A carotenoid pickering emulsion microcapsule and a method of preparing the same

Abstract

The application provides a kind of carotenoid Pickering emulsion microcapsule and its preparation method, belong to food microcapsule preparation technical field.The application uses octenyl succinic acid starch microparticle as the emulsifier of Pickering emulsion, its interface stability relies on the steric hindrance between microparticles, can adapt to high homogeneous pressure processing, so that the emulsion particle size can be further reduced;By pre-dissolving sucrose, malt dextrin and other hydrophilic macromolecules in water, the solubility of octenyl succinic acid starch in water can be effectively reduced, so that the Pickering emulsion can be successfully prepared;By reducing the ratio of crystallization and oil, the shearing time can be shortened;By improving the viscosity of emulsion, the contact time of material and oxygen can be effectively reduced during high-speed shearing and homogenization, so as to improve the crystallization yield and reduce the production cost.

Description

Technical Field

[0001] This invention belongs to the field of food microcapsule preparation technology, and particularly relates to a carotenoid Pickering emulsion microcapsule and its preparation method. Background Technology

[0002] Carotenoids (such as β-carotene, lycopene, and lutein) are an important class of fat-soluble natural pigments and bioactive substances, widely found in vegetables and fruits, and possess various physiological functions such as antioxidation, immune enhancement, and vision protection. However, the molecular structure of carotenoids contains multiple conjugated double bonds, making them extremely sensitive to light, heat, and oxygen. They are prone to oxidative degradation and isomerization reactions, leading to reduced bioactivity and color changes, severely limiting their application in the food industry.

[0003] Currently, the main industrialization processes for carotenoid microcapsules are grinding, solvent extraction, and hot-melt methods. The grinding process utilizes amphiphilic substances such as gum arabic, gelatin, and modified starch, which adsorb onto the surface of broken crystals during grinding. Steric hindrance prevents recombination, resulting in a suspension. In the solvent extraction method, the crystals are dissolved in a solvent as the oil phase, mixed with an aqueous phase consisting of water, modified starch, gelatin, and other emulsifiers and stabilizers. After high-speed shearing, the solvent is removed to prepare the liquid, which has a similar final form to the grinding method—a colloidally stable suspension. The hot-melt method involves dissolving fat-soluble crystals in vegetable oil. High temperatures transform the crystals from a crystalline state to a molten amorphous or molecular state, forming an oil phase. This oil phase is then sheared and emulsified with an aqueous phase composed of emulsifiers, fillers, and water, forming a typical oil-in-water emulsion stabilized by molecular emulsifiers. The grinding and solvent methods are suitable for high-content, high-value-added, and low-loss products, such as 10-20% β-carotene, due to their mild process characteristics. The hot-melt method is suitable for preparing products with lower content, such as 1-5% β-carotene.

[0004] Pickering emulsions are a special type of emulsion that uses insoluble solid particles instead of traditional molecular emulsifiers for stabilization. Named after the British scientist S.U. Pickering, who first systematically studied it in the early 20th century, it is a rapidly developing new emulsion system in the last two decades. Compared to traditional molecular emulsifier emulsions, Pickering emulsions have significant advantages, especially their high stability. The particles form a physical barrier at the interface through irreversible adsorption, exhibiting resistance to aggregation and Ostwald ripening, resulting in excellent long-term stability.

[0005] Starch granules are insoluble in water, but starch molecules are hydrophilic. Introducing hydrophobic functional groups into starch molecules gives them amphiphilic properties. Sodium octenyl succinate starch is obtained by reacting starch with octenyl succinic anhydride. This starch is soluble in hot water and can be dissolved in cold water after pregelatinization, exhibiting certain emulsifying properties.

[0006] Patent CN121058887A proposes using scaly cup umbrella residue as solid particles in a pickering emulsion, but its β-carotene loading concentration is only 1 mg / mL, which is low compared to currently available commercial products. Patent CN117441876B uses glycosylated proteins to prepare pickering emulsions, which is costly and has significant commercialization challenges. Patents CN117652666B, CN105747216B, CN116508996A, etc., although using sodium octenyl succinate starch as an emulsifier in the emulsion preparation process, require heating or long-term hydration in the aqueous phase preparation process to convert starch from a particulate state to a starch molecular state or an amorphous state before emulsification and homogenization. The resulting product is a molecular emulsifier emulsion, not a Pickering emulsion.

[0007] Currently, sodium octenyl succinate starch is commonly used as the microcapsule wall material. However, due to its starch properties, high-temperature hydration causes it to dissolve in water, posing a challenge to the preparation of Pickering emulsions. Furthermore, in the hot-melt method for preparing carotenoid microcapsules, thermal degradation and oxidation alter the structure of carotenoids, thereby reducing product yield and affecting the final product's application. Thermal degradation mainly occurs during the high-temperature melting process, reducing product yield. Oxidation occurs throughout the entire production process, and with the oxidation of the carotenoid structure, its use as a colorant diminishes, primarily manifested in the irreversible color change of its aqueous solution from orange to yellow as the degree of oxidation increases.

[0008] Based on existing technologies, there are currently no reports or solutions regarding the use of Pickering emulsions to control the oxidative degradation of carotenoids during the production process; therefore, there is a need to develop a carotenoid Pickering emulsion microcapsule product that is easy to commercialize and has a high yield. Summary of the Invention

[0009] In view of this, the purpose of this invention is to provide a Pickering emulsion microcapsule for carotenoids and its preparation method. Compared with existing conventional carotenoid microcapsule products, it can effectively reduce the oxidative degradation of the product during the production process, improve the yield and stability of the effective content of the product, and reduce the production cost.

[0010] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a carotenoid Pickering emulsion microcapsule comprising the following components in parts by weight: 0.9-1 parts carotenoid crystals, 2-5 parts oil solution, 0.3-1.5 parts oil-phase antioxidant, 5-20 parts sodium octenyl succinate starch, 0.1-1 parts aqueous-phase antioxidant, 35-55 parts filler, and 70-80 parts water.

[0011] Preferably, the carotenoid crystals include one or more of α-carotene, β-carotene, γ-carotene, lutein, zeaxanthin, capsanthin, astaxanthin, lycopene, crocin, carmine, and canthaxanthin.

[0012] Preferably, the oil solution comprises medium-chain triglycerides; the mass ratio of the oil solution to carotenoid crystals is ≥3:1; the oil phase antioxidant comprises tocopherol and ascorbyl palmitate; and the aqueous phase antioxidant comprises sodium isoascorbate.

[0013] Preferably, the filler includes sugars, hydrophilic small molecules, proteins, and hydrophilic colloidal substances; the sugars include one or more of glucose, fructose, lactose, sucrose, trehalose, sorbitol, mannitol, maltose, glucose syrup, fructose syrup, and isomaltooligosaccharide; the hydrophilic small molecules include one or more of glycerol, propylene glycol, ethanol, glycine, proline, and lysine; the proteins include one or more of gelatin, whey protein, soy protein, and sodium caseinate; and the hydrophilic colloidal substances include one or more of gum arabic, xanthan gum, carrageenan, sodium alginate, sodium carboxymethyl cellulose, and dextrin.

[0014] Preferably, the filler is sucrose and maltodextrin, and the ratio of the filler to sodium octenyl succinate starch is 1 to 9:1.

[0015] This invention also provides a method for preparing the aforementioned carotenoid Pickering emulsion microcapsules, comprising the following steps: (1) Mix water, filler, sodium octenyl succinate starch and aqueous antioxidant, stir to obtain aqueous solution; (2) Mix the oil, carotenoid crystals and oil phase antioxidant, heat up, dissolve for 10-20 min, cool down to obtain the oil phase; (3) The oil phase is slowly added to the aqueous phase, and the material is simultaneously emulsified by high-speed shearing; (4) The emulsified material was homogenized under high pressure, the solid content was adjusted, and then spray-dried to obtain Pickering emulsion microcapsules of carotenoids.

[0016] Preferably, the viscosity of the aqueous phase liquid in step (1) is >100 cP; the stirring temperature is ≤45℃; the stirring vacuum degree is -0.09~-0.085 MPa; the stirring is performed while shearing; the shearing linear velocity is >10 m / s; and the stirring time is 50~70 min.

[0017] Preferably, the temperature for heating in step (2) is >90°C, and the temperature for cooling is 50~90°C.

[0018] Preferably, the temperature of the high-speed shearing in step (3) is <50℃, the time of the high-speed shearing is <5min, and the shearing rate of the high-speed shearing is 10~15m / s.

[0019] Preferably, the conditions for high-pressure homogenization in step (4) are: first-stage homogenization pressure > 500 bar, second-stage homogenization pressure > 50 bar, and inlet and outlet material temperature < 50°C; the solid content is adjusted to 30%~60%; the inlet air temperature of the spray drying is 140~170°C, and the outlet air temperature of the spray drying is 70~90°C.

[0020] Compared with the prior art, the present invention has the following beneficial effects: Currently, commercially available low-content carotenoids, such as 0.5%, 1%, 2%, and 5%, are mostly produced using the hot-melt method. The emulsifiers used are primarily molecular emulsifiers. Even when using starch, gum arabic, gelatin, or protein systems for emulsification and encapsulation, aqueous preparation typically requires heating to ensure complete dissolution, transforming the emulsion from solid particles to molecular form dissolved in water. Their interfacial stability relies on electrostatic repulsion and intermolecular steric hindrance. When using high-pressure homogenizing equipment, molecular emulsifiers are prone to desorption, causing oil droplet aggregation and affecting emulsion stability. Therefore, using octenyl succinic acid starch microparticles as the emulsifier for Pickering emulsions allows for interfacial stability based on intermolecular steric hindrance, enabling processing under high homogenization pressure. This allows for further reduction in emulsion particle size, broadening the application range.

[0021] Commercially available octenyl succinic acid starch comes in various grades, but most are soluble in cold water. The inventors discovered that by pre-dissolving hydrophilic macromolecules such as sucrose and maltodextrin in water, the solubility of octenyl succinic acid starch in water can be effectively reduced, thus enabling the successful preparation of Pickering emulsions.

[0022] In the oil phase preparation process of emulsions, thermal degradation of crystals is unavoidable. The inventors attempted to melt the oil using nitrogen purging to isolate oxygen, but with little success. The hot-melt method inevitably requires high-speed shearing and high-pressure homogenization equipment. The high-speed shearing time varies depending on the emulsion formulation, generally requiring more than 20 minutes to achieve the desired particle size. The inventors discovered that reducing the ratio of crystals to oil can shorten the shearing time. By increasing the emulsion viscosity, the contact time between the material and oxygen during high-speed shearing and homogenization can be effectively reduced, thereby increasing the crystallization yield and reducing production costs.

[0023] Using the conventional process for producing 1% β-carotene powder, with a yield of 76%, approximately 15 kg of raw material is needed to produce 1 ton of product. If the yield is increased to 80%, approximately 14.3 kg of raw material is required. This reduces raw material input by about 4.7%. Furthermore, this process allows for the production of products with smaller particle sizes, which is beneficial for expanding downstream application markets. Detailed Implementation

[0024] This invention provides a carotenoid Pickering emulsion microcapsule comprising the following components in parts by weight: 0.9-1 parts carotenoid crystals, 2-5 parts oil solution, 0.3-1.5 parts oil-phase antioxidant, 5-20 parts sodium octenyl succinate starch, 0.1-1 parts aqueous-phase antioxidant, 35-55 parts filler, and 70-80 parts water.

[0025] In this invention, the carotenoid crystals include one or more of α-carotene, β-carotene, γ-carotene, lutein, zeaxanthin, capsanthin, astaxanthin, lycopene, crocin, carmine, and canthaxanthin; the oil solution includes medium-chain triglycerides; the mass ratio of the oil solution to the carotenoid crystals is ≥3:1; the oil-phase antioxidant includes tocopherol and ascorbyl palmitate; the aqueous-phase antioxidant includes sodium isoascorbate; the filler includes sugars, hydrophilic small molecules, proteins, and hydrophilic colloidal substances; the sugars include glucose, fructose, and lactose. The product comprises one or more of the following: sugar, sucrose, trehalose, sorbitol, mannitol, maltose, glucose syrup, fructose syrup, and isomaltooligosaccharide; the hydrophilic small molecule includes one or more of glycerol, propylene glycol, ethanol, glycine, proline, and lysine; the protein includes one or more of gelatin, whey protein, soy protein, and sodium caseinate; the hydrophilic colloidal includes one or more of gum arabic, xanthan gum, carrageenan, sodium alginate, sodium carboxymethyl cellulose, and dextrin; preferably sucrose and maltodextrin, and the ratio of the filler to sodium octenyl succinate starch is 1 to 9:1.

[0026] During the production of carotenoid microcapsules using the hot-melt method, oxidative degradation of carotenoid crystals occurs continuously. In our laboratory, we prepared β-carotene microcapsules using the conventional hot-melt method. Sampling at different stages of the preparation process revealed that carotenoid degradation mainly occurs during crystallization melting, shear emulsification, and homogenization. Through experiments, the inventors discovered that when the ratio of vegetable oil to crystals is ≥3:1 and the viscosity of the prepared aqueous phase is >100 cp, the shearing time can be shortened to less than 5 minutes, reducing oxidative degradation of the product during the shearing process. Adding a filler can reduce the solubility of sodium octenyl succinate starch in water, which not only facilitates the preparation of Pickering emulsions but also effectively reduces the oxidative degradation of β-carotene during homogenization.

[0027] This invention also provides a method for preparing the aforementioned carotenoid Pickering emulsion microcapsules, comprising the following steps: (1) Mix water, filler, sodium octenyl succinate starch and aqueous antioxidant, stir to obtain aqueous solution; (2) Mix the oil, carotenoid crystals and oil phase antioxidant, heat up, dissolve for 10-20 min, cool down to obtain the oil phase; (3) The oil phase is slowly added to the aqueous phase, and the material is simultaneously emulsified by high-speed shearing; (4) The emulsified material was homogenized under high pressure, the solid content was adjusted, and then spray-dried to obtain Pickering emulsion microcapsules of carotenoids.

[0028] In this invention, water, filler, sodium octenyl succinate starch, and an aqueous antioxidant are mixed and stirred to obtain an aqueous solution. The viscosity of the aqueous solution is >100 cP; high-viscosity materials are less prone to oxygen incorporation than low-viscosity materials, thus reducing oxidative degradation during the product shearing process. The stirring temperature is ≤45℃, which effectively reduces the solubility of starch in water. The vacuum degree of the stirring is -0.09~-0.085 MPa, and shearing is performed simultaneously with stirring. The shearing linear velocity is >10 m / s, and the stirring time is 50~70 min, preferably 55~65 min, and more preferably 60 min.

[0029] In this invention, an oil-soluble solvent, carotenoid crystals, and an oil-phase antioxidant are mixed, heated, and after no obvious crystallization occurs, the mixture is cooled to obtain the oil phase. The heating temperature is >90°C, and the cooling temperature is 50~90°C.

[0030] In this invention, the oil phase is slowly added to the aqueous phase, and the materials are simultaneously emulsified by high-speed shearing. The temperature of the high-speed shearing is <50°C, the time of the high-speed shearing is <5 min, and the shearing rate of the high-speed shearing is 10~15 m / s, preferably 11~14 m / s, and more preferably 12.5 m / s. In the preparation of the Pickering emulsion, the low temperature prevents the octenyl succinate starch particles from hydrating at high temperatures, and the short shearing time reduces the degree of oxidation of the material.

[0031] In this invention, the emulsified material is homogenized under high pressure, the solid content is adjusted, and then spray-dried to obtain Pickering emulsion microcapsules containing carotenoids. The high-pressure homogenization conditions are: primary homogenization pressure > 500 bar, secondary homogenization pressure > 50 bar, and inlet / outlet material temperature < 50°C. Using molecular emulsifiers, high pressure and increased temperature can cause the emulsifier to desorb from the oil phase surface, leading to increased emulsion particle size, surface oil formation, and reduced encapsulation efficiency of the final product. This invention uses starch microparticles to stabilize the emulsion. Under primary homogenization pressure > 500 bar and secondary homogenization pressure > 50 bar, it can effectively avoid unstable emulsion particle size and surface oil formation, thus improving encapsulation efficiency. The solid content is adjusted to 30%~60%; the inlet air temperature for spray drying is 140~170°C, and the outlet air temperature for spray drying is 70~90°C; this effectively prepares Pickering emulsion microcapsule powder with low oxidation and high effective content yield.

[0032] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0033] Example 1

[0034] Oil phase preparation: According to the emulsion ratio, 0.92 parts of β-carotene crystals, 4.62 parts of MCT (medium chain triglycerides), 1.15 parts of tocopherol, and 0.01 parts of ascorbyl palmitate were placed in a dissolving vessel. The temperature was raised to 160℃ and the timer was started. The mixture was dissolved for 15 minutes, and then the temperature was lowered to 50℃ for later use. Aqueous phase preparation: According to the emulsion ratio, 38.47 parts of pure water, 38.47 parts of maltodextrin, 15.34 parts of octenyl succinic acid starch (Yirui'an Food Ingredients Co., Ltd.), and 0.96 parts of sodium isoascorbate were added sequentially to a vacuum mixing vessel. The temperature was raised to 45℃ and maintained at that temperature. Vacuum mixing was then started, with a negative pressure of -0.085 MPa, and mixing was carried out for 60 minutes. During the mixing process, shearing was performed at a linear velocity of 12.5 m / s. The aqueous phase preparation was then complete. Emulsification shearing: The prepared oil phase material is slowly transferred to the aqueous phase material, and high-speed shearing is started simultaneously. The shearing time is 3 minutes and the high-speed shearing linear velocity is 12.5 m / s. Homogenization and Spraying: The sheared material was transferred into a homogenizer using a material pump. The homogenization pressure was set to 500 bar for the first stage and 50 bar for the second stage. After homogenization, the material was transferred to an autoclave and kept at 45°C. The viscosity was measured to be 8120 cp. 38.47 parts of water were added to prepare for spraying. The spray drying parameters were set to an inlet air temperature of 165°C and an outlet air temperature of 80°C. This yielded β-carotene Pickering emulsion microcapsule powder.

[0035] After rehydration, the powder was observed under a 400x microscope. No large oil droplets were observed in an average of 30 fields of view. The content was determined using ultraviolet (UV) spectroscopy. Specifically, the microcapsule powder was weighed and dissolved in water for dilution. A certain amount of the diluted solution was taken and brought to volume with acetone. Acetone was used as a blank control. The absorbance was measured at 450 nm. A standard curve was prepared using β-carotene as a solvent and acetone as a solvent. The absorbance range should be within 0.3–0.8; otherwise, the dilution factor needs to be readjusted. After determination, the effective β-carotene content in the microcapsule powder was 1.21%, with a yield of 80.66%.

[0036] Example 2

[0037] The preparation method and parameters of Example 2 are basically the same as those of Example 1, except for the formulation ratio: 0.93 parts β-carotene crystals, 2.78 parts MCT oil, 0.302 parts tocopherol, 5.24 parts octenyl succinic acid starch (Shanghai Jingcheng Food Co., Ltd.), 28.20 parts maltodextrin, 26.18 parts sucrose, 0.121 parts sodium isoascorbate, and 36.25 parts water; the primary homogenization pressure was 700 bar, and the secondary homogenization pressure was 70 bar (octenyl succinic acid starch produced by different processes has different tolerance to high-pressure homogenization, and increasing the homogenization pressure requires changing to starch produced by different processes), and the viscosity was measured to be 10327 cp. 36.25 parts water were added before spraying. After spray drying, the powder was rehydrated and observed under a 400x microscope. No obvious large oil droplets were observed under an average of 30 fields of view. The effective content of β-carotene in the microcapsule powder was determined to be 1.18% using ultraviolet light, with a yield of 81.54%.

[0038] Comparative Example 1

[0039] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the aqueous phase preparation temperature is 65°C.

[0040] The obtained powder was rehydrated and observed under a 400x microscope. On average, 15 out of 30 fields of view showed clearly visible large oil droplets. The effective β-carotene content in the microcapsule powder was determined to be 1.12% using ultraviolet light, with a yield of 76.19%.

[0041] Comparative Example 2

[0042] The preparation method of Comparative Example 2 is basically the same as that of Example 1, except that the emulsification shearing time is 30 min and the emulsification temperature is 65℃.

[0043] The obtained powder was rehydrated and observed under a 400x microscope. On average, 10 out of 30 fields of view showed clearly visible large oil droplets. The effective β-carotene content in the microcapsule powder was determined to be 1.13% using ultraviolet light, with a yield of 76.77%.

[0044] The results of Comparative Examples 1 and 2 indicate that the use of starch-based emulsifiers, prolonged shearing and high-pressure homogenization after starch gelatinization affect the product yield and emulsification effect. Excessive shearing leads to a decrease in yield, and overly vigorous high-pressure homogenization causes the oil phase of the emulsion to aggregate, resulting in floating oil after the powder is rehydrated.

[0045] Comparative Example 3

[0046] The preparation method of Comparative Example 3 was basically the same as that of Example 1, except for the formulation ratio, where the ratio of crystals to oil was 1:1. The specific formulation was as follows: 0.944 parts pigment crystals, 0.944 parts MCT oil, 0.308 parts tocopherol, 26.68 parts sucrose, 5.34 parts octenyl succinic acid starch, 28.73 parts maltodextrin, 0.1 parts sodium isoascorbate, and 36.94 parts water. 36.94 parts water were added before spray drying. After spray drying, the powder was rehydrated and observed under a 400x microscope. On average, 26 out of 30 fields of view showed obvious large oil droplets. The effective content of β-carotene in the microcapsule powder was determined to be 1.21% using ultraviolet light, with a yield of 80.83%.

[0047] Comparative Example 3 showed that a decrease in the proportion of pigment crystals and oil significantly increased the particle size of the emulsion. Unlike Comparative Examples 1 and 2, the increased particle size in this example was due to the lower proportion of oil in the oil phase, which increased the concentration of crystals per unit of oil-in-water emulsion. This resulted in larger particle sizes and more noticeable oil droplets throughout the production process. To achieve the same particle size as Examples 1 and 2, the shearing time must be extended, but prolonged processing would reduce product yield.

[0048] Comparative Example 4

[0049] The preparation method of Comparative Example 4 was basically the same as that of Example 1, except for the formulation ratio; hydrophilic macromolecular maltodextrin was not added. The specific formulation was: 0.48 parts pigment crystals, 2.41 parts MCT oil, 0.48 parts tocopherol, 0.03 parts ascorbyl palmitate, 28.29 parts octenyl succinate starch, 1.03 parts sodium isoascorbate, and 67.27 parts water. After spray drying, the powder was rehydrated and observed under a 400x microscope. On average, 11 out of 30 fields of view showed obvious large oil droplets. The effective content of β-carotene in the microcapsule powder was determined to be 1.10% using ultraviolet light, with a yield of 74.48%.

[0050] Comparative Example 4 shows that, without the addition of hydrophilic macromolecules such as maltodextrin, octenyl succinic acid starch will fully dissolve under sufficient moisture conditions, making it difficult to form a Pickering particle-stabilized emulsion. The dissolved starch molecules rely on electrostatic repulsion and intermolecular steric hindrance to adsorb onto the surface of oil droplets. High-pressure homogenization process will cause the emulsion to break down and the oil droplets to aggregate, resulting in a lower yield under the same processing technology.

[0051] Comparative Example 5

[0052] The preparation method of Comparative Example 5 was basically the same as that of Example 1, except that the viscosity of the emulsion was different during shearing and homogenization. The addition of water before spraying was omitted, and pure water was added all at once during the aqueous phase preparation process. The emulsion viscosity was measured to be 86 cp before spraying. After spray drying, the powder was rehydrated and observed under a 400x microscope. On average, 7 out of 30 fields of view showed obvious large oil droplets. The effective content of β-carotene in the microcapsule powder was determined to be 1.14% using ultraviolet light, with a yield of 75.95%.

[0053] The results of Comparative Example 5 indicate that viscosity primarily affects the following aspects during emulsion preparation: 1) Shear efficiency of emulsion particle size: In the range of crystallizer:oil ratio of 1:1 to 3, the emulsion particle size is mainly determined by the ratio of crystallizer to oil. However, when the crystallizer:oil ratio is 1:4 (or even higher), the shear efficiency of emulsion particle size is mainly affected by viscosity. Within a certain range, higher viscosity results in higher shear efficiency and a shorter time required to shear to the same particle size. 2) Effective content of the emulsion: During shearing and homogenization, as viscosity decreases, the effective content of the emulsion is more easily reduced under the same shearing and homogenization time. This may be related to the effect of viscosity on the contact efficiency between oxygen and the dispersed phase.

[0054] During the spray drying stage: higher viscosity results in a larger mesh size for the prepared microcapsule powder, and a larger moisture gradient between the powder shell and the powder interior, prolonging the drying time. Therefore, a second addition of water is required before drying to reduce the viscosity. However, because the spray drying process is very short, the effective content hardly decreases.

[0055] As can be seen from the above examples and comparative examples, the present invention uses octenyl succinic acid starch microparticles as the emulsifier for Pickering emulsions. Its interfacial stability relies on the steric hindrance between the microparticles, allowing it to adapt to high homogenization pressure processing, thereby further reducing the emulsion particle size. By pre-dissolving hydrophilic macromolecules such as sucrose and maltodextrin in water, the solubility of octenyl succinic acid starch in water can be effectively reduced, thus facilitating the preparation of Pickering emulsions. By reducing the ratio of crystals to oils, the shearing time can be shortened. By increasing the emulsion viscosity, the contact time between materials and oxygen during high-speed shearing and homogenization processes can be effectively reduced, thereby increasing the crystallization yield and reducing production costs.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A carotenoid Pickering emulsion microcapsule characterized in that, It includes the following components in parts by weight: 0.9 to 1 part carotenoid crystals, 2 to 5 parts oil solvent, 0.3 to 1.5 parts oil phase antioxidant, 5 to 20 parts sodium octenyl succinate starch, 0.1 to 1 part aqueous phase antioxidant, 35 to 55 parts filler and 70 to 80 parts water.

2. The carotenoid Pickering emulsion microcapsule according to claim 1, characterized in that, The carotenoid crystals include one or more of α-carotene, β-carotene, γ-carotene, lutein, zeaxanthin, capsanthin, astaxanthin, lycopene, crocin, carmine, and canthaxanthin.

3. The carotenoid Pickering emulsion microcapsule of claim 1, wherein, The oil-soluble component comprises medium-chain triglycerides; the mass ratio of the oil-soluble component to carotenoid crystals is ≥3:1; the oil-phase antioxidant comprises tocopherol and ascorbyl palmitate; and the aqueous-phase antioxidant comprises sodium isoascorbate.

4. The carotenoid Pickering emulsion microcapsule of claim 1, wherein, The filler includes sugars, hydrophilic small molecules, proteins, and hydrophilic colloidal substances; the sugars include one or more of glucose, fructose, lactose, sucrose, trehalose, sorbitol, mannitol, maltose, glucose syrup, fructose syrup, and isomaltooligosaccharides; the hydrophilic small molecules include one or more of glycerol, propylene glycol, ethanol, glycine, proline, and lysine; the proteins include one or more of gelatin, whey protein, soy protein, and sodium caseinate; and the hydrophilic colloidal substances include one or more of gum arabic, xanthan gum, carrageenan, sodium alginate, sodium carboxymethyl cellulose, and dextrin.

5. The carotenoid Pickering emulsion microcapsule according to claim 4, characterized in that, The filler is sucrose and maltodextrin, and the ratio of the filler to sodium octenyl succinate starch is 1~9:

1.

6. The process for the preparation of microcapsules of a Pickering emulsion of carotenoids according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Mix water, filler, sodium octenyl succinate starch and aqueous antioxidant, stir to obtain aqueous solution; (2) Mix the oil, carotenoid crystals and oil phase antioxidant, heat up, dissolve for 10-20 min, cool down to obtain the oil phase; (3) The oil phase is slowly added to the aqueous phase, and the material is simultaneously emulsified by high-speed shearing; (4) The emulsified material was homogenized under high pressure, the solid content was adjusted, and then spray-dried to obtain Pickering emulsion microcapsules of carotenoids.

7. The production method according to claim 6, wherein In step (1), the viscosity of the aqueous phase liquid is >100 cP; the stirring temperature is ≤45℃; the stirring vacuum degree is -0.09~-0.085 MPa; shearing is performed simultaneously with stirring; the shearing linear velocity is >10 m / s; and the stirring time is 50~70 min.

8. The preparation method according to claim 6, characterized in that, The temperature for heating in step (2) is >90℃, and the temperature for cooling is 50~90℃.

9. The preparation method according to claim 6, characterized in that, The temperature of the high-speed shearing in step (3) is <50℃, the time of the high-speed shearing is <5min, and the shearing rate of the high-speed shearing is 10~15m / s.

10. The method of claim 6, wherein, The conditions for high-pressure homogenization in step (4) are: first-stage homogenization pressure > 500 bar, second-stage homogenization pressure > 50 bar, and inlet and outlet material temperature < 50°C; the solid content is adjusted to 30%~60%; the inlet air temperature of the spray drying is 140~170°C, and the outlet air temperature of the spray drying is 70~90°C.