Method for preparing lutein ester microcapsule powder based on OSA modified starch

Abstract

The invention provides a method for preparing lutein ester microcapsule powder based on OSA modified starch, which comprises the following operations: core material preparation: mixing lutein ester and sunflower seed oil, and stirring at 60-80 DEG C to obtain a core material; wall material preparation: weighing OSA modified starch, dispersing the OSA modified starch in water, adding an emulsifier, and stirring until the OSA modified starch is completely hydrated to obtain a wall material solution; embedding: under the temperature condition of 60-80 DEG C, dropwise adding the core material into the continuously stirred wall material solution, stirring and mixing, and then shearing and emulsifying for 8-15 minutes to obtain a crude emulsion; the crude emulsion is homogenized under the condition of 50 to 70 Mpa; and drying: carrying out spray drying or vacuum freeze drying on the emulsion. According to the lutein ester microcapsule powder prepared by the method disclosed by the invention, the P-M embedding rate is 91.71%, the loading rate is 9.96%, and the moisture content is 3.36%. The lutein ester capsule is good in powder state, excellent in solubility and compact in capsule wall structure, and the stability, dispersity and machinability of lutein ester are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of food nutrition products, and in particular relates to a preparation method of lutein ester microcapsule powder and the obtained product. Background Art

[0002] Lutein esters are the esterification products of lutein and fatty acids. They are the primary form of lutein in plants and are widely distributed in natural plant resources such as marigold, corn, and spinach. After ingestion, they are hydrolyzed by lipase and converted into free lutein. Lutein esters have multiple physiological functions, including free radical scavenging, antioxidant protection, maintaining biomembrane stability, and protecting the retina. They are widely used in health foods, nutritional supplements, and natural colorants. Due to their natural origin and well-defined activity, lutein esters have been recognized as a new food ingredient and hold promising development prospects in the food industry.

[0003] However, as a highly conjugated, fat-soluble compound, lutein esters are sensitive to physical and chemical properties and are easily degraded under the influence of environmental factors such as light, heat, and oxygen, resulting in loss of functional activity. At the same time, they have poor dispersibility and low stability in aqueous systems. Under normal conditions, their solubility is extremely low. Even in edible oils, they can only dissolve in small amounts and require chloroform, dichloromethane and other organic solvents for full dissolution. This not only limits their application in various food systems such as liquid beverages and dairy products, but also poses challenges to the development of their formulations as supplements or functional ingredients. In addition, due to their hydrophobic structure, it is difficult to form a stable dispersion system in the gastrointestinal tract, and the absorption efficiency of lutein esters in the body is low, which seriously restricts the effective performance of their nutritional functions. Therefore, improving their water dispersibility, environmental stability and intestinal bioaccessibility has become a key technical difficulty in achieving their efficient industrial application.

[0004] In order to overcome the above obstacles, the development of delivery systems for lutein esters has become a research hotspot in recent years. Researchers have proposed a variety of encapsulation and modification strategies, including cyclodextrin inclusion complexes, nanoemulsions, Pickering emulsions, liposomes, nanocrystals, and ultrafine powders, in order to improve their physical and chemical properties and absorption behavior. In such studies, Ma Qing et al. prepared lutein ester freeze-dried sub-emulsions using algae oil as the oil phase and phospholipids as the water phase. The results showed that the lutein esters not only had good solubility and stability, but also had significantly improved oral bioavailability compared to lutein esters (Ma Qing, Jin Meixi, Wang Xiaoli, et al. Preparation and in vitro and in vivo evaluation of lutein ester freeze-dried sub-microemulsions [J]. Chinese Journal of Pharmaceutical Industry, 2023, 54(10): 1450-1458.). Feng Ziqi (Feng Ziqi. Preparation process, characterization and activity evaluation of lutein ester ultrafine powder by antisolvent deposition method [D]. Northeast Forestry University, 2017.) used the antisolvent deposition method to prepare lutein ester ultrafine powder with a particle size of 164.00±4.30nm. The water solubility, antioxidant activity and bioavailability were significantly improved. However, this method uses a variety of organic solvents, and there is a hidden danger of organic reagent residues.

[0005] In comparison, microencapsulation technology, as a mature form of delivery system for functional active substances, has been widely used in the stabilization processing of nutrients such as fat-soluble vitamins and functional oils due to its controllable structure, wide range of wall material sources, strong environmental adaptability, and high compatibility with food systems. By constructing a multi-level protective structure, the microencapsulation system can effectively block external environmental interference such as light, heat, and oxygen, delaying the degradation process of active ingredients, and possessing excellent controlled-release properties and potential targeted release capabilities, showing outstanding potential for industrial application. However, related products currently sold on the market and microencapsulation technologies reported in the literature mostly use a single wall material system, such as gum arabic, gelatin, and starch, and still have technical limitations such as low encapsulation efficiency, uneven particle size distribution, poor controlled-release performance, and insufficient environmental responsiveness. Some microencapsulation systems have limited research on the release behavior of lutein esters in simulated gastrointestinal environments, lacking a systematic analysis of their release mechanism and structural stability, making it difficult to achieve precise delivery of functional ingredients under physiological conditions. In addition, some wall materials have poor stability under food processing conditions such as high temperature and high shear, and are prone to denaturation or phase separation, making it difficult to adapt to the processing requirements of complex application scenarios such as beverages, milk powder, and baked products.

[0006] Therefore, the development of a new lutein ester microcapsule delivery system with high encapsulation rate, good dispersibility, strong environmental stability, controllable release behavior, and suitable for large-scale production in the food industry can not only significantly improve the in vivo utilization efficiency and application adaptability of its functional ingredients, but also provide technical support for the efficient utilization and precise delivery of functional nutrients, which has important research significance and application prospects. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of the present invention is to propose a method for preparing lutein ester microcapsule powder based on OSA modified starch, so as to obtain a new microcapsule encapsulation technology with simple process, equipment compatibility and functional targeting at a lower cost.

[0008] Another object of the present invention is to provide lutein ester microcapsule powder prepared by the method.

[0009] The technical solution for achieving the above-mentioned purpose of the present invention is:

[0010] A method for preparing lutein ester microcapsule powder based on OSA-modified starch comprises the following steps:

[0011] Core material preparation: lutein ester and sunflower oil are mixed and stirred at 60-80° C. for 1-3 hours to obtain a core material;

[0012] Preparation of wall material: Weigh OSA modified starch and disperse it in water, add emulsifier, and stir at 70-90°C until completely hydrated to obtain wall material solution;

[0013] Embedding: Add the core material dropwise to the continuously stirred wall material solution at a temperature of 60-80°C, stir and mix for 8-15 minutes, and then shear and emulsify for 8-15 minutes to obtain a crude emulsion; homogenize the crude emulsion at 50-70 MPa, and repeat 2-4 times to obtain a lutein ester emulsion;

[0014] Drying: spray drying the emulsion to obtain lutein ester microcapsule powder, or vacuum freeze drying is used for 40 to 60 hours.

[0015] Wherein, the OSA modified starch is selected from one of OSA modified starch 12633, OSA modified starch 12674, OSA modified starch 12670I, OSA modified starch PURITY GUM2000 and OSA modified starch HI-CAP100.

[0016] Octenyl succinic anhydride modified starch (OSA-modified starch) is derived from natural starch molecules through hydrophobic esterification. As an amphiphilic polymer, OSA-modified starch possesses unique molecular structure and physicochemical properties, making it the preferred wall material for this microencapsulated powder preparation method. Sunflower oil added during the preparation stage not only serves as a carrier for the lutein esters but also promotes their formation into micellar structures during simulated digestion, enhancing their bioaccessibility.

[0017] The mass proportion of the lutein ester is 0.50% to 2.50% of the total mass of the emulsion, the mass proportion of the sunflower oil is 4% to 8%, and the mass proportion of the OSA modified starch is 20% to 30%. The added amount of the emulsifier is 0.5% to 2.5%, and the balance is water.

[0018] Preferably, the emulsifier is selected from one of Tween 20, Tween 60 and Tween 80. The added amount of the emulsifier is 0.5% to 1.5%.

[0019] More preferably, the lutein ester is added in an amount of 0.50% to 1.50% by mass and mixed with 5 to 6% of sunflower oil.

[0020] In the preparation of the wall material, one or more of maltodextrin (MD), sodium caseinate (SC), and gelatin (GL) are selected and mixed with OSA modified starch in a mass ratio of 15-19:4-1 to form a composite wall material to prepare a wall material solution.

[0021] A preferred technical solution of the present invention is that, in the compound wall material, the wall material is compounded by OSA modified starch PURITYGUM2000 and sodium caseinate in a ratio of 18:2 (w / w).

[0022] The spray drying process parameters are: inlet air temperature 180-220°C, outlet air temperature 90°C, and injection speed 350-400 mL / h.

[0023] The vacuum freeze-drying process is as follows: the emulsion is thinly spread on a glass culture dish, pre-cooled at -80°C for 12 hours, and finally dried in a vacuum freeze dryer for 48 hours to obtain lutein ester microcapsule powder.

[0024] Furthermore, the spray drying is carried out under the synergistic effect of an inlet air temperature of 180° C. and an atomization pressure of 15-25 MPa.

[0025] A preferred technical solution of the present invention comprises the following operations:

[0026] Preparation of core material: 1.0% to 1.50% lutein ester and 5 to 6% sunflower oil are mixed and stirred in a hot water bath at 65 to 75°C for 2 hours to obtain the core material;

[0027] Preparation of wall material: Weigh 20-25% of the composite wall material consisting of OSA modified starch and sodium caseinate and disperse it in water, add 0.8%-1.0% Tween 60, and stir in a hot water bath at 80-85°C until completely hydrated to obtain a wall material solution;

[0028] Embedding: In a hot water bath at 70-80°C, the core material is added dropwise to the continuously stirred wall material solution, and the mixture is stirred for 8-15 minutes. The mixture is then emulsified at 5000-8000 r / min using a high-speed disperser for 8-15 minutes to obtain a crude emulsion. The crude emulsion is homogenized at 50-70 MPa for three cycles to obtain a lutein ester emulsion.

[0029] Drying: The emulsion is spray-dried to obtain lutein ester microcapsule powder.

[0030] Lutein ester microcapsule powder prepared by the method of the present invention.

[0031] The beneficial effects of the present invention are:

[0032] This proposed method for preparing lutein ester microencapsulated powders based on OSA-modified starch systematically optimizes the formulation for a high-load lutein ester emulsion, using encapsulation efficiency and loading as evaluation indicators. This emulsion formulation significantly improves the encapsulation efficiency of lutein esters in the emulsion system by optimizing the synergistic effects of the wall materials and the stability of the emulsification system.

[0033] The lutein ester microcapsule powder prepared by the present invention is a yellow powder free of impurities and odors, possessing the distinctive flavor of lutein esters and meeting the basic sensory quality requirements of microcapsule products. The DM encapsulation efficiency is 89.49±0.86%, the loading efficiency is 11.17±0.11%, and the moisture content is 4.38±0.09%. The PM encapsulation efficiency is 91.71±0.08%, the loading efficiency is 9.96±0.11%, and the moisture content is 3.36±0.13%. The powder is in good condition, has excellent solubility, and features a dense capsule wall structure, significantly improving the stability, dispersibility, and processability of the lutein esters. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a comparison chart of the entrapment efficiency (A), loading amount (B), Zeta potential (C), particle size distribution (D) and storage stability (E) of lutein ester emulsions prepared with different OSA-modified starches.

[0035] Figure 2 The encapsulation efficiency (A), loading capacity (B), zeta potential (C), particle size distribution (D) and 3d storage stability (E) of lutein ester emulsions prepared with different emulsifiers.

[0036] Figure 3 Graph comparing the entrapment efficiency (A), loading amount (B), zeta potential (C), particle size distribution (D), and 5-day storage stability (E) of the lutein ester emulsion prepared by gradient addition of Tween 60 in Example 3.

[0037] Figure 4Encapsulation efficiency (A), loading capacity (B), zeta potential (C), particle size distribution (D) and 7-day storage stability (E) of lutein ester emulsions prepared with different compound formulas.

[0038] Figure 5 Entrapment efficiency (A), loading amount (B), zeta potential (C), particle size distribution (D) and storage stability (E) of lutein ester emulsions prepared by gradient addition of lutein esters.

[0039] Figures 1 to 5 In the table, different letters indicate significant differences among different emulsions, p < 0.05.

[0040] Figure 6 Photos of PM (left) and DM (right).

[0041] Figure 7 Photos of aqueous dispersions of lutein esters (left), PM (middle), and DM (right);

[0042] Figure 8 is the particle size distribution of PM and DM.

[0043] Figure 9 Scanning electron microscopy images of lutein esters, PM, and DM.

[0044] Figure 10 FTIR analysis images of single component and lutein ester microcapsule powder.

[0045] Figure 11 DSC analysis images of PM and DM

[0046] Figure 12 Changes in the retention rates of lutein esters, PM, and DM under white light (A) and ultraviolet light (B); changes in the antioxidant activities of lutein esters, PM, and DM under white light (C) and ultraviolet light (D).

[0047] Figure 13 These are the XRD analysis images of lutein ester, PM and DM before and after 13 days of illumination.

[0048] Figure 14 DSC analysis images of PM and DM before and after 13 days of illumination.

[0049] Figure 15 The changes in the storage retention rates of lutein esters, PM and DM at 4°C (A), room temperature (B) and 50°C (C); the changes in the antioxidant activities of lutein esters, PM and DM at 4°C (D), room temperature (E) and 50°C (F).

[0050] Figure 16ΔL*(A), Δa*(B), Δb*(C) and ΔE(D) of lutein esters, PM and DM after 13 days of storage at different temperatures. Note: Different letters indicate significant differences between samples (p < 0.05)

[0051] Figure 17 These are the XRD analysis images of lutein ester, PM and DM before and after storage at different temperatures for 13 days.

[0052] Figure 18 The release curves of lutein ester, PM and DM.

[0053] Figure 19 Comparison of the recovery, release rate and bioaccessibility of lutein esters, PM and DM after digestion. DETAILED DESCRIPTION

[0054] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0055] Unless otherwise specified, the technical means used in the specification are all known in the art, and the raw materials used are all commercially available.

[0056] Some of the raw materials used in the examples are shown in the table below.

[0057] Table 0 Materials and reagents

[0058]

[0059] In the examples, the lutein ester content was measured using ultraviolet spectrophotometry.

[0060] Example 1 Preparation of High-Load Lutein Ester Emulsion (Effect of OSA Modified Starch Type)

[0061] Preparation of core material: 1.22 g of lutein ester and 5.50 g of sunflower oil were mixed and stirred in a 70° C. hot water bath for 2 hours to obtain the core material.

[0062] Preparation of wall material: 24 g each of OSA-modified starch 12633, OSA-modified starch 12674, OSA-modified starch 12670I, OSA-modified starch PURITY GUM2000, and OSA-modified starch HI-CAP100 were weighed and dispersed in water. The mixture was stirred in a hot water bath at 80°C until completely hydrated to obtain a wall material solution.

[0063] Embedding: In a 70°C hot water bath, add the core material dropwise to the continuously stirred wall material solution. Stir and mix for 10 minutes. Then, emulsify using a high-speed disperser at 7000 rpm for 10 minutes to obtain a crude emulsion. Finally, homogenize the crude emulsion at 60 MPa for three cycles to obtain a lutein ester emulsion. Store refrigerated at 4°C.

[0064] The lutein ester loading, electric potential, and particle size in the emulsion were determined, and the stability of the emulsion under refrigerated conditions at 4°C was observed.

[0065] Depend on Figure 1 From (A) and (B), we can see that the encapsulation rate and loading capacity of lutein esters in the emulsion prepared by 12633 are 36.94% and 9.01 mg / mL, respectively, that of 12674 are 42.53% and 10.38 mg / mL, that of 12670I are 42.99% and 10.49 mg / mL, that of GUM are 47.55% and 11.60 mg / mL, and that of HI are 42.26% and 10.31 mg / mL. Moreover, the encapsulation rate and loading capacity of lutein esters in the emulsion prepared by GUM are significantly higher (p<0.05) than those of the other four OSA modified starches. From the results of storage stability, it can be seen that after 24 hours of storage, except for the emulsion prepared by GUM, the other four emulsions all showed obvious oil phase precipitation and floating, that is, Figure 1 The reddish-brown part in (E) indicates that GUM as a wall material has a better encapsulation effect on lutein esters than the other four OSA-modified starches, has a stronger encapsulation effect on the core material, and is better able to maintain the stability of the emulsion.

[0066] The particle size distribution shows no significant differences in the lutein ester emulsions prepared with different OSA-modified starches. However, the emulsions prepared with different OSA-modified starches exhibited some differences in zeta potential, with the emulsion prepared with OSA-modified starch 12670I having a significantly lower zeta potential than the other four emulsions.

[0067] Example 2

[0068] Core material preparation: same as Example 1;

[0069] Preparation of wall material: Weigh 24 g of GUM and disperse it in water. Add 1.22 g each of emulsifiers Tween 20, Tween 60, and Tween 80, respectively. Stir in a hot water bath at 80°C until completely hydrated to obtain a wall material solution.

[0070] Embedding: Same as Example 1.

[0071] Figure 2 This reflects the effect of emulsifier types on lutein ester emulsion. Figure 2 From (A) and (B), we can see that the addition of emulsifiers has improved the embedding rate and loading capacity of lutein esters. When the emulsifier is Tween 60, the loading capacity is the highest, which is 19.85 mg / mL. According to the particle size distribution, it is found that the particle size of the three emulsions has shifted towards a smaller particle size as a whole compared to when no emulsifier is added, and the particle size distribution is also more concentrated. Figure 2In (D), no oil phase precipitation occurred in the three emulsions within 3 days, indicating that the stability of the emulsions was significantly improved.

[0072] Example 3 Tests on different emulsifier addition amounts

[0073] Core material preparation: same as in Example 1.

[0074] Wall material preparation: Weigh 24 g of GUM and disperse it in water. Add 0.5% (in this ratio, the total mass of the emulsion is 100 g, the emulsifier is 0.5 g, and the water is 68.78 g), 1.0%, 1.5%, 2.0%, and 2.5% of Tween 60, respectively. Stir in an 80°C hot water bath until completely hydrated to obtain a wall material solution.

[0075] Embedding: Same as Example 1.

[0076] The lutein ester encapsulation efficiency, loading amount, zeta potential and particle size distribution in the emulsion were determined, and the stability of the emulsion under refrigerated conditions at 4°C was observed. Figure 3 The effect of emulsifier addition on the properties of lutein ester emulsion is presented intuitively. Figure 3 (A) When the addition amount of Tween 60 was 1.0% and 1.5%, the entrapment efficiency and loading amount of lutein ester reached a high level. However, there was no significant difference in zeta potential and particle size distribution.

[0077] Further observation of the emulsion after refrigeration for 5 days showed that Figure 2-3 In (D), it can be clearly seen that the three emulsions with Tween 60 addition levels of 0.5%, 2.0%, and 2.5% all exhibited varying degrees of stratification. Considering that food additives should be used as little as possible or not at all in food processing, and based on the experimental results, while ensuring the same emulsification effect, the final Tween 60 addition level of 1% was selected. This not only meets the emulsification stability requirements of the lutein ester emulsion, but also complies with the regulatory and health requirements for the use of additives in food processing.

[0078] Example 4 Tests on different types and proportions of composite wall materials

[0079] Core material preparation: same as in Example 1.

[0080] Wall material preparation: Maltodextrin (MD), sodium caseinate (SC), and gelatin (GL) were blended in four mass ratios: GUM: composite wall material = 16:4, 17:3, 18:2, and 19:1 (total composite wall material mass was 24 g). The wall materials were weighed and dispersed in water. 1% Tween 60 was added and stirred in an 80°C hot water bath until completely hydrated to obtain a wall material solution.

[0081] Embedding: Same as Example 1.

[0082] Figure 4 The reaction reflects the influence of compound wall material type and compound ratio on lutein ester emulsion. Figure 4 As shown in (A) and (B), the emulsions prepared by combining GUM with MD maltodextrin and sodium caseinate (SC) exhibited higher encapsulation efficiency and loading capacity than those prepared by combining GUM with GL. The emulsions prepared by combining GUM with SC at a ratio of 18:2 achieved the highest encapsulation efficiency and loading capacity. The emulsions prepared by combining GUM with SC exhibited optimal stability at a ratio of 18:2, with no apparent stratification.

[0083] Example 5 Test of different lutein ester addition amounts

[0084] Core material preparation: Lutein ester was accurately weighed according to the addition amount of 0.50%, 0.75%, 1.00%, 1.25% and 1.50%, and mixed with 5.50g of sunflower oil respectively, and stirred in a hot water bath at 70°C for 2 hours to obtain core materials.

[0085] Preparation of wall material: GUM and sodium caseinate (24 g of composite wall material) were weighed in a ratio of 18:2 (w / w), dispersed in water, 1% Tween 60 was added, and stirred in an 80°C hot water bath until completely hydrated to obtain a wall material solution.

[0086] Embedding: Same as Example 1.

[0087] Figure 5 This reflects the effect of lutein ester addition on lutein ester emulsion. Figure 5 As shown in Figures (A) and (B), the amount of lutein ester added significantly affects the encapsulation efficiency and loading capacity of the emulsions: the encapsulation efficiency decreases with increasing lutein ester addition, while the loading capacity increases. After 7 days of refrigeration, no obvious stratification was observed in any of the emulsions. Taking into account factors such as encapsulation efficiency, loading capacity, and efficiency, the lutein ester addition level was set at 1.00%.

[0088] Example 6

[0089] The steps for preparing the emulsion in this example were the same as those in Example 5, with the following parameters: a lutein ester content of 1% (w / w), a wall material composed of OSA-modified starch PURITY GUM2000 and sodium caseinate in a ratio of 18:2 (w / w), and a 1% (w / w) emulsifier, Tween 60. The emulsion prepared under these conditions exhibited excellent encapsulation properties, with a lutein ester encapsulation efficiency of 84.74% and a loading of 22.51 mg / mL.

[0090] Example 7 Preparation of Lutein Ester Microcapsule Powder

[0091] Preparation of core material: Lutein ester was accurately weighed according to an addition amount of 1.00%, mixed with 5.50 g of sunflower oil, and stirred in a 70° C. hot water bath for 2 hours to obtain the core material.

[0092] Preparation of wall material: GUM and sodium caseinate were weighed in a ratio of 18:2 (w / w) and dispersed in water (the mass of the composite wall material was 24 g), 1% Tween 60 was added, and the mixture was stirred in an 80°C hot water bath until completely hydrated to obtain a wall material solution.

[0093] Embedding: In a 70°C hot water bath, add the core material dropwise to the continuously stirred wall material solution. Stir and mix for 10 minutes. Then, emulsify using a high-speed disperser at 7000 rpm for 10 minutes to obtain a crude emulsion. Finally, homogenize the crude emulsion at 60 MPa for three cycles to obtain a lutein ester emulsion. Store refrigerated at 4°C.

[0094] Drying: The emulsion was spray-dried to obtain lutein ester microcapsule powder (PM). The spray drying process parameters were: 15-25 MPa atomization pressure, 180°C inlet air temperature, 90°C outlet air temperature, and an injection rate of 350-400 mL / h.

[0095] The prepared lutein ester microcapsule powder is yellow powder, free of impurities and odor, has the special flavor of lutein ester, and meets the basic sensory quality requirements of microcapsule products.

[0096] Example 8 Preparation of Lutein Ester Microcapsule Powder

[0097] A high-load lutein ester emulsion was prepared according to the method of Example 5.

[0098] Drying: The emulsion was thinly spread on a glass culture dish, pre-cooled at -80°C for 12 hours, and finally dried in a vacuum freeze dryer for 48 hours to obtain lutein ester microcapsule powder (DM).

[0099] The prepared lutein ester microcapsule powder is yellow powder, free of impurities and odor, has the special flavor of lutein ester, and meets the basic sensory quality requirements of microcapsule products.

[0100] Morphology and performance testing of lutein ester microcapsule powder

[0101] Figure 6 The macromorphology of spray-dried lutein ester microencapsulated powder (PM) and freeze-dried lutein ester microencapsulated powder (DM) was demonstrated. Systematic sensory evaluation showed that both PM and DM presented a uniform yellow powder with evenly distributed particles, no visible impurities or unusual odors, and retained the unique flavor of lutein esters. A comparison of PM and DM revealed that DM had a looser texture and could be ground and broken, while PM was smooth and delicate.

[0102] By measuring the color value of PM and DM, it can be seen that PM has greater brightness and DM is reddish-yellow.

[0103] Table 1 Color space values ​​of lutein esters, PM and DM

[0104]

[0105] The DM encapsulation efficiency was 89.49±0.86%, and the loading efficiency was 11.17±0.11%. The PM encapsulation efficiency was 91.71±0.08%, and the loading efficiency was 9.96±0.11%. Significant differences were observed between the two materials in terms of both encapsulation efficiency and loading efficiency. Both PM and DM contain no more than 5% moisture, making them less susceptible to caking and mold formation during transportation and storage, facilitating their preservation.

[0106] Depend on Figure 7 It can be seen that lutein ester is difficult to disperse in water, while PM and DM can be quickly dispersed in water to form a relatively clear yellow solution.

[0107] like Figure 8 As shown in the figure, the particle size distribution of PM and DM was analyzed. The results showed that the PM particle size was primarily concentrated around 10 μm, forming a relatively concentrated particle size distribution. This indicates that the lutein ester microencapsulated powder particles were formed uniformly during the spray drying process, with good particle size control. In contrast, the DM particle size was primarily concentrated around 100 μm, with a broad peak in the particle size distribution.

[0108] Table 2 Physicochemical properties of P-M and DM

[0109]

[0110] In Tables 1 and 2, the experimental results are expressed as mean ± SD. Different superscript letters in the same column indicate significant differences between samples (p < 0.05).

[0111] SEM analysis: The microstructure of lutein ester microcapsule powder was observed by scanning electron microscope. Figure 9 PM particles are round, with wrinkles and depressions on their surfaces. DM particles are irregular in shape and have a looser structure. Overall, the capsule walls of both PM and DM remain intact and compact, effectively protecting the core material.

[0112] FTIR analysis: The infrared spectra of each single component, physical mixture, PM and DM are measured. The results are as follows: Figure 10As shown. Comparing the infrared spectra of lutein esters with PM and DM, it was found that most of the characteristic peaks of lutein esters did not appear in the microcapsules, which shows that the wall material successfully encapsulated the lutein esters. The infrared spectrum of the physical mixture showed the main absorption bands of lutein esters, OSA-modified starch PURITY GUM2000 and sodium caseinate, indicating that there was no obvious interaction between lutein esters and the wall material in the physical mixing state. In the infrared spectra of PM and DM, the broad band corresponding to OH was blue-shifted, indicating that OSA-modified starch PURITY GUM2000 exposed more hydroxyl groups during the preparation process, and proved the existence of hydrogen bond interaction between it and lutein esters.

[0113] DSC analysis: Lutein ester crystals show a strong thermal melting peak at around 86°C, with a peak temperature of 86.17°C and a thermal melting enthalpy of 20.09 J / g. This characteristic peak corresponds to the phase transition process from the crystalline state to the molten state. In sharp contrast, the first endothermic transition temperatures of PM and DM increased to 172.03°C and 161.35°C, respectively, and the thermal melting enthalpy increased significantly. This phenomenon shows that the microencapsulation treatment significantly increases the thermal transition temperature of lutein ester, enabling the microcapsule system to stably maintain a glassy state under conventional storage conditions, effectively inhibiting the thermal phase change process of the core material. Figure 11 It can be seen that the thermal deformation temperatures of PM and DM are 271.60℃ and 264.73℃, respectively, among which PM shows a higher thermal deformation threshold.

[0114] Effects of light and temperature on the stability of lutein ester microencapsulated powder: Equal amounts of PM and DM were weighed and placed in transparent sealed bags. Lutein ester retention and antioxidant activity were determined after 1, 3, 5, 7, 9, 11, and 13 days of exposure to UV light. The 13-day sample was subjected to colorimetry, XRD, DSC, and SEM analysis. Lutein ester was also tested as a control under the same conditions. Lutein ester retention was also determined.

[0115] Retention rate, antioxidant activity and color difference: Effects of light on the retention rate and antioxidant activity of lutein esters in PM and DM are shown in Figure 12 Under white light irradiation, the lutein ester content in PM and DM decreased with the extension of illumination time, with the retention rates of PM and DM at the end being 80.59% and 83.04%, respectively. Furthermore, the degree of lutein ester degradation after UV irradiation was significantly greater than that after white light irradiation, with DM having the highest lutein ester retention rate (77.61%), while PM had a lower retention rate of 69.59%. The untreated sample had the lowest retention rate of lutein esters, at only 54.53%. Figure 12(C) and (D) are the results of the antioxidant activity test, and the antioxidant capacity is expressed as the amount of antioxidant Trolox per mg of PM, DM or lutein ester. Overall, the antioxidant activity of PM and DM decreased with the increase of illumination time. After irradiation with white light and ultraviolet light, the X-diffraction patterns of PM and DM were highly consistent with the initial patterns. This phenomenon shows that under the illumination environment, the structure and phase composition of the two microcapsule powders remain stable, and no structural changes such as crystal transformation and lattice distortion occur, proving that the microencapsulation treatment gives lutein esters good light stability. In sharp contrast, the unencapsulated lutein ester ( Figure 13 The diffraction pattern of the lutein ester (labeled as "lutein ester") changes significantly after exposure to light. This means that light significantly destroys the ordered structure of the lutein ester crystals, resulting in a decrease in its crystallinity and the transformation of part of the crystal structure into an amorphous state. The DSC test results reveal the differential effects of light on the thermal properties of lutein ester microcapsule powder prepared by different processes. After irradiation with white light and ultraviolet light, the glass transition temperature and thermal deformation temperature of PM show small fluctuations, and the change in thermal melting enthalpy is not significant, indicating that PM can maintain relatively stable thermal properties under light conditions (see Figure 14 ).

[0116] Effect of temperature on the retention of lutein esters in PM and DM Figure 15 As shown. After 13 days of storage at 4°C, the lutein ester content of PM and DM remained unchanged, with PM retaining 95.25% and DM retaining 94.12%. However, the retention rate of unencapsulated lutein esters was only 84.10%. During room temperature storage, the degradation rate of lutein esters in the three groups of samples was significantly higher than that during storage at 4°C. At the end of storage, PM had the highest lutein ester retention rate (86.35%), followed by DM (84.00%), and the unencapsulated lutein ester retention rate was the lowest (69.97%). Lutein esters in the three groups of samples rapidly degraded at 50°C, and significant differences were observed in the lutein ester retention rates of the samples at the end of storage. The retention rates of lutein esters in PM, DM, and the control group were 52.35%, 35.01%, and 20.93%, respectively.

[0117] Figure 15 (D), (E) and (F) are the antioxidant activity test results. The antioxidant activity of PM and DM showed a trend of attenuation with the extension of storage time.

[0118] See also Figure 16 Color difference measurements provide intuitive visual evidence for the stability of the microencapsulated powder. Under storage conditions of 4°C and room temperature, the color changes of PM and DM were minimal, indicating that the microencapsulated structure's protective effect on the lutein esters effectively inhibited the degradation of the pigment components.

[0119] XRD, DSC and SEM analysis: see Figure 17 After storage at different temperatures of 4°C, room temperature and 50°C, the X-ray diffraction patterns of PM and DM were highly consistent with their initial states, indicating that the crystal structure and phase composition of the two microcapsule powders remained stable.

[0120] In vitro digestion experiment

[0121] In vitro digestion experiments were performed using the standardized INFOGEST method.

[0122] Sample preparation: Accurately weigh a certain amount of lutein ester microcapsule powder (PM, DM) and dissolve it in pure water to prepare a microcapsule aqueous solution with a lutein ester concentration of 100 μg / mL. Take 1 mL of the microcapsule aqueous solution and mix it with 4 mL of pure water so that the lutein ester content in the sample used for digestion is 100 μg and the sample volume is 5 mL.

[0123] Oral phase: Add 3 mL of simulated saliva, 1 mL of α-amylase solution, 25 μL of 0.3 M CaCl₂ solution, and 975 μL of purified water to the digestion sample. Shake the mixture in a water bath at 95 rpm at 37°C for 2 minutes to obtain the oral phase digestion mixture.

[0124] Gastric phase: Add 6 mL of simulated gastric fluid to the oral digestion mixture, adjusting the pH to 4 with 1 M HCl. Subsequently, add 2 mL of pepsin solution, 10 μL of 0.15 M CaCl₂ solution, and 1.99 mL of purified water, adjusting the pH to 3 with 1 M HCl, to a final volume of 20 mL. Cover the mixture with a nitrogen purge (approximately 1 minute) and shake in a water bath at 95 rpm at 37°C for 2 hours to obtain the oro-gastric digestion chyme.

[0125] Intestinal phase: Adjust the pH of the oro-gastric digestion chyme to 6 with 1M NaOH. Then, add 11mL of porcine pancreatic enzymes, 5mL of bile, and 40μL of 0.3M CaCl2 solution. Adjust the pH to 7 with 1M NaOH, and finally add purified water to a final volume of 40mL. Cover the mixture with nitrogen purge (approximately 1 minute) and shake in a water bath at 95 rpm at 37°C for 2 hours. After intestinal digestion, bring the digestion solution to 50mL with purified water and mix thoroughly to obtain the final digestion solution.

[0126] 5 mL of digestion solution was taken to determine the recovery rate of lutein esters after in vitro digestion.

[0127] Lutein ester microcapsule powder release during digestion: Following the in vitro digestion protocol described above, digestive fluids were collected at 2 minutes after the start of the oral phase, 0 minutes, 15 minutes, 30 minutes, 60 minutes, and 120 minutes after the start of the gastric phase, and 0 minutes, 15 minutes, 30 minutes, 60 minutes, and 120 minutes after the start of the intestinal phase. The digestive fluids were centrifuged at 10°C and 10,000 g for 1 hour, and the supernatant was collected and used to determine the lutein ester release rate at different digestion time points.

[0128] Results of in vitro simulated digestion of lutein ester microcapsule powder: The lutein ester release curve of lutein ester microcapsule powder during in vitro simulated digestion is as follows Figure 18 As shown in the figure, it can be clearly observed that during the oral digestion phase, the release rate of PM and DM approaches zero, with almost no lutein ester release occurring. After entering the gastric digestion phase, only partial release occurs. However, during the intestinal digestion phase, the release rate of lutein esters from PM and DM accelerates dramatically, achieving rapid release.

[0129] Digestion results revealed similarities and differences between unencapsulated lutein esters and PM and DM. The post-digestion recovery rates for all three were around 90%, with no significant differences between them. This suggests that encapsulation did not significantly impact material recovery. However, in terms of release rate and bioaccessibility, two key metrics, PM and DM significantly outperformed unencapsulated lutein esters.

[0130] Combine Figure 18 and Figure 19 Analysis showed that the release rate of unencapsulated lutein ester reached its maximum value in the early gastric digestion stage during the simulated digestion process, and the release rate and bioaccessibility were only 12.3±3.4% and 10.7±2.5%, respectively, which were significantly lower than those of PM and DM.

[0131] The results showed that microencapsulation significantly increased the release rate and bioaccessibility of lutein esters, with the release rate and bioaccessibility of PM reaching 36.8±5.0% and 35.1±3.3%, respectively, and the release rate and bioaccessibility of DM reaching 39.5±4.9% and 37.3±3.7%, respectively. Furthermore, PM and DM are virtually indestructible in the oral phase and exhibit a certain degree of structural stability in the gastric digestive environment, inhibiting the premature release of lutein esters. During intestinal digestion, the microcapsule structure disintegrates under the action of pancreatic enzymes and the alkaline environment, promoting the rapid and substantial release of lutein esters, achieving controlled release targeted to the intestine and effectively enhancing the bioavailability of lutein esters.

[0132] Although the present invention has been described above through the embodiments, those skilled in the art should understand that any improvements and modifications made to the present invention without departing from the spirit and essence of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preparing lutein ester microcapsule powder based on OSA modified starch, characterized in that: The following operations are included: Core material preparation: lutein ester and sunflower oil are mixed and stirred at 60-80° C. for 1-3 hours to obtain a core material; Preparation of wall material: Weigh OSA modified starch and disperse it in water, add emulsifier, and stir at 70-90°C until completely hydrated to obtain wall material solution; Embedding: Add the core material dropwise to the continuously stirred wall material solution at 60-80°C, stir and mix for 8-15 minutes, then shear and emulsify for 8-15 minutes to obtain a coarse emulsion; homogenizing the crude emulsion under the condition of 50-70 MPa, and circulating 2-4 times to obtain a lutein ester emulsion; Drying: spray drying the emulsion to obtain lutein ester microcapsule powder, or vacuum freeze drying is used for 40 to 60 hours.

2. The method for preparing lutein ester microcapsule powder based on OSA modified starch according to claim 1, characterized in that: The OSA modified starch is selected from one of OSA modified starch 12633, OSA modified starch 12674, OSA modified starch 12670I, OSA modified starch PURITY GUM2000 and OSA modified starch HI-CAP100.

3. The method for preparing lutein ester microcapsule powder based on OSA modified starch according to claim 1, characterized in that: The mass proportion of the lutein ester is 0.50% to 2.50% of the total mass of the emulsion, the mass proportion of sunflower oil is 4% to 8%, and the mass proportion of OSA modified starch is 20% to 30%. The added amount of the emulsifier is 0.5% to 2.5%, and the balance is water.

4. The method for preparing lutein ester microcapsule powder based on OSA modified starch according to claim 1, characterized in that: The emulsifier is selected from one of Tween 20, Tween 60 and Tween 80, and the amount of the emulsifier added is 0.5% to 1.5% of the total mass of the emulsion; and / or The lutein ester is added in a mass ratio of 0.50% to 1.50% and is mixed with 5% to 6% of sunflower oil.

5. The method for preparing lutein ester microcapsule powder based on OSA modified starch according to claim 1, characterized in that: In the preparation of the wall material, one or more of maltodextrin, sodium caseinate, and gelatin are selected and mixed with OSA modified starch in a mass ratio of 15-19:4-1 to form a composite wall material to prepare a wall material solution.

6. The method for preparing lutein ester microcapsule powder based on OSA modified starch according to claim 5, characterized in that: OSA modified starch PURITY GUM2000 and sodium caseinate were compounded at a ratio of 18:2 (w / w).

7. The method for preparing lutein ester microcapsule powder based on OSA modified starch according to claim 1, characterized in that: The spray drying process parameters are: inlet air temperature 180-220°C, outlet air temperature 90°C, and injection speed 350-400 mL / h; the vacuum freeze-drying process is: thinly spread the emulsion on a glass culture dish, pre-cool it at -80°C for 12 hours, and finally dry it in a vacuum freeze dryer for 48 hours to obtain lutein ester microcapsule powder.

8. The method for preparing lutein ester microcapsule powder based on OSA modified starch according to claim 7, characterized in that: The spray drying is carried out under the synergistic effect of an inlet air temperature of 180° C. and an atomization pressure of 15-25 MPa.

9. The method for preparing lutein ester microcapsule powder based on OSA modified starch according to any one of claims 1 to 8, characterized in that: The following operations are included: Core material preparation: 1.0% to 1.50% lutein ester and 5 to 6% sunflower oil are mixed and stirred in a hot water bath at 65 to 75°C for 2 to 3 hours to obtain the core material; Preparation of wall material: Weigh 20-25% of the composite wall material consisting of OSA modified starch and sodium caseinate and disperse it in water, add 0.8%-1.0% Tween 60, and stir in a hot water bath at 80-85°C until completely hydrated to obtain a wall material solution; Embedding: In a hot water bath at 70-80°C, add the core material dropwise to the continuously stirred wall material solution, stir and mix for 8-15 minutes, then use a high-speed disperser to shear and emulsify at 5000-8000 r / min for 8-15 minutes to obtain a coarse emulsion; The crude emulsion was homogenized at 50-70 MPa for 3 cycles to obtain a lutein ester emulsion; Drying: The emulsion is spray-dried to obtain lutein ester microcapsule powder.

10. Lutein ester microcapsule powder prepared by the method according to any one of claims 1 to 9.

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