Method for preparing carboxymethyl modified starch

Abstract

The invention discloses a method for preparing carboxymethyl modified starch, which uses non-crystallization granule state starch as a basis and a microwave method as a core, and combines a part of processes of a drying method and a solvent method. The method comprises the following steps : (1) mixing certain amount of pure water with 95 percent of ethanol; adding the starch at a stirring state, keeping stirring and keeping a reaction container to be obturated, maintaining the temperature of a reaction system, and stirring to react for several minutes; (2) crushing a filter cake at the stirring state, spraying the prepared sodium hydroxide solution to stir at 25 DEG C and react for several minutes, again spraying a sodium chloroacetate ethanol liquid after the reaction is finished, stirring and evenly mixing; (3) evenly spreading a reaction mixture and placing the reaction mixture in a microwave oven to irradiate for several minutes; (4) washing the reaction product after being irradiated by microwave with the ethanol and centrifuging; and (5) drying, pulverizing and screening to prepare the carboxymethyl modified starch. The carboxymethyl starch with high substitution degree prepared through the method has the advantages of high reaction efficiency, short reaction period and low reaction energy consumption.

Description

Technical field [0001] The invention belongs to the technical field of modified starch, and specifically relates to a method for preparing a carboxymethyl modified starch by combining a microwave method, a dry method, and a solvent method with an amorphous granular state treatment. Background technique [0002] With the rapid development of industry and science and technology, among many starch products, modified starch occupies a very important position and is the main way to broaden the application of starch. Modified starch refers to the use of physical, chemical or biological enzyme preparation methods, through molecular cutting, rearrangement, or introduction of functional groups in starch molecules to enhance certain qualities of native starch or introduce some characteristics that native starch does not have, so as to adapt to modern industry Starch derivatives prepared with higher requirements for starch quality. [0003] Carboxymentyl Starch (CMS), also known as sodium st...

AI Technical Summary

Problems solved by technology

Although carboxymethyl starch prepared by dry method and semi-dry method has a high degree of substitution, it has high requirements for equipment, it is difficult to mix starch and chemical reagents, the reaction is not uniform, and the substituents are only distributed on the surface of starch granules, so the solubility of the product is poor. , by-products are difficult to remove, affecting product quality

The solvent method overcomes the disadvantage that the water-based method cannot prepare products with a higher degree of substitution, but a large amount of organic solvent is required to wash the product, resulting in an increase in cost, and when producing a product with a high degree of substitution of DS>0.5, reactant condensation is prone to occur. blocks, causing the agitator to lock up and the reaction cannot continue

[0005] In summary, several preparation methods mentioned above usually use starch directly as a raw material. Starch granules are composed of crystalline regions and non-crystalline regions. Due to the existence of crystalline regions, it is difficult for reagents to enter the interior of starch granules. On the one hand, it leads to crystalline regions The efficiency and activity of internal chemical reactions are reduced, and on the other hand, the degree of chemical reactions between the exterior and interior of starch granules, as well as the crystalline and amorphous regions, is uneven, which affects the quality and application effect of modified starch.

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