Preparation method of low-cost potato hydroxypropyl starch ether

Abstract

The invention belongs to the technical field of hydroxypropyl starch ether, and relates to a preparation method of low-cost potato hydroxypropyl starch ether.The preparation method comprises the steps that an alkalizing agent, a solvent and an inhibitor are fully mixed, then potato starch is added for alkalization, then an etherifying agent is added, heating is conducted for modification, potato hydroxypropyl starch ether is obtained, and after a reaction product is subjected to desolvation, the potato hydroxypropyl starch ether is obtained. And drying is not needed, and crushing can be directly carried out. The preparation method has the advantages of small solvent addition amount, high utilization rate of the alcohol solvent and the etherifying agent, low reaction temperature and expansion pressure control, safety, high efficiency, small environmental pollution, improvement of the production stability and great reduction of the production cost; the produced product has the advantages of high hydroxypropyl content, high viscosity, high solution transparency, low ash content and the like; the process is simple, the cost is low, industrial production is facilitated, and the market prospect is wide.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation method of hydroxypropyl starch ether, and relates to a preparation method of hydroxypropyl starch ether using potatoes as raw materials. It can prepare high-quality hydroxypropyl starch ether with very little solvent and phosphating agent, and has a simple process and low cost. Background Art

[0002] Hydroxypropyl starch ether (English name: Hydroxypropyl starch ether, abbreviated as HPS) is a non-ionic mixed ether obtained from natural starch through processes such as alkalization and etherification.

[0003] Most of the hydroxypropyl starch ethers produced in China use corn starch and cassava starch as raw materials, and there is relatively little research on the hydroxypropylation of potato native starch or the production cost is too high. The degree of polymerization of potato starch is higher than that of corn starch and cassava starch. Potato hydroxypropyl starch ether is prepared by the etherification reaction of propylene oxide and starch to replace the hydroxyl groups in the high molecular structure of starch. It is a high-end etherified starch and has advantages such as better degree of polymerization and higher viscosity compared to hydroxypropyl starch ethers made from starch raw materials such as corn and cassava.

[0004] Currently, the processes for producing potato hydroxypropyl starch ether in China generally adopt the solvent method and the wet method. The raw material consumption is large, it is not environmentally friendly, the process is complex, and the production cost is high. The patent with the publication number CN113444185A discloses a method for preparing potato hydroxypropyl starch ether by the solvent method. In this method, potato starch is suspended in ethanol, an alkaline catalyst is added, and then propylene oxide is added. After the reaction is completed, the solvent is removed, washed, and dried. The ratio of potato starch to ethanol is 10:50 - 200. Although this method has a high yield, it requires a large amount of ethanol, which is neither environmentally friendly nor increases the production cost. And in the etherification stage of potato starch in this method, the temperature is as high as 70 - 80 °C, and at this temperature, potato starch is extremely easy to gelatinize, and the material state is relatively difficult to control. The patent with the publication number CN106543293A discloses a method for preparing potato hydroxypropyl starch ether by the wet method. In this preparation method, potato starch is dissolved in water to obtain a starch emulsion with a concentration of 30%, anhydrous sodium sulfate, sodium hydroxide, and propylene oxide are added, stirred and sealed, and reacted at a constant temperature for 12 h. Sulfuric acid is added to neutralize the pH value, and then it is filtered, washed, and dried for 8 h to obtain potato hydroxypropyl starch ether. This method consumes a large amount of water, the production steps are complex, there are many factors affecting production stability, and the time cost consumed is also high. The finished products produced by this preparation method are difficult to meet the market demand.

[0005] Therefore, aiming at problems such as the too high production cost of potato hydroxypropyl starch ether, there is an urgent need for a preparation method that can both reduce costs and not affect the quality of the finished product. Summary of the Invention

[0006] The object of the present invention is to solve the problems such as too high production cost of existing potato hydroxypropyl starch ether, optimize the preparation method on the premise of ensuring the quality of the finished product, reduce the production cost, improve the production stability, and make the product better meet the market demand.

[0007] To achieve the above object, the present invention provides a preparation method of low-cost potato hydroxypropyl starch ether, and its raw materials are as follows by weight: 10 parts of potato starch, 3 - 5 parts of etherifying agent, 1.5 - 2.5 parts of solvent, 0.2 - 0.3 parts of alkalizing agent, 1.0 - 1.5 parts of inhibitor; the specific preparation method includes the following steps: (1) Raw material mixing: Add 0.2 - 0.3 parts of alkalizing agent, 1.5 - 2.5 parts of solvent and 1.0 - 1.5 parts of inhibitor into the reaction kettle, and stir and disperse and mix at 40°C for 0.5 hour; (2) Alkalization: Put 10 parts of potato starch into the reaction kettle under continuous stirring, keep the temperature at 40 - 45°C, continue stirring, and alkalize for 0.8 - 1.2 hours; (3) Etherification: Add 3 - 5 parts of etherifying agent into the reaction kettle under continuous stirring, control the temperature at 45 - 55°C, and stir and react for 6 - 9 hours; (4) Solvent recovery: Turn on the vacuum condensation recovery device to recover the solvent, and the material after solvent recovery is the crude product; (5) Screening: Send the crude product to a micropulverizer for pulverization to obtain the finished product of potato hydroxypropyl starch ether.

[0008] The etherifying agent described in the present invention is one or more of chloroacetic acid, chloromethane, chloroethane, propylene glycol ether, propylene oxide and ethylene oxide; the solvent is an alcohol, specifically one or more of methanol, ethanol, isopropanol, n-butanol, tert-butanol, acetone and diethylene glycol; the alkalizing agent is granular alkali metal hydroxide or powdered alkali metal hydroxide; the inhibitor is any one or a mixture of several of anhydrous sodium sulfate, anhydrous sodium carbonate, anhydrous sodium bicarbonate and anhydrous sodium chloride.

[0009] The alkalizing agent described in the present invention is preferably sodium hydroxide.

[0010] Compared with the prior art, for high-degree-of-polymerization potato starch, less solvent is used to prepare potato hydroxypropyl starch ether. The solvent addition amount is small, the utilization rates of alcohol solvents and etherifying agents are high, and both the reaction temperature and the swelling pressure are controlled at relatively low levels. It is safe and efficient, causes little environmental pollution, improves production stability, greatly reduces the production cost of potato hydroxypropyl starch ether, and after the reaction product is desolvated, it does not need to be dried and can be directly pulverized. The produced finished product has the advantages of high hydroxypropyl content, high viscosity, high solution transparency, and low ash content. Its process is simple and the cost is low, which is conducive to industrial production and has a broad market prospect. Detailed implementation manners

[0011] The technical solutions of the present invention will be described in detail below through specific embodiments.

[0012] Example 1: This example relates to a preparation method of potato hydroxypropyl starch ether. Its raw materials are as follows by weight parts: 10 parts of potato starch (average degree of polymerization is 5500), 3 parts of propylene oxide, 1.5 parts of ethanol, 0.2 part of sodium hydroxide, and 1.0 part of anhydrous sodium sulfate; the propylene oxide is an etherifying agent, the ethanol is a solvent, the sodium hydroxide is an alkalizing agent, and the anhydrous sodium sulfate is an inhibitor; its specific preparation steps are as follows: (1) Raw material mixing: Add 0.2 part of sodium hydroxide, 1.5 parts of ethanol, and 1.0 part of anhydrous sodium sulfate into the reaction kettle, and stir and disperse at 40 °C for 0.5 hour; (2) Alkalization: Put 10 parts of potato starch into the reaction kettle under continuous stirring, keep the temperature at 40 °C, and continuously stir for alkalization for 0.8 hour; (3) Etherification: Add 3 parts of propylene oxide into the reaction kettle under continuous stirring, control the temperature at 45 °C, and stir and react for 6 hours; (4) Recovery: Turn on the vacuum condensation recovery device to recover the solvent; (5) Screening: Send the dried material to a micropulverizer, pulverize the material to a sieve passing rate of more than 99% through 80 meshes, and package and store it after passing the inspection.

[0013] Use the conventional detection methods in the art to detect the hydroxypropyl content, moisture, ash content, light transmittance, and viscosity of the potato hydroxypropyl starch ether prepared in Example 1. The results are shown in Table 1.

[0014] Table 1

[0015] Example 2: This embodiment relates to a method for preparing potato hydroxypropyl starch ether, and its raw materials are as follows by weight: 10 parts of potato starch (average degree of polymerization is 5500), 4 parts of propylene oxide, 2 parts of ethanol, 0.25 part of sodium hydroxide, and 1.5 parts of anhydrous sodium sulfate; the propylene oxide is an etherifying agent, the ethanol is a solvent, the sodium hydroxide is an alkalizing agent, and the anhydrous sodium sulfate is an inhibitor. The preparation steps are as follows: (1) Raw material mixing: Add 0.25 part of sodium hydroxide, 2 parts of ethanol, and 1.5 parts of anhydrous sodium sulfate into the reaction kettle, and stir and disperse at 40 °C for 0.5 hour; (2) Alkalization: Put 10 parts of potato starch into the reaction kettle under continuous stirring, keep the temperature at 50 °C, and continuously stir for alkalization for 1 hour; (3) Etherification: Add 5 parts of propylene oxide into the reaction kettle under continuous stirring, control the temperature at 50 °C, and stir and react for 8 hours; (4) Recovery: Turn on the vacuum condensation recovery device to recover the solvent; (5) Screening: Send the dried material to a micronizer, crush the material to a sieve passing rate of more than 99% through 80 meshes, and package and store it in the warehouse after passing the inspection.

[0016] Use the conventional detection methods in the art to detect the hydroxypropyl content, moisture, ash content, light transmittance, and viscosity of the potato hydroxypropyl starch ether prepared in Example 2. The results are shown in Table 2.

[0017] Table 2

[0018] Example 3: This embodiment relates to a method for preparing potato hydroxypropyl starch ether, and its raw materials are as follows by weight: 10 parts of potato starch (average degree of polymerization is 5500), 5 parts of propylene oxide, 2.5 parts of ethanol, 0.3 part of sodium hydroxide, and 1.5 parts of anhydrous sodium sulfate; the propylene oxide is an etherifying agent, the ethanol is a solvent, the sodium hydroxide is an alkalizing agent, and the anhydrous sodium sulfate is an inhibitor; the preparation steps are as follows: (1) Raw material mixing: Add 0.3 part of sodium hydroxide, 2.5 parts of ethanol, and 1.5 parts of anhydrous sodium sulfate into the reaction kettle, and stir and disperse at 40 °C for 0.5 hour; (2) Alkalization: Put 10 parts of potato starch into the reaction kettle under continuous stirring, keep the temperature at 45 °C, and continuously stir for alkalization for 1.2 hours; (3) Etherification: Add 5 parts of propylene oxide into the reaction kettle under continuous stirring, control the temperature at 55 °C, and stir and react for 9 hours; (4) Recovery: Turn on the vacuum condensation recovery device to recover the solvent; (5) Screening: The dried material is sent to a micropulverizer, where the material is pulverized to a sieve passing rate of over 99% through 80 meshes. After passing the inspection, it is packaged and stored in the warehouse.

[0019] The hydroxypropyl content, moisture, ash content, light transmittance, and viscosity of the potato hydroxypropyl starch ether prepared in Example 3 are detected by conventional detection methods in the art. The results are shown in Table 3.

[0020] Table 3

[0021] Comparative example: (1) Two types of potato hydroxypropyl starch ethers that are relatively widely circulated in the domestic market are selected. One is the potato hydroxypropyl starch ether obtained by the solvent method, denoted as Type A; the second is the potato hydroxypropyl starch ether obtained by the wet method, denoted as Type B.

[0022] (2) The potato hydroxypropyl starch ether produced in Example 1 of the present invention is selected, denoted as Type C.

[0023] The physical and chemical indexes of Type A, Type B, and Type C potato hydroxypropyl starch ethers are compared. The results are shown in Table 4.

[0024] Table 4

[0025] It can be seen from Table 4 that the physical and chemical indexes of Type C potato hydroxypropyl starch ether produced in Example 1 of the present invention are similar to those of Type A and Type B potato hydroxypropyl starch ethers circulated in the market, and even some indexes are slightly better than those of Type A and Type B potato hydroxypropyl starch ethers. Thus, it can be seen that the Type C potato hydroxypropyl starch ether produced in Example 1 has good quality, with advantages such as high hydroxypropyl content, high viscosity, high solution transparency, and low ash content, and can meet the industry requirements. The preparation method of the present invention greatly reduces the usage of solvents and etherifying agents, reduces the production cost, is conducive to expanding its production volume, and expanding the scope of product use.

Claims

1. A preparation method of low-cost potato hydroxypropyl starch ether, characterized in that, Its raw materials by weight include: 10 parts of potato starch, 3 - 5 parts of etherifying agent, 1.5 - 2.5 parts of solvent, 0.2 - 0.3 parts of alkalizing agent; 1.0 - 1.5 parts of inhibitor; the specific preparation steps are as follows: 1) Raw material mixing: Add the alkalizing agent, solvent, and inhibitor into the reaction kettle together, stir to make them fully dispersed and mixed. 2) Alkalization: Put the potato starch into the kettle, continuously stir to carry out the alkalization reaction to obtain the alkalized product. 3) Etherification: Add the etherifying agent into the reaction kettle, keep the temperature at 45 - 55 °C, continuously stir to carry out the etherification reaction. 4) Solvent recovery: Turn on the vacuum condensation device to recover the solvent, and the material after solvent recovery is the crude product. 5) Preparation of potato hydroxypropyl starch ether: Crush the crude product to obtain the finished product of potato hydroxypropyl starch ether.

2. The preparation method of the low-cost hydroxypropyl starch ether of potato according to claim 1, wherein, The etherifying agent is one or more of chloroacetic acid, chloromethane, chloroethane, propylene glycol ether, propylene oxide, and ethylene oxide; the solvent is an alcohol, specifically one or more of methanol, ethanol, isopropanol, n - butanol, tert - butanol, acetone, and diethylene glycol; the alkalizing agent is granular alkali metal hydroxide or powdered alkali metal hydroxide; the inhibitor is any one or a mixture of several of anhydrous sodium sulfate, anhydrous sodium carbonate, anhydrous sodium bicarbonate, and anhydrous sodium chloride.

3. The preparation method of the low-cost potato hydroxypropyl starch ether according to claim 1, characterized in that, The alkalizing agent is sodium hydroxide.

4. The preparation method of the low-cost hydroxypropyl starch ether of potato according to claim 1, characterized in that In step 1), the mixing temperature is kept at 40 °C, and the stirring and dispersion time is 0.5 hour.

5. The preparation method of the low-cost potato hydroxypropyl starch ether according to claim 1, wherein, In step 2), the alkalization temperature is kept at 40 - 45 °C, and the stirring and alkalization time is 0.8 - 1.2 hours.

6. The preparation method of the low-cost hydroxypropyl starch ether of potato according to claim 1, characterized in that, In step 3), the etherification reaction time is 6 - 9 hours.

7. A low - cost potato hydroxypropyl starch ether prepared by the preparation method according to any one of claims 1 - 6.

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