A method for efficiently preparing high-crystallin V-type dextrin

Abstract

The present invention discloses a method for efficiently preparing high-crystallinity V-type dextrin, belonging to the field of starch modification technology. The method first prepares V-type starch by continuously extruding starch through alcohol-water extrusion, and then high-temperature-treats the V-type starch in an alcohol-acid system to prepare V-type dextrin. The V-type dextrin has high V-type relative crystallinity, a short production cycle, and good application value.

Description

Technical Field

[0001] The invention belongs to the field of starch modification and processing, and particularly relates to a method for efficiently preparing high-crystallization V-type dextrin. Background Art

[0002] V-type dextrin is a degradation product of V-type starch. Its V-shaped single-helix cavity structure can form a heat-stable inclusion complex with the guest, thereby providing protection for the guest molecule. V-type starch is usually prepared by methods such as the ethanol alkali method, the high-temperature and high-pressure alcohol method, and the hot alcohol treatment method. These methods all have problems such as high wastewater volume, harsh conditions, and large amounts of ethanol. Patent 201911119850.2 discloses a method for preparing V-type cold-water soluble starch by alcohol-water extrusion, which is green, efficient, and does not produce wastewater. During the alcohol-water extrusion treatment, the original double-helix crystalline structure of the starch is destroyed, and the unfolded starch chain is transformed into a semi-stable single-helix V-shaped crystalline structure. A large number of hydrophilic hydroxyl groups are exposed, allowing it to quickly swell into a paste in cold water. However, the method disclosed in the above patent aims to improve the cold water solubility of starch, but the V-type starch produced has a low relative crystallinity and poor inclusion capacity. In addition, after extrusion, it needs to be rolled and dried with hot air for a long time, resulting in poor production continuity. The present invention improves the relative crystallinity of V-type starch while achieving simultaneous extrusion, granulation, and fluidized bed drying, with a high degree of continuity.

[0003] Patent 202011632449.1 discloses a method for preparing V-type starch by hydrothermal treatment of starch alcohol and further enzymatic hydrolysis in an alcohol solution to prepare V-type porous starch. Although enzymatic hydrolysis increases the specific surface area of ​​V-type starch and the relative crystallinity of V-type crystals, thereby greatly improving its adsorption capacity, the increase in crystallinity is very limited, that is, the inclusion capacity is limited. Moreover, the enzyme is easily inactivated in the alcohol solution and the enzymatic hydrolysis time is long. It is urgent to find new ways to efficiently prepare V-type dextrin with strong inclusion capacity.

[0004] The hydrogen ions in the acid can also act on the glycosidic bonds of starch to achieve the purpose of hydrolyzing starch into short-chain dextrins, and will not lose reactivity due to the presence of ethanol. Alkylation degradation is often used to purify specific chain length dextrins, but the published literature only performs alkylation degradation on native starch. In order to protect the double helix structure of native starch from being destroyed, the alkylation degradation temperature is below the gelatinization temperature of starch (no more than 60°C), and the alkylation degradation process lasts for several hours or even days. In the present invention, alkylation degradation is carried out at high temperature. As the reaction temperature increases, the acidolysis efficiency is greatly improved. The presence of ethanol can protect the single helical V-shaped crystalline region of the original V-type starch from being destroyed. Under a certain pressure, ethanol can form a new V-shaped single helical structure with short-chain dextrins, thereby obtaining a more ordered crystalline structure, i.e., a high-crystallinity V-type dextrin. This V-type dextrin greatly increases the embedding capacity of starch and has certain resistance to enzymatic hydrolysis. High-crystallinity V-type starch is prepared by continuous alcohol-water extrusion, and then high-crystallinity V-type dextrin is prepared by alcohol acid degradation at high temperature. The whole process is fast and efficient, and it is a new starch modification method worthy of promotion. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the present invention provides a method for efficiently preparing highly crystalline V-type dextrin. Natural starch is first extruded in an alcohol-water system to produce highly crystalline V-type starch. This is then subjected to high-temperature alcohol acid degradation, while preserving the V-type starch's crystalline structure, to produce V-type dextrin with enhanced encapsulation capacity. This method provides a fully, uniform, continuous, and efficient reaction, significantly improving production efficiency. The resulting V-type dextrin exhibits significantly higher crystallinity than V-type starch prepared by conventional methods, enabling better encapsulation of guest compounds.

[0006] The object of the present invention is to provide a method for efficiently preparing V-type dextrin, which comprises the following steps:

[0007] (1) Material mixing: adding ethanol solution to starch and mixing uniformly with a blender to form a mixed material;

[0008] (2) alcohol-water extrusion and cutting granulation: the mixture obtained in step (1) is fed into a twin-screw extruder, conveyed to the die by the extruder screw, and sheared into granules by a cutter at the end of the extrusion die of the twin-screw extruder;

[0009] (3) Drying: The granular material obtained in step (2) is transported to a fluidized bed for drying to obtain V-type starch;

[0010] (4) adding the V-type starch prepared in step (3) to an ethanol solution and mixing uniformly to prepare a starch suspension, then adding acid, and then heating and hydrolyzing;

[0011] (5) After the hydrolysis in step (4) is completed, the pH is adjusted to neutral, the supernatant is discarded by centrifugation, the precipitate is washed, and then filtered, dried, crushed, and sieved to obtain high-crystalline V-type dextrin.

[0012] In one embodiment of the present invention, the starch in step (1) is selected from one or more of ordinary corn starch, rice starch, and potato starch.

[0013] In one embodiment of the present invention, the concentration of the ethanol solution in step (1) is 20%-60% (v / v).

[0014] In one embodiment of the present invention, the ratio of starch to ethanol solution in step (1) is 1:0.3-1:0.8 (w / w).

[0015] In one embodiment of the present invention, the extrusion parameters described in step (2) are: the heating temperature of the premixing zone is 60°C, the temperature of the gelatinization zone is 90-130°C, the temperature of the molding zone is set to 60°C, the extrusion speed is 150-190r / min, and the cutter speed is 1800-2200r / min.

[0016] In one embodiment of the present invention, the drying condition in step (3) is fluidized bed drying at 40-60°C.

[0017] In one embodiment of the present invention, the ethanol concentration in the alcohol acid hydrolysis process in step (4) is 40%-70% (v / v).

[0018] In one embodiment of the present invention, the mass concentration of the V-type starch in step (4) is 20%.

[0019] In one embodiment of the present invention, the concentration of the acid in step (4) is 0.50%-1.72%, and the acid is hydrochloric acid.

[0020] In one embodiment of the present invention, the temperature of the acid hydrolysis in step (4) is 70-95°C.

[0021] In one embodiment of the present invention, the acid hydrolysis time in step (4) is 60-120 minutes.

[0022] In one embodiment of the present invention, the filtration in step (5) is suction filtration, and ethanol is used for washing during the suction filtration process, the ethanol concentration is 95%, and the number of washing times is 3 times; the drying temperature is 110°C, the drying time is 2 hours, and the powder is ground and passed through a 100-mesh sieve.

[0023] The present invention discloses a high-crystallin V-type dextrin prepared by the method.

[0024] The second object of the present invention is to apply the high crystallinity V-type dextrin in the fields of food, cosmetics and their preparation.

[0025] Beneficial effects:

[0026] The present invention provides a new modification method - preparing V-type starch by continuous alcohol-water extrusion, and further preparing high-crystallinity V-type dextrin by high-temperature alcohol acid degradation. The method is fast, efficient and has a high yield.

[0027] The invention discloses a method for continuously and efficiently preparing V-shaped starch by using high-concentration starch as raw material and carrying out alcohol-water extrusion, granulation, and fluidized bed drying. The V-shaped starch has strong diffraction peaks at 7.8°, 13.5°, and 20.8° in an X-ray diffraction pattern and a relative crystallinity of 5.20%-9.27%. After high-temperature alcohol-acid hydrolysis, the V-shaped relative crystallinity further increases to 19.37%-40.07%. The invention also ... a dense double helical structure and has extremely low acid hydrolysis efficiency below the gelatinization temperature. The alcohol-water extrusion can melt the dense double helical structure of the native starch to form a loose amorphous structure. At the same time, the dissolved amylose forms a single helical V-shaped crystalline structure with inclusion capacity with ethanol. The loose amorphous region facilitates acid hydrolysis, and the high temperature further improves the efficiency of acid hydrolysis. In addition, the presence of ethanol can protect the V-shaped crystals from acid hydrolysis, thereby purifying the V-shaped crystals. Similarly, the dextrin obtained by acid hydrolysis can also form a V-shaped crystalline structure with ethanol. Ultimately, high-temperature acid hydrolysis in an alcohol-water system has a multiplier effect on improving the V-shaped crystallinity. ③ V-shaped starch still maintains a V-shaped crystalline structure after high-temperature alcohol-acid hydrolysis. High-temperature drying causes the ethanol in the starch V-shaped complex to evaporate rapidly, leaving a semi-stable single helical cavity structure. The inclusion capacity of this V-shaped dextrin is proportional to the V-shaped relative crystallinity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The V-type dextrin prepared in the present invention, the V-type starch obtained by alcohol-water extrusion, the alcohol-acid hydrolysis of natural corn starch and the X-ray diffraction pattern of natural corn starch and the corresponding V-type crystallinity

[0029] Figure 2 On the left is regular corn starch; Figure 2 The right is a scanning electron microscope image of the V-type dextrin prepared in the present invention. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0031] Example 1:

[0032] (1) Weigh 1 kg of ordinary corn starch and mix the starch with 40% ethanol solution in a blender at a ratio of 1:0.7;

[0033] (2) feeding the mixed material obtained in step (1) into a twin-screw extruder for extrusion to obtain a granular material. The extruder parameters are as follows: the temperature of the premixing zone is 60°C, the temperature of the gelatinization zone is 90°C, the temperature of the forming zone is set to 60°C, the extrusion speed is 160 r / min, and the cutter speed is 1800 r / min;

[0034] (3) transporting the granular material obtained in step (2) to a fluidized bed for drying at a drying temperature of 50° C. to obtain V-type starch;

[0035] (4) Weigh 10 g of the V-type starch prepared in step (3), add 40 g of 70% ethanol solution, transfer to a 100 mL blue-capped bottle, add hydrochloric acid to make the acid concentration of the system reach 1.72%, and acid hydrolyze at 95°C for 60 min;

[0036] (5) After the reaction in step (4) is completed, the mixture is neutralized with 1 mol / L NaOH, vacuum filtered, washed three times with 95% ethanol solution, dried at 110°C for 2 hours, and crushed. The mixture is sieved through a 100-mesh sieve to obtain V-type dextrin.

[0037] X-ray diffraction analysis showed that the crystallinity of the V-type starch was as high as 40.07%.

[0038] Example 2:

[0039] (1) Weigh 1 kg of ordinary corn starch and mix the starch with 60% ethanol solution in a blender at a ratio of 1:0.8;

[0040] (2) feeding the mixed material obtained in step (1) into a twin-screw extruder for extrusion to obtain a granular material. The extruder parameters are as follows: the temperature of the premixing zone is 60°C, the temperature of the gelatinization zone is 130°C, the temperature of the forming zone is set to 60°C, the extrusion speed is 180 r / min, and the cutter speed is 2200 r / min;

[0041] (3) transporting the granular material obtained in step (2) to a fluidized bed for drying at a drying temperature of 50° C. to obtain V-type starch;

[0042] (4) Weigh 10 g of the V-type starch prepared in step (3), add 40 g of 60% ethanol solution, transfer to a 100 mL blue-capped bottle, add hydrochloric acid to make the acid concentration of the system reach 1.20%, and acid hydrolyze at 80°C for 120 min;

[0043] (5) After the reaction in step (4) is completed, the mixture is neutralized with 1 mol / L NaOH, vacuum filtered, washed three times with 95% ethanol solution, dried at 110°C for 2 hours, and crushed. The mixture is sieved through a 100-mesh sieve to obtain V-type dextrin.

[0044] X-ray diffraction analysis showed that the crystallinity of the V-type starch was 35.43%.

[0045] Example 3:

[0046] (1) Weigh 1 kg of ordinary corn starch and mix the starch with 20% ethanol solution in a blender at a ratio of 1:0.5;

[0047] (2) The mixed material obtained in step (1) is then fed into a twin-screw extruder for extrusion to obtain a granular material. The extruder parameters are as follows: the temperature of the premixing zone is 60°C, the temperature of the gelatinization zone is 90°C, the temperature of the forming zone is set to 60°C, the extrusion speed is 150 r / min, and the cutter speed is 1800 r / min;

[0048] (3) transporting the granular material obtained in step (2) to a fluidized bed for drying at a drying temperature of 60° C. to obtain V-type starch;

[0049] (4) Weigh 10 g of the V-type starch prepared in step (3), add 40 g of 40% ethanol solution, transfer to a 100 mL blue-capped bottle, add hydrochloric acid to make the acid concentration of the system reach 1.50%, and acid hydrolyze at 70°C for 120 min;

[0050] (5) After the reaction in step (4) is completed, the mixture is neutralized with 1 mol / L NaOH, vacuum filtered, washed three times with 95% ethanol solution, dried at 110°C for 2 hours, and crushed. The mixture is sieved through a 100-mesh sieve to obtain V-type dextrin.

[0051] X-ray diffraction analysis showed that the crystallinity of the V-type starch was 19.37%.

[0052] Example 4:

[0053] (1) Weigh 1 kg of ordinary corn starch and mix the starch with 40% ethanol solution in a blender at a ratio of 1:0.8;

[0054] (2) The mixed material obtained in step (1) is then fed into a twin-screw extruder for extrusion to obtain a granular material. The extruder parameters are as follows: the premixing zone temperature is 60°C, the gelatinization zone temperature is 110°C, the forming zone temperature is set to 60°C, the extrusion speed is 190 r / min, and the cutter speed is 1900 r / min;

[0055] (3) transporting the granular material obtained in step (2) to a fluidized bed for drying at a drying temperature of 40° C. to obtain V-type starch;

[0056] (4) Weigh 10 g of the V-type starch prepared in step (3), add 40 g of 50% ethanol solution, transfer to a 100 mL blue-capped bottle, add hydrochloric acid to make the acid concentration of the system reach 0.50%, and acid hydrolyze at 85°C for 120 min;

[0057] (5) After the reaction in step (4) is completed, the mixture is neutralized with 1 mol / L NaOH and vacuum filtered. The mixture is then washed three times with 95% ethanol solution, dried at 110° C. for 2 h, and crushed. The mixture is sieved through a 100-mesh sieve to obtain V-type dextrin.

[0058] X-ray diffraction analysis showed that the crystallinity of the V-type starch was 21.71%.

[0059] Example 5:

[0060] (1) Weigh 1 kg of ordinary corn starch and mix the starch with 40% ethanol solution in a blender at a ratio of 1:0.6;

[0061] (2) The mixed material obtained in step (1) is then fed into a twin-screw extruder for extrusion to obtain a granular material. The extruder parameters are as follows: the premixing zone temperature is 60°C, the gelatinization zone temperature is 110°C, the forming zone temperature is set to 60°C, the extrusion speed is 160 r / min, and the cutter speed is 2000 r / min;

[0062] (3) transporting the granular material obtained in step (2) to a fluidized bed for drying at a drying temperature of 60° C. to obtain V-type starch;

[0063] (4) Weigh 10 g of the V-type starch prepared in step (3), add 40 g of 60% ethanol solution, transfer to a 100 mL blue-capped bottle, add hydrochloric acid to make the acid concentration of the system reach 0.87%, and acid hydrolyze at 90°C for 90 min;

[0064] (5) After the reaction in step (4) is completed, the mixture is neutralized with 1 mol / L NaOH, vacuum filtered, washed three times with 95% ethanol solution, dried at 110°C for 2 hours, and crushed. The mixture is sieved through a 100-mesh sieve to obtain V-type dextrin.

[0065] X-ray diffraction analysis showed that the crystallinity of the V-type starch was 30.11%.

[0066] Comparative Example 1:

[0067] Regular corn starch, ie raw starch.

[0068] Comparative Example 2:

[0069] The method of Example 1 is referred to, except that the alcohol-acid hydrolysis step is omitted and V-type starch is prepared directly by alcohol-water extrusion.

[0070] According to X-ray diffraction analysis, the crystallinity of the V-type starch was 9.27%.

[0071] Comparative Example 3:

[0072] The method of Example 1 was used, except that the alcohol-water extrusion step was omitted, and the V-type starch obtained by extrusion in Example 1 was replaced with ordinary corn starch. Other conditions were the same as those of Example 1. X-ray diffraction analysis showed that the V-type crystallinity of the starch was 16.67%.

[0073] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for efficiently preparing high-crystallin V-type dextrin, characterized in that: The preparation method comprises the following steps: (1) Material mixing: adding ethanol solution to starch and mixing uniformly with a blender to form a mixed material, wherein the volume fraction of ethanol in the ethanol solution is 20 to 60%, and the mass ratio of the starch to the ethanol solution is 1:0.3 to 1:0.8; (2) alcohol-water extrusion and cutting granulation: the mixed material obtained in step (1) is fed into a twin-screw extruder, conveyed to a die head by the extruder screw, and sheared into granules by a cutter at the end of the extrusion die head of the twin-screw extruder; the extrusion parameters of the extruder are: the heating temperature of the premixing zone is 60°C, the temperature of the gelatinization zone is 90-130°C, the temperature of the forming zone is set to 60°C, the extrusion speed is 150-190r / min, and the cutter speed is 1800-2200r / min; (3) Drying: The granular material obtained in step (2) is transported to a fluidized bed for drying to obtain V-type starch; (4) adding the V-type starch prepared in step (3) to an ethanol solution and mixing uniformly to prepare a starch suspension, then adding acid, and then hydrolyzing at 70-95° C. for 60-120 min, wherein the concentration of the acid is 0.50%-1.72%, the acid is hydrochloric acid, and the volume fraction of ethanol in the ethanol solution is 40-70%; (5) After the hydrolysis in step (4) is completed, the pH is adjusted to neutral, the supernatant is discarded by centrifugation, the precipitate is washed, and then filtered, dried, crushed, and sieved to obtain high-crystalline V-type dextrin; The starch is one or more of ordinary corn starch, rice starch and potato starch.

2. The method according to claim 1, characterized in that The drying condition in step (3) is fluidized bed drying at 40-60°C.

3. A high-crystallin V-type dextrin prepared by the method of claim 1 or 2.

4. Use of the high-crystallin V-type dextrin according to claim 3 in the fields of food, cosmetics and their preparation.

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