Starch-based microcapsule and preparation method thereof

Abstract

The invention provides a starch-based microcapsule and a preparation method thereof. The preparation method of the starch-based microcapsule comprises the following steps: mixing a core material containing grease and a wall material containing starch sodium octenylsuccinate to obtain a feed liquid, homogenizing and drying to obtain the starch-based microcapsule, the content of starch sodium octenylsuccinate in the wall material is 6-14% of the total amount of the raw materials of the starch-based microcapsule, the wall material also contains an acidity regulator, and the dosage of the acidity regulator enables the pH value of the feed liquid to be 5.0-6.2. The pH value of the feed liquid obtained by mixing the core material containing grease and the wall material containing starch sodium octenylsuccinate in the microcapsule preparation process is adjusted to 5.0-6.2, so that the problem that the dosage of modified starch in high-oil-carrying-rate modified starch capsule powder is large is solved, and meanwhile, the stability problem of low-dosage modified starch microcapsules is also solved.

Description

Technical Field

[0001] The invention relates to the technical field of microcapsule synthesis, and more specifically to a starch-based microcapsule and a preparation method thereof. Background Art

[0002] Docosahexaenoic acid (DHA) and arachidonic acid (ARA), as important structural components of nervous tissue and retina, participate in the normal development of brain and vision. At the same time, as polyunsaturated fatty acids, they are also beneficial for alleviating cardiovascular diseases and reducing serum total cholesterol and low-density lipoprotein cholesterol levels. Although as optional ingredients, most of the infant formula milk powders and formula foods with special needs on the market choose to add DHA and ARA for nutritional supplementation. In order to expand the application of DHA and ARA oils, microencapsulation is often used to increase stability. DHA and ARA are rich in unsaturated double bonds and are sensitive to oxygen, light and heat, which makes polyunsaturated fatty acid oils very easy to oxidize and deteriorate. In order to prevent oil oxidation, oil microencapsulation has become a common method to protect oils and slow down the oxidation rate.

[0003] Protein systems such as sodium caseinate and whey protein are commonly used wall materials for embedding unsaturated fatty acid oils, while protein-free wall materials for people with food protein allergies have different structural characteristics, and their embedding ability, such as modified starch and gum arabic, is weaker than that of protein-based wall materials. Protein-free wall materials include starch and other materials. For starch-based microcapsules, modified starch is mainly used, that is, starch is esterified and modified by octenyl succinic anhydride (OSA) to introduce carboxylic acid group hydrophilic groups and alkenyl long-chain hydrophobic groups, so that the chemical structure of starch molecules changes. CN101115404B involves a preparation process for a microcapsule powder composition using modified starch to embed polyunsaturated fatty acids and its application in food, wherein the specific process is to mix and prepare concentrated marine oil rich in long-chain polyunsaturated fatty acids with antioxidants or other deodorants, and then compound and emulsify with modified starch to obtain an emulsion with a desired oil droplet size, and then dry it to obtain a powder with an average diameter of about 50-500 microns and an unsaturated fatty acid DHA / EPA / DPA content of 12.1%. CN114403225B uses different types of modified starch for compounding to obtain a high-stability, high-content polyunsaturated fatty acid microcapsule product.

[0004] Although sodium octenyl succinate starch is commonly used to establish a microcapsule system in the current process, due to its emulsification ability, sodium octenyl succinate starch is used in a large amount in the system (more than 20%). With the improvement of suitability in some special medical infant fields, the amount of sodium octenyl succinate starch in sodium octenyl succinate starch microcapsules is required to be as low as possible. However, simply reducing the amount of this modified starch will lead to poor stability of the microcapsules. In CN114403225B, the amount of modified starch in high-content polyunsaturated fatty acid microcapsules is reduced to less than 20% by compounding starches of different molecular weights, but it still cannot fully meet the needs of downstream applications. Therefore, while maintaining a high oil loading rate, reducing the amount of starch as much as possible (to less than 14%), but not affecting the stability of the microcapsules, is a major challenge for the establishment of a starch-based microcapsule system.

[0005] At the same time, in the field of other non-polyunsaturated fatty acid fat powders, because some people are allergic to certain substances, they also need fat powders with low starch content but high oil content. Summary of the invention

[0006] In order to solve or at least partially solve the problems in the prior art, the present invention provides a method for preparing starch-based microcapsules, in which the amount of sodium starch octenylsuccinate is only 6-14%, the stability of the obtained microcapsules is not affected, and the quality of the microcapsules remains unchanged.

[0007] The method for preparing starch-based microcapsules provided by the present invention comprises the following steps:

[0008] The core material containing oil and fat and the wall material containing sodium starch octenyl succinate are mixed to obtain a liquid, which is then homogenized and dried;

[0009] The content of sodium starch octenyl succinate in the wall material is 6-14% of the total raw material of the starch-based microcapsule. The wall material also contains an acidity regulator, and the amount of the acidity regulator is such that the pH of the feed liquid is 5.0-6.2.

[0010] In one embodiment of the present invention, the starch-based microcapsules are water-soluble microcapsules.

[0011] In the prior art, in the past, there were no excessive restrictions on the pH of the microcapsule feed solution. In some special water-insoluble microcapsules, such as complex coacervation microcapsules, the pH of the feed solution is adjusted to help it form a gel state smoothly, while most conventional water-soluble microcapsules are described in CN118575949A: The function of the pH regulator is mainly to maintain the feed solution at a neutral level, and it can be selectively added according to the raw material conditions. When adding a pH regulator, its dosage is usually based on adjusting the raw material to 6.5-7.5. Therefore, in the prior art such as CN114403225B, sodium citrate is mainly used as an acidity regulator, and its purpose is to adjust the pH value of the feed solution to a neutral range.

[0012] The present invention unexpectedly found that when the pH of the liquid obtained by mixing the core material containing oil and fat and the wall material containing sodium octenyl succinate starch is controlled at 5.0-6.2, the thermal stability of the liquid containing sodium octenyl succinate starch and the embedding capacity of the wall material can be effectively improved, that is, only a smaller amount (less than 14%, further less than 12%, more preferably as low as 6%) of sodium octenyl succinate starch is needed to achieve the embedding effect that can only be achieved by using more than 20% sodium octenyl succinate starch. At the same time, the obtained microcapsules have a high oil loading rate, which well realizes the requirement of "reducing the amount of starch as much as possible while maintaining a high oil loading rate, but not affecting the stability of the microcapsules". Among them, a pH value that is too small will affect the dissolution of protein in subsequent milk powder applications, and a pH value greater than 6.2 cannot achieve the purpose of the present invention when a smaller amount of sodium octenyl succinate starch is used. In a preferred embodiment of the present invention, the amount of acidity regulator is such that the pH of the liquid is 5.5-6.0. In this pH range, the application environment can be better balanced and the application effect of sodium starch octenyl succinate can be reduced. In a preferred embodiment of the present invention, the acidity regulator is an acidulant or a buffer salt combination, wherein the acidulant includes but is not limited to one or more of citric acid, malic acid, tartaric acid, lactic acid, fumaric acid, acetic acid, phosphoric acid, and gluconic acid; the buffer salt includes but is not limited to one or more of potassium citrate, sodium citrate, monosodium citrate, potassium lactate, sodium lactate, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, disodium hydrogen phosphate, and sodium dihydrogen phosphate.

[0013] In a specific embodiment of the present invention, citric acid, which is the most widely used in food, is used in an amount of 0.02-0.5%, so that the pH of the feed solution can be controlled at 5.0-6.2.

[0014] Other acidulants or buffer salt combinations can be used as substitutes as long as they meet food safety requirements and can adjust the pH of the feed solution to 5.0-6.2 according to the present invention.

[0015] The preparation method provided by the present invention is suitable for the preparation of a variety of fat microcapsules, and among them, polyunsaturated fatty acid oils have the highest embedding technology difficulty due to their easy oxidation and special smell and taste. That is, in a specific embodiment of the present invention, the oil in the core material can be one or more of polyunsaturated fatty acid oils, OPO structured fats, and animal / plant oils. Among them, the polyunsaturated fatty acids in the polyunsaturated fatty acid oils include but are not limited to one or more of γ-linoleic acid, DHA (docosahexaenoic acid), DPA (docosapentaenoic acid), EPA (eicosapentaenoic acid), ARA (arachidonic acid, i.e., eicosatetraenoic acid, also known as AA), and DPA (docosapentaenoic acid), and the oils can be derived from microorganisms, fish, etc. Although other fats such as OPO structured fats and animal / plant oils are more stable than polyunsaturated fatty acid oils, the preparation method of the present invention can still be used to obtain fat powder with low starch content and high oil loading, which can be better applied to the field of infant formula that needs to avoid or reduce allergens. Among them, the vegetable oils in the animal / vegetable oils include, but are not limited to, soybean oil, sunflower oil, linseed oil, conjugated linoleic acid glyceride, medium chain triglyceride, pumpkin seed oil, tomato seed oil, rapeseed oil, palm oil, coconut oil, etc. Animal oils include, but are not limited to, lard, butter, etc. In a preferred embodiment of the present invention, the content of oil is 20-60% of the total amount of raw materials of the starch-based microcapsules.

[0016] In the present invention, the DE value of sodium starch octenyl succinate only needs to be no higher than 10%, which corresponds to the conventional medium-high molecular weight (molecular weight at least greater than 1*10 7 g / mol) of sodium starch octenyl succinate. DE value (also called glucose value) indicates the degree of hydrolysis or saccharification of starch. All reducing sugars in the saccharified liquid are calculated as glucose, and the percentage of dry matter is called DE value. In the scheme of the present invention, it is confirmed by experiments that if the DE value of sodium starch octenyl succinate used is greater than 10% (the conventional low molecular weight sodium starch octenyl succinate in the art), the purpose of the present invention cannot be achieved. A typical comparative example is given in the embodiment. In a preferred embodiment of the present invention, the content of sodium starch octenyl succinate may be only 6% to 12% of the total amount of raw materials of the starch-based microcapsules.

[0017] In a specific embodiment of the present invention, whether the oil used as the core material is a polyunsaturated fatty acid oil, an OPO structured fat or a vegetable oil, the wall material can include raw materials commonly used in the art, such as antioxidants, anti-caking agents and fillers. Among them, the antioxidant can include one or more of sodium ascorbate, ascorbic acid, ascorbyl palmitate, vitamin E, phospholipids, and tea polyphenols. The anti-caking agent can include tricalcium phosphate, calcium hydrogen phosphate, silicon dioxide, microcrystalline cellulose, and magnesium stearate. The filler can include one or more of lactose, starch, cellulose, syrup, and dextrin. Additives such as antioxidants, anti-caking agents, and fillers can be selected in accordance with the corresponding regulations in the application field, and the dosage can be selected in the conventional dosage in the art. In a specific embodiment of the present invention, strictly speaking, except for water, the total amount of raw materials in the core material and the wall material is 100%. In other words, because water will be dried and removed during the preparation process of microcapsules, water is generally not considered to be a raw material component of microcapsules in the art.

[0018] In a specific embodiment of the present invention, if the oil is a polyunsaturated fatty acid oil (preferably DHA oil and / or ARA oil), the wall material includes an antioxidant, an anti-caking agent and a filler; the content of the antioxidant is 0.2-6% of the total amount of raw materials of the starch-based microcapsules, the content of the anti-caking agent is 0-1% of the total amount of raw materials of the starch-based microcapsules, the content of the oil is 30-50% of the total amount of raw materials of the starch-based microcapsules, and the content of the filler is such that the total amount of raw materials of the starch-based microcapsules reaches 100% (i.e., the total amount of other raw materials excluding water is 100%). In this scheme, the content of fatty acids with more than 20 carbon chains and more than 4 unsaturated double bonds in the polyunsaturated fatty acid oil is not less than 50%, and the acidity regulator is an acidulant.

[0019] In a specific embodiment of the present invention, if the oil is OPO structured oil or animal / plant oil, the wall material also includes an antioxidant and a filler; the content of the antioxidant is 0.1-1% of the total amount of raw materials of the starch-based microcapsules, the content of the anti-caking agent is 0-1% of the total amount of raw materials of the starch-based microcapsules, the content of the oil is 20-60% of the total amount of raw materials of the starch-based microcapsules, and the content of the filler is such that the total amount of raw materials of the starch-based microcapsules (excluding the total amount of other raw materials excluding water) reaches 100%.

[0020] In the preparation method of the present invention, the preparation method of the microcapsule is a very common preparation method in the art, which does not affect the realization of the purpose of the present invention. For example, the preparation method can evenly shear the oil and fat to obtain the oil phase material; mix the wall material and add water to the solid content of 40% to 50%, evenly shear to obtain the water phase material, and then mix the oil phase material and the water phase material to obtain the liquid, homogenize and dry. Among them, homogenization and drying are also commonly used homogenization and drying steps in the art, which do not affect the realization of the purpose of the present invention. In some specific embodiments, due to the relationship between the production steps, pasteurization operation can be performed after homogenization and then the subsequent drying process is performed. In a specific embodiment, for example, homogenization is performed at 80MPa. Spray drying is used for drying, and the air inlet temperature of the spray drying can be 180°C, the air outlet temperature can be 75°C, and the pressure can be 20bar. These are very conventional parameters in the art. In some specific embodiments, the anti-caking agent can be mixed with the microcapsule particles during or after drying.

[0021] Another object of the present invention is to provide starch-based microcapsules obtained by the above preparation method.

[0022] Another object of the present invention is to provide a polyunsaturated fatty acid microcapsule with low modified starch content, wherein the content of polyunsaturated fatty acid oil in the raw materials of the microcapsule is 30-50%, the content of sodium starch octenyl succinate is 6-12%, the content of antioxidant is 0.2-6%, the content of anticaking agent is 0-1%, the content of acidity regulator is 0.02-0.5%, and the content of filler is such that the total amount of raw materials of starch-based microcapsules reaches 100% (i.e. the total amount of other raw materials excluding water is 100%); wherein the content of fatty acids with carbon chain length of 20 or more and unsaturated double bonds of 4 or more in the polyunsaturated fatty acid oil is not less than 50%. Preferably, the acidity regulator is citric acid.

[0023] The preparation method provided by the present invention and the starch-based microcapsules obtained by the preparation method can be applied to the preparation of infant formula milk powder, including the field of infant formula that needs to avoid or reduce allergens.

[0024] Beneficial effects of the present invention:

[0025] The present invention adjusts the pH of the liquid obtained by mixing the core material containing oil and the wall material containing sodium starch octenyl succinate in the microcapsule preparation process to 5.0-6.2, thereby solving the problem of large amount of modified starch in modified starch capsule powder with high oil loading rate, and also solving the stability problem of low amount modified starch microcapsules (sodium starch octenyl succinate amount ≤ 14%), and also achieving the purpose of reducing the cost of microcapsules. The amount of modified starch (sodium starch octenyl succinate) in the starch-based microcapsules provided by the present invention can be less than 14% (preferably as low as 6%), and the same quality (such as stability, etc.) as that of microcapsules prepared by using more than 20% modified starch can be achieved. DETAILED DESCRIPTION

[0026] The following examples are used to further describe the specific embodiments of the present invention. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. In the present invention, unless otherwise specified, "%" is a percentage by mass, and the amount of raw materials and the content of the raw materials in the present invention are all weight ratios.

[0027] In the present invention, compared with other types of oils, polyunsaturated fatty acid oils have a high instability problem, which is also one of the objects that the present invention focuses on solving the technical problems. Among polyunsaturated fatty acid oils, DHA oil has the most special smell. Unsaturated fatty acids have the most double bonds, are most easily oxidized, and are most difficult to embed. Therefore, the embodiments of the present invention only show the research embodiments of DHA oil microcapsules, and the application scope of the present invention is not limited to polyunsaturated fatty acid microcapsules. In addition, the DHA oil shown in the present invention is produced by Schizochytrium. Due to the strain, the special flavor of DHA produced by Schizochytrium is more obvious than that of DHA oils from other microorganisms / plants. The DHA oil used in the typical embodiments and comparative examples described in detail in the present invention is a commercially available product fermented by Schizochytrium by the applicant, in which the DHA content is 50%.

[0028] The sodium starch octenylsuccinate used in the embodiments of the present invention is Purity BE type starch from Ingredion, with a DE value of 6-8%, which is a medium-high molecular weight commodity commonly used in the art (as for the selection of modified starch with a DE value of less than 10%, you can also choose Cargill's 12633, Ingredion's N46, Huahao Huafeng's per46 and other medium-high molecular weight modified starch models well known to those skilled in the art).

[0029] Example 1

[0030] This embodiment provides a starch-based microcapsule, and the preparation method thereof comprises the following steps:

[0031] 1) Shearing the DHA oil at 35°C and 5000 r / min for 5 min to obtain an oil phase material;

[0032] 2) adding water to sodium starch octenylsuccinate, sodium ascorbate, tricalcium phosphate, glucose syrup powder and citric acid until the solid content is 40%, and shearing at 9000 r / min for 15 min at 35° C. to obtain an aqueous phase material;

[0033] 3) The oil phase material and the water phase material are mixed to obtain a liquid, which is homogenized at 80 MPa and spray dried to obtain microcapsules. The spray drying has an air inlet temperature of 180° C., an air outlet temperature of 75° C., and a pressure of 20 bar.

[0034] Among them, the percentage of each substance used is: DHA oil 40%, sodium starch octenyl succinate 12%, sodium ascorbate 5.5%, tricalcium phosphate 0.6%; wherein, the total amount of DHA oil, sodium starch octenyl succinate, sodium ascorbate, tricalcium phosphate, citric acid and glucose syrup powder is 100%; the amount of citric acid used is 0.2%, and the pH value of the feed solution in step 3) is 5.57.

[0035] Example 2

[0036] This embodiment provides a starch-based microcapsule, and the preparation method thereof is the same as that of Embodiment 1, except that the percentage of each substance used is different:

[0037] DHA oil 40%, sodium starch octenyl succinate 8%, sodium ascorbate 5.5%, tricalcium phosphate 0.6%; wherein the total amount of DHA oil, sodium starch octenyl succinate, sodium ascorbate, tricalcium phosphate, citric acid and glucose syrup powder is 100%; the amount of citric acid is 0.05%, and the pH value of the feed solution in step 3) is 6.00.

[0038] Example 3

[0039] This embodiment provides a starch-based microcapsule, and the preparation method thereof is the same as that of Embodiment 1, except that the percentage of each substance used is different:

[0040] DHA oil 40%, sodium starch octenyl succinate 8%, sodium ascorbate 5.5%, tricalcium phosphate 0.6%; wherein the total amount of DHA oil, sodium starch octenyl succinate, sodium ascorbate, tricalcium phosphate, citric acid and glucose syrup powder is 100%; the amount of citric acid is 0.02%, and the pH value of the feed solution in step 3) is 6.20.

[0041] Example 4

[0042] This embodiment provides a starch-based microcapsule, and the preparation method thereof is the same as that of Embodiment 1, except that the percentage of each substance used is different:

[0043] DHA oil 40%, sodium starch octenyl succinate 6%, sodium ascorbate 5.5%, tricalcium phosphate 0.6%; wherein the total amount of DHA oil, sodium starch octenyl succinate, sodium ascorbate, tricalcium phosphate, citric acid and glucose syrup powder is 100%; the amount of citric acid is 0.28%, and the pH value of the feed solution in step 3) is 5.59.

[0044] Example 5

[0045] This embodiment provides a starch-based microcapsule, and the preparation method thereof comprises the following steps:

[0046] 1) shearing low-erucic acid rapeseed oil at 35° C. and 5000 r / min for 5 min to obtain an oil phase material;

[0047] 2) adding water to sodium starch octenylsuccinate, sodium ascorbate, tricalcium phosphate, glucose syrup powder and citric acid until the solid content is 40%, and shearing at 9000 r / min for 15 min at 35° C. to obtain an aqueous phase material;

[0048] 3) The oil phase material and the water phase material are mixed to obtain a liquid, which is homogenized at 80 MPa and spray dried to obtain microcapsules. The spray drying has an air inlet temperature of 180° C., an air outlet temperature of 75° C., and a pressure of 20 bar.

[0049] The percentage of each substance used is: 60% of rapeseed oil, 8% of sodium starch octenylsuccinate, 1% of sodium ascorbate and 0.6% of tricalcium phosphate; the total amount of rapeseed oil, sodium starch octenylsuccinate, sodium ascorbate, tricalcium phosphate, citric acid and glucose syrup powder is 100%; the amount of citric acid used is 0.29%, and the pH value of the feed solution in step 3) is 5.50.

[0050] The surface area of ​​the rapeseed oil obtained in this embodiment is 0.56%, and the embedding effect is good. After a 6-month accelerated test at 37°C, there is no smell to the senses.

[0051] Comparative Example 1

[0052] This comparative example provides a starch-based microcapsule, and its preparation method is the same as that of Example 1, except that sodium citrate is used to replace citric acid, and the percentage of each substance used is different:

[0053] DHA oil 40%, sodium starch octenylsuccinate 20%, sodium ascorbate 5.5%, tricalcium phosphate 0.6%, sodium citrate 0.01%; wherein the total amount of DHA oil, sodium starch octenylsuccinate, sodium ascorbate, tricalcium phosphate, sodium citrate and glucose syrup powder is 100%.

[0054] In this comparative example, the pH value of the feed solution in step 3) is 6.53.

[0055] Comparative Example 2

[0056] This comparative example provides a starch-based microcapsule, and its preparation method is the same as that of Example 1, except that sodium citrate is used to replace citric acid, and the percentage of each substance used is different:

[0057] DHA oil 40%, sodium starch octenylsuccinate 16%, sodium ascorbate 5.5%, tricalcium phosphate 0.6%, sodium citrate 0.01%; wherein the total amount of DHA oil, sodium starch octenylsuccinate, sodium ascorbate, tricalcium phosphate, sodium citrate and glucose syrup powder is 100%.

[0058] In this comparative example, the pH value of the feed solution in step 3) is 6.41.

[0059] Comparative Example 3

[0060] This comparative example provides a starch-based microcapsule, and its preparation method is the same as that of Example 1, except that sodium citrate is used to replace citric acid, and the percentage of each substance used is different:

[0061] DHA oil 40%, sodium starch octenylsuccinate 12%, sodium ascorbate 5.5%, tricalcium phosphate 0.6%, sodium citrate 0.01%; wherein the total amount of DHA oil, sodium starch octenylsuccinate, sodium ascorbate, tricalcium phosphate, sodium citrate and glucose syrup powder is 100%.

[0062] In this comparative example, the pH value of the feed solution in step 3) is 6.38.

[0063] Comparative Example 4

[0064] This comparative example provides a starch-based microcapsule, and its preparation method is the same as that of Example 1, except that the percentage of each substance used is different:

[0065] DHA oil 40%, sodium starch octenyl succinate 4%, sodium ascorbate 5.5%, tricalcium phosphate 0.6%; wherein the total amount of DHA oil, sodium starch octenyl succinate, sodium ascorbate, tricalcium phosphate, citric acid and glucose syrup powder is 100%; the amount of citric acid is such that the pH value of the feed solution in step 3) is 5.56.

[0066] Comparative Example 5

[0067] This comparative example provides a starch-based microcapsule, and its preparation method is the same as that of Example 1, except that sodium citrate is used to replace citric acid, and the percentage of each substance used is different:

[0068] DHA oil 40%, sodium starch octenylsuccinate 30%, sodium ascorbate 5.5%, tricalcium phosphate 0.6%, sodium citrate 0.01%; wherein the total amount of DHA oil, sodium starch octenylsuccinate, sodium ascorbate, tricalcium phosphate, sodium citrate and glucose syrup powder is 100%.

[0069] In this comparative example, the pH value of the feed solution in step 3) is 6.67.

[0070] Comparative Example 6

[0071] This comparative example provides a starch-based microcapsule, and its preparation method is the same as that of Example 1, except that this comparative example uses low molecular weight octenyl succinate starch with a larger DE value (Ingredion Capsul, DE 30%), and its preparation method and the amount of each substance used are the same as those in Example 1.

[0072] Experimental example

[0073] Physicochemical properties of starch-based microcapsules obtained in the examples of the present invention and the comparative examples

[0074] 1. Thermal stability of emulsion

[0075] The homogenized emulsion obtained in step 3) was added to a 20 mL glass bottle with a pipette, and the height of the emulsion in the bottle was 1-2 cm. The glass bottle was placed in a 50° C. constant temperature water bath for 2 hours, and the oil droplet size of the emulsion was measured with a laser particle size analyzer. The results are shown in Table 1.

[0076] Table 1

[0077]

[0078]

[0079] As can be seen from Table 1, the oil droplet size of the emulsion obtained in the present invention after the thermal stability test is smaller than that of the comparative example, and is not greater than 1 micron, which is equivalent to the thermal stability of the comparative example 5 obtained by the prior art, indicating that the emulsion obtained in the embodiment has a lower risk of demulsification during storage after pasteurization and before spraying.

[0080] 2. Powder encapsulation effect

[0081] The detection method of surface oil is:

[0082] (1) Determination of surface oil content: Weigh 50.00 g of microcapsules into a 250 mL conical flask, add 100 mL of petroleum ether, shake for 1 min, let stand to separate layers, and filter the supernatant into a flat-bottom flask of constant weight. Then add 100 mL of petroleum ether to rinse the iodine volume flask and the microcapsules in the flask, and filter them into a flat-bottom flask. After desolventizing, put it in a vacuum oven at 60°C for 4 hours, take it out and put it in a desiccator, cool it to room temperature, and weigh it on a 1 / 10,000 electronic balance.

[0083] The surface oil content (X%) is calculated as follows:

[0084] Surface oil content (X%) = (m1-m0) / m;

[0085] Where: m1—mass of flat-bottom flask plus surface oil, g;

[0086] m0—mass of the flat-bottom flask after constant weight, g;

[0087] m—the mass of the weighed powder, g.

[0088] The results are shown in Table 2:

[0089] Table 2

[0090]

[0091]

[0092] From Table 2, it can be seen that the present invention can improve the emulsification performance of sodium starch octenyl succinate by adjusting the pH of the emulsion, and can achieve the same encapsulation level as the current higher dosage at a lower dosage. However, the comparative example group without adjusting the pH cannot achieve a higher overall surface oil content after the dosage of sodium starch octenyl succinate is reduced, and cannot achieve a good encapsulation effect.

[0093] 3. Shelf life

[0094] The sensory evaluation results (open the bag and smell the sample directly) and the DHA attenuation rate (DHA content after 6 months minus the initial DHA content) of the microcapsules of some embodiments and comparative examples after 6 months of accelerated testing at 37°C are shown in Table 3 below, among which the surface oil content of comparative examples 2-4 and comparative example 6 is relatively high, and no accelerated test is performed:

[0095] Table 3

[0096] sample Shelf life at 37℃ PUFA decay Example 1 2 fishy 3.5％ Example 2 2 fishy 4.3％ Example 3 3. Fishy 8.0％ Example 4 2 fishy 6.4％ Comparative Example 1 3. Fishy 8.3％ Comparative Example 2 - - Comparative Example 3 - - Comparative Example 4 - - Comparative Example 5 2 fishy 4.1％ Comparative Example 6 - -

[0097] In Table 3, the sensory evaluation score 1 represents fishy smell, 2 represents slight smell, 3 represents medium smell, and 4 represents strong smell. As can be seen from Table 3, the sensory smell of the starch microcapsule powder provided by the present invention can be maintained at 2-3 fishy smell, and the PUFA attenuation rate is below 10%, which can ensure better effects in subsequent applications.

[0098] Finally, the method of the present invention is only a preferred embodiment and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing starch-based microcapsules, characterized in that: The steps include: The core material containing oil and fat and the wall material containing sodium starch octenyl succinate are mixed to obtain a liquid, which is then homogenized and dried; The content of sodium starch octenyl succinate in the wall material is 6-14% of the total raw material of the starch-based microcapsule. The wall material also contains an acidity regulator, and the amount of the acidity regulator is such that the pH of the feed liquid is 5.0-6.

2.

2. The preparation method according to claim 1, characterized in that: The acidity regulator is used in an amount such that the pH of the feed solution is 5.5 to 6.

0.

3. The preparation method according to claim 1 or 2, characterized in that: The acidity regulator is an acidifier or a buffer salt.

4. The preparation method according to claim 1 or 2, characterized in that: The DE value of the sodium starch octenylsuccinate is not higher than 10%.

5. The preparation method according to claim 1 or 2, characterized in that: The oil is one or more of polyunsaturated fatty acid oil, OPO structured fat, animal oil, and vegetable oil.

6. The preparation method according to claim 5, characterized in that: The polyunsaturated fatty acids in the polyunsaturated fatty acid oil include, but are not limited to, one or more of γ-linoleic acid, DHA, DPA, EPA, ARA, and DPA.

7. The preparation method according to claim 6, characterized in that: The wall material also includes antioxidants, anticaking agents and fillers; The content of the antioxidant is 0.2-6% of the total amount of raw materials of the starch-based microcapsules, the content of the anti-caking agent is 0-1% of the total amount of raw materials of the starch-based microcapsules, the content of the oil is 30-50% of the total amount of raw materials of the starch-based microcapsules, and the content of the filler is such that the total amount of raw materials of the starch-based microcapsules reaches 100%.

8. The preparation method according to claim 5, characterized in that: The grease is OPO structured grease, animal grease or vegetable grease, and the wall material also includes an antioxidant, an anticaking agent and a filler; The content of the antioxidant is 0.1-1% of the total amount of raw materials of the starch-based microcapsules, the content of the anti-caking agent is 0-1% of the total amount of raw materials of the starch-based microcapsules, the content of the oil is 20-60% of the total amount of raw materials of the starch-based microcapsules, and the content of the filler is such that the total amount of raw materials of the starch-based microcapsules reaches 100%.

9. The starch-based microcapsule obtained by the preparation method according to any one of claims 1 to 8.

10. A polyunsaturated fatty acid microcapsule, characterized in that: The raw materials of the microcapsules contain 30-50% polyunsaturated fatty acid oil, 6-12% sodium starch octenyl succinate, 0.2-6% antioxidant, 0-1% anti-caking agent, 0.02-0.5% acidity regulator, and filler so that the total amount of raw materials of the microcapsules reaches 100%; wherein the content of fatty acids with a carbon chain length of 20 or more and with more than 4 unsaturated double bonds in the polyunsaturated fatty acid oil is not less than 50%.

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