Process for the preparation of a double modified starch and an emulsifier and process for the preparation thereof

Abstract

The application discloses a preparation method of double modified starch and an emulsifier and a preparation method thereof, wherein the preparation method of the double modified starch comprises the following steps: S10, providing a starch solution; S20, mixing the starch solution and an octenyl succinic anhydride solution under alkaline conditions to obtain a mixed solution; S30, adjusting the mixed solution to be acidic, centrifuging to obtain a precipitate, cleaning and drying the precipitate to obtain an octenyl succinic anhydride starch emulsifier; and S40, reacting the octenyl succinic anhydride starch emulsifier with ozone to obtain double modified starch. When the double modified starch is made into an emulsion, the molecules in the emulsion are weakly cross-linked to form an internal gel structure through charge repulsion between the molecules, the emulsion is uniformly dispersed, and the storage stability of the emulsion is improved.

Description

Technical Field

[0001] This invention relates to the field of modified starch technology, and particularly to a method for preparing dual-modified starch and an emulsifier and its preparation method. Background Technology

[0002] Octenyl succinic anhydride modification is one of the most studied methods for modifying the hydrophobicity of starch. Octenyl succinic anhydride has a hydrophobic group, and its introduction into hydrophilic starch can give the starch good amphiphilic properties. However, the emulsifying ability of the modified starch largely depends on the hydrophobicity of the octenyl succinic anhydride (OSA) group, which leads to the easy aggregation of emulsion droplets formed by the modified starch during storage and insufficient stability. Summary of the Invention

[0003] The main objective of this invention is to propose a method for preparing dual-modified starch and an emulsifier and its preparation method, aiming to solve the problems of easy aggregation and insufficient stability of emulsion droplets formed by existing modified starches during storage.

[0004] To achieve the above objectives, this invention proposes a method for preparing dual-modified starch, comprising the following steps:

[0005] S10, Provide starch solution;

[0006] S20. Under alkaline conditions, the starch solution and the octenyl succinic anhydride solution are mixed to obtain a mixed solution;

[0007] S30. Adjust the mixture to acidity, centrifuge to collect the precipitate, wash and dry the precipitate to obtain octenyl succinic anhydride starch emulsifier.

[0008] S40. The octenyl succinic anhydride starch emulsifier is reacted with ozone to obtain double-modified starch.

[0009] Optionally, in step S10, the mass ratio of starch to water in the starch solution is (7-8):(20-22).

[0010] Optionally, in step S20, the pH value of the alkaline condition is 8.65–8.70; and / or,

[0011] In step S30, the mixture is adjusted to an acidic pH of 6.55 to 6.50.

[0012] Optionally, in step S20, the reaction conditions of the starch solution and the octenyl succinic anhydride solution are adjusted to alkaline by using a NaOH solution with a mass fraction of 3-4%.

[0013] Optionally, in step S20, the starch solution and octenyl succinic anhydride solution are mixed and reacted for 4 to 5 hours.

[0014] Optionally, in step S30, the mixture is adjusted to acidity using a hydrochloric acid solution with a mass fraction of 3-4%.

[0015] Optionally, in step S40, during the reaction of the octenyl succinic anhydride starch emulsifier with ozone:

[0016] The ozone flow rate is 1–1.1 L / min; and / or,

[0017] The reaction time is 30–70 min.

[0018] This invention provides an emulsifier, including the double-modified starch prepared by the aforementioned method for preparing double-modified starch.

[0019] This invention provides a method for preparing an emulsifier, comprising the following steps:

[0020] S100. Mix the double-modified starch with water to obtain a double-modified starch solution;

[0021] S200. The double-modified starch solution and edible oil are mixed to obtain an emulsifier.

[0022] Optionally, in step S200, the edible oil includes either soybean oil or rapeseed oil.

[0023] In the technical solution provided by this invention, starch is first modified with octenyl succinic anhydride, and then modified with ozone to obtain starch that has been modified by both octenyl succinic anhydride and ozone. The octenyl succinic anhydride is added to the hydrophilic starch. Since the octenyl succinic anhydride contains hydrophobic groups, its addition enhances the hydrophobicity of the starch. The participation of ozone introduces carbonyl groups into the starch, further enhancing its hydrophobicity and also increasing its charge. When the double-modified starch is made into an emulsion, the molecules in the emulsion form an internal gel structure through weak cross-linking under charge repulsion, resulting in uniform dispersion of the emulsion and improved storage stability. Attached Figure Description

[0024] Figure 1 A flowchart of an embodiment of the method for preparing dual-modified starch provided by the present invention;

[0025] Figure 2 This is a schematic diagram of the contact angle of the emulsifier provided in Embodiment 5, Comparative Examples 2, and 4-6 of the present invention;

[0026] Figure 3 These are laser confocal images of the emulsifiers provided in Embodiment 5 and Comparative Examples 4-5 of the present invention;

[0027] Figure 4These are storage state diagrams of the emulsifiers provided in Examples 4-5 and Comparative Examples 1-5 of the present invention;

[0028] Figure 5 The above are bar charts showing the particle size distribution of the emulsifiers provided in Examples 4-5 and Comparative Examples 1-5 of this invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, or solution B, or a solution where both A and B are satisfied simultaneously. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Octenyl succinic anhydride modification is one of the most studied methods for modifying the hydrophobicity of starch. Octenyl succinic anhydride has a hydrophobic group, and its introduction into hydrophilic starch can give the starch good amphiphilic properties. However, the emulsifying ability of the modified starch largely depends on the hydrophobicity of the octenyl succinic anhydride (OSA) group, which leads to the easy aggregation of emulsion droplets formed by the modified starch during storage and insufficient stability.

[0031] In view of this, the present invention proposes a method for preparing dual-modified starch and an emulsifier and its preparation method, wherein the emulsion formed by dual-modified starch is uniformly dispersed and has high stability.

[0032] like Figure 1 As shown, the preparation method of the dual-modified starch in the technical solution of the present invention includes the following steps:

[0033] S10, Provide starch solution;

[0034] Specifically, there is no restriction on whether the starch solution is homemade or purchased, and there is no restriction on the type of starch. For example, the starch can be glutinous rice starch, wheat starch, tapioca starch, etc. If the starch is provided by homemade method, the starch can be mixed with water and stirred evenly with a magnetic stirrer to obtain a starch solution.

[0035] S20. Under alkaline conditions, the starch solution and the octenyl succinic anhydride solution are mixed to obtain a mixed solution;

[0036] Specifically, since the anhydride in octenyl succinic anhydride can only be opened under alkaline conditions, one of the carboxyl groups undergoes a nucleophilic substitution reaction with the carboxyl group of the starch molecule via an ester bond, while the other carboxyl group forms sodium carboxylate under alkaline conditions. The generation of carboxyl groups causes the pH of the reaction system to continuously decrease, thus requiring continuous replenishment of alkali to maintain pH stability and allow the reaction to proceed towards esterification substitution. In practice, to maintain an alkaline reaction environment, the pH of the starch solution can be adjusted first to make it alkaline before mixing the octenyl succinic anhydride solution with the alkaline starch solution; alternatively, the pH of the octenyl succinic anhydride solution can be adjusted to alkaline first, and then the alkaline octenyl succinic anhydride solution can be mixed with the starch solution for the reaction; or the starch solution and octenyl succinic anhydride solution can be mixed first, and then an alkaline substance can be added to the mixture to adjust the pH of the mixture to be alkaline. Regardless of which method is used to obtain the mixture, an alkaline substance needs to be continuously added to the starch solution and the octenyl succinic anhydride solution during the reaction to maintain an alkaline environment so that the starch solution and the octenyl succinic anhydride solution can react fully.

[0037] S30. Adjust the mixture to acidity, centrifuge to collect the precipitate, wash and dry the precipitate to obtain octenyl succinic anhydride starch emulsifier.

[0038] Specifically, since the octenyl succinic anhydride does not undergo acetylation under acidic conditions, the reaction between the starch solution and the octenyl succinic anhydride solution is terminated after adding an acidic substance to adjust the mixture to acidity. By centrifuging to collect the precipitate, washing and drying the precipitate, starch modified with the octenyl succinic anhydride can be obtained. Since the octenyl succinic anhydride contains hydrophobic groups, it increases the hydrophobicity of the starch, giving the starch an amphiphilic effect.

[0039] In some embodiments, the precipitation washing and drying process is as follows: filter with a Buchner funnel, wash three times with 75% ethanol, wash three times with water, and air dry at room temperature.

[0040] S40. The octenyl succinic anhydride starch emulsifier is reacted with ozone to obtain double-modified starch.

[0041] In some embodiments, ozone gas is fully reacted with the octenyl succinic anhydride starch emulsifier. The participation of ozone introduces carbonyl groups into the starch, further enhancing the hydrophobicity of the starch. At the same time, the addition of ozone also enhances the charge of the starch. When the double-modified starch is made into an emulsion, the molecules in the emulsion form an internal gel structure through weak cross-linking by charge repulsion, which makes the emulsion uniformly dispersed and improves the storage stability of the emulsion.

[0042] Further, in step S10, the mass ratio of starch to water in the starch solution is (7-8):(20-22).

[0043] For example, in some embodiments, the mass ratio of starch to water is 7:20, 7:21, 7:22, 8:20, 8:21, 8:22, etc. At this ratio, starch and water can be fully mixed to form a starch solution. When there is too much starch, it cannot be fully dissolved, resulting in waste. When there is too little starch, the starch solution formed is too thin.

[0044] In some embodiments, to ensure the starch dissolves fully in water, a stirring tool is used when mixing the starch and water, such as a magnetic stirrer or a homogenizer, to promote the dissolution of the starch and water. The stirring time is generally 30-35 minutes, which is quick and convenient. When using a stirring tool, the stirring temperature often rises. Since starch will undergo a gelatinization reaction at higher temperatures, it is necessary to control the stirring temperature during the process. This can be achieved by cooling the mixture with ice water or ice cubes, keeping it at around 35°C as much as possible.

[0045] Furthermore, in step S20, the pH value of the alkaline condition is 8.65 to 8.70, that is, the suitable pH value for the reaction between the starch solution and the octenyl succinic anhydride is 8.65 to 8.70. Under this condition, the octenyl succinic anhydride reacts most fully with the starch. If the pH value is too high or too low, the octenyl succinic anhydride will not open completely.

[0046] Furthermore, the mixture is adjusted to an acidic pH of 6.55–6.50. That is, after the starch solution and the octenyl succinic anhydride have reacted completely, the pH is adjusted to 6.55–6.50. Under this condition, the octenyl succinic anhydride will terminate the reaction. If the pH is too high or too low, the esterification reaction of the octenyl succinic anhydride cannot be completely terminated.

[0047] Understandably, in step S20, the reaction pH of the starch solution and the octenyl succinic anhydride solution is adjusted using NaOH solution. Since NaOH solution is a strong alkaline solution, the concentration of NaOH solution cannot be too high in order to adjust the pH more accurately. Preferably, the mass fraction of NaOH solution is 3-4%. When the concentration of NaOH solution is too high, the pH value is easily not adjusted accurately, and when the concentration is too low, the preparation time is long.

[0048] Furthermore, in step S20, the starch solution and the octenyl succinic anhydride solution are mixed and reacted for 4 to 5 hours. When the reaction time is 4 to 5 hours, the starch solution and the octenyl succinic anhydride solution can react sufficiently to completely modify the starch. If the time is too short, the starch solution cannot be fully modified, and if the time is too long, it wastes operation time.

[0049] Furthermore, in step S30, the mixture is adjusted to acidity using a hydrochloric acid solution with a mass fraction of 3-4%. Since hydrochloric acid solution is readily available, it is effective for pH adjustment. However, because hydrochloric acid solution is a strong acid, its concentration should not be too high in order to adjust the pH value more accurately. Preferably, the mass fraction of the hydrochloric acid solution is 3-4%. When the concentration of the hydrochloric acid solution is too high, the pH value is easily misadjusted, and when the concentration is too low, the preparation time is long.

[0050] Further, in step S40, when the octenyl succinic anhydride starch emulsifier reacts with ozone: the ozone flow rate is 1 to 1.1 L / min; and / or the reaction time is 60 to 70 min.

[0051] In the technical solution of this invention, ozone gas reacts with the octenyl succinic anhydride starch emulsifier. In some embodiments, flowing ozone is continuously introduced into the octenyl succinic anhydride starch emulsifier to carry out the reaction and modify it. The completion of the modification is indicated by Fourier transform infrared spectroscopy at 1386 cm⁻¹. -1 A new characteristic peak appeared, indicating that oxidation was complete. Experiments revealed that the optimal flow rate for the reaction between ozone and the octenyl succinic anhydride starch emulsifier was 1–1.1 L / min. Excessive flow would result in unreacted ozone, wasting raw materials, while insufficient flow would require excessively long reaction times. At this flow rate, ozone could be fully utilized while saving time. Experimental verification showed that the octenyl succinic anhydride starch emulsifier was completely modified after 30–70 minutes; excessively long ozone flow would lead to unnecessary waste.

[0052] For example, in some embodiments, ozone may be introduced by directly introducing ozone.

[0053] This invention provides an emulsifier, including the double-modified starch prepared by the aforementioned method for preparing double-modified starch.

[0054] The emulsifier includes all the technical solutions of the preparation method of the double-modified starch, and therefore has all the beneficial effects brought about by the above solutions, which will not be elaborated here.

[0055] This invention provides a method for preparing the emulsifier described above, comprising the following steps:

[0056] S100. Mix the double-modified starch with water to obtain a double-modified starch solution;

[0057] Specifically, the dual-modified starch solution is a starch solution modified by the octenyl succinic anhydride and the ozone. In some embodiments, to enable rapid mixing of the dual-modified starch solution with water, stirring is generally performed using tools such as a mixer or homogenizer. The suitable mixing temperature for the dual-modified starch and water is 90–92°C because the dual-modified starch is highly hydrophobic and disperses unevenly in aqueous solution, resulting in poor emulsion formation. Heating the dual-modified starch at 90–92°C allows for thorough gelatinization and uniform dispersion in the aqueous solution.

[0058] S200. The double-modified starch solution and edible oil are mixed to obtain an emulsifier.

[0059] Specifically, the mixture of the double-modified starch solution and edible oil yields a stable emulsion of solid particles adsorbed at the interface between the aqueous and oil phases. Due to the double modification by ozone and octenyl succinic anhydride, the weak cross-linking between molecules in the emulsifier forms an internal gel structure, which makes the emulsifier evenly dispersed and improves the storage stability of the emulsifier.

[0060] The preparation method of the emulsifier includes all the technical solutions of the emulsifier, and therefore has all the beneficial effects brought about by the above solutions, which will not be elaborated here.

[0061] Furthermore, in step S200, the double-modified starch can be emulsified with any edible oil, but since soybean oil and rapeseed oil are inexpensive and readily available, the edible oil used is either soybean oil or rapeseed oil.

[0062] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0063] Example 1

[0064] The preparation of a dual-modified starch includes the following steps:

[0065] Weigh 35g of dry glutinous rice starch sample and place it in a 250mL beaker. Add 100mL of water. Place the sample on a magnetic stirrer and stir at 35℃ at a constant speed. Measure the pH using a pH meter to prepare for the reaction. Add 1.05g of octenyl succinic anhydride solution to the beaker and add NaOH solution (3% w / v) dropwise, maintaining the pH at 8.65 throughout the reaction. React for 4 hours. Adjust the pH to 6.5 with dilute hydrochloric acid solution (3% w / v) to terminate the reaction. Transfer the sample to a centrifuge at 6000r / min for 10 minutes to obtain the precipitate.

[0066] Remove the precipitate, filter it using a Buchner funnel, wash it three times with 75% ethanol and three times with water, and air dry it at room temperature to obtain octenyl succinic anhydride glutinous rice starch emulsifier.

[0067] Using an ozone generator, the ozone flow rate was adjusted to 1 L / min, and the dry ozone reaction time was controlled to 30 min to obtain double-modified starch.

[0068] Example 2

[0069] The preparation of a dual-modified starch includes the following steps:

[0070] Weigh 35g of dry glutinous rice starch sample and place it in a 250mL beaker. Add 110mL of water. Place the sample on a magnetic stirrer and stir at a constant speed of 35℃. Measure the pH using a pH meter to prepare for the reaction. Add 1.05g of octenyl succinic anhydride solution to the beaker and add NaOH solution (3.5% w / v) dropwise, maintaining the pH at 8.67 throughout the reaction. React for 5 hours. Adjust the pH to 6.57 with dilute hydrochloric acid solution (3.5% w / v) to terminate the reaction. Transfer the sample to a centrifuge at 6000r / min for 10 minutes to obtain the precipitate.

[0071] Remove the precipitate, filter it using a Buchner funnel, wash it three times with 75% ethanol and three times with water, and air dry it at room temperature to obtain octenyl succinic anhydride glutinous rice starch emulsifier.

[0072] Using an ozone generator, the ozone flow rate was adjusted to 1.15 L / min, and the dry ozone reaction time was controlled to 60 min to obtain double-modified starch.

[0073] Example 3

[0074] The preparation of a dual-modified starch includes the following steps:

[0075] Weigh 40g of dry glutinous rice starch sample and place it in a 250mL beaker. Add 110mL of water. Place the sample on a magnetic stirrer and stir at 35℃. Measure the pH using a pH meter to prepare for the reaction. Add 1.05g of octenyl succinic anhydride solution to the beaker and add NaOH solution (4% w / v) dropwise, maintaining the pH at 8.70 throughout the reaction. React for 5 hours. Adjust the pH to 6.55 using dilute hydrochloric acid solution (4% w / v) to terminate the reaction. Transfer the sample to a centrifuge at 6000r / min for 10 minutes to obtain the precipitate.

[0076] Remove the precipitate, filter it using a Buchner funnel, wash it three times with 75% ethanol and three times with water, and air dry it at room temperature to obtain octenyl succinic anhydride glutinous rice starch emulsifier.

[0077] Using an ozone generator, the ozone flow rate was adjusted to 1.1 L / min, and the dry ozone reaction time was controlled to 70 min to obtain double-modified starch.

[0078] Example 4

[0079] The preparation of an emulsifier includes the following steps:

[0080] The dual-modified starch prepared in Example 1 was suspended in distilled water at 3% (w / v), heated to 90°C, and stirred for 20 min. Then, soybean oil was added to the starch solution and mixed with a high-speed homogenizer at 10,000 rpm for 2 min. High-pressure homogenization was performed for 3 cycles at 20 MPa to obtain an O / W (oil-in-water) emulsifier.

[0081] Example 5

[0082] The preparation of an emulsifier includes the following steps:

[0083] The dual-modified starch prepared in Example 2 was suspended in distilled water at 3% (w / v), heated to 90°C, and stirred for 20 min. Then, rapeseed oil was added to the starch solution and mixed with a high-speed homogenizer at 10,000 rpm for 2 min. High-pressure homogenization was performed for 3 cycles at 20 MPa to obtain an O / W (oil-in-water) emulsifier.

[0084] Comparative Example 1

[0085] An emulsifier was prepared, wherein the preparation method of the dual-modified starch was similar to that of Example 1, except that the dry ozone reaction time was controlled to be 120 min. The prepared dual-modified starch was used to prepare an O / W (oil-in-water) emulsifier through a similar procedure to that of Example 5.

[0086] Comparative Example 2

[0087] An emulsifier was prepared, wherein the preparation method of the dual-modified starch was similar to that in Example 1, except that the dry ozone reaction time was controlled to be 180 min. The prepared dual-modified starch was used to prepare an O / W (oil-in-water) emulsifier through a similar procedure to that in Example 5.

[0088] Comparative Example 3

[0089] An emulsifier was prepared, wherein the preparation method of the dual-modified starch was similar to that of Example 1, except that the dry ozone reaction time was controlled to be 240 min. The prepared dual-modified starch was used to prepare an O / W (oil-in-water) emulsifier through a similar procedure to that of Example 5.

[0090] Comparative Example 4

[0091] An emulsifier was prepared, and the preparation method was similar to that in step 5, except that the double-modified starch prepared in Example 2 of Example 5 was replaced with an unmodified starch solution.

[0092] Comparative Example 5

[0093] An emulsifier was prepared, with preparation steps similar to those in Example 5, except that the double-modified starch prepared in Example 2 in Example 5 was replaced with starch modified with octenyl succinic anhydride. The modification method included the following steps:

[0094] Weigh 35g of dry glutinous rice starch sample and place it in a 250mL beaker. Add 110mL of water. Place the sample on a magnetic stirrer and stir at 35℃. Measure the pH using a pH meter to prepare for the reaction. Add 1.05g of octenyl succinic anhydride solution to the beaker and add NaOH solution (3.5% w / v) dropwise, maintaining the pH at 8.70 throughout the reaction. React for 5 hours. Adjust the pH to 6.55 with dilute hydrochloric acid solution (3.5% w / v) to terminate the reaction. Transfer the sample to a centrifuge at 6000r / min for 10 minutes to obtain the precipitate.

[0095] Remove the precipitate, filter it using a Buchner funnel, wash it three times with 75% ethanol and three times with water, and air dry it at room temperature to obtain octenyl succinic anhydride glutinous rice starch emulsifier.

[0096] Comparative Example 6

[0097] An emulsifier was prepared, with preparation steps similar to those in Example 5, except that the double-modified starch prepared in Example 1 in Example 5 was replaced with ozone-modified starch. The modification method included the following steps:

[0098] Starch was placed in a Buchner funnel lined with four layers of defatted gauze. The funnel head was sealed with eight layers of defatted gauze and secured with cotton thread. A filtration flask was connected to the bottom of the Buchner funnel, and the outlet of the flask was connected to an ozone generator. The ozone flow rate was set to 1 L / min. The oxidation time was controlled for 2 hours to obtain the OWRS sample. The sample was then placed in an open sample bag for 14 hours to remove any excess ozone.

[0099] Performance Tests and Results

[0100] 1. The emulsifiers prepared in Example 5 and Comparative Examples 2, 4, 5, and 6 were subjected to contact angle experiments, and the results are as follows: Figure 2 As shown, when solid particles adsorb at the oil-water interface, they provide a physical barrier to prevent droplet coalescence. In this process, the wettability of the solid particles at the oil-water interface significantly affects the stability of the emulsion. The wettability of solid particles is usually represented by the θ angle, i.e., the contact angle of the solid particles. Generally, the θ angle required to achieve irreversible adsorption should not be too close to 0 or too close to 180°, and the emulsion will be more stable when particles with appropriate wettability (θ approximately 90°) are present. The θ of the glutinous rice starch emulsifier (the emulsifier prepared in Comparative Example 4) is 34.9°, indicating poor particle wettability of glutinous rice starch. After octenyl succinic anhydride modification of glutinous rice starch (i.e., the emulsifier prepared in Comparative Example 5), the presence of the OSA group enhances the hydrophobicity of the starch particle surface, causing θ to increase from 34.9° to 43.3°. With the progress of ozone treatment, θ gradually increases with increasing ozonation time. This may be because the introduction of the carbonyl group increases the surface hydrophobicity of the starch. Simply using ozone to oxidize starch resulted in a contact angle of 37.2°, indicating that the hydrophilic groups of the starch were converted into carbonyl groups after ozone treatment, increasing the starch's hydrophobicity. However, ozone did not act as an emulsifier in the emulsion, causing it to separate into layers within a short period. (The remaining text appears to be incomplete and possibly contains errors.) Figure 2 In this context, OOWRS 1h is the emulsifier prepared in Example 5, OOWRS 3h is the emulsifier prepared in Comparative Example 2, and OWRS is the emulsifier obtained in Comparative Example 6.

[0101] 2. The emulsifiers prepared in Example 5 and Comparative Examples 4-5 were subjected to laser confocal microscopy experiments, and the results are as follows: Figure 3All samples exhibited typical O / W emulsion characteristics. Glutinous rice starch granules (the emulsifier prepared in Comparative Example 4) could adsorb onto the droplet surface and form a certain particle adsorption layer; however, due to the limited emulsifying ability of the particles, the resulting droplets had varying sizes, wide distribution, and uneven dispersion. Esterified starch (the emulsifier prepared in Comparative Example 5) produced emulsion droplets with more uniform size and formed a dense and uniform spatial arrangement. In the emulsion of the dual-modified starch (the emulsifier prepared in Example 5), droplets were observed to be very close together, forming a more stable three-dimensional spatial network structure (weak gel system) through mutual compression. This indicates that the dual-modified starch granules obtained after ozone treatment can adsorb onto the water-oil interface to form a highly stable Pickering emulsion. This demonstrates that the change in the surface properties of esterified starch after ozone treatment is beneficial to the stability of the emulsifier.

[0102] 3. The emulsifiers prepared in Examples 4-5 and Comparative Examples 1-5 were subjected to storage experiments, such as... Figure 4 and 5 As shown, from Figure 4 It can be observed that, except for glutinous rice starch and esterified starch emulsions, almost all oxidized starch emulsion samples exhibited high stability after being stored at room temperature for 21 days. For example... Figure 5 As shown, by measuring the droplet size of the emulsion, the droplets in the sample treated with both octenyl succinic anhydride and ozone exhibited smaller sizes during storage compared to the esterified starch emulsion. This implies that the dual-modified starch emulsion can limit droplet aggregation during long-term storage.

[0103] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A method for preparing a double modified starch, characterized by, The method comprises the following steps: S10, providing a starch solution, wherein the mass ratio of starch to water is (7-8) : (20-22) ; S20, mixing the starch solution and an octenyl succinic anhydride solution under alkaline conditions to obtain a mixed solution; S30, adjusting the mixed solution to be acidic, centrifuging to obtain a precipitate, washing and drying the precipitate to obtain an octenyl succinic anhydride starch emulsifier; S40, reacting the octenyl succinic anhydride starch emulsifier with gaseous ozone to obtain a double-modified starch; in the reaction of the octenyl succinic anhydride starch emulsifier with gaseous ozone, the flow rate of the ozone is 1-1.1 L / min, and the reaction time is 30-70 min.

2. The method of claim 1, wherein, in step S20, the pH value of the alkaline condition is 8.65-8.70; and / or, in step S30, the pH value of the mixed solution adjusted to be acidic is 6.55-6.

50. In step S20, the reaction condition of the starch solution and the octenyl succinic anhydride solution is adjusted to be alkaline by a NaOH solution with a mass fraction of 3-4%. In step S20, the mixing reaction time of the starch solution and the octenyl succinic anhydride solution is 4-5 h.

3. The method for preparing the dual-modified starch as described in claim 1, characterized in that, In step S30, the mixed solution is adjusted to be acidic by a hydrochloric acid solution with a mass fraction of 3-4%.

4. The method for preparing the dual-modified starch as described in claim 1, characterized in that, The double-modified starch is prepared by the method of any one of claims 1-5.

5. The method for preparing the dual-modified starch as described in claim 1, characterized in that, The method comprises the following steps:

6. An emulsifier characterized by, S100, mixing the double-modified starch with water to obtain a double-modified starch solution; 7. A process for the preparation of an emulsifier as claimed in claim 6, characterized in that, S200, mixing the double-modified starch solution and edible oil to obtain an emulsifier. In step S200, the edible oil comprises any one of soybean oil or rapeseed oil. In step S200, the edible oil comprises any one of soybean oil or rapeseed oil.

8. The method for preparing an emulsifier according to claim 7, characterized by, ​

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