Preparation method of modified starch and application thereof

Abstract

The present invention relates to the technical field of starch processing, and in particular to a preparation method and application of modified starch. The modified starch is prepared from the following raw materials in parts by mass: 15-30 parts of pre-modified starch A and 55-70 parts of pre-modified starch B; the pre-modified starch A is prepared from pre-treated starch A, acetic anhydride and acetaldehyde dehydrogenase; the pre-treated starch A is starch subjected to freeze ball milling; the pre-modified starch B is prepared from pre-treated starch B and octenylsuccinic anhydride; the pre-treated starch B is starch subjected to step-by-step toughening treatment; the step-by-step toughening treatment comprises first subjecting the starch to a low-temperature sealing treatment and then to short-time ultrasound, then subjecting the starch to a heating reaction and then to a secondary ultrasound, and then subjecting the starch to a high-temperature treatment and then to a further ultrasound. The pre-modified starch A and the pre-modified starch B are mixed in a specific proportion to obtain a modified starch having high solubility and freeze-thaw stability and being widely applicable to the fields of food, papermaking, textile and medicine.

Description

Technical Field

[0001] The present invention relates to the technical field of starch processing, and in particular to a preparation method of modified starch and application thereof. Background Art

[0002] Starch is a high-molecular polymer divided into amylose and amylopectin. Amylose is an essentially linear polymer with a simple single helical structure, typically found in the amorphous regions of starch granules; amylopectin is a branched polymer with a complex double helical structure, typically found in the crystalline regions of starch. Starch is widely used in the production of desserts, dairy products, snacks, soups, sauces, meat products, vermicelli noodles, and food additives. In addition to its edible properties, starch is also widely used in the textile, pharmaceutical, and chemical industries.

[0003] Due to factors such as high viscosity, low solubility, thermal decomposition and poor stability of natural starch, its use is limited. For example, under long-term heating, acidic environment or high shear, the gelatinization stability is poor, resulting in the easy destruction of the starch gel network. In addition, when frozen, starch has a strong retrograde ability, which easily leads to dehydration. Therefore, it should be modified by physical or chemical modification methods to enhance the functional properties of natural starch to adapt to different industrial uses. Modified starch can change the rheological and structural properties, such as gelatinization performance and gelatinization temperature, to obtain ideal and acceptable quality. These changes also play an important role in improving the texture properties and storage stability of food.

[0004] For example, patent document CN115873139B discloses a method for preparing dilute alkali hydrothermal modified starch. This method involves mixing starch with alkali solution, modifying it at a certain temperature, and then washing and drying it to obtain the modified starch. The modified starch produced by this method exhibits reduced gelatinization viscosity and retrogradation. However, the freeze-thaw stability and solubility of the starch modified using existing methods still need to be improved.

[0005] Therefore, according to the above-mentioned related technologies, it is urgent to develop a preparation method and application of modified starch. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a preparation method of modified starch and its application, so as to solve the problems of poor freeze-thaw stability and solubility of starch in the prior art.

[0007] Based on the above purpose, the present invention provides a preparation method of modified starch and application thereof.

[0008] A method for preparing modified starch, comprising the following raw materials in parts by weight: 15-30 parts of pre-modified starch A and 55-70 parts of pre-modified starch B;

[0009] The pre-modified starch A is prepared from pre-treated starch A, acetic anhydride and acetaldehyde dehydrogenase;

[0010] The pretreated starch A is frozen ball milled starch;

[0011] The pre-modified starch B is prepared from pre-treated starch B and octenylsuccinic anhydride;

[0012] The pretreated starch B is a starch subjected to step-by-step toughening treatment;

[0013] The step-by-step toughening treatment is to first subject the starch to a low-temperature sealing treatment and then to a short-time ultrasound treatment, then to a heating reaction and then to a second ultrasound treatment, and then to a high-temperature treatment and then to a third ultrasound treatment.

[0014] Preferably, the starch is any one of corn starch, potato starch, mung bean starch and wheat starch.

[0015] Preferably, the preparation method of the pre-modified starch A is as follows:

[0016] Step A1. Dry-milling the starch at 500-600 rpm for 30-40 min at -15-10°C to obtain pretreated starch A;

[0017] Step A2. Add distilled water to the pretreated starch A and adjust the pH to 8-9. Then, add acetic anhydride dropwise over 30-40 minutes while controlling the pH at 8-9. After adding acetaldehyde dehydrogenase and reacting for 1-2 hours, adjust the pH to 6-7. After washing 5-7 times, dry the mixture at 45-50°C, grind, and sieve to obtain pre-modified starch A.

[0018] Preferably, the mass ratio of the pretreated starch A, distilled water, acetic anhydride and acetaldehyde dehydrogenase is 70-80:200-210:5.6-6.4:0.3-0.5.

[0019] Preferably, the preparation method of the pre-modified starch B is as follows:

[0020] Step B1. Add distilled water to the starch, stir well, seal at low temperature, and then perform a short ultrasonic treatment. Then, heat the mixture and perform a second ultrasonic treatment. Then, perform a high temperature treatment and perform another ultrasonic treatment. Finally, dry the mixture at 35-40°C, grind it, and sieve it to obtain pretreated starch B.

[0021] Step B2. octenyl succinic anhydride was added to anhydrous ethanol and stirred to obtain a dispersion;

[0022] Step B3. Add distilled water to the pretreated starch B, adjust the pH to 8-9 with sodium hydroxide at 35-40°C, add the dispersion, maintain the pH and stir the reaction for 2-3 hours, then adjust the pH to 6-7, wash with anhydrous ethanol and distilled water 3-5 times in sequence, and finally dry, crush, and sieve at 35-40°C to obtain pre-modified starch B.

[0023] Preferably, the mass ratio of starch to distilled water in step B1 is 100-120:15-30; the mass ratio of anhydrous ethanol to octenylsuccinic anhydride in step B2 is 15-20:3-4; and the mass ratio of pretreated starch B, distilled water, and dispersion in step B3 is 100-120:400-500:18-24.

[0024] Preferably, the duration of the short ultrasonic treatment is 3-5 minutes, the power is 280-300W, and the frequency is 35-40kHz; the duration of the secondary ultrasonic treatment is 15-20 minutes, the power is 280-300W, and the frequency is 35-40kHz; the duration of the third ultrasonic treatment is 25-30 minutes, the power is 280-300W, and the frequency is 35-40kHz.

[0025] Preferably, the temperature of the low-temperature sealing in step B1 is 3-5°C, and the duration is 25-30 hours; the temperature of the heating reaction is 55-60°C, and the duration is 5-7 hours; the temperature of the high-temperature treatment is 105-110°C, and the duration is 4-6 hours.

[0026] Preferably, the preparation method of the modified starch is as follows:

[0027] The pre-modified starch A and the pre-modified starch B are mixed evenly to obtain modified starch.

[0028] The invention discloses an application of modified starch, wherein the modified starch is applied in the fields of food, papermaking, textile and medicine.

[0029] Beneficial effects of the present invention:

[0030] The present invention provides a preparation method and application of modified starch. The present invention prepares pre-modified starch A having high solubility and freeze-thaw stability, high content of rapidly digestible starch and extremely low content of acetaldehyde by subjecting starch to freeze-ball milling and composite acetylation modification. The pre-modified starch B having high solubility and freeze-thaw stability, high content of slowly digestible starch and resistant starch is prepared by step-by-step toughening and composite octenylsuccinic anhydride treatment. The pre-modified starch B is then mixed in a specific proportion to obtain a modified starch having high solubility and freeze-thaw stability and capable of providing energy to the human body both quickly and for a long time. Therefore, compared with the prior art, the modified starch prepared by the present invention has broad application prospects. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0032] The sources and properties of some of the raw materials used in the present invention are as follows:

[0033] Acetic anhydride was purchased from Tianjin Kemeiou Chemical Reagent Co., Ltd.; acetaldehyde dehydrogenase was purchased from Shanghai Yuanye Biotechnology Co., Ltd., CAS: 9028-88-0; octenylsuccinic anhydride was purchased from Hubei Xinrunde Chemical Co., Ltd.

[0034] Example 1: A method for preparing modified starch, comprising the following steps:

[0035] S1. Dry-mill 100 g of corn starch at 500 rpm for 30 min at -15°C to obtain pretreated starch A.

[0036] S2. To 70 g of pretreated starch A, 200 g of distilled water was added and the pH was adjusted to 8. 5.6 g of acetic anhydride was then added dropwise over 30 min while controlling the pH at 8. 0.3 g of acetaldehyde dehydrogenase was added and reacted for 1 h before adjusting the pH to 6. The mixture was washed five times, dried at 45 ° C, crushed, and sieved to obtain pre-modified starch A.

[0037] S3. 15 g of distilled water was added to 100 g of corn starch, stirred, and sealed at 3°C ​​for 25 h. The mixture was then sonicated at 280 W and 35 kHz for 3 min. The mixture was then incubated at 55°C for 5 h, sonicated again at 300 W and 40 kHz for 15 min, and then incubated at 105°C for 4 h. The mixture was then sonicated again at 300 W and 40 kHz for 25 min. Finally, the mixture was dried at 35°C, crushed, and sieved to obtain pretreated starch B.

[0038] S4 was added 3g of octenyl succinic anhydride in 15g of anhydrous ethanol and stirred to obtain a dispersion;

[0039] S5. 400 g of distilled water was added to 100 g of pretreated starch B, the pH was adjusted to 8 with sodium hydroxide at 35 ° C, and 18 g of the dispersion was added. The pH was maintained and stirred for 2 h. After that, the pH was adjusted to 6. The mixture was washed three times with anhydrous ethanol and distilled water, and finally dried at 35 ° C, crushed, and sieved to obtain pre-modified starch B;

[0040] S6. 15 g of pre-modified starch A and 55 g of pre-modified starch B were mixed to obtain modified starch.

[0041] Example 2: A method for preparing modified starch, comprising the following steps:

[0042] S1. Dry-mill 108 g of potato starch at -14°C and 530 rpm for 33 min to obtain pretreated starch A.

[0043] S2. To 73 g of pretreated starch A, 203 g of distilled water was added and the pH was adjusted to 8.3. 5.9 g of acetic anhydride was then added dropwise over 33 min while controlling the pH at 8.3. 0.4 g of acetaldehyde dehydrogenase was added and the reaction was continued for 1.3 h. The pH was then adjusted to 6.3. The mixture was washed six times, dried at 47 ° C, crushed, and sieved to obtain pre-modified starch A.

[0044] S3. 20 g of distilled water was added to 104 g of potato starch, stirred, and sealed at 4°C for 27 h. The mixture was then sonicated at 285 W and 37 kHz for 3.7 min. The mixture was then reacted at 57°C for 5.7 h, sonicated again at 300 W and 40 kHz for 17 min, and then sonicated again at 107°C for 4.7 h, sonicated again at 300 W and 40 kHz for 27 min. The mixture was then dried at 37°C, crushed, and sieved to obtain pretreated starch B.

[0045] S4 was added 3.3g of octenyl succinic anhydride in 17g of anhydrous ethanol and stirred to obtain a dispersion;

[0046] S5. To 107 g of pretreated starch B was added 430 g of distilled water, the pH was adjusted to 8.3 with sodium hydroxide at 37°C, and 20 g of the dispersion was added. The pH was maintained and the reaction was stirred for 2.3 h. The pH was then adjusted to 6.3, and the mixture was washed four times with anhydrous ethanol and then with distilled water. Finally, the mixture was dried at 37°C, crushed, and sieved to obtain pre-modified starch B.

[0047] S6. Mix 20 g of pre-modified starch A and 60 g of pre-modified starch B to obtain modified starch.

[0048] Example 3: A method for preparing modified starch, comprising the following steps:

[0049] S1. Dry-mill 115 g of mung bean starch at -12°C and 580 rpm for 37 min to obtain pretreated starch A.

[0050] S2. To 77 g of pretreated starch A, 207 g of distilled water was added and the pH was adjusted to 8.7. Then, 6.1 g of acetic anhydride was added dropwise over 37 min while controlling the pH at 8.7. 0.4 g of acetaldehyde dehydrogenase was added and reacted for 1.7 h. The pH was then adjusted to 6.7. The mixture was washed six times, dried at 47 ° C, crushed, and sieved to obtain pre-modified starch A.

[0051] S3. 25 g of distilled water was added to 115 g of mung bean starch, stirred, and sealed at 4°C for 28 h. The mixture was then sonicated at 290 W and 39 kHz for 4.2 min. The mixture was then reacted at 58°C for 6.2 h, sonicated again at 300 W and 40 kHz for 18 min, and then sonicated again at 108°C for 5.5 h and again at 300 W and 40 kHz for 28 min. The mixture was then dried at 38°C, crushed, and sieved to obtain pretreated starch B.

[0052] S4 was added 3.7g of octenyl succinic anhydride in 18g of anhydrous ethanol and stirred to obtain a dispersion;

[0053] S5. To 113 g of pretreated starch B was added 480 g of distilled water, the pH was adjusted to 8.8 with sodium hydroxide at 38°C, and 22 g of the dispersion was added. The pH was maintained and the reaction was stirred for 2.8 h. The pH was then adjusted to 6.8, and the mixture was washed four times with anhydrous ethanol and then with distilled water. Finally, the mixture was dried at 38°C, crushed, and sieved to obtain pre-modified starch B.

[0054] S6. Mix 25 g of pre-modified starch A and 65 g of pre-modified starch B to obtain modified starch.

[0055] Example 4: A method for preparing modified starch, comprising the following steps:

[0056] S1. Dry-mill 120 g of wheat starch at -10°C and 600 rpm for 40 min to obtain pretreated starch A.

[0057] S2. To 80 g of pretreated starch A, 210 g of distilled water was added and the pH was adjusted to 9. Then, 6.4 g of acetic anhydride was added dropwise over 40 min while controlling the pH at 9. 0.5 g of acetaldehyde dehydrogenase was added and reacted for 2 h before adjusting the pH to 7. The mixture was washed seven times, dried at 50 ° C, crushed, and sieved to obtain pre-modified starch A.

[0058] S3. 30 g of distilled water was added to 120 g of wheat starch, stirred, and sealed at 5°C for 30 h. The mixture was then sonicated at 300 W and 40 kHz for 5 min. The mixture was then reacted at 60°C for 7 h, sonicated again at 300 W and 40 kHz for 20 min. The mixture was then treated at 110°C for 6 h, sonicated again at 300 W and 40 kHz for 30 min. The mixture was then dried at 40°C, crushed, and sieved to obtain pretreated starch B.

[0059] S4 was added 4g of octenyl succinic anhydride in 20g of anhydrous ethanol and stirred to obtain a dispersion;

[0060] S5. 500 g of distilled water was added to 120 g of pretreated starch B, the pH was adjusted to 9 with sodium hydroxide at 40 ° C, and 24 g of the dispersion was added. The pH was maintained and stirred for 3 h. After that, the pH was adjusted to 7, and then washed with anhydrous ethanol and distilled water five times in sequence. Finally, it was dried at 40 ° C, crushed, and sieved to obtain pre-modified starch B;

[0061] S6. 30 g of pre-modified starch A and 70 g of pre-modified starch B were mixed to obtain modified starch.

[0062] Comparative Example 1:

[0063] Compared with Example 1, this comparative example only replaces the "pretreated starch A" added during the preparation of pre-modified starch A with "corn starch", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally modified starch is obtained.

[0064] Comparative Example 2:

[0065] Compared with Example 1, this comparative example did not add "acetaldehyde dehydrogenase" during the preparation of pre-modified starch A. The remaining steps and parameters were the same and will not be repeated in this comparative example. Modified starch was finally obtained.

[0066] Comparative Example 3:

[0067] Compared with Example 1, this comparative example only replaces the "pre-modified starch A" added during the preparation of the modified starch with "pretreated starch A", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally the modified starch is obtained.

[0068] Comparative Example 4:

[0069] Compared with Example 1, this comparative example only replaces the "pre-modified starch A" added during the preparation of the modified starch with "corn starch", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally the modified starch is obtained.

[0070] Comparative Example 5:

[0071] Compared with Example 1, this comparative example only replaced the "15g distilled water" added during the preparation of pretreated starch B with "150g distilled water". The remaining steps and parameters were the same and will not be repeated in this comparative example. Finally, modified starch was obtained.

[0072] Comparative Example 6: A method for preparing modified starch, comprising the following steps:

[0073] S1. Dry-mill 100 g of corn starch at 500 rpm for 30 min at -15°C to obtain pretreated starch A.

[0074] S2. To 70 g of pretreated starch A, 200 g of distilled water was added and the pH was adjusted to 8. 5.6 g of acetic anhydride was then added dropwise over 30 min while controlling the pH at 8. 0.3 g of acetaldehyde dehydrogenase was added and reacted for 1 h before adjusting the pH to 6. The mixture was washed five times, dried at 45 ° C, crushed, and sieved to obtain pre-modified starch A.

[0075] S3. Add 15 g of distilled water to 100 g of corn starch, stir well, seal at 3 ° C for 25 h, then treat at 105 ° C for 4 h, and finally dry at 35 ° C, crush, and sieve to obtain pretreated starch B;

[0076] S4 was added 3g of octenyl succinic anhydride in 15g of anhydrous ethanol and stirred to obtain a dispersion;

[0077] S5. 400 g of distilled water was added to 100 g of pretreated starch B, the pH was adjusted to 8 with sodium hydroxide at 35 ° C, and 18 g of the dispersion was added. The pH was maintained and stirred for 2 h. After that, the pH was adjusted to 6. The mixture was washed three times with anhydrous ethanol and distilled water, and finally dried at 35 ° C, crushed, and sieved to obtain pre-modified starch B;

[0078] S6. 15 g of pre-modified starch A and 55 g of pre-modified starch B were mixed to obtain modified starch.

[0079] Comparative Example 7: A method for preparing modified starch, comprising the following steps:

[0080] S1. Dry-mill 100 g of corn starch at 500 rpm for 30 min at -15°C to obtain pretreated starch A.

[0081] S2. To 70 g of pretreated starch A, 200 g of distilled water was added and the pH was adjusted to 8. 5.6 g of acetic anhydride was then added dropwise over 30 min while controlling the pH at 8. 0.3 g of acetaldehyde dehydrogenase was added and reacted for 1 h before adjusting the pH to 6. The mixture was washed five times, dried at 45 ° C, crushed, and sieved to obtain pre-modified starch A.

[0082] S3. Add 15 g of distilled water to 100 g of corn starch, stir well, seal and incubate at 3°C ​​for 25 h, sonicate at 280 W, 35 kHz for 3 min, then react at 55°C for 5 h. Finally, dry at 35°C, grind, and sieve to obtain pretreated starch B.

[0083] S4 was added 3g of octenyl succinic anhydride in 15g of anhydrous ethanol and stirred to obtain a dispersion;

[0084] S5. 400 g of distilled water was added to 100 g of pretreated starch B, the pH was adjusted to 8 with sodium hydroxide at 35 ° C, and 18 g of the dispersion was added. The pH was maintained and stirred for 2 h. After that, the pH was adjusted to 6. The mixture was washed three times with anhydrous ethanol and distilled water, and finally dried at 35 ° C, crushed, and sieved to obtain pre-modified starch B;

[0085] S6. 15 g of pre-modified starch A and 55 g of pre-modified starch B were mixed to obtain modified starch.

[0086] Comparative Example 8:

[0087] Compared with Example 1, this comparative example only replaces the "pretreated starch B" added in the preparation process of modified starch B with "corn starch", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally modified starch is obtained.

[0088] Comparative Example 9:

[0089] Compared with Example 1, this comparative example only replaces the "pre-modified starch B" added during the preparation of the modified starch with "pretreated starch B", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally the modified starch is obtained.

[0090] Comparative Example 10:

[0091] Compared with Example 1, this comparative example only replaces the "pre-modified starch B" added in the preparation process of the modified starch with "corn starch", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and finally the modified starch is obtained.

[0092] Performance testing:

[0093] Determination of solubility:

[0094] 1.0 g of corn starch and modified starch samples were respectively weighed and placed in a triangular pyramid with a lid. 99 g of distilled water was added. After dispersion, the mixture was placed in a constant temperature water bath at 25°C and shaken for 60 minutes. The solution was centrifuged for 15 minutes. The supernatant was dried at 105°C to constant weight and the mass of dissolved starch (w) was weighed. The solubility formula was calculated as follows. The solubility (%) of the modified starches prepared in Examples 1 to 4 and Comparative Examples 1 to 10 was determined using this method.

[0095] Solubility calculation formula:

[0096] Determination of transparency:

[0097] 1.0 g of the modified starch was added to 99 g of distilled water, heated and stirred in a boiling water bath for 30 minutes, and then cooled to room temperature. The transmittance (%) was measured at 640 nm using an ultraviolet spectrophotometer (TU-1810, Beijing Puxi General Instrument Co., Ltd.). The transmittance value represented the transparency of the starch paste, with distilled water as a reference. The transparency (%) of the modified starches prepared in Examples 1 to 4 and Comparative Examples 1 to 10 was measured using this method.

[0098] Determination of freeze-thaw stability:

[0099] 3 g of modified starch sample was mixed with 97 g of distilled water, and then placed in a boiling water bath and stirred for 30 min. After gelatinization was completed, the starch paste was cooled to room temperature, and then the starch paste was divided into 5 portions and placed in centrifuge tubes. The mixture was placed in a -18 ° C refrigerator and frozen for 24 h, and then thawed in a 30 ° C water bath for 2 h. One tube of sample was taken out and centrifuged at 6500 r / min for 20 min. The supernatant was discarded. This operation was repeated 5 times, and the total mass of the precipitate was weighed 5 times as W. The starch desorption rate was calculated according to the following formula; the desorption rate (%) of the modified starch prepared in Examples 1 to 4 and Comparative Examples 1 to 10 was determined according to this method, wherein the desorption rate was negatively correlated with the freeze-thaw stability;

[0100] The calculation formula of water separation rate:

[0101] Determination of acetaldehyde content:

[0102] Add 30.0 mL of 4°C distilled water to 10.00 g of modified starch sample, vortex and oscillate for 2 minutes, and then centrifuge in a refrigerated centrifuge at 10°C and 10,000 r / min for 5 minutes. Take 20.00 mL of the supernatant, add 15 ml of water, 15 ml of sodium bisulfite solution, and 7 mL of hydrochloric acid solution, shake well, and place in a dark place for 1 hour. Rinse the bottle stopper with 50 ml of water, and titrate with iodine standard solution. When approaching the end point, add 0.5 ml of starch indicator solution and titrate with iodine standard titration solution until light blue-purple appears (do not count). Add 20 mL of sodium bicarbonate solution, slightly open the bottle stopper, shake for 0.5 minutes (colorless), and continue titrating with iodine standard titration solution until blue-purple is the end point. At the same time, perform a blank test and calculate the acetaldehyde content using the following formula; use this method to determine the acetaldehyde content (mg / kg) of the modified starch prepared in Examples 1 to 4 and Comparative Examples 1 to 10;

[0103] Acetaldehyde content calculation formula:

[0104] Where: V1 is the volume of iodine standard titration solution consumed by the sample (mL); V2 is the volume of iodine standard titration solution consumed by the blank (mL); c is the concentration of iodine standard titration solution (mol / L); the result is rounded to the nearest integer;

[0105] Determination of digestibility:

[0106] 200 mg of modified starch sample was added to 15 mL of 0.2 mol / L and pH 5.2

[0107] phosphate buffer and shake well, continue stirring and heating in a boiling water bath for 30 minutes, then cool to room temperature and shake it in a shaking water bath at 37°C for 5 minutes, then add 5 mL of the prepared 37°C mixed enzyme solution (290 U / mL porcine pancreatic α-amylase and 50 U / mL amyloglucosidase mixed with phosphate buffer), and shake in a shaker at 37°C and 160 r / min; at 0 min, 20 min, and 120 min of shaking, 0.5 mL of the enzymatic hydrolysis supernatant of the starch sample was drawn into a centrifuge tube, and then 4.5 mL of anhydrous ethanol was added for inactivation; after centrifugation at 4000 r / min for 10 minutes, the supernatant was taken and the glucose content was determined using a glucose (GLU) kit, with distilled water and starch as controls; and the contents of rapidly digestible starch RDS, slowly digestible starch SDS, and resistant starch RS were calculated using the following formula; according to this method, the digestibility of the modified starches prepared in Examples 1 to 4 and Comparative Examples 1 to 10 was determined; the determination results are shown below;

[0108] RDS calculation formula:

[0109] SDS calculation formula:

[0110] RS calculation formula:

[0111] Where: G 20 Glucose content produced by amylase hydrolysis for 20 min, mg / g; 120 is the glucose content produced by amylase hydrolysis for 120 min, mg / g; FG is the free glucose content in starch, mg / g; TS is the starch content, mg.

[0112] Table 1

[0113]

[0114] Data Analysis:

[0115] As can be seen from Table 1, the modified starch prepared by the present invention has higher solubility, transparency, freeze-thaw stability and digestibility, and lower acetaldehyde content;

[0116] This may be because freeze-milling pretreatment of starch causes starch granules to break up, resulting in a rough lamellar structure on the surface, increasing the specific surface area of ​​the starch and making it more susceptible to hydrolysis by enzyme molecules, thereby increasing the content of fast-digestible starch. Furthermore, because the specific surface area of ​​the starch increases after freeze-milling treatment, the degree of substitution also increases during acetylation. Acetylation treatment causes the starch to swell significantly, absorbing a large amount of water molecules, which weakens the reflective ability of the starch granules and allows more light energy to pass through them, thereby increasing the transparency of the starch paste. Furthermore, the addition of acetyl groups causes repulsion between adjacent starch molecules, greatly weakening the hydrogen bonding between starch molecules and making starch more easily gelatinized. This further increases the transmittance of pre-modified starch A. Furthermore, since starch molecules may recombine during the freezing process, but this bonding is very limited, the introduced acetyl groups interrupt the original interchain bonding between starch chains and increase steric hindrance to restrict the reorganization of amylose. Therefore, acetylation reduces the amount of water discharged during freeze-thaw while increasing its water retention, further improving the freeze-thaw stability of pre-modified starch A. The addition of an appropriate amount of acetaldehyde dehydrogenase can effectively reduce the content of acetaldehyde introduced during starch acetylation.

[0117] While step-by-step toughening treatment can cause severe depressions and damage to the surface of starch granules, the present invention adds a certain amount of distilled water during the treatment process to ensure that the starch moisture content remains within a specific range. This improves the solubility, freeze-thaw stability, slowly digestible starch content, and resistant starch content of the pretreated starch B, while also ensuring that its transparency is improved rather than reduced. Furthermore, the step-by-step toughening treatment promotes the reaction between octenylsuccinic anhydride and the hydroxyl groups in the starch. The present invention further improves the solubility and freeze-thaw stability of the pre-modified starch B by treating the pretreated starch B with octenylsuccinic anhydride.

[0118] The present invention mixes the two prepared starches in a specific proportion, which not only improves the solubility, freeze-thaw stability and transparency of the starch in multiple dimensions, but also enables the starch to be quickly digested to provide the body with energy for a long time while providing the body with capacity.

[0119] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0120] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing modified starch, characterized in that: The invention comprises the following raw materials in parts by weight: 15-30 parts of pre-modified starch A and 55-70 parts of pre-modified starch B; The pre-modified starch A is prepared from pre-treated starch A, acetic anhydride and acetaldehyde dehydrogenase; The pretreatment in the pretreated starch A is a frozen ball milling process; The pre-modified starch B is prepared from pre-treated starch B and octenylsuccinic anhydride; The pretreatment in the pretreated starch B is a step-by-step toughening treatment; The step-by-step toughening treatment is to first subject the starch to a low-temperature sealing treatment and then to a short-time ultrasonic treatment, then to a heating reaction and then to a second ultrasonic treatment, and then to a high-temperature treatment and then to a third ultrasonic treatment; The preparation method of the pre-modified starch B is as follows: Step B1. Add distilled water to the starch, stir well, seal at low temperature, and then perform a short ultrasonic treatment. Then, heat the mixture and perform a second ultrasonic treatment. Then, perform a high temperature treatment and perform another ultrasonic treatment. Finally, dry the mixture at 35-40°C, grind it, and sieve it to obtain pretreated starch B. Step B2. octenyl succinic anhydride was added to anhydrous ethanol and stirred to obtain a dispersion; Step B3. Add distilled water to the pretreated starch B, adjust the pH to 8-9 with sodium hydroxide at 35-40°C, add the dispersion, maintain the pH, and react with stirring for 2-3 hours. Then adjust the pH to 6-7, wash with anhydrous ethanol and distilled water 3-5 times, and finally dry at 35-40°C, grind, and sieve to obtain pre-modified starch B. The mass ratio of starch to distilled water in step B1 is 100-120:15-30; The duration of the short ultrasonic treatment is 3-5 minutes, the power is 280-300W, and the frequency is 35-40kHz; the duration of the secondary ultrasonic treatment is 15-20 minutes, the power is 280-300W, and the frequency is 35-40kHz; the duration of the third ultrasonic treatment is 25-30 minutes, the power is 280-300W, and the frequency is 35-40kHz; The temperature of the low-temperature sealing in step B1 is 3-5°C, and the duration is 25-30 hours; the temperature of the heating reaction is 55-60°C, and the duration is 5-7 hours; the temperature of the high-temperature treatment is 105-110°C, and the duration is 4-6 hours.

2. The method for preparing modified starch according to claim 1, wherein The starch is any one of corn starch, potato starch, mung bean starch and wheat starch.

3. The method for preparing modified starch according to claim 1, wherein The preparation method of the pre-modified starch A is as follows: Step A1. Dry-milling the starch at 500-600 rpm for 30-40 min at -15-10°C to obtain pretreated starch A; Step A2. Add distilled water to the pretreated starch A and adjust the pH to 8-9. Then, add acetic anhydride dropwise over 30-40 minutes while controlling the pH at 8-9. After adding acetaldehyde dehydrogenase and reacting for 1-2 hours, adjust the pH to 6-7. After washing 5-7 times, dry the mixture at 45-50°C, grind, and sieve to obtain pre-modified starch A.

4. The method for preparing modified starch according to claim 3, wherein The mass ratio of the pretreated starch A, distilled water, acetic anhydride and acetaldehyde dehydrogenase is 70-80:200-210:5.6-6.4:0.3-0.

5.

5. The method for preparing modified starch according to claim 1, wherein The mass ratio of anhydrous ethanol to octenylsuccinic anhydride in step B2 is 15-20:3-4; the mass ratio of pretreated starch B, distilled water, and dispersion in step B3 is 100-120:400-500:18-24.

6. The method for preparing modified starch according to claim 1, wherein The preparation method of the modified starch is as follows: The pre-modified starch A and the pre-modified starch B are mixed evenly to obtain modified starch.

7. An application of modified starch prepared by the method for preparing modified starch according to any one of claims 1 to 6, characterized in that: The modified starch is used in the fields of food, papermaking, textile and medicine.

Images