prepare fish oil microcapsules (PPI / β-CD / FO) with PPI / β-CD as composite wall material and test their POV value;

[0140] 6. Prepare fish oil microcapsules (PPI / CQDs / FO) with PPI / CQDs as composite wall material and test their POV value;

[0141] 7. Prepare fish oil microcapsules (β-CD / CQDs / FO) with β-CD / CQDs as composite wall material and test their POV value;

[0142] 8. Prepare fish oil microcapsules (PPI / β-CD / CQDs / FO) with PPI / β-CD / CQDs as composite wall material and test their POV value;

[0143] Specific results are as follows Figure 8 As shown, from Figure 8 As can be seen from the data, the microcapsules with PPI / β-CD / CQDs as wall materials exhibit the smallest change in POV value.

[0144] 1) With the passage of time, the POV of unmicroencapsulated fish oil increased significantly compared to microencapsulated fish oil (p<0.05); 2) The POV values ​​of PPI / FO, β-CD / FO, CQDs / FO, PPI / β-CD / FO, PPI / CQDs, and β-CD / CQDs / FO microcapsules changed much less than those of unmicroencapsulated fish oil; 3) The POV value of PPI / β-CD / CQDs / FO composite wall material microcapsules changed the slowest and was significantly lower than that of the first six types of fish oil microcapsules (p<0.05), while the POV values ​​of the first six types of fish oil microcapsules were similar.

[0145] The oxidation rate of microencapsulated fish oil was significantly lower than that of non-microencapsulated fish oil (p<0.05). This may be because there is a certain relationship between the oxidation rate of oil and the rate of oxygen permeation through the wall material. Since the microcapsule wall material has a dense structure, it can effectively block oxygen permeation, thus significantly improving its shelf life.

[0146] After 12 days, the oxidation rate of fish oil microcapsules increased significantly (p<0.05). This is likely because the wall material of the microcapsules changed under the long-term action of high temperature environment, which led to changes in their physical characteristics, destroyed the original dense structure, and caused the fish oil to seep out, thereby accelerating the oxidation of fish oil.

[0147] Comparing the changes in POV of fish oil microcapsules encapsulated with different wall materials, it was found that when each of the three materials was used alone as a wall material to encapsulate fish oil, the POV value of all three materials increased significantly. However, under PPI / β-CD / CQDs encapsulation, the POV of fish oil microcapsules encapsulated with PPI / β-CD / CQDs showed a significant difference from that of fish oil microcapsules encapsulated with other wall materials in the later stage of storage (p<0.05). This may be because when the three materials were used in combination to prepare a composite wall material, the properties of the composite wall material changed accordingly. On the basis of the original antioxidant properties of CQDs, the antioxidant properties of the composite wall material were significantly enhanced, which alleviated the oxidation of fish oil to a certain extent.

[0148] Therefore, under optimal storage conditions, the fish oil microcapsules prepared in Example 1, using PPI / β-CD / CQDs as composite wall material, exhibit the strongest antioxidant properties and alleviate the oxidation of fish oil.

[0149] Example 9: Screening of the ratio of PPI to β-CD in wall material solution

[0150] To prepare the fish oil microcapsules with the best performance as in Example 1, this example investigated the ratio of PPI to β-CD in the wall material solution. The specific steps are as follows: PPI and β-CD stock solutions were mixed to achieve a mixing ratio of (1:1, 2:1, 4:1, 6:1, 8:1, and 10:1, w / v), with the total amount of the biopolymer mixture fixed at 2.00%. Under pH conditions of 2–10, the OD value (absorbance at 600 nm) was measured using a TU-1810PC UV-Vis spectrophotometer (Beijing Purkinje General Instrument Co., Ltd.). The pH-dependent turbidity (visual observation of solution turbidity) and zeta potential of PPI were measured using a zeta-sizer laser particle size analyzer (Shanghai Sibaiji Instrument System Co., Ltd.). The effect of adding or not adding β-CD on the solution was investigated.

[0151] Table 1. Effect of the mixing ratio of PPI to β-CD on the wall material solution at pH = 4.5

[0152] Mixture ratio of PPI and β-CD <![CDATA[OD 600 ]]> ζ-potential 1：1 1.65412 -51.78 2：1 1.86523 -56.82333 4：1 1.89482 -53.03667 6：1 1.96532 -59.05667 8：1 2.02354 -58.09667 10：1 2.13462 -63.55

[0153] As shown in Table 1, at pH = 4.5, when the mixing ratio of PPI to β-CD is 1:1, the solution is the clearest, with the highest OD value. 600 The absolute value of the ζ-potential is the lowest, but there is no significant difference. Figure 9A The turbidity curve and zeta potential of PPI solution are shown below, from... Figure 9AAs can be seen, the zeta potential of PPI solution decreases with increasing pH. The isoelectric point (pI) of PPI is approximately 4.6; below this value, the solution carries a positive charge. Simultaneously, as the pH decreases, the PPI solution exhibits three distinct phase regions: clear and transparent at pH 10–6.5, turbid at pH 6–3, and returning to clear and transparent at pH 3–2. This is because the zeta potential of the PPI solution tends to stabilize within the pH range of 10–6.5, and its absolute value is relatively large. When the pH reaches 6, the absorbance of the solution increases slightly, possibly related to the gradual decrease in the absolute value of the PPI solution's zeta potential. When the pH is between 5.5 and 3.5, the absorbance increases significantly, and the turbidity of the solution increases rapidly. This may be because as the pH decreases, the zeta potential of the PPI solution changes from negative to positive, and the amount of insoluble matter continuously increases. Subsequently, as the pH decreases further, the zeta potential of the PPI solution tends to stabilize, the turbidity decreases, and the solution tends to become clearer.

[0154] Figure 9B To determine OD at different pH values 600 The variation with PPI concentration, from Figure 9B As can be seen from this, at pH=4.5, OD 600 The values ​​were all the highest, and the OD of the solution increased with increasing PPI concentration. 600 The continuously increasing value indicates a continuous increase in the turbidity of the solution; therefore, OD is preferred. 600 The lowest value.

[0155] Table 1 shows that when the PPI / β-CD mass ratio is 1:1, the OD of the complex solution is... 600 The value is the lowest because of OD 600 The size of OD is mainly affected by the PPI content. When the PPI content is low, its ability to bind with water decreases with changes in pH, resulting in precipitation and a corresponding decrease in its binding with β-CD. As the PPI content increases, it exceeds the binding capacity with β-CD, leading to supersaturation of the solution. Consequently, the binding capacity with β-CD decreases, and the turbidity of the solution increases. Therefore, when the PPI / β-CD mass ratio is 1:1, OD... 600 It has the lowest value, the largest absolute value of ζ-potential, the lowest turbidity of solution, and the best binding ability of PPI to β-CD.

[0156] Therefore, it can be seen that the best effect can be achieved when the optimal mixing mass ratio of PPI to β-CD in the wall material solution is 1:1. In Example 1, the preferred mass ratio of PPI to β-CD in the preparation of the wall material solution is 1:1.

[0157] Example 10: Screening of the ratio of composite wall material to core material in fish oil microcapsules

[0158] To prepare the fish oil microcapsules with the best performance as in Example 1, this example investigates the effect of the amount of core material added on the fish oil microcapsules. The specific steps are as follows: PPI / β-CD composite wall material and core material (fish oil:FO) are mixed at mass ratios of 1:1, 2:1, 4:1, 6:1, 8:1, and 10:1. The PPI / β-CD / FO mixture is homogenized at 10,000 rpm for 3 min at room temperature to form a uniform emulsion. It is then pre-frozen at -80°C for 2 h. Microcapsules are formed by freeze-drying (vacuum degree 0.1 mbar, cold trap temperature -54°C, partition temperature -10°C, time 25 h (based on complete freeze-drying)). The prepared microcapsule products are then placed in a desiccator for later use.

[0159] The results are as follows Figure 10 As shown, the wall-to-core ratio significantly affects the encapsulation efficiency of fish oil (p<0.5). With increasing wall-to-core ratio, the encapsulation efficiency continuously increases. The highest encapsulation efficiency (85.92%) is achieved at a wall-to-core ratio of 10:1, which is significantly different from the encapsulation efficiency at other wall-to-core ratios. Simultaneously, the loading rate also indicates that with increasing wall-to-core ratio, the loading rate of fish oil continuously increases, resulting in better encapsulation. The highest loading rate (84%) is achieved at a wall-to-core ratio of 10:1, which is significantly different from the loading rate at other wall-to-core ratios.

[0160] Therefore, it can be seen that when the wall-to-core ratio is 10:1, PPI / β-CD exhibits good performance in improving the encapsulation and loading rates of fish oil. In Example 1, the preferred mass ratio of composite wall material to core material is 10:1.

[0161] Example 11 Screening of the ratio of PPI / β-CD to CQDs in fish oil microcapsules

[0162] To prepare fish oil microcapsules with optimal performance as in Example 1, this example investigated the effect of CQDs concentration on microencapsulation efficiency. The specific steps are as follows: Different amounts of CQDs were added to a PPI / β-CD solution to obtain different mass ratios of PPI / β-CD to CQDs (100:0, 100:1, 50:1, 20:1, 10:1, 5:1), and the mixture was continuously stirred at 1200 rpm for 2 hours. The resulting PPI / β-CD / CQDs mixed solution was then mixed with fish oil in a predetermined ratio, homogenized at 10000 rpm for 3 minutes at room temperature, and finally dried in a freeze dryer to obtain PPI / β-CD / CQDs / FO microcapsules.

[0163] The results are as follows Figure 11As shown, when the ratio of PPI / β-CD to CQDs reached 20:1, the encapsulation efficiency significantly increased to 86.96% (p<0.05). PPI / β-CD and CQDs have a synergistic effect on improving the encapsulation efficiency of fish oil, because CQDs can promote the capture of more fish oil into nanoparticles.

[0164] When the ratio of PPI / β-CD to CQDs was 10:1, the encapsulation efficiency decreased. This was because there was an excess of CQDs in the system, and single CQDs could not effectively encapsulate fish oil. Therefore, it can be seen that when only CQDs are used as the wall material to encapsulate fish oil, the encapsulation efficiency will decrease significantly. Compared with PPI / β-CD encapsulation of fish oil, the addition of CQDs reduced the loading rate. However, the loading rate varied with the amount of CQDs added. As the proportion of CQDs increased, the loading rate first increased and then decreased, reaching its highest point when the ratio of PPI / β-CD to CQDs was 20:1. These results indicate that adding an appropriate amount of CQDs can significantly improve the encapsulation efficiency of fish oil microcapsules while maintaining a good loading rate.

[0165] Therefore, it can be seen that when the ratio of PPI / β-CD to CQDs is 20:1, the fish oil microcapsules have the best encapsulation efficiency and good loading rate. In Example 1, the preferred mass ratio of PPI / β-CD to CQDs is 20:1.

[0166] Example 12: Infrared spectra of PPI, β-CD, CQDs, fish oil, and microcapsule samples

[0167] Infrared spectroscopy was performed on the PPI, β-CD, CQDs, and fish oil used as wall materials in Example 1, as well as the prepared PPI / β-CD / CQDs fish oil microcapsules. The specific results are as follows: Figure 10 As shown.

[0168] from Figure 12 As can be seen from the infrared spectrum of PPI, 3310 cm⁻¹ -1 The absorption peak is the stretching vibration of -OH, at 1636 cm⁻¹. -1 For C=O or antisymmetric carboxyl stretching vibration, 1460 cm⁻¹ -1 CH bending vibration, CN stretching vibration at 1146 cm⁻¹; β-CD spectrum at 3333 cm⁻¹ -1 1649cm -1 The key peak (stretching) shown at [location] belongs to the OH and HOH stretching modes; in the infrared spectrum of fish oil, [value] is 2923 cm⁻¹. -1 and 2857cm -1 For antisymmetric and symmetric stretching vibrations of the CH bond in CH2, 1744 cm. -1 This is the characteristic peak of C=O in fatty acid ester bonds, 1465 cm⁻¹.-1 This represents the scissor vibration of the CH bond in fatty acids, 1158 cm⁻¹. -1 The nearby characteristic peaks represent the stretching vibrations of CO and COC in the ester bond, 717 cm⁻¹. -1 This refers to the out-of-plane bending vibration of the CH bond in CH2.

[0169] The results showed that, after freeze-drying, the fish oil microcapsules exhibited two different characteristic absorption peaks in the infrared spectra of the composite wall materials PPI / β-CD and PPI / β-CD / CQDs, indicating that the fish oil was successfully encapsulated. Furthermore, no chemical changes occurred after encapsulation of PPI, β-CD, CQDs, and fish oil, making them ideal wall materials.

[0170] In summary, this invention preferably uses PPI, β-CD, and CQDs together as composite wall materials, with a preferred PPI:β-CD ratio of 1:1, a core-to-wall ratio of 1:10, and a PPI / β-CD:CQDs ratio of 20:1. The resulting fish oil microcapsules not only have uniform particle size and intact morphology, but also possess high solubility, high stability, strong antioxidant properties, and high encapsulation efficiency, effectively protecting the fish oil while enhancing its targeted sustained-release ability in intestinal fluid, thus facilitating human absorption.

[0171] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A fish oil microcapsule, characterized in that, The invention comprises a composite wall material and a core material. The composite wall material includes pea protein, β-cyclodextrin, and carbon quantum dots, and the core material is fish oil. In the composite wall material, the mixing concentration ratio of pea protein to β-cyclodextrin is 1–10:1; the mass ratio of the pea protein / β-cyclodextrin composite wall material solution to the core material is 1–10:1; the mass ratio of the pea protein / β-cyclodextrin mixed solution to carbon quantum dots is 5–100:

1. The carbon quantum dots are prepared as follows: Step 1: Carbon quantum dots are prepared using the Maillard reaction; firstly, 0… 6g of glucose and 0.6g / L-lysine were ultrasonically dissolved in 40mL of deionized water and heated in a microwave oven for 10min. Then, the prepared carbon quantum dots were dissolved in a small amount of deionized water and centrifuged at 10000r / min for 10min to remove solid precipitates and obtain supernatant. The supernatant was further filtered using a 0.22μm disposable syringe filter to remove solid impurities. Finally, the supernatant was placed in a dialysis bag and dialyzed in deionized water for 24h. Then, it was transferred to a vacuum freeze dryer and dried at -40℃ for one day to obtain solid pure carbon quantum dots.

2. The fish oil microcapsule as described in claim 1, characterized in that, In the composite wall material, the mixing concentration ratio of pea protein to β-cyclodextrin is 1:

1.

3. The fish oil microcapsule as described in claim 1, characterized in that, The mass ratio of the pea protein / β-cyclodextrin composite wall material solution to the core material is 10:

1.

4. The fish oil microcapsule as described in claim 1, characterized in that, In the composite wall material, the mass ratio of the pea protein / β-cyclodextrin mixed solution to carbon quantum dots is 20:

1.

5. The method for preparing fish oil microcapsules according to any one of claims 1 to 4, characterized in that, Includes the following steps: 1) Preparation of wall material: Solid pure carbon quantum dots were prepared by Maillard reaction; pea protein and β-cyclodextrin solutions were prepared separately, with the mixing concentration ratio of pea protein to β-cyclodextrin being 1 to 10:1, and mixed to obtain wall material solution; 2) Preparation of microcapsules: Microcapsules were prepared according to a mass ratio of pea protein / β-cyclodextrin composite wall material solution to core material of 1 to 10:1; a mixed solution was obtained according to a mass ratio of pea protein / β-cyclodextrin mixed solution to carbon quantum dots of 5 to 100:1, and then the mixed solution was mixed with fish oil according to a determined ratio and dried to obtain pea protein / β-cyclodextrin / carbon quantum dots / fish oil microcapsules.

6. The preparation method according to claim 5, characterized in that, In the preparation of the wall material, carbon quantum dots are prepared using glucose and L-lysine in a mass ratio of 1:1; the wall material solution contains 2% pea protein and 2% β-cyclodextrin.

7. The use of a composite wall material as described in any one of claims 1-4 for preparing fish oil microcapsules with high solubility, high stability, strong antioxidant properties, or high encapsulation efficiency, characterized in that, The composite wall material includes pea protein, β-cyclodextrin, and carbon quantum dots; in the composite wall material, the mixing concentration ratio of pea protein to β-cyclodextrin is 1 to 10:1, and the mass ratio of the pea protein / β-cyclodextrin mixed solution to carbon quantum dots is 5 to 100:

1.

8. The use of a composite wall material as described in any one of claims 1-4 for preparing fish oil microcapsules with no fishy odor and a long shelf life, characterized in that, The composite wall material includes pea protein, β-cyclodextrin, and carbon quantum dots; in the composite wall material, the mixing concentration ratio of pea protein to β-cyclodextrin is 1 to 10:1, and the mass ratio of the pea protein / β-cyclodextrin mixed solution to carbon quantum dots is 5 to 100:1.

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